Surgical microscope system

A surgical microscope comprises an illuminating light source for observation and/or photographing, an observation optical system, an index projecting optical system and a cornea configuration measuring optical system. The index projecting optical system includes an index which is removably inserted in the illuminating light beam emitted from the illuminating light source and transmitted through an objective of the observation optical system, thereby dispensing with any particular light source for measuring a cornea configuration, and a cornea configuration measuring mode and a photographing mode being automatically changeable by automatically detecting the presence or absence of the index within the optical path of the microscope.

BACKGROUND OF THE INVENTION 
The present invention relates to a surgical microscope system, and more 
particularly, to a surgical microscope system for performing a microscopic 
surgical operation. 
In recent years, the so-called microsurgery of performing a microscopic 
surgical operation while observing with a microscope is widely used in 
public. The so-called microsurgery, which makes it possible to perform a 
high precision microscopic surgical operation, has greatly contributed to 
the wide fields including the ophthalmology, neurosurgery, 
otorhinolaryngology, plastic surgery and the like. Particularly, there has 
been an increasing demand in the field of ophthalmology for performing a 
cornea operation by measuring a radius of curvature of the cornea and 
controlling the extent of a suturing operation in accordance with the 
measured value so as to prevent the corneal astigmatism from occurring 
after the operation. To meet the demand, for example, Japanese Laid-Open 
Publication No. Sho 59/1984- 155232 discloses an apparatus for measuring 
the cornea configuration which is mounted on a surgical microscope in a 
unitary manner therewith. The apparatus will be described hereinafter with 
reference to FIGS. 1 to 4. 
In FIG. 1, a surgical microscope includes a body 1, an objective lens 2, a 
light source 3 such as a circular fluorescent lamp for illuminating a 
projection index 4. When the index 4 is projected onto a cornea Ec of an 
eye to be measured, a reflected image 4' (virtual image) of the cornea Ec 
is formed to the index 4 by the convex-mirror action of the cornea Ec. The 
reflected image 4' varies in its size in accordance with a curvature of 
the radius of the cornea Ec. When the cornea Ec has regular astigmatism, 
the reflected image 4' is in an elliptic form and when the cornea Ec has 
irregular astigmatism, the reflected image 4' is in an irregular form. For 
this reason, it is possible to determine a surface configuration of the 
cornea Ec by measuring the reflected image 4' thereof. 
An optical path change member 5 is provided in an optical system for 
measuring a cornea configuration which has a reflecting surface oblique to 
the exterior of an observation optical system in a space between the 
binocular observation optical paths. The optical path change member 5 is 
fixed adjacent to the objective lens 2 to the microscope body 1. 
Reference numeral 6 is an objective lens of the cornea configuration 
measuring optical system. A diaphragm plate 7 is disposed adjacent to the 
rear side focus of the objective lens 6. A deflecting prism 8 is fixed 
adjacent to the rear side of the diaphragm plate 7. The diaphragm plate 7 
has, for example, five small trough-holes at its center portion, as shown 
in FIG. 2. The deflecting prism 8 is in such a form as five prism pieces 
of the wedge type are put together in a unitary form, as shown in FIG. 3. 
The through-hole openings of the diaphragm plate 7 agree with the 
respective centers of the prism pieces of the deflecting prism 8. 
Projecting light beams from the reflected image 4' incident upon the 
objective lens 6 are divided into five beams through the openings of the 
diaphragm plate 7 and the deflecting prism 8. The five beams are then 
reflected by a reflecting mirror 9 to form images respectively upon light 
receiving surfaces of detector elements 10, such as one dimensional 
photodiode array. The five detector elements 10 are arranged respectively 
at positions where projected images 4" are formed to the reflected image 
4', for example, as shown in FIG. 4. 
With the cornea configuration measuring device of the structure just 
described above, a measuring switch (not shown) is turned on and at the 
same time a configuration of the reflected image 4' is detected by the 
detector elements 10. The detected signals are electrically amplified and 
calculated by a signal operating circuit (not shown) to determine the 
major and minor axes of an ellipse and the elliptic axes for the reflected 
image 4'. From these data a radius of curvature, a degree of astigmatism, 
an axial angle of astigmatism and the like are determined and displayed. 
When the cornea reflected image is not circular or elliptic because of 
irregular astigmatism, radii of curvature are determined and displayed 
respectively for meridional directions of the cornea. 
Since a conventional apparatus is constructed as described above, it is 
necessary to provide a light source only for the cornea configuration 
measurement in addition to an illumination light source for observation or 
photographing. In addition, switches are provided for respective light 
sources. As a result, the apparatus becomes bulky, expensive and 
complicated in operation. Furthermore, since it is very troublesome to 
remove the measuring device from the apparatus after the cornea 
configuration measurement is completed, an operation must be performed 
with the measuring device attached to the apparatus between the objective 
lens and eyes to be measured, resulting in difficulty in operation, that 
is very dangerous. 
SUMMARY OF THE INVENTION 
It is an object of the present invention to provide a surgical microscope 
which is capable of measuring a cornea configuration with a simple and 
inexpensive structure and an easy and safe operation. 
According to the present invention, the surgical microscope comprises an 
illumination light source for observation and/or photographing, an 
observation optical system, an index projecting optical system and a 
cornea configuration measuring optical system, the index projecting 
optical system including an index which is removably inserted in 
illumination light beams emitted from the illumination light source and 
passing through an objective lens of the observation optical system, 
thereby dispensing with a particular light source and its switch for 
measuring the cornea configuration and securing an operation space with a 
simple operation except during the measurement. 
Besides, according to the present invention, a perforated index which is 
illuminated by a light source for photographing of the surgery microscope 
is insertably disposed in the microscope optical path between the 
objective lens and an eye to be measured and a detector is provided for 
detecting whether the perforated index lies with the microscope optical 
path, whereby a cornea configuration measuring mode and a photographing 
mode are automatically switched with an output from the detector when the 
perforated index lies within the microscope optical path or not, 
respectively, thus allowing an operator to concentrate his attention on an 
operation. 
Furthermore, according to the present invention, since the cornea 
configuration can be measured with a light source for photographing and 
its switching operation, any particular light source and its switch for 
measuring the cornea configuration can be dispensed with, so that it is 
possible to provide an inexpensive surgery microscope which is improved in 
operation and has a compact and simple structure. In addition, since an 
illumination during the cornea configuration measurement is given by a 
bright light source for an electronic flashlight emission, it is possible 
to momentarily perform the measurement even with a photosensitive element 
of low sensitivity. The cornea configuration measuring and the 
photographing modes can be automatically switched by detecting whether the 
index exists or not and in order to develop a trigger signal only a single 
switch, for example, may be arranged at a proximal portion, so that it is 
still possible to easily operate and to allow an operator to concentrate 
his attention on the operation. Upon completion of the cornea 
configuration measurement, it is possible to simply remove the index so as 
to make a surgical operation safe and reliable.

DESCRIPTION OF THE PREFERRED EMBODIMENTS 
In FIG. 5, which illustrates an optical system of a first embodiment of the 
present invention, E designates an eye to be measured and C designates a 
cornea of the eye E. An illumination light source 11 such as a halogen 
lamp illuminates the eye E through an objective lens 13 by light beams 
reflected by a prism 12 and thus forms the so-called coaxial illumination 
optical system of a surgical microscope. The objective lens 13, a relay 
lens 14 and an eyepiece 15 form an observation optical system of the 
surgical microscope. Although not shown, pairs of the relay lens 14 and 
the eyepiece 15 are disposed in symmetry with respect to the optical axis 
O of the objective lens 13 in a plane perpendicular to the drawing sheet 
so as to stereoscopically observe the eye E with right and left eyes of an 
observer. 
Next, an index projecting optical system will be described. Light beams 
emitted from the light source 11 pass through the prism 12 and the 
objective lens 13 to illuminate an index provided by perforated slit plate 
16. The slit plate 16 has a central opening 16a, as shown in FIG. 6, 
viewed from the direction of the optical axis of the surgical microscope 
and further includes shade plates 16b, 16b' around the periphery of the 
hole 16a. An annular belt-shaped slit 16c is provided between the shade 
plates 16b, 16b'. Light beams passing through the slit 16c impinge upon 
the cornea C of the eye E after passed through a collimator lens 17. The 
collimator lens 17 forms a cylindrical lens which has the refractive power 
in each of meridian surfaces and has no refractive power in a surface 
perpendicular to each of the meridian surface, that is, a surface 
including a ring-shaped circumference. The collimator lens 17 is disposed 
at a distance of its focal length from the slit 16c, which makes light 
rays appeared from the slit 16c parallel so as to project the light rays 
from the optically infinite point onto the cornea C. Light rays appeared 
from the slit 16c have the same angle .theta. around the optical axis O. A 
virtual image 16' of the annular slit 16c is formed on the cornea C by 
mirror reflection. The slit plate 16 and the collimator lens 17 are 
attached to a microscope body 27, as shown in FIG. 7, which are integrally 
supported by a slide arm 20 fixed into a guide 19 provided on the 
microscope body 27. The slide arm 20 is insertable at a predetermined 
position in such a manner that it is rotatable around an axis parallel to 
the optical axis of the microscope and is movable up and down in the 
direction of the optical axis. 
FIGS. 8 and 9 show modifications of a structure including the perforated 
slit plate 16 and the collimator lens 17. The slit plate 16 and the 
collimator lens 17 are supported by a rotary arm 21 and a magnet arm or 
support member 22 to secure to the microscope body 27. In FIG. 8, the slit 
plate 16 and the collimator lens 17 are insertable in a predetermined 
position on the optical axis O of the microscope by turning the support 
member or arm 21. In FIG. 9, the slit plate 16 and the collimator lens 17 
are insertable in a predetermined position on the optical axis O of the 
microscope by attaching the support member 22 to the microscope body 27 
utilizing the magnetic force of a magnet portion 22a of the support member 
22, resulting in a simple operation. 
The cornea configuration measuring optical system will now be described 
hereinafter. The virtual image 16c' of the slit 16c which is formed on the 
cornea C of the eye E is transmitted through the collimator lens 17, the 
central opening 16a of the slit plate 16, the objective lens 13 and an 
interference filter 18 such as a dichroic mirror which transmits visible 
rays and reflects infrared rays. Accordingly, reflected infrared rays pass 
through a relay lens system 19 and further are transmitted through or 
reflected by half mirrors 20a, 20b and finally are formed in an image on 
three pieces of one-dimensional sensors 21a, 21b, such as CCDs which are 
sensitive to infrared rays. The sensors 21a, 21b, 21c as viewed from the 
direction of the optical axis O' are arranged, as shown in FIG. 10, so as 
to be angularly displaced with respect to each other by 120.degree.. 
Since the cornea C is generally regarded as a toric plane, even though the 
annular slit 16c is in a true circle, the virtual image 16c' on the cornea 
C and images 16c" on the sensors 21a, 21b, 21c take a form of ellipse. 
Consequently, a radius of curvature r, a degree of astigmatism and an 
astigmatic axial angle A of the cornea C can be determined by measuring 
the elliptic configuration. 
In general, the equation of an ellipse is expressed with reference to any 
coordinate axes X and Y as follows: 
EQU ax.sup.2 +by.sup.2 +2cxy+dx+ey+1=0 
where a to e are five unknown quantities, which can be determined by taking 
coordinates of five points out of six on the image 16 formed on the three 
one-dimensional sensors 21a, 21b, 21c. 
In operation, when the cornea configuration is measured, the optical axis 
of the eye E to be measured is aligned with the optical axis O of the 
microscope and a distance between the objective lens 13 and the cornea C 
of the eye E is adjusted by effecting a focusing operation with the 
microscope body 27 moving vertically together with the objective lens 13. 
Then, the cornea configuration is measured by interposing the slit plate 
16 and the collimator lens 17 of the index projecting optical system at a 
predetermined position on the optical axis O between the objective lens 13 
and the cornea C. In general, a binocular stereoscopic microscope has a 
large depth of focus and it is difficult to adjust a distance between the 
objective lens 13 and the cornea C of the eye E. Accordingly, while there 
may be some variations in the distance between the cornea C and the slit 
plate 16 and the collimator lens 17, such variations do not practically 
affect a measuring accuracy since an image of the slit 16c is projected 
onto the cornea C with parallel light rays. 
Upon completion of the cornea configuration measurement, the slit plate 16 
and the collimator lens 17 are immediately removed from the optical axis O 
so as not to interrupt a surgical operation to secure an operational 
space, resulting in a smooth and safe surgical operation. 
In addition, as described above, no particular light source for measuring 
the cornea configuration is required, so that the apparatus is simple in 
structure and inexpensive. 
FIG. 11 shows an optical system of a second embodiment of a surgical 
microscope according to the present invention. Like reference numerals 
designate like or corresponding parts and hence their descriptions will be 
omited. 
In FIG. 11, the illumination light source 11 for observation, relay lens 
24, flashlight emission source 23 for photographing, prism 12 and 
objective lens 13 constitute the so-called coaxial illumination optical 
system of the surgical microscope. The objective lens 13, relay lens 14 
and eyepiece 15 constitute the observation optical system. The light 
source 11, prism 12, objective lens 13, perforated slit plate 16 and 
collimator lens 17 constitute the index projecting optical system. The 
flashlight emission source 23, prism 12, objective lens 13, perforated 
slit plate 16, collimator lens 17, dichroic mirror 18, relay lens system 
19, half mirrors 20a, 20b and one-dimensional sensors 21a, 21b, 21c 
constitute the cornea configuration measuring optical system. The 
flashlight emission source 23, prism 12, objective lens 13, dichroic 
mirror 18, relay lens 14, beam splitter 25, image forming lens 26 and 
camera 57 constitute the photographing optical system. 
Although not shown, the eyepieces 15 constitute a pair of optical system 
together with the relay lenses 14 in symmetry with respect to the optical 
axis O of the objective lens 13 on the plane perpendicular to the drawing 
sheet. 
Both perforated slit plate 16 and the collimator lens 17 is removably 
attached to the microscope body 27 by means of the support member 22, as 
shown in FIG. 9. The magnet portion 22a of the magnet arm is insertable in 
the recess 27b formed in the side wall of the microscope body 27. The tip 
end of a movable contact piece 50a of a microswitch 50 is sticking out of 
the recess 27b, which is used as an index detector provided in the side 
wall of the microscope body 27 which will be described later. 
In FIG. 13, reference numerals 50 designates the above-mentioned index 
detector. A changeover device 51 includes a main switch (not shown) for 
turning a flashlight emission control on and off by selecting either of a 
cornea measuring control 55 and a camera control 56 which will be 
described later, in response to an output from the index detector 50. A 
portion I enclosed by a dotted lines forms the cornea configuration 
measuring system which includes an index image detector 52 for detecting 
an index image by cornea reflection, a calculator 53 for calculating 
parameters of a cornea configuration, a cornea measuring indicator 54 and 
the above-mentioned cornea measuring control 55 for controlling the index 
image detector 52, calculator 53 and cornea measuring indicator 54. A 
portion II enclosed by other dotted lines forms the photographing system 
which includes a camera 57, a film winder 58 and the abovementioned camera 
control 56 for controlling the camera 57 and the winder 58 which are 
constituted so as to deliver a signal for indicating shutter opening 
conditions. In addition, there are provided a flashlight emission control 
60 for controlling a flashlight power source 61 and a flashlight emission 
tube 62 and a trigger signal generating means 63 such as a foot switch and 
the like. 
In operation, when the eye E to be inspected is observed, light rays from 
the illumination light source 11 for observation is reflected by the prism 
24 to illuminate the eye E through the objective lens 13. At this time, it 
is possible to stereoscopically observe the eye E by observing a pair of 
the observation optical systems with the left and right eyes, which 
systems are constructed perpendicularly to the drawing sheet. 
When a cornea configuration is measured, the support member 22 is first 
mounted at a predetermined position of the microscope body 27. The cornea 
configuration is measured by light rays from the flashlight emission 
source 23 in the same manner as described in the first embodiment. At this 
time, when the perforated slit plate 16 and the collimator lens 17 are 
inserted in the optical path by mounting the support member 22 on the 
microscope body 27, the contact piece 50a of the index detector 50 is 
pushed by the magnet portion 22a to produce a detection signal which is 
fed to the changeover device 51. The changeover device 51 selects one of 
the cornea configuration measuring control 55 and the camera control 56 in 
response to the signal from the image detector 50 and maintains the 
selected control on standby. On the other hand, a main switch (not shown) 
within the device also turns on to maintain the flashlight emission 
control 60 on standby. Consequently, the condition that a series of 
operations will be commenced by a trigger signal input from a trigger 
signal generating means 63 is caused. Consequently, assuming that the 
cornea configuration measuring control 55 is selected in the changeover 
device 51 by an output from the index detector 50 to be in the cornea 
configuration measuring mode, when a trigger signal is given from the 
trigger signal generating means 63 to the changeover device 51, it 
delivers the trigger signal to both the cornea configuration measuring 
control 55 and the flashlight emission control 60. Then, the cornea 
configuration measuring device 55 is ready for receiving an output from 
the index image detector 52. At the same time, the flashlight emission 
control 60 causes the flashlight emission tube 62 to emit flashlight by 
receiving the trigger signal. Also, a light amount detector (not shown) 
within the flashlight emission control 60 commences the photometric 
operation simultaneously with the commencement of flashlight emission. 
When a sufficient amount of light is reached, the emission control 60 
causes the tube 62 terminate the flashlight emission and delivers a 
flashlight emission terminate signal to the cornea configuration measuring 
control 55. With the flashlight emission the index image detector 52 
delivers an output corresponding to a configuration of an index image 
which is obtained by reflection of the cornea C of the eye E to the cornea 
configuration measuring control 55. When received the index image 
configuration output, the control 55 temporarily retains the output signal 
and inhibits an input from the index image detector 52 until the 
flashlight emission terminate signal from the emission control 60 is 
inputted to feed the retained data of the index image to the calculator 
53. Then, the calculator 3 calculates parameters of the cornea 
configuration using the quadratic equation described above to feed an 
output through the control 55 to the cornea configuration measuring 
indicator 54 which displays the calculated results. At this time, it is to 
be understood that when the control 55 is directly connected to an 
exterior apparatus such as a personal computer or the like, the calculator 
53 is not required. Thus, the cornea configuration can be measured by a 
series of operations described above. 
In the photographing operation, the support member 22 is removed from the 
microscope body 27 to eliminate both the slit plate 16 and the collimator 
lens 17 from the optical path. When the eye E and the cornea C are 
illuminated through the prism 12 and the objective lens 13 by allowing the 
flashlight emission source 23 to emit flashlight, light rays from the 
cornea C is transmitted through the objective lens 13 to the dichroic 
mirror 18 in which only visible rays are transmitted. Part of the 
transmitted rays are reflected by the beam splitter 25 to take a 
photograph of the cornea C by the camera 57 through the image forming lens 
26. 
While the photographing mode is on with the series of operations described 
above after the support member 22 from the microscope body 27 is removed, 
the camera control 56 detects whether the film winding operation of the 
camera 57 is completed. When not completed, the camera control 56 causes 
the film winder 58 to operate. After the completion of the film winding, 
when the changeover device 51 receives a trigger signal from the trigger 
signal generating means 63, the device 51 transmits the trigger signal to 
the camera control 56. Then, the camera control 56 causes the camera 57 to 
release a shutter. When the shutter is fully opened, the camera 57 
delivers a flashlight emission initiate signal to the flashlight emission 
control 60. Then, a flashlight emission and a photometric operation are 
performed in the same manner as in the cornea configuration measurement. 
When the shutter is closed, the camera control 56 receives photographing 
completion signal from the camera 57 to operate the film winder, whereby a 
film is wound. Thus, the photographing is performed by the above-mentioned 
series of operations. 
As is clear from the foregoing, the support member 22 for supporting the 
slit plate 16 and the collimator lens 17 is easily and promptly detachable 
to the microscope body 27 except during the cornea configuration 
measurement, so as not to be hindrance to a surgical operation. With the 
microscope of the present invention, the cornea configuration measuring 
mode and the photographing mode are automatically switched depending upon 
whether the support member 22 is in the optical axis in response to an 
output from the index detector 50. Furthermore, since the recess 27b of 
the microscope body 27 in which the support member 22 is inserted is 
positioned at a predetermined distance, a relative distance between the 
slit plate 16 and the collimator lens 17 and the eye E under inspection is 
determined by a working distance of the objective lens when the microscope 
is brought into focus on the cornea while viewing through the microscope. 
Although in the above embodiment the changeover device 51, the cornea 
configuration measuring control 55, the calculator 53 and the camera 
control 56 are separately provided, it will be easily understood that the 
controlling and the calculating operations may be achieved using a 
computer with software of the same functional structure. While the index 
detector 50 is constituted by a microswitch, it is further understood that 
the detector 50 is not limited thereto but may be a photo-interrupter or 
the like which is disposed so as to be interrupted by the support member 
22 when the slit plate 16 and the collimator lens 17 are within the 
optical path. 
As described above, according to the present invention, since the cornea 
configuration can be measured with the light source for photographing and 
its switch operation, no particular light source for cornea configuration 
measurement and its switch is required, so that it is possible to provide 
a compact and inexpensive surgical microscope of a simple structure and of 
an easy handling. In addition, since the illumination during the cornea 
configuration measurement is performed with a bright flashlight emission 
source, it is possible to use even a photosensitive element of low 
sensitivity and to effect the measurement momentarily. Furthermore, it is 
possible to effect either the cornea configuration measurement or the 
photographing by automatically detecting the presence of the index and to 
provide only one switch, for example, near the proximal portion of the 
microscope as the trigger signal generating means. Consequently, 
operations are not cumbersome and an operator can concentrate his 
attention on a surgical operation. Also, upon completion of the cornea 
configuration measurement the index can be easily removed, so that the 
ease and safety of operation are improved. 
FIG. 14 shows another optical system utilizing a flashlight source for 
photographing which is housed within a surgical microscope as an 
illumination light source for the cornea configuration measurement 
according to a third embodiment of the present invention. The system 
causes the flashlight source 23 to emit light rays in synchronism with the 
time of the measurement and has advantages of obtaining a sufficient 
amount of measuring light and a high-speed measurement.