[Intrastromal corneal segments implantation in keratoconus].

Up-to-date models of intrastromal corneal segments are reviewed. Different techniques of up-to-date models of intrastromal corneal segments implantation in keratoconus are described. Mechanical and laser techniques of forming of corneal tunnels are analyzed. Information about potential complications of intrastromal corneal segment implantation is given.

[Intrastromal corneal segments implantation in keratoconus].

Comparative analysis of intrastromal corneal segments Keraring implantation using either femtosecond laser or manual technique to create corneal tunnel in 47 patients (47 eyes) with keratoconus stage II-III is presented. Refractional and functional results in groups with femtosecond laser and manual technique did not show significant difference. The main advantage of femtosecond laser revealed in the study is technical simplification of intrastromal tunnels creation.

[Investigation of the impact of pterygium on ocular optic system aberration. Communication 1. Relationship of induced aberrations to the stage of pterygium].

The authors made a study in two areas: they investigated corneal aberrations in patients from different age groups in health; analyzed the corneal aberration pattern at different stages of pterygium in the matched age groups; and comparatively estimated values in pterygium and in health in the similar age groups. High-order aberrations (HOA) of the corneal were studied in 45 patients (84 eyes) aged 20 to 76 years. The corneal aberration pattern was analyzed in 44 patients (55 eyes) aged 25 to 74 years who had pterygium of different stages. The study covered patients with Stages II (24 eyes), III (n=20), and IV (n=11). The results of corneal HOA in health suggest that coma aberrations significantly increase with age while the rise of spherical aberrations is not decisive. Comparative analysis of aberrations in health and in pterygium of different stages showed that its stage II causes no significant changes in the corneal aberration pattern; the characteristic features of the latter in Stages III and IV pterygium are increases in trefoil and aberrations of the fourth and fifth orders: tetra- and pentafoil, secondary trefoil. The increase in the above parameters is proportional to the stage of pterygium. The comprehensive examination of patients with pterygium of different stages should comprise a study of corneal HOA, it is required for more detailed evaluation of disorders induced by the extent of pterygium, which in turn makes it possible to optimize the latter's removing technology.

[Investigation of the impact of pterygium on ocular optic system aberration. Communication 2. New approaches to reducing aberrations during surgical treatment for pterygium].

The authors made a detailed comparative analysis of the aberration pattern of the cornea as a result of surgical treatment for pterygium, by applying various technologies. Forty-four patients (55 eyes) with primary Stages II to IV pterygium were examined. According to the surgical techniques, the patients were divided into 2 groups: (1) those in whom pterygium was surgically removed, followed by abrasive microsurgery and plastic repair with an autoconjunctiva (29 eyes) (a control group); (2) those who had undergone surgical pterygium removal, abrasive microsurgery, and plastic repair with an autoconjunctiva, followed by phototherapeutic eximer laser keratoablation (26 eyes). The study has revealed that phototherapeutic eximer laser ablation of the cornea after surgical excision and abrasive treatment of the corneal bed in Stages II to IV pterygium causes a considerable reduction in the level of aberrations of higher orders. The expedience of phototherapeutic keratoablation as part of multimodality treatment for Stages III and IV pterygium, which has been shown by the aberration analysis, is only one of the first steps in evaluating the efficiency of this technology of surgical treatment for pterygium. Studies involving an integrated clinicofunctional and ophthalmoergonomic assessment of this treatment technology should be continued, which makes it possible to evaluate the clinical efficiency of this procedure and to define a place of the presented technology in the surgical treatment of pterygium.

[Indications for optimized refractive keratoablation. Communication 1. Dependence on the grade of myopia and baseline high-order aberrations].

The authors made a detailed comparative analysis of the aberration pattern of patients before and after aspheric individualized keratoablation (ORK-CAM) and the LASIK operation by routine technology, by taking into account the grade of correctable myopia and the size of baseline high-order aberrations (HOA). Investigations were made in 2 groups: 1) 20 patients (39 eyes) who had undergone routine ablation (a study group); 2) 19 patients (38 eyes) who had aspheric individualized keratoablation (a control group). The findings suggest that individualized aspheric keratoablation is effective in patients with mild and moderate myopia with varying baseline HOA. In addition, a relationship was found between the results of standard and optimized correction and one more key parameter of the aberration pattern, namely the magnitude of 4th-order spherical aberration that should be also taken into account on choosing an eximer laser correction technology. There is an outstanding question whether it is expedient to perform ORK-CAM in patients with high-grade myopia. The above problems require that further studies be continued and will be considered in part 2 of the present investigation.

[Indications for optimized refractive keratoablation. Communication 2. Dependence on baseline spherical aberrations].

The authors made a detailed comparative analysis of the aberration pattern of patients before and after aspheric individualized keratoablation (ORK-CAM) and the LASIK operation by routine technology, by taking into account the magnitude of 4th-order spherical aberration. Investigations were made in 2 groups: 1) 20 patients (39 eyes) who had undergone routine ablation (a study group); 2) 19 patients (38 eyes) who had aspheric individualized keratoablation (a control group). The detailed comparative analysis of the aberration pattern in patients after eximer laser correction by different technologies yielded major criteria predetermining the choice of an eximer laser correction technology. Indications for routine and individualized aspheric keratoablation are defined. Further studies of the impact of high-order aberrations on different visual functions are required to solve the vexed questions whether it is aberrationally expedient to choose laser correction. Ophthalmo-ergonomic studies should be also performed to provide a clinical verification of the consistency of the proposed concept of the indications and the choice of the optimal technology of eximer laser correction.

[Evaluation of the efficiency of aspheric eximer laser keratoablation (a preliminary communication)].

The authors have evaluated the efficiency of aspheric customized keratoablation (ORK-CAM) versus LASIK operation by the routine technology. The studies were conducted in 2 groups: 1) 11 patients (22 eyes) who had undergone aspheric individualized keratoablation (a study group); 2) 13 patients (24 eyes) who had LASIK operation by the routine technology (a control group). After aspheric individualized correction, the clinical and functional results were comparable in visual acuity and correction accuracy with those after routine laser operations. After optimized ablation, there was a statistically significantly less increase in spheric aberration, cumulative high-grade aberrations than after routine LASIK operation. Questioning about visual comfort revealed that aspheric individualized keratoablation was effective in solving characteristic optical problems. The studies have yielded encouraging preliminary results. Further complex studies are required for comprehensive evaluation of the efficiency of aspheric keratoablation.

[Eximer laser methods for correction of astigmatism in cataract surgery].

This paper deals with refractive disorders in cataract surgery. The authors have studied the efficiency of eximer laser correction (LASIK) of astigmatism on pseudophakic eyes and proposed their own modification of the technology "Pre-flap" that provides the most advantageous conditions for laser correction. In addition, preflapping permits correction of astigmatism in the immediate period after cataract extraction, thus reducing the time of the patients' rehabilitation. Clinical and functional studies have provided evidence for the proposed procedure.

[Comparative clinical study of the standard lasik operation versus optimized ORK "Corwave" keratoablation (a preliminary communication)].

The efficiency of primary ORK "Corwave" versus LASIK operation was evaluated. Studies were conducted in 2 groups: 1) 12 patients (34 eyes) with bilateral ORK "Corwave" (a study group); 2) 18 patients (36 years) undergone bilateral LASIK by the conventional technology (a control group). The following parameters: uncorrected visual acuity, values of refraction 1 and 3 months after surgery; high-order aberrations (values of RMS coma, spherical aberrations, RMS HOA of orders 3 to 6), spatial contrast sensitivity, blindness sensitivity, questionnaire data on visual comfort, were studied for comparative evaluation of the results of eximer laser correction made by different technologies. In the acuity of vision and in the accuracy of correction of refractive disorders, the clinical and functional results following the optimized correction by the "Corwave" technology were comparable with those after standard laser operations. After ORK "Corwave", spatial contrast sensitivity was found to tend to improve at average and high frequencies. After optimized ablation, the increase in high-order aberrations was less than that after traditional LASIK in terms of all three analyzed parameters; however, this difference was statistically insignificant. The questionnaire test for visual comfort revealed that ORK was effective in overcoming the characteristic optical problems: visual disorders were detected in fewer cases after optimized correction.

[Spatial contrast sensitivity in patients with high myopia after refraction lamellar keratoplasty]. / Prostranstvennaia kontrastnaia chuvstvitel'nost' u patsientov s vysokoi miopiei posle refraktsionnoi lamelliarnoi keratoplastiki.

Spatial contrast sensitivity (SCS) is one of the most important visual functions. SCS was examined in 23 patients (38 eyes) with high myopia before and after refraction lamellar keratoplasty (RLK) and in 21 healthy controls. Before surgery an appreciable (p < 0.01) reduction of SCS was observed in patients with high myopia in the entire range of spatial frequencies in comparison with the controls. After the operation the maximally corrected vision acuity was virtually unchanged, whereas the parameters of SCS somewhat increased for all frequencies, the increase being statistically reliable at frequencies of 0.23 to 3.75 and 15 cycles/degree. Hence, the studies demonstrated that changes in the topography of the cornea after refraction lamellar keratoplasty do not deteriorate the visual function.

[A surgical method for the treatment of traumatic low-solubility hyphema]. / Khirurgicheskii sposob lecheniia travmaticheskikh trudno- rassasyvaiushchikhsia gifem.

Presents experimental and clinical data on the operation of 'angular drainage' of the anterior chamber in traumatic poorly soluble hyphemas. The operation consists in conduction of a supramide thread through performed orifices in the cornea and formation of an angular drainage for blood evacuation from the anterior chamber. High efficacy and safety of the suggested method for treatment of recurrent complicated hyphemas is proved.