Abstract:
A device for calibrating retinoscopes for diverging and/or converging streak and spot retinoscopy and a method for calibrating retinoscopes to produce a given convergence or divergence of light emitted from the retinoscope from a fixed retinoscopic working distance to produce a predetermined pupillary reflex endpoint at neutralization of a refractive error, thereby resulting in a more accurate corrective eye prescriptions and evaluation of the visual system.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    This invention relates to devices and methods for measuring and determining the refractive error in eyes and more particularly, a device for calibrating retinoscopes for diverging and/or converging retinoscopy and a method for calibrating retinoscopes using the device. 
         [0002]    Retinoscopy is a technique used by practitioners, such as optometrists and ophthalmologists, to obtain an objective measurement of the refractive error of a patient&#39;s eyes in order to determine the patient&#39;s prescription for spectacles and/or contacts lenses. Varying retinoscopic measurements are frequently obtained with the current retinoscopes. These retinoscopic errors are due the distance between the condensing lens within the retinoscope and filament of the bulb not being standardized and the inability of the examiner to adjust the divergence of the emitted retinoscopy light to their retinoscopic working distance. The divergence of the light rays emitted from all retinoscopes presently on the market is determined by each manufacturer. Subjective refractions using trial frames and phoropters are used as a more accurate alternative for measuring the refractive error. Phoropters are large and expensive pieces of equipment, which means that many practitioners do not have access to them especially in third world countries. Subjective refractions require a feedback from the patient as to whether one lens is clearer than another lens in order to obtain an accurate measurement of the refractive error. Since subjective refractions cannot be used on patients, such as infants, small children, foreign speaking patients and deaf and/mute patients, an objective measurement using retinoscopy is required. Auto-refractors are used frequently in industrialized countries to replace retinoscopy; however the results are inaccurate in many cases, especially in older patients. As a result, many of these patients are dispensed incorrect lenses. 
         [0003]    Jack Copeland was the originator of streak retinoscopy as practiced and taught today and designed the Copeland Optec 360 Streak Retinoscope. The technique of streak retinoscopy is illustrated in Videotape No. 5063 for the American Academy of Ophthalmology&#39;s Continuing Ophthalmic Video Education series, entitled “Retinoscopy; Plus Cylinder Technique.” U.S. Pat. No. 3,597,051 of Copeland illustrates his streak retinoscope assembly which has a thumb-slide adapted to move the power capsule housing the bulb and battery up and down relative to the shaft of the retinoscope. The ridges on the knurl on the power capsule allow one to rotate the power capsule housing the bulb 360°. Advancing the thumb-slide to its upper position causes light rays emanating from the retinoscope to diverge. By contrast convergence of the light rays occurs when thumb-slide is moved to it lower position. The Copeland Optec 360 Streak Retinoscope contains a +20.00 D condensing lens and a bi-pin lamp. When the thumb-slide is in its upper position, the filament of the lamp is less than five centimeters from the condensing lens and the rays emanating from the filament and passing through the condensing lens are diverging. Moving the slide to a lower position causes the light rays to converge. The filaments of the light bulbs for the Copeland Optec 360 Streak vary in height which results in differences of the divergence power of the emitted retinoscopic light ranging from 0.00 D to 1.00 D. Many retinoscopes on the market work in the opposite manner as the Copeland Optec 360 in that converging rays are produced when the knurl is in the up position and diverging rays when the knurl is in the down position. 
         [0004]    In retinoscopy, the examiner uses a retinoscope to shine light into the patient&#39;s eye and observes the retinal reflection which is referred to as a pupillary reflex. While moving the streak of light across the pupil the examiner observes the relative movement of the pupillary reflex as they use a phoropter or manually placed lenses over the eye to “neutralize” the pupillary reflex. Streak retinoscopy uses three images to measure the refractive state of the eye. The first image, Image I 1  is the luminous streak of the retinoscopic bulb. The second image, Image I 2 , is the focus or non-focus of image I 1  onto the reflecting membrane of the retina. The reflection of the Image I 2  produces a third image, Image I 3 , the pupillary reflex. The non-focus light of Image I 1  on the iris is the intercept. The examiner can only see the intercept and the Image I 3 . The examiner draws all signals from the intercept and third image, Image I 3 , as when to rotate the pupillary reflex to align the astigmatic axis and to add or subtract lenses (+ or −) to neutralize a refractive error. The retinoscopic working distance is the distance between the luminous filament of the light bulb from the pupillary plane of the eye. Clinically, the retinoscopic working distance in conventional retinoscopy is manually measured with a string from the examiner&#39;s nose to the spectacle lens plane in the phoropter or trial frame. The principals of spot retinoscopy are the same as streak retinoscopy; the only difference is the pupillary streak is a spot of light instead of a streak. Streak retinoscopy is popular in the United States, South America and Canada and spot retinoscopy in the European countries. 
         [0005]    In retinoscopy, upon neutralization of the refractive error, the diverging retinoscopic light rays used in streak and spot retinoscopy are focused into the eye with a spherical lens placed in front of the eye. This spherical lens is called a retinoscopic spherical lens or fogging lens and its focal length is equal to the examiner&#39;s retinoscopic working distance. A neutrality reflex, indicating neutralization of the refractive error, occurs when emitted retinoscopic light exits the retinoscopic spherical lens and enters the pupil as parallel light rays and is focused onto the reflecting membrane of the retina. The reflected light then exits the eye as parallel light rays and is focused by the retinoscopic spherical lens into the hole of a mirror or surface of a semi-reflecting mirror within the retinoscope. This endpoint is called “gross retinoscopy.” “Net retinoscopy” occurs on removing the retinoscopic spherical lens, thereby allowing the patient&#39;s visual focal point to be extended from the mirror to the end of the refracting lane. If the focal lengths of the retinoscopic working distance, the retinoscopic spherical lens and the emitted diverging retinoscopic light are not equal, the pupillary image will be focused in front or behind the mirror, creating myopic and hyperopic retinoscopic errors respectively. When the pupillary reflex is refocused to the hole in the mirror by the retinoscopist to obtain an infinity pupillary reflex, myopic and hyperopic retinoscopic errors are created. 
         [0006]    The variability of conventional retinoscopy is due to several factors, which include the exponentially expanding and moving pupillary reflex which becomes infinite and cannot be seen at neutralization of the patient&#39;s refractive error, the low luminosity of the pupillary reflex created by the diverging retinoscopic light which is not calibrated to the examiner&#39;s retinoscopic working distance and/or the focal length of the retinoscopic spherical lens. Accommodation and pupillary constriction induced by the retinoscopic light, whether on or off-axis, further reduce the illumination of the pupillary reflex. Retinoscopy through dilated pupils induces optical aberrations and peripheral movements that are different and more myopic than the central pupillary reflex. These factors make it difficult to recognize a definitive endpoint and have contributed to the variability and inaccuracy of conventional retinoscopy. 
         [0007]    Retinoscopists use a meridional straddle to confirm the accuracy of the retinoscopic endpoint in conventional retinoscopy. The quote below is from the editorial staff of the American Academy of Pediatrics and Strabismus: “In the 25 years that I taught Retinoscopy and in the 45 years that Copeland taught the subject, calibration of the Scope was to be avoided. Why? Because the endpoint did not depend on calibration of the instrument but rather meridional comparison and ability to utilize all of the various steps together to get to the working distance endpoint.” 
         [0008]    The reason that an accurate meridional straddle with conventional retinoscopy is important is due to the fact that the endpoint image signifying neutralization of the refractive error cannot be seen when focused into the hole in the mirror or mirror. A meridional balance is when the myopic pupillary reflex is under corrected 0.50 D to create a hyperopic pupillary reflex, which is easily seen and then overcorrected 0.50 D to create a myopic reflex. This process is repeated several times during a retinoscopic examination. Most retinoscopists use the hyperopic reflex as their endpoint which under-corrects the retinoscopic endpoint. As previously described myopic and hyperopic retinoscopic errors occur when the divergence power of the emitted retinoscopic light is not neutralized by the power of the retinoscopic spherical lens and the retinoscopic working distance not being equal to the focal length of the retinoscopic spherical lens. If these three variables are not equal, the retinoscopic endpoint is focused in front of the mirror or beyond the mirror in which case the meridional balance only confirms the accuracy or inaccuracy of the retinoscopic endpoint. The accuracy of the spherical retinoscopic measurement is dependent on the three variables being equal. Statistically, the inaccuracy of the spherical retinoscopic measurement as compared to the measurements of the cylinder and axis supports this theory. 
         [0009]    To improve the endpoints of conventional retinoscopy and eliminate other optical problems of conventional retinoscopy Boeder and Kolder developed a retinoscopic technique using parallel light rays emanating from the retinoscope and claimed this produced “neutralization at infinity” or the ability of the patient to read the Snellen chart during retinoscopy. In their formula describing neutralization at infinity, emmetropia or RSR=1 was achieved when the relative speed of movement of the intercept and pupillary reflex were equal and the pupillary reflex was no less than 2.0 mm. This is expressed in the following formula: 
         [0000]      RSR=[1 −t/I   1 ]/[1 +t/I   3 ]=1       RSR=relative speed of pupillary reflex   I 1 =focal length of Image I 1      I 3 =focal length of Image I 3      t=retinoscopic distance (cm)   Image I 1 =luminous filament of the bulb   Image I 3 =pupillary reflex is the reflection of the retinoscopic light         
         [0016]    Unfortunately, their technique required the retinoscopist to recognize the width of a 2.5 mm with-motion pupillary streak as the endpoint, or one no less than 2 mm, an unfamiliar unit of measurement to retinoscopists and many of their claims are invalid:
       1. The premise that their infinity retinoscopic technique placed the endpoint of neutralization at infinity instead of the aperture of the retinoscope.   2. The intercept and pupillary reflex will move at different speeds if infinity neutralization is not achieved. That is, if I 3  is on the myopic side of neutralization, the with-motion pupillary reflex I 3  moves slightly ahead of the intercept and slower if I 3  is on the hyperopic side of neutralization.   3. At infinity neutralization, the power of Image I 3  is independent of the retinoscopic working distance.   4. The pupillary reflex is characterized by “well defined borders” and “evenly distributed brightness” only at neutralization.   5. The endpoint of infinity retinoscopy or emmetropia occurs only when I 1 =I 3  is incorrect since in converging infinity retinoscopy, I 1  can be greater or less or equal to I 3  when emmetropia is obtained.   6. Naming the article “Neutralization at Infinity in Streak Retinoscopy” since neutralization occurs at the examiner&#39;s retinoscopic working distance, not infinity.   7. In the derivation of the infinity formula, Image I 1  and I 3  are located at the position where the retinoscope is located, not beyond the retinoscope and this makes RSR=∞, not 1, when parallel light rays are emitted from the retinoscope.   8. The formula RSR=[1−t/I 1 ]/[1+t/I 3 ]=1 does not apply to parallel light emitted from the retinoscope, since the formula is derived on the assumption that the focal lengths I 1  and I 3  will be greater than t, the retinoscopic working distance. In contrast, with parallel light emitted from the retinoscope, RSR is equal to 1 and t is equal to the focal length of I 1  and I 3 .       
 
         [0025]    On an inter-national scale, the average optical remake of spectacle lenses is 6-10%. These lenses are remade at no cost to the patient. This extrapolates to a financial and efficiency loss to the physician and optical shop as well as a reduction of the patient&#39;s opinion of the professional skills obtained in that office. The optical remakes and complaints have not been reduced by the auto-refractors or the present day refraction and/or retinoscopic techniques. 
         [0026]    Therefore, a need exists for a device and method that eliminates many of the factors responsible for the variability and retinoscopic errors of conventional retinoscopy. More specifically, a need exists for a calibration technique calibrating a retinoscope to the examiner&#39;s retinoscopic working distance using either converging or diverging light emanating from the retinoscope. 
         [0027]    The relevant prior art includes the following references (U.S. unless stated otherwise): 
         [0000]    
       
         
               
               
               
             
               
               
               
             
           
               
                   
               
               
                 Pat. No. 
                 Inventor 
                 Issue/Publication Date 
               
               
                   
               
             
             
               
                   
               
             
          
           
               
                 5,650,839 
                 Sims 
                 Jul. 22, 1997 
               
               
                 5,500,698 
                 Sims 
                 Mar. 19, 1996 
               
               
                 5,430,508 
                 Sims 
                 Jul. 04, 1995 
               
               
                 3,597,051 
                 Copeland 
                 Aug. 03, 1971 
               
               
                   
               
             
          
         
       
     
       SUMMARY OF THE INVENTION 
       [0028]    The primary objective of the present invention is to improve the accuracy of streak and spot retinoscopy using diverging retinoscopic light rays and converging infinity retinoscopy using converging rays. Infinity retinoscopy is equivalent to “net retinoscopy”. 
         [0029]    Another objective of the present invention is to provide standardization for retinoscopic endpoints using either converging or diverging light emanating from the retinoscope. 
         [0030]    Another objective of the present invention is to improve the accuracy and repeatability of measurements using retinoscopy. 
         [0031]    An even further objective of the present invention is to provide more accurate endpoints for retinoscopes which use converging and diverging light rays. 
         [0032]    Another objective of the present invention is to decrease the need to dilate patient&#39;s pupils for retinoscopy. 
         [0033]    Another objective of the present invention is to eliminate the potential errors prevalent in conventional retinoscopy as practiced today. 
         [0034]    Another objective of the present invention is to provide a brighter and more defined endpoint through the use of converging and diverging retinoscopic light rays. 
         [0035]    Another objective of the present invention is to eliminate the need of a retinoscopic fogging or spherical lens. 
         [0036]    An even further objective of the present invention is to eliminate the need to perform a meridional straddle. 
         [0037]    An even further objective of the present invention is to improve the accuracy of the meridional straddle if performed. 
         [0038]    An even further objective of the present invention is to allow a practitioner to obtain more accurate retinoscopic measurements from patients who cannot communicate with the practitioner. 
         [0039]    An even further objective of the present invention is to reduce the amount of follow-up appointments for spectacle re-checks due to inaccurate measurements. 
         [0040]    An even further objective of the present invention is to provide a quick accuracy check of a patient&#39;s glasses. 
         [0041]    Another objective of the present invention is to provide a method that is easy to teach to technicians and easy to learn. 
         [0042]    The present invention fulfills the above and other objectives by providing an infinity retinoscopic technique using converging rays emitted from the retinoscope and improving the accuracy of retinoscopy which uses diverging rays emitted from the retinoscope by calibrating a manual retinoscope to produce a given convergence or divergence of light (“Image I 1 ”) emitted from the retinoscope from a fixed retinoscopic working distance (“t”) to produce a predetermined pupillary reflex endpoint (“Image I 3 ”) at neutralization of the refractive error. 
         [0043]    Improvement in the accuracy of conventional retinoscopy using diverging light rays can be accomplished by adjusting the divergence of the emitted retinoscopic light to neutralize the power of the retinoscopic fogging lens and using a lens whose focal length is equal to the examiner&#39;s retinoscopic working distance. From the following formula, the required divergence of the emitted retinoscopic light can be determined to produce an infinity endpoint pupillary reflex or a +0.50 D with-motion endpoint pupillary reflex for one&#39;s retinoscopic working distance. 
         [0000]      2RL+Image  I   1 +Image  I   3   =t          Image I 1 =vergence power of light rays emitted from retinoscope   Image I 3 =power of pupillary reflex   t=retinoscopic working distance expressed in diopters   RL=retinoscopic fogging lens         
         [0048]    The steps for calibrating a retinoscope for diverging retinoscopy are as follows.
       1. First, a circumferential line is made in the knurl area of the power capsule.   2. Next, the examiner&#39;s working distance is optically measured by focusing a retinoscope into an emmetropic eye from their retinoscopic working distance by moving the thumb-slide on the retinoscope until a neutrality reflex occurs, holding the thumb-slide in place, focusing the retinoscopic streak onto a wall and measuring the distance between the retinoscope and the wall.   3. With the aid of the calibration chart, the examiner&#39;s retinoscopic working distance is matched to the required calibration spherical lens to be placed in front of the retinoscope for calibrating the divergence of the emitted retinoscopic light rays to the examiner&#39;s retinoscopic working distance for an infinity or a +0.50 D retinoscopic endpoint.   4. The retinoscope is then held from a wall a distance equal to the examiner&#39;s retinoscopic working distance and the calibration sphere held in front of the retinoscope.   5. The thumb-slide is held in its maximal upward position and the diverging light directed or shined through the calibration sphere onto the wall. The light rays are made less diverging by moving the thumb-slide downward until the retinoscopic streak is focused on the wall.   6. When the retinoscopic streak or spot is focused, the thumb slide is held in this position and the infinity or +0.50 D calibration plate adjusted on the body of the retinoscope to align the alignment line on the plate with the calibration line above the knurl and then secured into position. The divergence of the emitted retinoscopic light for an infinity or a +0.50 D retinoscopic endpoint is now calibrated to the examiner&#39;s retinoscopic working distance.   7. After calibration of the retinoscope, the slide bar can be adjusted to maintain the thumb-slide in a fixed position to maintain the calibration of the retinoscope for future retinoscopies.       
 
         [0056]    If the light rays need to be made more diverging to focus the retinoscopic streak onto the wall, the light bulb within the retinoscope is advanced towards the condensing lens to increase the divergence of the emitted retinoscopic light and the above procedures repeated. 
         [0057]    Converging infinity retinoscopy eliminates many of the factors responsible for the retinoscopic errors made using conventional retinoscopy. For converging infinity retinoscopy, the required convergence of the emitted retinoscope light to produce a given endpoint pupillary reflex measured in diopters is determined from the following formula: 
         [0000]      Image  I   1 +Image  I   3   =t          Image I 1 =vergence power of light rays emitted from retinoscope   Image I 3 =power of pupillary reflex   t=retinoscopic working distance in diopters         
         [0061]    The steps for calibrating a retinoscope for converging retinoscopy are:
       1. A circumferential calibration line in the knurl area of the power capsule which is moved up and down by the thumb-slide.   2. Next, the examiner&#39;s retinoscopic working distance is optically measured by focusing a retinoscope into an emmetropic eye from one&#39;s retinoscopic working distance by moving the thumb-slide on the retinoscope until a neutrality reflex occurs and then holding the thumb-slide in place. The retinoscopic light is then focused onto a wall and the distance between the retinoscope and the wall measured.   3. With the calibration chart, the examiner&#39;s retinoscopic working distance is matched to the required focal length of the retinoscopic light for performing +0.50 D or +0.75 D converging infinity retinoscopy.   4. Next, the retinoscope is placed at the required distance from a wall as specified by the calibration chart, the retinoscopic light rays focused onto the wall and the thumb-slide secured in place.   5. A calibration plate is attached to the side of the retinoscope, aligning the +0.50 D or +0.75 D alignment line with the circumferential calibration line above the knurl to mark the position of the power capsule housing the bulb for future converging infinity retinoscopies.   6. After calibration of the retinoscope, the slide bar can be adjusted to maintain the thumb-slide in a fixed position to maintain the calibration of the retinoscope for future retinoscopies.       
 
         [0068]    The above and other objects, features and advantages of the present invention should become even more readily apparent to those skilled in the art of retinoscopy upon reading the following detailed description in conjunction with the drawings wherein shown and the described illustrative embodiments of the invention. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0069]      FIG. 1  is a side partial cutaway view of a condensing lens, a mirror, a lamp, a power capsule with a knurl for rotating the power capsule and a thumb-slide which moves the power capsule housing the lamp; 
           [0070]      FIG. 2  is a schematic of the knurl area on the power capsule with a circumferential line; 
           [0071]      FIG. 3  is a schematic view of light rays emanating from a retinoscope in a diverging pattern; 
           [0072]      FIG. 4  is a schematic view of light rays emanating from a retinoscope in a converging pattern; 
           [0073]      FIG. 5  is a flow chart for optically measuring one&#39;s retinoscopic working distance; 
           [0074]      FIG. 6  is a chart for calibrating the retinoscope using diverging rays for an infinity retinoscopic and +0.50 D endpoints and for calibrating a retinoscope using converging rays for +0.50 D and +0.75 D retinoscopic endpoints; 
           [0075]      FIG. 7-A  is an attachable plate for retrofitting a retinoscope for a +0.50 D retinoscopic endpoint using converging rays calibrated to the examiner&#39;s retinoscopic working distance; 
           [0076]      FIG. 7-B  is an attachable plate for retrofitting a retinoscope for a +0.75 D retinoscopic endpoint using converging rays calibrated to the examiner&#39;s retinoscopic working distance; 
           [0077]      FIG. 7-C  is an attachable plate for retrofitting a retinoscope for an infinity retinoscopic endpoint using diverging rays calibrated to the examiner&#39;s retinoscopic working distance; 
           [0078]      FIG. 7-D  is an attachable plate for retrofitting a retinoscope for a +0.50 D retinoscopic endpoint using diverging rays calibrated to the examiner&#39;s retinoscopic working distance; 
           [0079]      FIG. 8  is a flow chart showing the steps for calibrating a retinoscope for a +0.50 D retinoscopic endpoint using converging retinoscopic light rays calibrated to the examiner&#39;s retinoscopic working distance; 
           [0080]      FIG. 8-A  is a retinoscope showing proper attachment of the +0.50 D converging plate after calibration of retinoscope light rays to the examiner&#39;s retinoscopic working distance; 
           [0081]      FIG. 9  is a flow chart showing the steps for calibrating a retinoscope for a +0.75 D pupillary reflex endpoint using converging retinoscopic light rays; 
           [0082]      FIG. 9-A  is a retinoscope showing proper attachment of the +0.75 D converging plate after calibration of retinoscopic light rays to the examiner&#39;s retinoscopic working distance; 
           [0083]      FIG. 10  is a flow chart showing the steps for calibrating a retinoscope for an infinity retinoscopic endpoint using diverging retinoscopic light rays calibrated to the examiner&#39;s retinoscopic working distance; 
           [0084]      FIG. 10-A  is a retinoscope showing proper attachment of the infinity diverging plate after calibration of the retinoscopic light rays to the examiner&#39;s retinoscopic working distance; 
           [0085]      FIG. 11  is a flow chart showing the steps for calibrating a retinoscope for a +0.50 D retinoscopic endpoint using diverging retinoscopic light rays calibrated to the examiner&#39;s retinoscopic working distance; 
           [0086]      FIG. 11-A  is a retinoscope showing the proper attachment of the +0.50 D diverging plate after calibration of retinoscopic light rays to the examiner&#39;s retinoscopic working distance; 
           [0087]      FIG. 12  is a flow chart showing the steps for performing a calibration check of a retinoscope emanating converging rays calibrated to the examiner&#39;s retinoscopic working distance; 
           [0088]      FIG. 13  is a retinoscope showing a slide bar which can be adjusted to maintain the thumb-slide in a fixed position to maintain the calibration of the retinoscope for future retinoscopies; and 
           [0089]      FIG. 14 , a front perspective view of a bulb extender  52  of the present invention. 
       
    
    
       [0090]      
         [0000]    
       
         
               
             
               
               
               
               
             
           
               
                   
               
               
                 DESCRIPTION OF THE PREFERRED EMBODIMENTS 
               
               
                   
               
             
             
               
                   
               
             
          
           
               
                  1.  
                 retinoscope 
                 31.  
                 +0.75D converging plate 
               
               
                  2.  
                 thumb-slide 
                 32. 
                 infinity diverging plate 
               
               
                  3.  
                 condensing lens 
                 33.  
                 +0.50D diverging plate 
               
               
                  4.  
                 lamp 
                 34.  
                 optically measure the 
               
               
                  5.  
                 filament 
                   
                 retinoscopic working distance 
               
               
                  6.  
                 handle of retinoscope 
                 35.  
                 Using the calibration chart, match 
               
               
                  7.  
                 hole in mirror 
                   
                 the distance the retinoscope must 
               
               
                  8.  
                 mirror 
                   
                 be held from wall to the 
               
               
                  9.  
                 knurl on power capsule 
                   
                 retinoscopic working distance 
               
               
                 10.  
                 power capsule 
                 36.  
                 place retinoscope at required 
               
               
                 11.  
                 calibration line on power  
                   
                 distance from a wall 
               
               
                   
                 capsule 
                 37.  
                 focus retinoscope and hold  
               
               
                 12.  
                 retinoscopic light rays 
                   
                 thumb-slide in place 
               
               
                 13.  
                 diverging pattern 
                 38.  
                 align the alignment on plate with 
               
               
                 14.  
                 converging pattern 
                   
                 the calibration line 
               
               
                 15.  
                 optical measurement of 
                 39.  
                 secure +0.50D converging plate  
               
               
                   
                 retinoscopic working 
                   
                 to retinoscope 
               
               
                   
                 distance: 
                 40.  
                 secure +0.75D converging plate 
               
               
                 16.  
                 hold thumb-slide in place 
                   
                 to retinoscope 
               
               
                   
                 and focus retinoscope 
                 41.  
                 using calibration chart, match 
               
               
                   
                 onto wall. 
                   
                 retinoscopic working distance to 
               
               
                 17. 
                 measure distance between 
                   
                 power of calibration lens required 
               
               
                   
                 retinoscope and wall 
                 42.  
                 place retinoscope a distance from  
               
               
                 18.  
                 calibration chart 
                   
                 a wall equal to the retinoscopic 
               
               
                 19.  
                 retinoscopic working 
                   
                 working distance 
               
               
                   
                 distance (cm) 
                 43.  
                 place calibration sphere in front  
               
               
                 20.  
                 calibration sphere required for 
                   
                 of retinoscope 
               
               
                   
                 calibrated infinity endpoint 
                 44.  
                 if retinoscopic light fails to focus, 
               
               
                   
                 using diverging light rays 
                   
                 move bulb towards condensing 
               
               
                 21.  
                 calibration sphere required for 
                   
                 lens and refocus reflex onto wall 
               
               
                   
                 calibrated +0.50D endpoint 
                 45.  
                 align calibration line with 
               
               
                   
                 using diverging light rays 
                   
                 alignment line on the infinity 
               
               
                 22.  
                 required focal length of 
                   
                 diverging plate 
               
               
                   
                 retinoscopic 
                 46.  
                 secure infinity diverging plate to 
               
               
                   
                 light for +0.50D endpoint  
                   
                 retinoscope 
               
               
                   
                 using converging light rays 
                 47.  
                 align calibration line with 
               
               
                 23.  
                 required focal length of 
                   
                 alignment line on the +0.50D 
               
               
                   
                 retinoscopic 
                   
                 diverging plate 
               
               
                   
                 light for +0.75D endpoint  
                 48.  
                 secure the +0.50D diverging  
               
               
                   
                 using converging light rays 
                   
                 plate to retinoscope 
               
               
                 24.  
                 plate 
                 49.  
                 assume one&#39;s routine retinoscopic 
               
               
                 25.  
                 +0.50D converging plate 
                   
                 working distance 
               
               
                 26.  
                 front surface of calibration  
                 50.  
                 check alignment of calibration  
               
               
                   
                 plate 
                   
                 and alignment lines 
               
               
                 27.  
                 rear surface of calibration  
                 51.  
                 slide bar 
               
               
                   
                 plate 
                 52.  
                 bulb extender 
               
               
                 28.  
                 alignment line 
                 53.  
                 aperture 
               
               
                 29.  
                 attachment means 
                   
                   
               
               
                 30.  
                 adjustment means 
               
               
                   
               
             
          
         
       
     
         [0091]    With reference to  FIG. 1 , a side partial cutaway view of a retinoscope  1  having a thumb-slide  2  and a condensing lens  3  and a lamp  4  is shown. The lamp  4  includes a linear filament  5  designed to create a “streak” image which is reflected from a patient&#39;s retina and seen by a practitioner, such as an optometrist or ophthalmologist. The thumb-slide  2  moves the power capsule housing the lamp  4  moves up and down along a handle of the retinoscope  6  so that when the thumb-slide  2  is in a maximal upward position, the filament  5  is less than 5 cm from lens  3  which has an approximate power of +20.00 D. When the thumb-slide  2  is in a maximal down position, the filament  5  is approximately 6.6 cm from the lamp  4 . The practitioner can view the light rays reflected from the patient&#39;s retina through a small opening  7  in mirror  8 . The examiner can only see the retinoscopic light on the patient&#39;s iris and the reflected pupillary reflex. The examiner nevertheless is able to move the pupillary reflex toward neutralization by the movement and orientation of the pupillary reflex. The examiner draws all of the retinoscopic signals from the pupillary reflex, that is, when to change or rotate the retinoscopic streak to achieve neutralization of the spherical and cylindrical error. 
         [0092]    With reference to  FIG. 2 , calibration of the retinoscope requires a calibration line  11  in the knurl area  9  on the power capsule  10  to align the Plates  7 A and  7 B for converging infinity retinoscopy and Plates  7 C and  7 D for diverging retinoscopy after the retinoscope is calibrated to the specifications in the Calibration Chart  18 . 
         [0093]    With reference to  FIG. 3 , a schematic view of light rays  12  emanating from a retinoscope  1  in a diverging pattern  13  is shown. In diverging retinoscopy the lamp  4  is within the focal length of lens  3 . The proximity of the lamp  4  to the lens  3  causes the light rays  12  emitted from the retinoscope  1  to spread out into a diverging pattern  13 . 
         [0094]    The retinoscopic technique of identifying and neutralizing a refractive error is the same with calibrated diverging retinoscopy as with conventional retinoscopy. Calibrated diverging retinoscopy differs from conventional retinoscopy in that the divergence of the emitted retinoscopic light rays  12  is calibrated to one&#39;s retinoscopic working distance. The endpoint of calibrated diverging retinoscopy can be an infinity retinoscopic endpoint which is identical to the endpoint of conventional retinoscopy or a +0.50 D with-motion pupillary reflex. 
         [0095]    With reference to  FIG. 4 , a schematic view of light rays  12  emanating from a retinoscope  1  in a converging pattern  14  is shown. In converging retinoscopy, the lamp  4  is displaced beyond the focal length of lens  3 . The increased distance of the lamp  4  from the lens  3  causes the light rays  12  emitted from the retinoscope  1  to focus into a converging pattern  14 . 
         [0096]    With reference to  FIG. 5 , a flow chart showing the steps for measuring a retinoscopic working distance for use in calibrating a retinoscope for converging and diverging retinoscopy is shown. The examiner&#39;s retinoscopic working distance is optically measured by focusing the retinoscopic light into an emmetropic eye using the thumb slide until a neutrality reflex occurs  15 . Then, the retinoscopist holds the thumb-slide on the retinoscope in place and the emitted retinoscopic light is focused onto a wall by moving the retinoscope towards the wall until the streak is in focus  16 . Finally, the distance between the wall and retinoscope is measured to obtain the examiner&#39;s retinoscopic working distance  17 . 
         [0097]    With reference to  FIG. 6 , a calibration chart  18  is shown. The calibration chart  18  lists the retinoscopic working distance in centimeters  19  and the required power of the calibration lens to be held in front of the retinoscope, which is held from a wall a distance equal to the examiner&#39;s retinoscopic working distance  19 , in order to calibrated the diverging retinoscopic light for an infinity endpoint  20  and a +0.50 D endpoint  21 . Chart  18  also lists the distance a retinoscope must be held from a wall to calibrated the retinoscope using converging light for a +0.50 D endpoint  22  and a +0.75 D endpoint  23 , when performing retinoscopy from one&#39;s retinoscopic working distance. 
         [0098]    With reference to  FIG. 7-A , an attachable plate  24  for retrofitting a retinoscope  1  when calibrated for a +0.50 D with-motion endpoint pupillary reflex using converging rays  14  emitted from the retinoscope  1  is shown. The plate  24  shown here is a +0.50 D converging plate  25  and is used when the converging light emanating from the retinoscopies is calibrated for a +0.50 D with-motion retinoscopic endpoint, as shown further in  FIG. 8 . The +0.50 D converging plate  25  has a front surface  26 , a rear surface  27  and an alignment line  28 . The plate  24  is attachable to the retinoscope via an attachment means  29 , such as screws nuts, etc. The plate  24  is moveable via an adjustment means  30 , such as a slot that moves along a screw, so that a user may adjust the alignment line  28  up or down to be in alignment with the calibration line  11  on the power capsule  10 . After the retinoscope is calibrated and plate  24  secured into position, the alignment line  28  on plate  24  allows the retinoscopist to know where to place the calibration line  11  on the power capsule  10  to obtain a +0.50 D retinoscopic endpoint using converging light, as shown further in  FIG. 8-A . 
         [0099]    With reference to  FIG. 7-B , an attachable plate  24  for retrofitting a retinoscope  1  when calibrated for a +0.75 D with-motion retinoscopic reflex using converging light rays  14  emitted from the retinoscope  1  is shown. The plate  24  shown here is a +0.75 D converging plate  31  and is used when the converging light  14  emanating from the retinoscope is calibrated for a +0.75 D with-motion retinoscopic endpoint, as shown further in  FIG. 9 . The +0.75 D converging plate  31  has a front surface  26 , a rear surface  27  and an alignment line  28 . The plate  24  is attachable to the retinoscope via an attachment means  29 , such as screws nuts, etc. The plate  24  is moveable via an adjustment means  30 , such as a slot that moves along a screw, so that a user may adjust the alignment line  28  up or down to be in level with the calibration line  11  on the power capsule  10 . After the retinoscope is calibrated and plate  24  secured into position, the alignment line  28  on plate  31  allows the retinoscopist to know where to place the calibration line  11  on the power capsule  10  to obtain a +0.75 D retinoscopic endpoint using converging light, as shown further in  FIG. 9-A . 
         [0100]    With reference to  FIG. 7-C , an attachable plate  24  for retrofitting a retinoscope  1  when calibrated for an infinity endpoint using diverging light rays  13  emitted from the retinoscope  1  is shown. The plate  24  shown here is an infinity endpoint diverging plate  32  and is used when the diverging light  13  emitted from the retinoscope is calibrated for an infinity retinoscopic endpoint, as shown further in  FIG. 10 . The infinity diverging plate  32  has a front surface  26 , a rear surface  27  and an alignment line  28 . The plate  24  is attachable to the retinoscope via an attachment means  29  such as screws, adhesive, nuts, etc. The plate  24  is moveable via an adjustment means  30 , such as a slot that moves along a screw, so that a user may adjust the alignment line  28  up or down to be level with the calibration line  11  on the power capsule  10  after the retinoscope is calibrated. After the retinoscope is calibrated and plate  32  secured into position, the alignment line  28  on plate  32  allows the retinoscopist to know where to place the calibration line  11  on the power capsule  10  to perforin retinoscopy with diverging light rays to obtain an infinity retinoscopic endpoint adjusted to one retinoscopic working distance as shown further in  FIG. 10-A . 
         [0101]    With reference to  FIG. 7-D , an attachable plate  24  for retrofitting a retinoscope  1  when calibrated to a +0.50 D with-motion pupillary reflex endpoint using diverging retinoscopic light rays  13  is shown. The plate  24  shown here is a diverging plate  33  and is used when the diverging light emanating from the retinoscope is calibrated for a +0.50 D with motion retinoscopic endpoint as shown further in  FIG. 11 . The +0.50 D diverging plate  33  has a front surface  26 , a rear surface  27  and an alignment line  28 . The plate  24  is attachable to the retinoscope via an attachment means  29 , such as screws, adhesive, nuts, etc. The plate  24  is moveable via an adjustment means  30 , such as a slot that moves along a screw, so that a user may adjust the alignment line  28  up or down to be in alignment with the calibration line  11  on the power capsule  10  after the retinoscope is calibrated. The alignment line  28  on plate  33  allows the retinoscopist to know where to place the calibration line  11  on the power capsule  10  to perform retinoscopy with diverging light rays to obtain a +0.50 D retinoscopic endpoint adjusted to one retinoscopic working distance as shown further in  FIG. 11-A . 
         [0102]    With reference to  FIG. 8 , a flow chart showing the steps for calibrating a retinoscope for a +0.50 D with-motions retinoscopic endpoint using converging retinoscope light rays  14  is show. First, the retinoscopic working distance is optically measured  34  as shown in  FIG. 5 . Then, the required focal length of the emitted retinoscope light for a +0.50 D retinoscopic endpoint is determined  35  using the calibration chart  18  illustrated in  FIG. 6 . For example, if the retinoscopic working distance is 67 cm, the required focal length of the emitted retinoscopic light is 100 cm. Next, the retinoscope is placed at the proper focal length from a wall  36  and focused  37 . Finally  38 , the alignment line  28  on the +0.50 D converging plate  25  is aligned with the calibration line  11  on the power capsule  10  as shown further in  FIG. 8-A  and secured  39 . 
         [0103]    With reference to  FIG. 8-A , a retinoscope  1  having a +0.50 D converging plate  25  attached thereto is shown. The retinoscope  1  has been calibrated for a +0.50 D pupillary reflex endpoint using converging retinoscope light rays  14 . The technique for performing retinoscope using a retinoscope calibrated for a +0.50 D retinoscopic endpoint is the same as in conventional retinoscopy, except that the calibration line  11  on the power capsule  10  is level with the alignment line  28  on the +050 D converging plate  25  and the retinoscopic endpoint is a +0.50 D with-motion retinoscopic reflex with the +0.50 D pupillary reflex and intercept moving in unison. 
         [0104]    With reference to  FIG. 9 , a flow chart showing the steps for calibrating a retinoscope for a +0.75 D with-motions retinoscopic endpoint using converging retinoscope light rays  14  is show. First, the retinoscopic working distance is measured  34  as shown in  FIG. 5 . Then, the required focal length of the emitted retinoscope light is determined  35  using the calibration chart  18  illustrated in  FIG. 6 . For example, if the retinoscopic working distance is 67 cm, the required focal length of the emitted retinoscopic light is 133 cm. Next, the retinoscope is placed at the proper focal length from a wall  36  and focused  37  and the thumb-slide held in position. Finally  38 , the alignment line  28  on the +0.75 D converging plate  31  is aligned with the calibration line  11  on the power capsule  10  of retinoscope  1  as shown further in  FIG. 8-A  and secured  40 . 
         [0105]    With reference to  FIG. 9-A , a retinoscope  1  having a +0.75 D converging plate  31  attached thereto is shown. The retinoscope  1  has been calibrated for a +0.75 D endpoint using converging retinoscopic light rays  14 . The technique for performing retinoscopy using a retinoscope calibrated for a +0.75 D retinoscopic endpoint is the same as in conventional retinoscopy, except the calibration line  11  on power capsule  10  is level with the alignment line  28  on the +075 D converging plate  31  and the retinoscopic endpoint is a +0.75 D retinoscopic and moves in unison with the intercept. 
         [0106]    With reference to  FIG. 10 , a flow chart showing the steps for calibrating a retinoscope  1  for an infinity retinoscopic endpoint using diverging retinoscopic rays  13  is shown. First, the retinoscopic working distance  34  is measured in centimeters, as shown in  FIG. 5 . Next  41 , the retinoscopic working distance in centimeters  19  is matched to the power of the calibration lens required  20  using the calibration chart  18 . For example, if the retinoscopic working distance is 67 cm, the power of calibration sphere would be +3.00 D. Next, the retinoscope  1  is placed at a distance from the wall equal to the retinoscopic working distance  42 . Next, the +3.00 D calibration sphere as determined from  41  is placed in front of the retinoscope  43 . With the thumb-slide  2  in the maximal upward position and the diverging retinoscopic light shinning through the +3.00 D calibration spherical lens, the thumb-slide  2  is lowered until the retinoscopic streak is focused onto the wall  37 . If the retinoscopic streak fails to focus onto the wall, the bulb  4  is advanced towards the condensing lens  3  within the retinoscope  1  and the procedure repeated until the retinoscopic streak is focused onto the wall,  44 . Next  45 , the alignment line  28  on the infinity diverging plate  32  is aligned with the calibration line  11  on the power capsule  10  and secured in position  46  as shown further in  FIG. 10-A . 
         [0107]    With reference to  FIG. 10-A , a retinoscope  1  having an diverging plate  32  attached thereto is shown. The retinoscope  1  has been calibrated for an infinity retinoscopic endpoint using diverging retinoscope light rays  13 . The technique for performing retinoscopy using an infinity retinoscopic endpoint with the emitted retinoscopic light rays calibrated to the examiner&#39;s retinoscopic working distance is the same as in conventional retinoscopy, except that the calibration line  11  on the power capsule  10  is level with the measuring line  28  on the infinity plate  32 . 
         [0108]    With reference to  FIG. 11 , a flow chart showing the steps for calibrating a retinoscope  1  for a +0.50 D retinoscopic endpoint using diverging retinoscope light rays  13  is show. 
         [0109]    First the working distance is measure centimeters  34 , as shown in  FIG. 5 . Next  41 , the retinoscopic working distance in centimeters  19  is matched to the power of the calibration lens required  21  using the calibration chart  18 . For example, if the retinoscopic working distance is 67 cm the power of the calibration sphere would be +3.50 D. Next, the retinoscope  1  is placed at a distance from the wall equal to the retinoscopic working distance  42 . Next, the +3.50 D sphere is placed in front of the retinoscope  43 . With the thumb-slide  2  in the maximal upward position and the diverging retinoscopic light shinning through the +3.50 D calibration lens, the thumb-slide  2  lowered until the retinoscopic streak is focused onto the wall  37 . If the retinoscopic streak fails to focus onto the wall, the bulb  4  is displaced toward the +20 D condensing lens  3  within the retinoscope and the procedure repeated until the retinoscopic streak is focused onto the wall,  44 . Next  47 , the alignment line  28  on +0.50 D diverging plate  33  is aligned with the calibration line  11  on the power capsule  10  and secured in position  48  as shown further in  FIG. 11-A . 
         [0110]    With reference to  FIG. 11-A , a retinoscope  1  having a +0.50 D diverging plate  33  attached thereto is shown. The retinoscope  1  has been calibrated for a +0.50 D retinoscopic endpoint using diverging light rays  13  exiting the retinoscope. The technique for performing retinoscopy using a retinoscope calibrated to one&#39;s retinoscopic working distance for a +0.50 D retinoscopic endpoint is the same as conventional retinoscopy except the retinoscopic endpoint is a +0.50 D with-motion retinoscopic endpoint and the calibration line  11  is level with the alignment line  28 . In contrast to the +0.50 D retinoscopic endpoint produced with converging rays emitted from the retinoscope in  FIG. 8-A , with diverging rays the +0.50 D retinoscopic endpoint moves faster than the intercept. 
         [0111]    With reference to  FIG. 12 , a flow chart showing the steps for performing a calibration check on retinoscopes calibrated to emit converging rays  14  as shown in  FIGS. 8-A  and  9 -A is shown. First, the practitioner assumes his or her routine retinoscope distance  49 . Then the practitioner lowers the thumb-slide  2  of the retinoscope from its maximal upward position until a neutrality reflex is seen in an emmetropic eye  12  and holds the thumb-slide in this position  15 . If the calibration line  11  on the power capsule  10  is level with the alignment line  28  on the converging plates  25  or  31 , the retinoscope is calibrated  50 . In the Copeland Optec 360 Streak Retinoscope, the thumb-side is kept in the most superior position by a spring. 
         [0112]    With reference to  FIG. 13 , a retinoscope  1  having a slide bar  51  attached to the body of the retinoscope and locate superiorly to the thumb-slide  2  thereto is shown. The slide bar  51  is attachable to the retinoscope via an attachment means  29 , such as screws, nut, etc. The slide bar  51  is moveable via an adjustment means  30 , such as a slot that moves along a screw. After the retinoscope is calibrated, the slide bar  51  is adjusted to touch the top of the thumb-slide  2  to prevent it from moving upward and secured to the retinoscope. 
         [0113]    Although a practitioner may use a +0.50 D retinoscopic endpoint or a +0.75 D retinoscopic endpoint, the +0.50 D retinoscopic endpoint is easier, faster and more convenient to confirm than the +0.75 D retinoscopic endpoint, since during retinoscopy, the neutrality reflex is displaced 2 lenses from the +0.50 D retinoscopic endpoint and 3 lenses from the +0.75 D retinoscopic endpoint. 
         [0114]    Finally with reference to  FIG. 14 , a front perspective view of a bulb extender  52  of the present invention is shown. The bulb extender  52  acts as a spacer to increase the height of a lamp  4  and filament  5  within the retinoscope  1 . The bulb extender  52  elevates lamps  4  having shorter filaments  5  towards the lens  3  in order to increase the divergence of emitted retinscopic light. The bulb extender  52  has at least one aperture  53  to allow electronic communication between a power source of the retinoscope  1  and the filament  5 . 
         [0115]    It is to be understood that while a preferred embodiment of the invention is illustrated, it is not to be limited to the specific form or arrangement of parts herein described and shown. It will be apparent to those skilled in the art that various changes may be made without departing from the scope of the invention and the invention is not to be considered limited to what is shown and described in the specification and drawings.