PRK using an absorbing cell delivery system for correction of myopia from 4 to 26 D in 3251 eyes.

An ophthalmic laser unit with a Lambda-Physik LPX excimer emitting 193 nm and a unique beam shaping system was designed at the Complex "Eye Microsurgery." An absorbing cell, used as the main element of the delivery system, allowed us to obtain a precise profile of the laser energy density on the patient's cornea, smoothly changing the corneal refraction with each shot in the whole ablation area. The absorbing cell also allowed for varying the shape of distribution of radiation energy density depending on the patient's corneal shape. We performed more than 7000 photorefractive keratectomy laser operations in myopic patients, and report results in 3251 myopic eyes (approximately 46%) from -4.00 to -26.00 D, up to 4 years after surgery. In eyes with myopia greater than 6.00 D, emmetropia was obtained in 48% of cases; 42% had a residual mild myopia within 5.00 D; and 12% had a residual myopia more than 3.00 D. The corneal haze disappeared in 48.8% of cases; haze not affecting the visual acuity remained in 39%; and clinically significant haze remained in 12.2%. These eyes required a powerful medication or repeated PRK. After surgery, 87.7% of patients needed no spectacle correction. Excimer laser PRK with the use of the forming system efficiently corrects high myopia.

Comparative study of two protein-coding regions of mitochondrial DNA from three endemic sculpins (Cottoidei) of Lake Baikal.

Two protein-coding regions (cytochrome b, ATPase 8, and part of ATPase 6) from mitochondrial DNA of Cottus kessleri, Cottocomephorus grewingki, and Cottocomephorus inermis--Baikalian endemic sculpins--were amplified via polymerase chain reaction, and sequenced. Two novel primers--L8352 (5'-TAAAGATTGGTGAC TCCCAACCACC) and H8773 (5'-GTAGGGAGT AAGCCCAATATGTT)--were used for the latter region. Phylogenies suggested by sequence divergence of the genes of ATPases appeared to be different from those computed from data for cytochrome b. The time of species branching was estimated as 1-2 million years (Myr) on the basis of merged sequences. Hence, members of the Baikalian cottoid species flock are much more distant from each other than members of the cichlid fish flocks of the great lakes of Africa (0.2 Myr). Topology of the phylogenetic tree does not contradict the relationships derived from morphological data. However, genetic distances suggest that C. grewingki and C. inermis are not sister species, contrary to general belief.

Radial thermokeratoplasty for the correction of hyperopia.

Hyperopic thermokeratoplasty involves making controlled thermal burns in the corneal stroma in a radial pattern up to a premarked clear zone. It steepens the central cornea and reduces the hyperopia. A series of 117 radial thermokeratoplasty eyes done in the Soviet Union were analyzed. Mean preoperative hyperopia of +5.27 diopters (range = +0.50 to +17.00 D) was reduced at 12 months after surgery by a mean of -3.48 D, resulting in a mean postoperative spherical equivalent of +1.84 D. Average correction was 70.8%. Forty percent of eyes were corrected to less than 1.00 D residual refractive error; however, 58% were undercorrected by 1.00 D or more. The proportion of eyes seeing 20/40 or better unaided increased from 10% preoperatively to 52% by 3 months after surgery and remained at 53% at 12 months after surgery. Overall refractive stability was demonstrated during the 1st postoperative year. Stepwise regression showed that none of the preoperative or surgical factors significantly predicted outcome when all eyes were evaluated.

Influence of some factors on the sutures of the lens.

A clinical study of the lens transparency conditions was made on 118 patients with regard for an applicable treatment, the use of hyperbaric oxygenation and a type of lesion. It showed, that sutures of the lens were wider in patients with uveitis and in diabetic patients as compared with the control-group patients who had no other pathologies. Glaucomatous patients had very narrow sutures. Initial opacifications of the lens were perceived in patients with uveitis and in diabetic patients as stars oriented along sutures beneath the posterior capsule in the area of the nucleus. Following hyperbaric oxygenation and equally the corticosteroid therapy, there was a decrease in the thickness of the sutures, and the degree of transparency of the lenticular nucleus changed as well mainly in the zone bordering on the posterior cortex strata. The study underlines the importance of examination of the condition of the lens sutures in determining the toxic impact produced by different factors on the lens.

Corneal biomicroscopy following repeated radial keratotomy.

Two distinct forms of corneal incision healing are described following repeated radial keratotomy. The new incisions were made along the old corneal scars. No complications were observed intra- or postoperatively. Following the repeated surgical intervention, the form of cornea healing did not change, ie, the incisions just increased in width and volume by 15 to 40%. Form A healing corneas experienced a two times larger refractive power change than corneas with form B healing. The type of cornea healing is dependent upon the characteristics of the cornea itself, ie, each cornea responds in an identical manner to both surgical interventions and the frequency of the form A healing response increases with patient's age.

1004 cases of traumatic cataract surgery with implantation of an intraocular lens.

Traumatic cataracts occurring after ocular trauma were removed by phacoemulsification, cryoextraction or extracapsular cataract extraction, depending on the degree of lens absorption. All eyes received sputnik-style iridocapsular lenses. Most cases were complicated by the presence of synechiae and/or the need for iridoplasty. The surgical technique varied with the specific nature of the ocular pathology. Eyes with penetrating injuries has a higher complication rate. Anterior chamber shallowing or collapse was the most frequent intraoperative complication, and was directly related to the incidence of postoperative complications. Most postoperative complications were typical of those associated with cataract surgery in complicated situations.

The state of eye hydrocircular system in view of age pathology and open-angle glaucoma.

With age the eye drainage system undergoes a number of changes because less favorable conditions arise for intraocular fluid reflux. The manifestation and extent of these changes were closely connected with the manifestation of arteriosclerotic affection of the cardiovascular system. The changes in eye drainage passages in persons with pronounced complicated arteriosclerosis and advanced open-angle glaucoma were identical in character and comparable in the manifestation. The changes in eye drainage passages in persons with pronounced arteriosclerosis and open-angle glaucoma did not have the character of isolated trabecular lesion or lesions of Schlemm's canal or intrascleral tracts, but they were detected in all these sectors. The obtained data indicate that the changes in the eye drainage system connected with age pathology an open-angle glaucoma took place and were more pronounced in the superior sectors of the eye, gradually spreading downward. The conditions for intraocular fluid reflux along the primary tracts being deteriorated, its reflux appears to increase through the uveal tract.

Calculation of the optical power of intraocular lenses.

A rather simple clinical approach has been used to derive formulas necessary to calculate the power of pupillary intracameral prosthetics and these have been applied in 150 eyes. In 136 eyes, the postoperative measurements were within one diopter of preoperative calculations.