The white-light confocal microscope offers an in vivo, cellular-level resolution view of the cornea. This instrument has proven to be a valuable research and diagnostic tool for the study of infectious keratitis. In this study, we investigate the direct visualization of herpes simplex virus type 1 (HSV-1)-infected corneal epithelium, with in vivo confocal microscopy, using HSV-1 immunofluorescent antibodies. New Zealand white rabbits were infected with McKrae strain of HSV-1 in one eye; the other eye of each rabbit was used as an uninfected control. Four days later, the rabbits were anesthetized and a cellulose sponge was applied to each cornea, and a drop of direct HSV fluorescein-tagged antibody was placed on each sponge every 3 to 5 minutes for 1 hour. Fluorescence confocal microscopy was then performed. The HSV-infected corneas showed broad regions of hyperfluorescent epithelial cells. The uninfected corneas revealed no background fluorescence. Thus, using the confocal microscope with a fluorescent cube, we were able to visualize HSV-infected corneal epithelial cells tagged with a direct fluorescent antibody. This process may prove to be a useful clinical tool for the in vivo diagnosis of HSV keratitis.

The presence of disodium fluorescein as a fluorescent marker in the vitreous body and also in the chorioretina, as a consequence of the administration for fluorescein angiography, influences the effectiveness of laser retinal photocoagulation on a time- and wavelength- dependent basis, in diabetic patients affected by proliferative diabetic retinopathy. In this work we discuss the problem of photocoagulation in the presence of fluorescein, from the viewpoints of (1) shielding of laser radiation by vitreous, (2) heating of the vitreous, and (3) the role of fluorescein in the chorioretina.

A newly developed backscattering fiber optic probe using the technique of dynamic light scattering (DLS) has been applied to obtain three-dimensional structural information in excised, but intact bovine lens and vitreous humor.

Recently, extended studies are provided in order to find a robust, accurate measurement method with adjustable sensitivity for determining corneal topography or for the best fitting of contact lenses. A promising method can be moire deflectometry (Talbot interferometry) which is the incoherent analogy to sharing interferometry. Here, an experimental setup for measurement of the topography of the cornea is presented. The possible application of Twyman-Green interferometry for measurement of contact lenses is discussed. The evaluation methods for retrieving the data from the interferograms is discussed.

We describe initial experimental results of a new hybrid digital and analog design for retinal tracking and laser beam control. Initial results demonstrate tracking rates which exceed the equivalent of 50 degrees per second in the eye, with automatic lesion pattern creation and robust loss of lock detection. Robotically assisted laser surgery to treat conditions such as diabetic retinopathy, macular degeneration, and retinal tears can now be realized under clinical conditions with requisite safety using standard video hardware and inexpensive optical components.

The high degree of mobility of mammal's eye components largely reduces efficiency of diagnostics and realization of surgical operations at a microlevel with usage of laser equipment. A system of precision installation of a laser beam in a given point of an eye, and maintenance adaptive (fixed in relation to a given point) its deduction in it, in current whole time of observation or realization of surgical interference, irrespective of a duration is developed and created. The system is constructed on the basis of executive gears, executed with piezoceramics, enabling us to execute practically inertia less management of influencing laser radiation in given sector of angles. The experimental research of a developed system has demonstrated an opportunity of reduction of errors of prompting and stabilization coherent of a light beam in a given point of an eye in 5 . . . 8 times in comparison with results received under usual conditions of realization of similar surgical operations.

Endoscopy is a method of observation that allows direct viewing of certain internal structures of the eye which cannot be easily visualized through conventional slit lamp/microscope arrangements. An endoscopic system can also be helpful when a transparent structure of the eye becomes turbid, e.g., a hazy cornea. Over the past years substantial efforts have been oriented to miniaturize endoscopes for use in ophthalmology. Ophthalmic endoscopes have been presented on the basis either of coherently ordered fiber bundles or of optical lenses such as the gradient-index ones (GRIN). Endoscopes that provide a basic visualization function can also be fitted with one or more ancillary channels that may provide additional features such as aspiration/injection or laser treatment.

Purpose: To develop a simple suture lysis technique for post-trabeculectomy examinations under anesthesia since slit lamp laser suture lysis in the clinic cannot be performed on infants and young children. Methods: An argon endolaser probe lysed 10-0 nylon suture through conjunctiva harvested from human cadaver eyes. Since suture lysis failed with the thick Hoskins lens, clear plastic from the suture package compressed the conjunctiva. The conjunctiva was examined histologically. Results: Argon laser suture lysis (250 mW, 0.1 sec, 488 - 514 nm) was achieved without conjunctival damage. Conclusion: The argon endolaser probe is effective for suture lysis when the slit lamp cannot be used.

The smoothness and accuracy of PMMA ablations with a prototype scanning photorefractive keratectomy (SPRK) system were evaluated by optical profilometry. A prototype frequency- quintupled Nd:YAG laser (Laser Harmonic, LaserSight, Orlando, FL) was used (wavelength: 213 nm, pulse duration: 15 ns, repetition rate: 10 Hz). The laser energy was delivered through two computer-controlled galvanometer scanners that were controlled with our own hardware and software. The system was programmed to create on a block of PMMA the ablations corresponding to the correction of 6 diopters of myopia with 60%, 70%, and 80% spot overlap. The energy was 1.25 mJ. After ablation, the topography of the samples was measured with an optical profilometer (UBM Messtechnik, Ettlingen, Germany). The ablation depth was 10 to 15 micrometer larger than expected. The surfaces created with 50% to 70% overlap exhibited large saw-tooth like variations, with a maximum peak to peak variation of approximately 20 micrometer. With 80% overlap, the rms roughness was 1.3 micrometer and the central flattening was 7 diopters. This study shows that scanning PRK can produce smooth and accurate ablations.

Thermal keratoplasty is currently performed with a Ho:YAG laser at 2.1 micrometer wavelength. Long term stability critically depends upon the coagulation depth of each cone and thus upon emission wavelength, absorption and focusation, all contributing to controlled collagen shrinkage in order to induce central corneal steepening. Cw properties meet coagulation requirements more effectively by avoiding tissue cooling by thermal diffusion as well as peak temperatures of pulsed lasers. Both of these factors interfere negatively with collagen shrinkage. Therefore, a cw diode laser has been developed, emitting at 1.9 micrometer (absorption in water, comparable to Ho:YAG) with a maximal energy output of 400 mJ. For corneal application, the laser was coupled into a depth adjustable handpiece which allows the user to react to corneal thickness (maximal in the 6 h position) and its interindividual variation, covering a depth range between 350 micrometer and 800 micrometers. The histology of 10 porcine and 6 human cadaver corneas coagulated in vitro, revealed a similar spot geometry compared to conventional Ho:YAG radiation if the same total energy is applied. Higher corrections and better long term stability appear to be clinically achievable.

Thermokeratoplasty is a procedure utilizing heat to reshape the surface of the cornea through shrinkage of collagen within the stroma. We have constructed an apparatus for measurements of thermally induced corneal shrinkage. Using this apparatus, we have defined the cornea shrinkage rate and examined the relationships between age, shock temperature, and shock temperature duration to the amount of shrinkage on fifteen corneal strips from Eye-Bank eyes. The results show that less heat energy was required to induce shrinkage in older corneas, that acute shrinkage increases with increasing shock temperature and that shrinkage increases with increasing shock temperature duration.

Laser scleral buckling (LSB) experiments were performed by irradiating human cadaver eyes with a focused beam from a 2.1-micrometer Ho:YAG laser. Spatially and temporally resolved temperature maps of the sclera were inferred from infrared images of the tissue's thermal radiation. An infrared focal-plane camera operating in the 3- to 5-micrometer wavelength interval was used for the measurements, from which we derived absorption and thermal diffusivity coefficients of the scleral tissue, along with the temperature dependence of these coefficients. A thermal-response model was developed, which describes the tissue surface temperature in response to a train of laser pulses, given the pulse repetition rate, beam fluence, spot size, and total energy delivered. This model provides guidance for optimization of laser-irradiation parameters for LSB treatment.

A free electron laser (FEL) may be tuned to novel wavelengths to explore laser-tissue interactions for development or improvement of laser surgical procedures. This study investigated the effect of selected infrared wavelengths upon human cornea and optic nerve tissues. Human cadaver eyes were placed in 10% dextran solution to normalize corneal thickness, and solution was injected intraocularly to achieve a physiologic intraocular pressure. The corneas and optic nerves were lased with the 6.0 micrometer amide I band, 6.1 micrometer water absorbency peak, 6.45 micrometer amide II band, and 7.7 micrometer. The Vanderbilt FEL produces 5 microsecond long macropulses at 10 Hz with each macropulse consisting of 1 ps micropulses at 3 GHz. Histologic examination of the corneal tissue showed the least amount of collateral damage (10 - 20 micrometers) with the 6.0 micrometer amide I band, while marked shrinkage occurred with the 7.7 micrometer wavelength. For optic nerve tissue, the least amount of collateral damage (0 micrometer visible) occurred at 6.1 micrometer water absorbency peak and 6.45 micrometer amide II band, while the most damage (30 - 50 micrometers) was observed with the 7.7 micrometer wavelength. We conclude that different tissues may have different optimal wavelengths for surgical laser procedures.

Time dispersion plays an important role in the propagation of femtosecond pulses through water. The combined effects of time dispersion, radial diffraction and the Kerr nonlinearity on the pulse propagation are analyzed and it is shown that normal time dispersion leads to significant temporal broadening of ultrashort pulses and that it increases the threshold power for catastrophic self-focusing.

Choroidal melanoma is the most common primary malignant ocular tumor, yet none of the several available treatments is wholly successful. One therapy recently tried in humans was transpupillary thermotherapy. In this procedure, an 810 nm wavelength laser beam passes through the cornea, aqueous, lens, and vitreous to be absorbed by the tumor in the back of the eye. The results of transpupillary thermotherapy were encouraging, but in some patients only the anterior portion of the tumor was necrosed while the center and posterior portions remained viable. The new treatment modality proposed in this study is similar in concept to transpupillary thermotherapy, but we propose to apply the laser energy through the sclera onto the posterior portion of the tumor, known as the tumor bed. At infrared wavelengths, sclera has excellent transmission characteristics, while most ocular tumors are mildly absorbing. Some of the laser energy is absorbed in the posterior portion of the tumor, but some transmission of the energy through the tumor allows the anterior portion of the tumor to be heated as well. In qualitative terms, this scheme sounds appealing, but it is not yet known whether it will fulfill the quantitative requirements required to achieve the appropriate biological response -- that is, raising the temperature of the tumor to the level which causes cell necrosis (greater than or equal to 43 degrees Celsius) for the appropriate amount of time, without causing photocoagulation of the tumor (approximately equal to 60 degrees Celsius) or damage to the sclera (approximately equal to 55 degrees Celsius). The calculation of temperature distribution is a complicated matter, however, because the actual result of a rise in temperature happens only after the applied laser light has undergone several physical processes.

A new technology brings the full aperture single vision pseudophakic eye's effective hyperfocal distance within the half-meter range. A modulated index IOL containing a subsurface zeroth order coherent microlenticular mosaic defined by an index gradient adds a normalizing function to the vergences or parallactic angles of incoming light rays subtended from field object points and redirects them, in the case of near-field images, to that of far-field images. Along with a scalar reduction of the IOL's linear focal range, this results in an extreme depth of field with a narrow depth of focus and avoids the focal split-up, halo, and inherent reduction in contrast of multifocal IOLs. A high microlenticular spatial frequency, which, while still retaining an anisotropic medium, results in a nearly total zeroth order propagation throughout the visible spectrum. The curved lens surfaces still provide most of the refractive power of the IOL, and the unique holographic fabrication technology is especially suitable not only for IOLs but also for contact lenses, artificial corneas, and miniature lens elements for cameras and other optical devices.

Both theoretical an experimental results have shown that transversal chromatic aberration (TCA), also called chromatic difference in image position (CDP) in the object space, is the aberration that most deteriorates ocular image quality. In this paper we study the image quality of pseudophakic eyes based on the transversal spherical aberration (TA) and on the TCA. This study has been done from the point of view of geometrical and wave optics. The eye model that we use is a modified version of the whole theoretical eye used by Navarro et al. Using geometrical optics, we calculate the TA and the TCA for plano-convex or concave intraocular lenses (IOLs) and for meniscus IOLs. The loss of image quality and visual acuity increases as the TA and TCA increase. In addition to this, we have calculated the polychromatic modulation transfer functions (MTF) based on point spread functions (PSF) taking into account spherical aberration and defocus coefficients for the same cases. Finally, as regards chromatic and spherical aberrations, we can establish what type of IOL and which bending factor would best improve image quality for a given patient.

The concept and invention of the non-penetrating keratoprosthesis were described in 1991 by Legeais, Parel, Villain, Tseng and Lacombe. The main advantage of the non-penetrating keratoprosthesis is that Descemet's membrane and the endothelium are kept in place. Therefore, the risk of endophtalmitis may be reduced, and anterior chamber effraction and pressure modification may be avoided. The prosthesis was designed with a 7 mm diameter optic and a 10 mm diameter skirt made of expanded polytetrafluoroethylene (ePTFE). A flange in teflon was used to ensure biointegration of the prosthesis. We carried out 3 preliminary studies in Eye-Bank eyes and rabbits, in order to assess surgical feasibility, Descemet membrane strength, and biocompatibility of different types of polymers. We are also currently conducting a study on rabbits.

Polymethyl methacrylate (PMMA) surface was photochemically modified in open air by using an ArF excimer laser and an ammonia-water solution. Photo-excited C-H bonds of the surface were effectively dehydrogenated with hydrogen atoms which were photodissociated from the ammonia-water solution. The dangling bonds of the dehydrogenated carbon atoms were combined with the NH₂ and OH radicals which were also photodissociated. Thus, the sample surface showed hydrophilic property only on the photomodified parts. Based on the photomodification technique, a commercial hard-contact lens was also photomodified for tear affinity.

Er:YAG laser-mediated tissue disruption and removal results from both direct ablation and the acousto-mechanical sequelae of explosive vaporization of the tissue water. We investigated the scaling laws for photoablative and photodisruptive interactions, and interpret these results towards optimizing energy delivery for vitreoretinal surgical maneuvers. Experimental studies were performed with a free-running Er:YAG laser (100 - 300 microseconds FWHM, 0.5 - 20 mJ, 1 - 30 Hz). Energy was delivered by fiberoptic to a custom-made handpiece with a 75 - 600 micrometer quartz tip, and applied to excised, en bloc samples of bovine vitreous or model systems of saline solution. Sample temperature was measured with 33 gauge copper- constantan thermocouples. Expansion and collapse of the bubble following explosive vaporization of tissue water was optically detected. The bubble size was calculated from the period of the bubble oscillation and known material properties. A model for bubble expansion is presented based on energy principles and adiabatic gas expansion. Pressure transients associated with bubble dynamics are estimated following available experimental and analytical data. The temperature rise in vitreous and model systems depends on the pulse energy and repetition rate, but is independent of the probe-tip diameter at constant laser power; at moderate repetition rates, the temperature rise depends only on the total energy (mJ) delivered. The maximum bubble diameter increases as the cube root of the pulse energy with a reverberation period of 110 microseconds and a maximum bubble diameter of 1.2 mm following one mJ delivery to saline through a 100 micrometer tip. Our modeling studies generate predictions similar to experimental data and predicts that the maximum bubble diameter increases as the cube root of the pulse energy. We demonstrate that tissue ablation depends on radiant exposure (J/cm²), while temperature rise, bubble size, and pressure depends on total pulse energy. Further, we show that mechanical injury should be minimized by delivering low pulse energy, through small diameter probe tips, at high repetition rates. These results allow for optimization strategies relevant to achieving vitreoretinal surgical goals while minimizing the potential for unintentional injury.

Successful retinal tracking subsystem testing results in vivo on rhesus monkeys using an argon continuous wave laser and an ultra-short pulse laser are presented. Progress on developing an integrated robotic retinal laser surgery system is also presented. Several interesting areas of study have developed: (1) 'doughnut' shaped lesions that occur under certain combinations of laser power, spot size, and irradiation time complicating measurements of central lesion reflectance, (2) the optimal retinal field of view to achieve simultaneous tracking and lesion parameter control, and (3) a fully digital versus a hybrid analog/digital tracker using confocal reflectometry integrated system implementation. These areas are investigated in detail in this paper. The hybrid system warrants a separate presentation and appears in another paper at this conference.

The aim of this study was to investigate the use of photodynamic therapy (PDT) using tin ethyl etiopurpurin (SnET2) for occluding the choriocapillaris in the eyes of pigmented rabbits. Following intravenous injection of SnET2 (0.5 and 1.0 mg/kg) or lipid emulsion alone, the fundus of pigmented rabbits was irradiated within 5 - 15 minutes of photosensitizer injection using 664 nm light at a fluence of 300 mW/cm² and light doses of 5 - 20 J/cm². Fundoscopy, fluorescein angiography (FA), and histology were performed at 1, 14 and 28 days after PDT. Following PDT, closure of choriocapillaris was achieved with light doses as low as 5 J/cm² (17 seconds). Control eyes of rabbits demonstrated no effect to light irradiation at the parameters tested. PDT with SnET2 was effective in this animal model using low levels of activating light for the treatment of choriocapillaris.

We have in the last two years, performed PRK operation on over 300 human myopic eyes using ArF excimer laser with a Summit 'Omnimed' machine. For the initial 53 myopic eyes we treated, results were very good for those with correction less than minus 6 diopters. However, as previously reported, we also witnessed some regression for those eyes exceeding correction of more than minus 6 diopters. To counter such ill results of PRK we devised and suggested many new procedures for PRK with very good results. One such invention is the 'Okamoto-type' cooling machine for the cornea which reduces and stabilizes cornea temperature at 0 degrees Celsius while simultaneously bathing the cornea with special cooling fluid. After the operation, EGF, fibronectin and hexapeptide were administered using eyedrops. Soft contact lenses were used to protect the cornea, improve delivery of medication to the operated area, prevent infection and inflammation and also promote uniform and faster ephiterium regrowth. We were able to document very good post-operative results using this method, thereby giving us strong assurance that we have reached a significant milestone in PRK operation. Our report today covers post operative results of the 52 eyes we operated on and tracked for more than one year.

Multivariable regression analysis was used to evaluate the combined effects of some preoperative and operative variables on the change of refraction following excimer laser photorefractive keratectomy for myopia (PRK). This analysis was performed on 152 eyes (at 6 months postoperatively) and 156 eyes (at 12 months postoperatively). The following variables were considered: intended refractive correction, patient age, treatment zone, central corneal thickness, average corneal curvature, and intraocular pressure. At 6 months after surgery, the cumulative R₂ was 0.43 with 0.38 attributed to the intended correction and 0.06 attributed to the preoperative corneal curvature. At 12 months, the cumulative R² was 0.37 where 0.33 was attributed to the intended correction, 0.02 to the preoperative corneal curvature, and 0.01 to both preoperative corneal thickness and to the patient age. Further model augmentation is necessary to account for the remaining variability and the behavior of the residuals.

The ciliochorioidal detachment often appears after anti-glaucoma surgery operations because of blood circulation breaks in ciliar body which leads to eye's hypotonia and to stagnant inflammation [4,6]. The positive clinical effect was achieved after the use of low-intensive helium-neon laser radiation in treatment of ciliochorioidal detachment [2,5], but the mechanism of this influence wasn't researched well until now.

Hyphema is often associated with traumatic eye injuries. Its blood is subjected to considerable changes in agueous humor and causes toxic effect on eye tissues. The metabolism disturbances in eye tissues unfavourably affecting their cell structures play a significant role in the development of patologic conditions in cases of intraocular haemorrhages (2,8). This is to be attributed to the correlation of lipid peroxidation (LP) processes and antioxidant system (AOS) activity of both the cellular membrane and its environment necessary for maintaining cell homeostasis as a whole (1).

Hyphema is often associated with traumatic eye injuries. Its blood is subjected to considerable changes in aqueous humor and causes toxic effect on eye tissues. The metabolism disturbances in eye tissues unfavorably affecting their cell structures play a significant role in the development of pathologic conditions in cases of intraocular hemorrhages. This is to be attributed to the correlation of lipid peroxidation (LP) processes and antioxidant system (AOS) activity of both the cellular membrane and its environment necessary for maintaining cell homeostasis as a whole. The aim of the present work is an experimental study of LP processes of aqueous humor (AH) in total traumatic hyphema (TTH) after magnet-laser stimulation different doses (3 and 6 minutes). TTH and aqueous humor collection were made on the eyes on rabbit (Schinchilla) according to Krasnov A.M. under the local anaesthesia (dicaine 0.25%). The study of biochemical aqueous indices was carried out on healthy eyes and after development of hyphema on day 1, 3, 5, 7, 10, 14, 30, and 45. The animals were divided into three groups: in the first group the biochemical indices were defined in the aqueous humor in TTH; in the second and the third groups the similar investigation was carried out after magnet- laser radiation with 3 and 6 minutes exposition. The malonic dialdehyde (MDA) was defined according to Ishihara, Shiff's bases -- and their concentration was determined on the total amount of lipids (reagent kit of 'Lachema'). He-Ne laser (with power density of 0.05 mVt) was used, streaming impulsed magnet field voltage being 10 mTl. The magnet head of a magnet radiator was fixed 0.5 cm from the eye; laser beam being sent to the central hole of the magnet head. The duration of exposure was 3 minutes in the second group and 6 minutes in the third group, daily for 10 days. Significant increase of LP product concentration level with two clear ascending peaks was seen on the third and tenth days in the first group. The maximal increase of these indices was noted on the third day, that coincides with hemolysis of outpouring blood and release of powerful LP processes initiators into aqueous humor -- that is haemoglobin and Fe++2. The MDA and Shiff's bases concentration levels increased equally during this period with reference to their initial data, whereas on the tenth day the level of Shiff's bases concentration became higher than the MDA amount level. The normalized values of the indices studied were obtained on the 30 - 45th days. The use of magnet-laser radiation caused the significant fall in MDA concentration and Shiff's bases in aqueous humor in TTH in the second group (1.8 and 1.7 correspondingly). On the 7th - 10th days already the values of indices studied were reliably similar to norm (P greater than 0.05). In the third group the levels of LP product concentration fell in the first phase of hyphema resolution. It had been determined that the MDA values were lower than the values of indices of the first group on the third - fifth days (1.5 and 1.7 correspondingly). The values of Shiff's bases on the first day were 1.4 lower than the indices of the first group and were reliably similar to indices of the first group on the third - seventh days (P greater than 0.05).

Real-time, in vivo, confocal microscopic examination permits visualization of human corneal endothelium cells as bright bodies organized into a densely packed hexagonal arrangement. Quantification of endothelial cell number would be useful in assessing the condition of this cell layer in various disease states. In this study, we sought to use an image analysis method developed in this laboratory that utilizes digital filtering techniques and morphological operations to determine the boundaries of each cell. Images were corrected to establish a uniform luminance level, and then convolved by various matrices until distinct peaks in luminance value were identified. These peaks were used as seed points from which cell boundaries were recursively expanded until they collided with other cell boundaries. This method automatically counts the number of cells and determines the size and position of each cell. The resulting histograms of cell size are readily indicative of changes in cellular density, cell loss, and deviation from uniform arrangement. The numbers of cells counted by this method are consistently within 3% of the numbers counted manually. Results relating cell counts obtained by manual and computerized methods are as follows: 200/184; 276/262; 87/87; 234/232; 236/232; 299/297; 145/147; 119/122; 237/243; 119/119; 245/253; 189/193. Thus, confocal microscopy coupled with these image analysis and statistical procedures provides an accurate quantitative approach to monitoring the endothelium under normal, pathological, and experimental conditions, such as those following surgery and trauma or in the evaluation of the efficacy of topical therapeutic agents.

Asimple method of the eye bottom hologram recording, using coherent source and Denisj uck .is suggested . The metod allows to compensate in the process of recording optical distortions, produced by the eye crystalline.

Far-zone speckles statistical and correlation properties has been investigated in the case of He- Ne laser light scattering by the human sclera samples. Application of some agents such as Trazograph (or Verographin) leads to the decrease of the tissue turbidity and allows us to study the transition from strong scattering mode to weak scattering mode. Usage of this technique in combination with the spatial speckle correlometry gives the possibility for analysis of the sclera's scattering structure for different stages of its turbidity decay. Potentialities of such a method are discussed.

Ocular refractive errors (myopia, hyperopia and astigmatism) are automatic and objectively determined by projecting a light target onto the retina using an infra-red (850 nm) diode laser. The light vergence which emerges from the eye (light scattered from the retina) is evaluated in order to determine the corresponding ametropia. The system basically consists of projecting a target (ring) onto the retina and analyzing the scattered light with a CCD camera. The light scattered by the eye is divided into six portions (3 meridians) by using a mask and a set of six prisms. The distance between the two images provided by each of the meridians, leads to the refractive error of the referred meridian. Hence, it is possible to determine the refractive error at three different meridians, which gives the exact solution for the eye's refractive error (spherical and cylindrical components and the axis of the astigmatism). The computational basis used for the image analysis is a heuristic search, which provides satisfactory calculation times for our purposes. The peculiar shape of the target, a ring, provides a wider range of measurement and also saves parts of the retina from unnecessary laser irradiation. Measurements were done in artificial and in vivo eyes (using cicloplegics) and the results were in good agreement with the retinoscopic measurements.

We present a new technique to quantify the pupillary escape with an image-processing system during visual field examination in routine ophthalmological practice. Visual field evaluation is important in the detection, diagnosis and assessment of ophthalmologic and neurologic dysfunction. With the conditions during the perimetric study: an initially large pupil and a small step light stimuli, it presents the pupillary escape where the pupil responds with a very fast constriction and then redilates almost back to its original level. In order to measure this response, we obtain automatic and objective determinations for each spot of light in peripheric and central zones. The automatic perimeter is based on the physical dimensions of Goldmann perimeter and the index projector is based on fiber optics target. The pupillary escape and the pupillary response are captured by means of an infrared-sensitive camera and recorded in a VCR to analyze off line with an image processing system. This system consists of a computer equipped with a frame grabber DT2853 and eye movements detector for monitoring the initial position of the eye, during the examination. The algorithms to detect and analyze are: mensuration (area, perimeter, latencies) and matching template based on the stochastic sign change criterion.

The need to measure the optical properties of IOLs in a wet cell stems from the required in- situ conditions. Soft contact lenses also benefit from wet conditions since the blotting procedure introduces significant errors. An instrument with a high degree of accuracy is needed to compensate for the reduced sensitivity due to the small refractive index difference between the lens and saline. An optical setup based on a new deflectometer module with continuous tuning of shear and tilt provides the necessary resolution and flexibility. Various optical properties can be evaluated from the fringe pattern: Power and cylinder distributions across the lens, aberrations, OTF curve, through focus MTF, and others. A criterion for determining the lens quality may be derived from the power distribution, from the full MTF curve or from the through power MTF. The width of the through power MTF curve relative to the resolution of the visual system is a good quality criterion, while the maximum provides a repeatable outcome for the overall power or cylinder. A single measurement yields both power and MTF of intraocular lenses immersed in a model-eye type wet cell. Arbitrary values of spatial frequency and pupil size up to the full diameter of the IOL can be selected.

New advances of copper vapor laser (CVL-laser) have been studied. Two wavelength radiation of the laser (511 nm and 578 nm) gives deeper permeability into organic tissues. Besides, the short pulse prevents the warm relaxation of small vessels. The technical data of CVL-laser: operating regime -- pulse, pulse duration -- 20 ns, pulse frequency 15000 pulse/sec. The shutter works in intervals from 0.05 to 2.0 sec. The power varies in accordance with wavelength: 511 nm (green) -- 1.5 W, 578 nm (yellow) -- 1, 2 W. The diameter of coagulate may be different: 100, 150, 400, 1000 mkm. We chose CVL-laser 'Femta,' created by P. N. Lebedev Physical Institute of RAS, for ophthalmological use. Thirty eight eyes of 37 patients with different types and stages of glaucoma were studied and treated with CVL-laser. The operations of photomydriasis, gonioplasty and trabeculoplasty have been performed. CVL- laser demonstrated efficient application in treatment of interior eye segment of glaucoma patients. The advantages and disadvantages of the CVL-laser application in glaucoma surgery were discussed.

The transmittance of the lens capsule decreases towards shorter wavelengths from around 300 nm. There is a minimum in the transmittance of around 70% at 280 nm followed by a peak of around 75% at 250 nm and then a quick decrease to 2 - 4% at 225 nm. These results were obtained from in vitro measurement of rabbit lens capsules. It is believed that the cyclic amino acids tryptophan, tyrosine and phenylalanine are responsible for the minimum transmittance at 280 nm. It is concluded that the lens capsule efficiently protects the interior of the lens from short wave ultraviolet radiation.