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A total of 151 photorefraction operations for correction of medium and high astigmatism in 38 children (9-15 years) and 47 adolescents (16-17 years) carried out by LASIK method are analyzed. The operations were performed under local anesthesia with EC-5000 eximer laser (Nidek) and Hansatome microkeratome (B & L). Complicated and common myopic astigmatism (2.07 +/- 0.89 to 2.91 +/- 0.63 diopters) was decreased by 61.2% in children and by 62.2% in adolescents. Visual acuity without correction increased by 0.58 +/- 01.2. Correction of astigmatic anisometropia resulted in its decrease to 0.75-1.5 diopters in 77.9% children and 62.8% adolescents. Hypermetropic astigmatism decreased by 64.9% of its initial value in children and by 56.9% in adolescents. Mixed astigmatism decreased by 62.7% of its initial value. The resultant visual acuity without correction was 0.39 +/- 0.13 in children and 0.47 +/- 0.17 in adolescents. According to questionnaires distributed among parents, 13.5% patients studied better at school after the operation and 19.2% went in for sports in athletic sections. The main causes for the intervention were limitations in choice of profession (for 49.6%) and desire to practice modern athletics (in 13.8%). Photorefraction correction of astigmatism in children and adolescents brings about an effective stable result decreasing refraction amblyopia and improving the quality of life.

Pharmacodynamics of dexamethasone, fluoromethanol, sodium diclofenak, and tobramicin after photorefraction keratectomy (PRK) and intrastromal laser keratectomy (ILK) was studied in rabbits. Eximer laser operations modulated the barrier functions of the cornea. The highest concentrations of drugs in anterior chamber humor during the first 20 min after instillations was observed after ILK in comparison with the control (intact cornea). The highest coefficient of effective drug diffusion through the cornea was observed after PRK in comparison with ILK. The drug efficiency was higher after ILK than after PRK, which is seen from the maximum concentrations of drugs entering the cornea immediately after instillation and prolongation of the drug effect due to its decelerated diffusion through the cornea.

Variants of corneal injuries and their complications in various periods after laser keratomileusis are described. The causes and probable mechanisms of injuries are analyzed with consideration for pathohistological findings. A total of 3507 operations were performed in 1796 patients with myopia of 1.5-14.5 diopters. Hansatome microkeratotome was used for lamellar section of the cornea and EC 500 eximer laser (Nidek) for laser keratoablation. According to the consultation rate, the incidence of injuries was 0.45% (16 eyes). The injuries occurred 1 week to 6 months after the operation and were as follows: epithelial injuries (10 cases), foreign bodies in the cornea (4 cases), and displacement of corneal flap (2 cases). The causes of injuries were mainly communal, the outcomes were favorable, microsurgical reoperation was needed in 3 cases. The mechanisms of injuries were analyzed with consideration for the histology of human cornea. The most complete fixation of corneal flap after laser keratomileusis was attained in the wound channel and at the site of the flap stromal apposition. Mechanical displacement of the corneal flap resultant from the injury is the most probable during the 4-week formation of cicatricial tissue in the wound; later the direction of the traumatic agent is significant. Prevention of corneal injuries after laser keratomileusis is important.

Pathological changes in the retina in myopia of 1.5-17 diopters are analyzed, based on analysis of more than 4800 cases. Detachments of the retina were responsible for 0.5% cases. Photocoagulation of the retina was carried out using 2 lasers: diode DC-3000 NIDEK (790-830 nm) and Nd-YAG Alcon (532 nm). Photorefraction operations of two types (photorefraction keratectomy and LASIK) were carried out on a Nidek EC-5000 laser. The results evidence a possibility of photorefraction operations for correction of myopia 6 months to 11 years after a previous intervention for detachment of the retina (21 operations). Visual acuity without correction was 0.69 +/- 0.08, spherical equivalent of clinical refraction 0.80 +/- 0.34. Repeated laser coagulation at the retinal periphery for blocking newly forming ruptures was needed in 14.2% cases. No relapses occurred during 3 years postoperation.

A total of 6682 intrastromal photokeratoablations (LASIK) for myopia of 1.5-16 diopters and hypermetropia of 1.5-8 diopters are analyzed. Lamellar incision of the cornea was formed with a Hansatome microkeratotome and photokeratoablation was carried out using a Nidek EC-5000 laser. Primary and secondary deformations of a corneal flap and primary and secondary adaptation are defined. During LASIK for correction of myopia, the areas of corneal flap and corneal bed can fail to correspond to each other. This non-correspondence is the greater, the deeper is keratoablation. The corneal flap undergoes several stages of changes during the early and remote postoperative periods: primary deformation during lamellar incision, primary dysadaptation presenting as various forms of corneal dystrophy, and secondary deformation developing under new adaptation conditions. The velocity of the corneal flap adaptation depends on its reposition during the final stage of the operation, which can essentially decrease the risk of complications. The incidence of central dystrophy (pseudodiffuse lamellar keratitis) in various methods of the flap reposition varies from 0 to 1.5%.

Peripheral retinal abnormalities detected in examinations of 4840 patients with myopia are analyzed. The incidence of subclinical detachments of the retina was 8.7%. Two-staged laser therapy of detachments and its results are discussed and laser refraction operations in such abnormalities of the fundus oculi are considered. Results of photorefraction operations of different types in patients previously operated on the retina by the laser method are analyzed. Only 5 patients needed repeated laser therapy on the fundus oculi during 3 years postoperation. Hence, photorefraction correction of refraction abnormalities can be carried out in patients with subclinical detachments of the retina after previous effective laser therapy.

The barrier function of the cornea was studied before and after eximer laser photorefraction keratectomies and laser specialized keratomileusis (LASIK) for residual myopia after previous radial keratotomy. The barrier function of the cornea was studied by local keratofluoropenetrometry making use of computer system for analyzing TV images of the eye. Impaired barrier function of the cornea at the site of keratotomic cicatrices did not recover even many years after radial keratotomy, while after LASIK it recovered in 2-4 weeks. The time of recovery of this function depends on the state of the space between the flaps. LASIK does not affect the fluorescein permeability of keratotomic cicatrices.

The technique and results of an original method for correction of common myopic astigmatism and mixed small-sphere astigmatism by means of bitoric photokeratoablation are described. Forty-six operations were performed on patients with 2-7 diopter astigmatism. Residual 0.87 diopter astigmatism was observed in patients with the initial value of less than 3 diopters. At initial astigmatism higher than 3 diopters, residual value was 1.49 diopters 3 months postoperation. No changes in the spheric component of initial refraction occurred. The proposed technique includes estimation of bitoric keratoablation, order of steps, and values of ablation algorithm enhancement. The method helps decrease the depth of keratoablation, rules out hypercorrection, and creates optimal conditions for reoperations.

The content of potassium ions in the lacrimal fluid was evaluated before and in various periods after laser specialized keratomileusis (LASIK) in order to determine the scope and terms of therapeutic measures. Seventeen patients with myopia were examined before and after LASIK. Lacrimal production before the operation was evaluated by Schirmer's and Norn's tests. The concentration of K+ ions in the lacrimal fluid was measured on a Reflotron IV biochemical analyzer. Before operation the concentrations of potassium ions were 1.5 times higher than normally in the patients complaining of discomfort. Lacrimal concentration of K+ ions and results of Norn's and Schirmer's tests were in high correlation. After LASIK potassium ion concentrations were increased in all patients and returned to the initial level almost completely within 1 week postoperation. Treatment with artificial tear preparations containing no potassium ions during the early postoperative period is physiological.

Changes in the protein spectrum of the lacrimal fluid, resultant from refraction ocular surgery (photorefraction keratectomy, PRK, and laser specialized keratomileusis, LASIK) were evaluated. Lacrimal fluid was collected before operation and in various terms after it in 28 patients (48 eyes) subjected to PRK and in 34 patients (59 eyes) subjected to LASIK. Biochemical analysis of the lacrimal fluid was performed on a mass spectrometer. After PRK the greatest changes in the protein spectrum occurred immediately after the operation before reepithelialization. Changes after LASIK were negligible. Refraction laser operations cause changes in the protein composition of tears, LASIK being more physiological than PRK from viewpoint of intactness of the protein composition of tears.

Topographic disorders in the cornea, regression of the refraction effect, and subepithelial corneal opacities are characteristic complications of photorefraction keratectomy. Disorders in corneal topography are early haze, asymmetrical haze, and optic zone decentration. Disorders in topography lead to decrease in visual acuity, numerous optic effects (monocular doubling, aureola, blurred image, etc.). Methods for these complications control by means of transepithelial ablation, which is carried out with due consideration for the data of topographic examinations under pseudofluorescence control, normalizes corneal topography in the majority of cases, notably increases visual acuity, decreases doubling, etc. No side effects were observed after transepithelial phototherapeutic keratectomy for a period of up to 12 months.

Photorefraction keratectomy was performed with a Nidek EC-5000 excimer laser in 29 patients (58 eyes) with slight and medium myopia aged 40-60 years. After 12 months the mean visual acuity in the leading eye without correction was 0.82 +/- 0.12 in patients aged 40-50 (group 1) and 0.76 +/- 0.11 in those aged 51-60 years (group 2). The mean refraction of the leading eye in group 1 was -0.97 +/- 0.02 diopters and in group 2 0.72 +/- 0.04 diopters. In group 1 the resultant undercorrection was -1.6 +/- 0.4 diopters (107% of planned undercorrection) and in group 2 -1.8 +/- 0.4 diopters (72% of planned undercorrection). The proposed method effectively corrects slight and medium myopia in patients of presbyopia age. 82% patients were satisfied with the results of treatment: 67% of them did not need eyeglasses for reading and 54% could drive a car without eyeglasses.

Twenty patients (28 eyes) with primary keratoconus of stages I-II (Amsler) were operated using photorefraction keratectomy (PRK) supplemented by phototherapeutic keratectomy (PRK). Mean UCVA before surgery was 0.04 +/- 0.004, BCVA 0.68 +/- 0.03. Eximer laser EC-5000(NIDEK) was used in the treatment. PRK included spherical, cylindrical ablations, or both. The diameter of ablation zone in PRK was 6 mm. in PTK the diameter of ablation zone was 8 mm, transition zone 9 mm. In PTK the ablation zone was decentered towards the cone apex (according to corneal computer topography). The method is patented in the Russian Federation. Visual acuity without correction notably improved in all 20 patients and its mean value after the operation was 0.73 +/- 0.03, 68% eye having visual acuity of 1.0. In one female patient keratoconus progressed 6 months after the operation. Haze was observed in 1 patient as a result of delayed reepithelialization. No progress of keratoconus was observed in other patients (period of observation 17.3 +/- 1.5 months). Hence, the new PRK-PTK method is an effective method for treating primary keratoconus of the first-second stage according to Amsler; the method arrests the progress of the condition in 96% cases.

Reviews the results of correction of complex myopic astigmatism with asymmetric form of disposition on the cornea by two methods, with centered and decentered photokeratoablation. Analyzes the results of 80 laser keratomileusis operations for medium and high myopia. Describes a method of calculations and keratotopographic detection of asymmetric astigmatism and a method for transferring it into symmetrical form in computer-aided keratotopography. Two types of interventions brought about a good refraction result (sphere equivalent -0.66 +/- 0.54 diopters) and high resolving capacity of the eye (0.88-0.99). Decentered keratoablation led to a significant increase in visual acuity without correction, this indicating a better adequacy of this method, discussed in this paper.

Main types of dystrophic complications on the corneal flap associated with laser specialized keratomileusis (LASIK) are discussed. A total of 6507 down-up LASIK operations were performed. The most grave form of corneal flap disadaptation syndrome (CFDS) (central dystrophy) occurred in 1.59% cases only in patients with myopic keratoablation. Slight manifestations of this syndrome were observed in patients with myopia and hypermetropia. The authors discuss a concept of CFDS development in which the leading role is attributed to the initial disagreement between the size of corneal flap before and after keratoablation. The incidence of such complications depends on the method of corneal flap positioning during the final phase of the operation. Clinical picture, outcome, and treatment of CFDS are discussed.

Ninety-four repeated refraction operations were performed by laser specialized keratomileusis (LASIK) after a previous photorefraction keratectomy in order to correct the complications (undercorrection and regression of the refraction result). LASIK operation can be performed no earlier than 12 months after the first operations if subepithelial corneal fleur develops; the fleur severity is to be about 0.5 points and the optimal thickness of corneal section is 180 mu. Causes of complications of reoperations are discussed. The majority of complications are due to corneal epithelium fixation after photorefraction keratectomy. Refraction and visual results of surgery are presented to characterize its efficiency.

Terms of re-epithelialization, severity of the painful syndrome, intensity of corneal "crepe" (opacity) are assessed in myopic patients treated by maxitrol, eubetal, colbiocin ointments and maxitrol eyedrops in the early postoperative period after photorefraction keratectomy. The crepe intensity was assessed routinely according to a clinical score: 0) transparent cornea, 1) trace crepe; 2) moderate crepe; and 3) intensive crepe. Biomicroscopy on day 4 after photorefraction keratectomy showed complete epithelialization in 91.7% patients after colbiocin ointment, in 91.% after maxitrol eyedrops, 87% after eubetal ointment, and 82.6% after maxitrol ointment. The least corneal opacity (0 and 0-1) was observed after eubetal ointment and maxitrol eyedrops. The mean score for pain was virtually the same in all groups; in the colbiocin ointment group more patients complained of pain for more than 24 h in comparison with other groups.

The area of corneal epithelialization was evaluated and densitometry of corneal surface carried out by computer analysis of images in order to detect the relationship between epithelialization and formation of corneal fleur in patients with delayed healing after photorefraction keratectomy for hypermetropia. An arbitrary parameter: corneal epithelialization rate, a mathematical difference between the area of corneal defect every next day of observation in comparison with the day before, expressed in mm2/day, is proposed for evaluating the efficacy of various drugs used to stimulate corneal defect epithelialization. Computer analysis of images helps objectively evaluate epithelialization and corneal transparency after eximer laser keratectomy. The method is diagnostically and prognostically valuable, particularly in cases with delayed epithelialization and stubborn epithelial defects of the cornea.

Complications of specialized laser keratomileusis (LASIK) are analyzed in 1667 patients with 1.0-19.5 diopter myopia and hypermetropia of +2.25-10.0 diopters. LASIK was carried out by the standard method using Hansatome TM 230 HT device and eximer laser Nidek EC-5000. Classification of LASIK complications depending on the mechanism of exposure and stage at which they manifest is offered. Such complications as inadequate adaptation of the corneal flap (0.7%), lensodonesis (0.1%), viral keratitis (0.05%), turned-under edge of a flap (0.4%), stromal "feedback" pouch are described for the first time. Causes of complications are enumerated and analyzed and methods for their correction are described. The authors claim that the type and incidence of LASIK complications are largely determined by the experience of the surgeon and quality of equipment. Use of new lasers and new keratomes will rule out many complications.

Morphological characteristics of the haze [correction of fleur] (subepithelial corneal opacity) observed after photorefraction interventions are described. Early haze [correction of fleur] (during the first 14 days) is caused by structural and spatial disorders and edema of the surface stromal layers under the hyperplastic epithelium. By its pattern and localization it can be classified as early subepithelial exudative. With differentiation of the epithelium and restructuring of the extracellular matrix, early haze [correction of fleur] as a rule gradually and spontaneously resolves within 10-14 days. Late haze [correction of fleur] is more stable and stubborn; it develops as a result of proliferation and migration of activated keratocytes into surface layers of the stroma at the site of photoablation usually 3 months and more after photorefraction keratectomy. Therefore, exposure of the cornea to an eximer laser is a source of its exogenous (physical) injury leading to an aseptic inflammation. The task of the refraction surgeon is timely drug correction, adequate to phases of inflammation, in order to create conditions for rapid complete regeneration of corneal tissue and restoration of its transparency.

The results of correction of residual myopia by photorefraction keratectomy (PRK) (51 eyes) and laser specialized keratomileusis (LASIK) (36 eyes) after radial keratotomy (RK) are compared. The patients were observed for up to 12 months. After PRK, 7.3% patients developed late fleur of the cornea, evaluated by at least 2 points. The incidence of fleur directly depended on the value of residual myopia. After LASIK none of the patients developed such fleur. The best visual acuity (0.5 and higher without correction) was attained in 70.73% after PRK and RK, vs. 100% after LASIK. The results of photorefraction operations and severity of residual myopia after RK correlated. In residual myopia of up to -3 diopters the results of correction by PRK and LASIK were virtually the same. In residual myopia higher than -3 diopters, LASIK is preferable.

Laser in-situ keratomileusis has been performed on 2023 eyes of 1162 patients with myopia of 1-18 diopters and complex myopic astigmatism of 0.75-5 diopters. A Hansatome TM 230 HT keratome and Nidek EC 5000 eximer laser device were employed. The resultant refraction and visual acuity were analyzed during one year postoperation in different age groups and groups with myopia of different degree. In myopia of up to 6 diopters high visual acuity without correction (0.93-0.99) was attained in all age groups. In higher myopia, visual acuity has been increasing over the entire period of observation, the gradient of its alteration being 0.17-0.27. The final visual acuity formed in presbiopes during 3 months. The spherical refraction equivalent of up to 1 diopter was 96.1%. The mean refraction values were stable during the entire period of observation. In myopia of 9.5 diopters and higher the residual myopia in patients aged over 30 years was approximating 1.0 diopters. Hypercorrection was observed in 1.3%, hypocorrection in 2.6% cases. The described combination of equipment for laser keratomileusis provides stable visual and refraction results at a lower incidence of complications.

Myopia and astigmatism were corrected by laser specialized keratomylesis in 1357 eyes with myopia of 1-18.0 diopters and astigmatism up to -5.5 diopters. The proposed method is highly effective in myopia of different severity and astigmatism and is preferable to photorefraction keratectomy.

Effects of corticosteroid and nonsteroid antiinflammatory drugs on corneal transparency after photorefraction keratectomy (PFK) in myopia are studied. Corneal transparency was assessed by computer analytical system for the anterior segment of the eye, designed by the authors. Corticosteroids (0.1% dexamethasone solution) more effectively control bacterial contamination of the cornea in high myopia than nonsteroids (0.1% sodium diclofenac solution). A significant improvement of optic density of the cornea was observed 2 weeks after PFK when corticosteroids were discontinued. On the other hand, replacement of diclofenac with dexamethasone 2 weeks after PFK did not result in decrease of optic density of corneal image. Apparently, corticosteroids contribute to decrease of bacterial contamination of the cornea during the very first days after PFK. In myopia of up to -6.0 diopters, the densitometric parameters were virtually the same in the patients treated with nonsteroids and corticosteroids.

Video images of the cornea in photorefraction keratectomy (PFK) are analyzed by computer-aided microdensitometric analysis of televideo images of the eye. Optic density of various layers of the cornea and fluorescein penetration through the cornea were assessed in patients with myopia (235 eyes) and hypermetropia (65 eyes) before the after PFK. PFK was carried out by Nidek excimer laser (Japan). Analysis was carried out with consideration for the degree of emmetropia and patients' ages. Corneal transparency and index of fluorescein penetration through the cornea correlated with patient's age and emmetropia. Computer-aided microdensitometric analysis of televideo images of the eye earlier detects changes in the cornea than routine methods. The authors discuss the probability of assessing corneal transparency for selection of patients for PFK.

Photorefraction keratectomy (PRK) was carried out using Nidek EC-5000 eximer laser in patients with myopia of different degree and myopic astigmatism. After 12 months, visual acuity without correction was 0.6-1.0 diopters in all patients with slight myopia, 0.7-1.0 in 95% of patients with medium myopia, and 0.8-1.0 in 86% of patients with high myopia. A lower visual acuity in high myopia was caused by retinal complications of myopia. The results of refraction after PRK depended on the severity of myopia and patient's age. The degree of myopia regression depended on preoperative refraction and was more expressed in high myopia. Young patients developed a more expressed tendency to decrease of postoperative refraction. The results indicate that eximer laser is an effective and reliable tool for correcting myopia of different degree and myopic astigmatism.