bluuebunny/crossref_metadata_2025_split huggingface dataset:
Photoastigmatic Refractive Keratectomy in Myopes
Authors: MacRae Scott M , Peterson Jan S , Koch Douglas D , Rich Larry F , Durrie Daniel S 
Published: April 2021

ABSTRACT
PURPOSE: Photoastigmatic refractive keratectomy (PARK) was studied in a multi-center clinical trial. The Nidek EC-5000 excimer laser was evaluated for its effect on refraction, visual acuity, and safety measures as part of a U.S. Food and Drug Administration (FDA) regulated study.
METHODS: Eight U.S. centers enrolled adults with eyes having refractive astigmatism up to 4.00 D and a myopic spherical equivalent refraction up to -8.00 D. Results are reported for 749 eyes of 486 patients with at least 6 months follow-up. The rectangular beam scanning Nidek EC-5000 used a 5.5-mm-diameter treatment zone, a 7.0-mmdiameter peripheral blend zone, and a 40 Hz pulse rate for surface treatment of myopic astigmatism. Nomogram corrections to machine settings were required to achieve the desired results.
RESULTS: Preoperative average spherical equivalent refraction of -4.90 ± 1.74 D was reduced to -0.02 ± 0.79 D at 6 months. Refractive stability was established at 3 months. Over 62% of eyes were within ±0.50 D of desired correction at 6 months, with over 86% within ±1.00 D. Uncorrected visual acuity improved by an average of 10 Snellen lines; over 64% of eyes saw 20/20 or better uncorrected and over 93% saw 20/40 or better uncorrected at 6 and 12 months. PARK treatment effectively reduced astigmatism with little average axis error or magnitude error. Corneal haze and safety concerns were minimal.
CONCLUSIONS: Photoastigmatic refractive keratectomy using the Nidek EC-5000 excimer laser provided significant reduction of myopia and astigmatism, with minimal complications. [J Refract Surg 2000;16:122-132]
A Mathematical Model for Laser in situ Keratomileusis and Photorefractive Keratectomy
Authors: Lieberman David M , Grierson Jonathan W 
Published: April 2021

ABSTRACT
PURPOSE: The purpose of ablation refractive surgery is to remove the refractive error from the inherently asymmetric aspheric cornea. Although the technique is gaining wide acceptance and popularity, some patients are left with irregular corneas. Our objective was to develop a methodology to analyze corneal shape, reduce the shape to arcs, modify the local arc value to the desired new arc value, and render a new continuous Euclidean surface without discontinuity.
METHODS: The method to reconstruct the corneal surface consists of importing scanner output elevation data points into a computer-aided design (CAD) application to form the surface model. The corneal arc measurements are derived at 5° increments and centered about the Gauss point of symmetry. Each arc is manipulated to adjust the corresponding arc on the proposed corneal surface to reflect the new arc value, correcting for the refractive error. The method determines the amount of corneal tilt and ablation depth at a given diameter required for the refractive error with a smooth transition zone to the base cornea.
RESULTS: The case example is a patient who began with a spherical refraction of -8.75 D and after LASDX was emmetropic, but had irregular astigmatism and 20/30 best spectacle-corrected Snellen visual acuity. The proposed mathematical model compares the achieved surface shape to the mathematically planned surface contour. An enhancement procedure to remove the LASIK-induced corneal irregularity was designed.
CONCLUSION: A mathematical technique to plan myopic ablative surgery to make the corneal surface regular and symmetric is proposed. [J Refract Surg 2000;16:177-186]
Mycobacterium Keratitis After Laser in situ Keratomileusis
Authors: Gelender Henry , Carter Harvey L , Bowman Bradley , Beebe Walter E , Walters George R 
Published: April 2021

ABSTRACT
PURPOSE: The authors report two cases of Mycobacterium keratitis following LASIK.
METHODS: The case reports are based on a retrospective review of clinical history and associated findings.
RESULTS: Two patients developed infectious keratitis after undergoing laser in situ keratomileusis (LASLK). In case #1, the infection developed after manipulation of the lamellar flap to remove epithelium from the stromal bed. In case #2, prior radial keratotomy may have been a contributing factor to development of the infection. Corneal infiltrates appeared as focal, white, stromal deposits. Cultures isolated Mycobacterium fortuitum from case #1 and Mycobacterium chelonae from case #2. Topical fortified amikacin, clarithromycin, tobramycin, and ciprofloxacin eventually controlled the infection. Topical prednisolone acetate and bandage contact lenses were necessary to control inflammation and pain. Infiltrates were slow to resolve until focal necrosis eroded through the flaps leading to rapid clearing of the infiltrates; however, scarring of the cornea developed at the site of necrosis. Visual recovery was good in the first case but limited in the second.
CONCLUSIONS: Mycobacterium keratitis complicating LASIK may be difficult to eradicate until the sequestered stromal infiltrate drains. Rapid recognition of the causative organism and aggressive medical and surgical management of the infection may improve the outcome. [J Refract Surg 2000;16:191-1951
Laser in situ Keratomileusis for Anisometropic Amblyopia
Authors: Dedhia Niteen C , Behl Seema 
Published: April 2021

ABSTRACT
PURPOSE: To evaluate the efficacy and benefit of laser in situ keratomileusis (LASIK) for correction of anisometropic amblyopia.
METHODS: LASER was performed in 21 eyes of 21 anisometropic amblyopes with a mean age of 27.71 ± 12.24 years. Three patients were less than 18 years of age. LASIK was performed in the more myopic and amblyopic eye using the Chiron Automated Corneal Shaper microkeratome and the Nidek EC-5000 excimer laser system.
RESULTS: Results of 3-month follow-up are presented. Preoperative mean manifest spherical equivalent refraction was -13.20 ± 3.84 D (range, -5.25 to -20.00 D). Mean attempted correction was -12.28 ± 3.47 D. Mean postoperative refraction at 3 months was -0.78 ± 1.63 D. Postoperative uncorrected visual acuity improved by 2 or more lines in all patients and was the same or better than preoperative best spectacle-corrected visual acuity in 95.2% of eyes. Best spectacle-corrected visual acuity improved by 1 or more lines in 61.9% of eyes. The 12-year-old child had a gain of more than 4 lines of uncorrected visual acuity.
CONCLUSION: LASIK was a good alternative to contact lenses in adults for anisometropia and resulted in a gain of best spectacle-corrected visual acuity. In children it may be an alternative method of treatment for amblyopia. [J Refract Surg 2000;16(suppl):S264-S267]
Holmium Laser Thermal Keratoplasty for Hyperopia and Astigmatism After Photorefractive Keratectomy
Authors: Eggink Catharina A , Meurs Piet , Bardak Yavuz , Deutman August F 
Published: April 2021

ABSTRACT
PURPOSE: To report results of holmium laser thermal keratoplasty used to treat induced hyperopia and induced, as well as pre-existing astigmatism after photorefractive keratectomy.
METHODS: Sixteen eyes of 16 patients were included in this study. Contact holmium laser (Technomed Holmium 25) was used in 7 patients to correct hyperopia (8 spots at 8 or 9 nun) and in 9 patients to correct astigmatism (4 spots at 7, 8, or 9 mm). Follow-up evaluation was done after at least 6 months. The effectiveness, stability, and safety of the procedure were investigated.
RESULTS: Spherical correction was ineffective (1.00 D or less) when applied at the 9-mm diameter treatment zone. Spherical correction applied at the 8-mm diameter treatment zone was ineffective in 1 eye. Three eyes achieved 1.00 to 2.00 D change, but 2 of these eyes showed an induced astigmatic change as well. Correction of astigmatism at the 7-mm diameter treatment zone resulted in a 0 to 4.00 D cylinder component change. Treatment at the 8-mm diameter treatment zone showed a 0 to 1.50 D effect and at the 9-mm treatment zone, 0.25 to 1.50 D. All eyes that achieved significant improvement (1.00 D or more change in cylinder component) showed significant overcorrection in the first postoperative phase. There were no sight threatening complications.
CONCLUSION: Holmium laser thermal keratoplasty can be useful for the treatment of overcorrection and induced as well as pre-existing astigmatism after photorefractive keratectomy. However, predictability is low and astigmatism can be induced with the attempted spherical correction. [J Refract Surg 2000;16:317-322]
A Model to Explain the Difference Between Changes in Refraction and Central Ocular Surface Power After Laser in situ Keratomileusis
Authors: Patel Sudi , Alió Jorge L , Pérez-Santonja Juan J 
Published: April 2021

ABSTRACT
PURPOSE: After refractive surgery, changes in central ocular surface power are usually less than actual changes in refraction. The aim of this paper was to examine the theoretical changes in the radius of the epithelial-stromal interface and corneal stromal refractive index which could take place to account for some of the empirical findings.
METHODS: The parameters of an aspheric human eye model featuring grathent index optics was modified using data from a clinical study evaluating effects of laser in situ keratomileusis (LASIK) for correction of moderate to high myopia. Computations were performed to determine: 1) theoretical postoperative radius of the epithelialstromal interface and hence distribution of epithelial thickness, and 2) refractive index of the stroma when the epithelium was of fixed uniform thickness.
RESULTS: Within the central 2-mm diameter refractive zone of the cornea after LASIK for myopia, either of two factors could account for the difference between changes in central ocular surface power and the actual change in ocular refraction: 1) a steepening of the epithelial-stromal interface resulting from a 400% centrifugal increase in epithelial thickness, or 2) a reduction in stromal refractive index from an average of 1.376 to 1.364.
CONCLUSION: The difference between the observed changes in refraction and central ocular surface power could be explained by reduction in stromal refractive index and this could be secondary to a 6.5% increase in water content of the stroma during the postoperative period. The epithelial-stromal interface after LASIK is unlikely to steepen by the extent predicted by our model. This surface is not the source of the difference between the change in refraction and change in central ocular surface power. [J Refract Surg 2000;16:330-3351
Corneal First Surface Optical Aberrations and Visual Performance
Authors: Applegate Raymond A , Hilmantel Gene , Howland Howard C , Tu Elmer Y , Starck Tomy , Zayac E Joseph 
Published: April 2021

ABSTRACT
PURPOSE: Wavefront analysis has demonstrated that refractive surgery-induced corneal first surface aberrations are large, are dominated by symmetric aberrations (spherical-like aberrations), and are correlated to measures of visual performance. It is not clear whether the correlation between corneal first surface aberrations and visual performance can be generalized to other corneal conditions where large asymmetric aberrations (coma-like aberrations) may dominate the aberration structure. The purpose of the research reported here was to determine the general utility of corneal first surface wavefront analysis in predicting visual performance.
METHODS: Patients were 13 normals and 78 patients with a variety of corneal conditions including surgically removed pterygia, penetrating keratoplasty, keratoconus, radial keratotomy, laser in situ keratomileusis, and others. Videokeratographs were taken for all patients and used to calculate corneal first surface wavefront variance for 3 and 7 mm pupils. Similarly, visual performance was quantified by measurements of contrast sensitivity and high and low contrast acuities through both 3 and 7 mm pupils.
RESULTS: Statistically significant correlations existed between all three measures of visual performance and the corneal wavefront variance. All relationships were stronger for the 7 mm diameterpupil condition than the 3 mm pupil.
CONCLUSION: Regardless of the cause, corneas with increased wavefront variance showed a quantifiable decrease in visual performance that was pupil size dependent. [J Refract Surg 2000; 16: 507-514]
Measurement of Corneal Thickness By Videopachymetry: Preliminary Results
Authors: Franco Sandra , Almeida José B , Parafita M 
Published: April 2021

ABSTRACT
Corneal thickness measurements find applications in areas such as diagnosis and management of corneal disorders and corneal surgery. We present a technique for the measurement of corneal thickness using a CCD camera mounted on a slit-lamp biomicroscope and common image processing software. Thickness measurements were performed on three RGP contact lenses of known thickness with an average error of 5 µm, SD of 8 µm. Measurements of a living cornea yielded a thickness of 505 µm and a SD of 8 µm for 10 consecutive measurements; this is an acceptable value. [J Refract Surg 2000;16:S661-S663]
Geometric Ray Tracing Analysis of Visual Acuity After Laser in situ Keratomileusis
Authors: del Cotero Jose N Fernández , Moreno Fernando , Ortiz Dolores , Vélez Enrique , González Francisco , Saiz Jose M , Velarde Jose I , De Valentín-Gamazo Luis , García-Antón Paula 
Published: April 2021

ABSTRACT
PURPOSE: Using a geometric ray tracing model, we explain the increase in visual acuity observed in myopic patients after laser in situ keratomileusis (LASIK).
METHODS: This study included 37 eyes of 23 patients who underwent LASIK. All patients had myopia and a spectacle-corrected visual acuity of 0.95 or worse. Clinical tests included biometry, corneal topography, pachymetry, and refraction (with and without cycloplegia). Calculations were made by tracing rays through all the refractive surfaces of the eye based on a Le Grand-type theoretical model of the whole eye.
RESULTS: Comparison of spectacle-corrected visual acuity of the eye before surgery, the size of the blur circle calculated by ray tracing, and the magnification for the ocular system facilitated a numerical criterion to assess visual acuity by geometric calculation. This criterion was applied to myopic eyes that underwent LASIK, and the maximum increase in spectacle-corrected visual acuity was predicted. An actual increase in visual acuity of approximately 40% of the predicted maximum was observed in patients.
CONCLUSIONS: With geometric ray tracing, it was possible not only to obtain an estimate of the visual acuity before LASIK but also to assess the value of the maximum and probable increases in visual acuity after LASIK. [J Refract Surg 2001;17:305-309]
Epithelial and Stromal Changes Induced by Intacs Examined by Three-dimensional Very High-frequency Digital Ultrasound
Authors: Reinstein Dan Z , Srivannaboon Sabong , Holland Simon P 
Published: April 2021

ABSTRACT
PURPOSE: To examine epithelial and stromal layers by three-dimensional very high-frequency (VHF) digital ultrasound scanning before and after implantation of Intacs (intracorneal ring segments [ICRS]).
METHODS: Three-dimensional scanning was performed in five eyes before and 3 months after Intacs insertion. Digital signal processing techniques provided high-resolution B-scan imaging and I-scan traces for high-precision (1-µm) three-dimensional pachymetry. Thickness maps of individual corneal layers were constructed of the epithelium, stroma, and full cornea before and after surgery. Difference maps for epithelium and stroma were produced to examine anatomical changes in the thickness profile induced in each layer and correlate these to refractive changes.
RESULTS: B-scan examination revealed stromal and epithelial anatomy anterior and adjacent to the Intac. Ring depth could be measured topographically. There was stromal lamellar displacement by the ring segments that produced a concave anterior stromal groove within an annulus central to the ring. Epithelial filling of this concavity was shown in three dimensions in such a way as to produce orthogonally asymmetrical flattening of the corneal surface, thus potentially accounting for induced astigmatism. Mapping of the central stroma demonstrated thickening, potentially also accounting for astigmatic changes ascribable to orthogonal asymmetry.
CONCLUSIONS: VHF digital ultrasound scanning provided imaging and three-dimensional thickness mapping of corneal layers, enabling anatomical evaluation of the changes induced in the cornea by Intacs. [J Refract Surg 2001;17:310-318]
Complications of Laser in situ Keratomileusis: Etiology, Prevention, and Treatment
Authors: Ambrósio Renato , Wilson Steven E 
Published: April 2021

ABSTRACT
PURPOSE: To review the etiology, prevention, and management of laser in situ keratomileusis (LASIK) complications.
METHODS: Review of literature and the experience of the authors.
RESULTS: Careful preoperative screening is critical to prevention of many potential complications of LASIK. Flap complications that occur during surgery are typically managed by replacement of the flap and repeating the surgery or applying special methods such as transepithelial photorefractive keratectomy weeks to months following the initial procedure. A common source of serious complications is the use of a microkeratome that functions after improper assembly. Timely treatment of postoperative complications such as diffuse lamellar keratitis, flap striae, and infection is critical to an optimal outcome.
CONCLUSION: Most complications of LASIK can be treated effectively and have minimal effect on the final outcome after surgery, if appropriate methods are used for management. [J Refract Surg 2001;17:350-379]
Orbital Aspergillosis
Authors: Dortzbach Richard K , Segrest David R 
Published: April 2021

SUMMARY
We treated a 40-year-old male who had orbital aspergillosis and presumed early intracranial extension with limited orbital exenteration and adjunctive amphotericin B. Forty-two months later the patient is alive without recurrence. Our patient illustrates the typical presentation of orbital aspergillosis with severe periorbital pain and proptosis; however, he did not have the usual concomitant sinusitis. Aggressive surgical and antifungal therapy in this case was successful in preventing further intracranial extension, which usually has a high mortality rate.
Surgery for Involutional Entropion
Authors: Jackson Steven T 
Published: April 2021

SUMMARY
Surgery for involutional entropion must correct horizontal eyelid laxity, vertical laxity, and overriding of the tarsus by the infra-tarsal tissues. The surgery should give lasting functional and pleasing cosmetic results. These goals are achieved with: 1) a blepharoplasty incision and reflection of a skin-muscle flap; 2) excision of a wedge of eyelid tissue at the lateral canthus; 3) barrier sutures or tuck of the retractors; 4) reattachment of the lid to the lateral orbital rim; and 5) excision of excess skin.
Cryotherapy and Photocoagulation in the Management of Retinoblastoma: Treatment Failure and Unusual Complication
Authors: Margo Curtis , Hidayat Ahmed A , Marshall Charles F , Renaldo Donald P 
Published: April 2021

SUMMARY
Ophthalmologists treating children with retinoblastoma need to be aware of the limitations of new forms of therapy and their complications. For this reason the following case of a child with a small peripheral retinoblastoma that failed to respond to treatment with both cryotherapy and photocoagulation is recorded. The development of a rapidly growing juxta papillary lesion prompted immediate enucleation. Histological examination revealed viable tumor cells remaining in the areas that were previously treated. The juxtapapillary mass consisted of optic nerve and detached peripapillary retina that were "dragged" towards the tumor by a thick fibrocellular membrane containing many myofibroblasts.
Surgical Therapy of Traumatic Hyphema
Authors: Weiss Jayne S , Parrish Richard K , Anderson Douglas R 
Published: April 2021

SUMMARY
The usual management of traumatic hyphemas in our institution has been to avoid or delay surgery until absolutely demanded by the clinical course. Despite this, most (73%) of our in-patients with total hyphema underwent surgery before leaving the hospital. In those who required surgery, 43% developed corneal staining. Optic nerve damage occurred in half of the patients whose surgery was performed eight or more days after the hyphema occurred, but was absent in those undergoing earlier surgery.
The usual procedure used in this series was a trabeculectomy with iridectomy and gentle irrigation of the anterior chamber, and no surgical complications occurred. We believe that surgery, being relatively safe, should be performed early in cases of total hyphema unless the elevated intraocular pressure is controlled medically and spontaneous resolution is clearly imminent. For cases in which surgery is nearly inevitable, we suggest that earlier surgery might reduce the incidence of optic nerve damage and corneal staining.
Management of an Intact Vitreous Face in Penetrating Keratoplasty
Authors: Schanzlin David J , Smith Ronald E 
Published: April 2021

SUMMARY
Recent evidence suggests that the manipulation of the vitreous face may be a factor in increasing the incidence of cystoid macular edema. Since a bulging vitreous face at the ti me of penetrating keratoplasty may cause complications with the corneal transplant, we have devised a technique of pars plana vitrectomy that allows for an adequate vitrectomy while maintaining an intact vitreous face.
Conjunctivodacryocystorhinostomy With Mucous Membrane Graft
Authors: Campbell Charles B , Shannon Gerard M , Flanagan Joseph C 
Published: April 2021

SUMMARY
Eleven patients with obstructed lacrimal canaliculi underwent conjunctivodacryocystorhinostomy modified by lining the fistula with buccal mucosa at the time of surgery. Four patients had the tube removed after six months. All four have patent mucous membrane lined fistulas with follow-up ranging from ten to 13 months. One patient removed his tube on the second post-operative day. His fistula closed immediately.
For comparison, the remaining six patients retain their tubes. They are free from epiphora but suffer from some of the complications of the tube itself, namely tube extrusion, tube migration, and chronic conjunctival irritation and discharge.
The surgical technique is described, histopathologic material is presented, and the initial results are discussed.
Variation in the Pathophysiology of Involutional Entropion and its Treatment
Authors: Schaefer Arthur J 
Published: April 2021

SUMMARY
It is essential to understand the anatomy in detail, the normal physiology and pathophysiology of the lower eyelid to properly correct an involutional entropion surgically.
The fact that 50% of involutional entropion cases show an actual defect (dehiscence or complete detachment) of the retractor aponeurosis of the lower eyelid is important. The surgeon must be cognizant of the high rate of occurrence of these defects and look for them during the surgical repair. The direct external approach of the imbrication procedure makes it easy to identify these aponeurotic retractor defects.
The pathophysiologic changes can vary with each case and are as follows: involutional changes (attenuation, dehiscence, detachment) taking place in the lower lid retractors; atony of the lateral and medial canthal tendons may be present and must be recognized; enophthalmus of the aging is present; the septal orbicularis loses it firm attachment to the orbital septum.
It is paramount that the pathophysiologic changes present in each case be recognized and surgically corrected to prevent recurrences.
Treatment of Lower Lid Retraction by Tarsal-Conjunctival and Skin-Muscle Transposition Flaps
Authors: Wiggs Eugene O 
Published: April 2021

SUMMARY
A method of alleviating full thickness lower eyelid retraction is described. Transposition flaps of tarsus-conjunctiva and skin-muscle are transposed from the ipsilateral upper lid into an infratarsal transverse blepharotomy in the retracted lower lid.