[Analysis of light scattering ability of the cornea before and after endothelial keratoplasty]. / Analiz svetorasseivayushchei sposobnosti rogovitsy do i posle endotelial'noi keratoplastiki.

PURPOSE: To evaluate light scattering ability of the cornea before and after Descemet's stripping automated endothelial keratoplasty (DSAEK) and Descemet's membrane endothelial keratoplasty (DMEK) endothelial keratoplasty. MATERIAL AND METHODS: The study included 70 patients (70 eyes) who had undergone DSAEK and DMEK (35 patients, 35 eyes in each group). In addition to standard ophthalmological examinations before and during the one-year follow-up after surgery, the patients had their central corneal thickness, stromal thickness, thickness of the interface area and the graft measured with optical coherence tomography (Optovue, U.S.A.). Intensity of light scattering by corneal structures was evaluated using Pentacam HR (Oculus, Germany) topographer with proprietary software and algorithms for calculation of corneal transparency. RESULTS: Comparison of the outcomes revealed that indices of general integral and stromal light-scattering were higher in patients after DSAEK. Integral light scattering in the interface and graft areas in the DMEK group was significantly lower than in the DSAEK group during the whole follow-up period. CONCLUSION: The reason for decrease of visual acuity after endothelial keratoplasty, regardless of the surgery type, may be higher light-scattering ability of patient's corneal stroma due to residual opacifications. Better visual acuity outcomes after DMEK in comparison to DSAEK are associated with higher transparency of the interface and graft areas. The suggested new method of assessing the intensity of light-scattering allows more precise evaluation of the influence of light-scattering ability of the stroma, interface and corneal graft after different modifications of endothelial keratoplasty, considering the respective layer thickness and excluding the influence of light scattering on the air-epithelium interface.

[Refractive changes after different modifications of endothelial keratoplasty]. / Refraktsionnye izmeneniia posle razlichnykh modifikatsii éndotelial'noi keratoplastiki.

PURPOSE: To evaluate changes in clinical refraction after Descemet Stripping Automated Endothelial Keratoplasty (DSAEK) and Descemet Membrane Endothelial Keratoplasty (DMEK), and assess their correlation to the thickness of the transplant. MATERIAL AND METHODS: The main study group included 40 patients (40 eyes) after DSAEK and 20 patients (20 eyes) after DMEK, the control group consisted of 20 patients (20 eyes) without any corneal pathologies or history of surgical treatment. In addition to standard examination, patients of the main group had central corneal thickness and transplant thickness regularly measured; they were also monitored by optical coherence tomography (Optovue, U.S.A.), computed tomography and aberrometry of the cornea performed on Pentacam device. The control group had the same examination regimen. RESULTS: Best corrected visual acuity after 6 months was on average 0.2 higher in DMEK patients compared to those who underwent DSAEK; after one year - 0.1 higher. Clinical refraction data shows presence of hypermetropic changes after DSAEK surgery. Induced astigmatism after one year was 0.4 Diopters in DSAEK patients, but did not exceed 0.1 Diopters in DMEK patients. Stabilization of the corneal thickness in DMEK group occurred on the 3-4th month, in DSAEK group - 6-7th month. Certain values of higher-order aberrations (3-6) and root-mean-square deviation (RMS) of the wave-front of anterior corneal surface in DSAEK and DMEK groups were higher than in the control group. Aberrations on the posterior corneal surface in DMEK group were significantly lower than in DSAEK group. There were no statistically significant differences in 'final' RMS higher-order aberrations between DMEK and DSAEK groups.

[Mushroom keratoplasty in rosacea keratitis complicated by corneal perforation (a clinical case)]. / Gribovidnaia keratoplastika pri rozatsea-keratite, oslozhnennom perforatsiei rogovitsy (klinicheskii sluchai).

Rosacea is a polyethiologic chronic inflammatory disease with varying clinical manifestations. It is primarily a dermatologic disease, which often manifests in the eyes affecting eyelids, cornea and conjunctiva. The leading role in the pathological process belongs to disruption of regulatory mechanisms in the vascular, immune and nervous systems. It is accompanied by increased levels of metalloproteinases and vascular endothelial growth factor (VEGF). Treatment depends on the severity of the disease and may vary from hygiene of the eyelid margins and use of artificial tears for dry eye disease management, to antibiotics and anti-inflammatory agents in moderate cases, and surgical treatment in severe or neglected state. A clinical case of severe rosacea shows that keratoplasty with mushroom-shaped profile of the surgical incision helps achieve good functional results and reduce the post-operative rehabilitation time, while significantly reducing the risk of postsurgical complications. Anti-VEGF therapy significantly reduces the risk of histoincompatibility reaction typical for rosacea keratitis.

[Comparative analysis of modern methods of preparing donor material for endothelial keratoplasty]. / Sravnitel'naia otsenka sovremennykh sposobov podgotovki donorskogo materiala dlia éndotelial'noi keratoplastiki.

PURPOSE: To evaluate various methods of stripping Descemet's membrane of a donor corneoscleral flap for Descemet's membrane endothelial keratoplasty (DMEK). MATERIAL AND METHODS: The study included 60 corneoscleral flaps (mean donor age was 62.9 years) from the eye bank of Research Institute of Eye Diseases, which were not suitable for clinical use due to positive serological results. Four alternative methods of donor material dissection in preparation for DMEK were compared: SCUBA (group A), our newly suggested method utilizing intracapsular ring (group B), 'liquid bubble' (group C), 'big bubble' (group D). Parameters under evaluation were mean transplant preparation time, density of endothelial cells before and after dissection, presence of complications during detachment of Descemet's membrane. RESULTS: Mean detachment time in group A was 8.5 min, in group B - 7 min, in group C - 8 min, and in group D - 5 min. Loss of endothelial cells as compared with baseline was in average 10.5% in group A, 9.3% in group B, 10.7% in group C, and 10.3% in group D. Group A had two cases with complications occurring during separation of Descemet's membrane, group B had one such case, group C - 2 cases, and group D - 3 cases. Histologic examination confirmed absence of stromal fibers on the detached Descemet's membrane in groups A, B and C. CONCLUSION: Among the described methods of preparing donor material for DMEK surgery, all except 'big bubble' proved equal in terms of resulting transplant quality. The 'big bubble' dissection technique requires more time to complete, while the resulting transplant has stromal fibers. Our newly suggested method of Descemet's membrane stripping that utilizes intracapsular ring proved safe and effective alternative for preparing donor material for DMEK.

[Corneal degenerations]. / Degeneratsii rogovitsy.

Degeneration is the process of change occurring in cells, their parts or intracellular matter that happens due to external factors affecting the life of an organism and results in gradual disruption of normal condition of the tissue or the organ, and possibly complete loss of its functionality. Corneal degenerations may be caused by age-related physiological changes, associated with a certain systemic disease or local inflammations, or be the consequence of chronic toxic action of unhealthy environmental factors on the eye. Unlike dystrophies, corneal degenerations cannot be inherited and do not onset early. When corneal degenerations significantly affect visual acuity, the treatment should aim at alleviating the primary disease before inducing changes in the cornea. The existence of such pathology is important to remember and timely differentiate from acute inflammatory processes of various etiology that require immediate treatment. The right diagnosis is the key factor in choosing effective treatment strategy and thus achieving positive clinical results.

[Corneal dystrophies]. / Distrofii rogovitsy.

The article reviews modern clinical, morphological, and genetic aspects of corneal dystrophies based on the most recent international classification updated in 2015. Corneal dystrophies is a group of slow progressing, non-inflammatory corneal pathologies, most of which are characterized by variability of the associated traits. The existence of such pathologies makes important their differential diagnosis from acute inflammatory processes of various etiology, which require urgent therapy. Conservative treatment suitable for dystrophies is usually associated with disorders of the anterior corneal surface and employ symptomatic tactic (lubricants, epithelizing agents, soft contact lenses). No effective etiopathogenetically targeted treatment is currently known. In cases with significant visual acuity decrease, it is possible to perform phototherapeutic keratectomy, abrasive polishing of Bowman's membrane with diamond bur and various types of keratoplasty depending on the depth of involvement.

[Influence of endothelial graft thickness on postoperative visual acuity]. / Otsenka vliianiia tolshchiny éndotelial'nogo transplantata na posleoperatsionnuiu ostrotu zreniia.

AIM: to assess the influence of the endothelial graft thickness on postoperative visual acuity following modified endothelial keratoplasty (UTDSAEK). MATERIAL AND METHODS: The study included 49 patients with pseudophakic bullous keratopathy and no concomitant disorders of either the retina or optic nerve. Ultrathin Descemet's stripping automated endothelial keratoplasty (UTDSAEK) was performed in all cases. Corneal graft thickness was measured 1 year after UTDSAEK by means of optical coherence tomography. Postoperative visual acuity values were compared in patients with the endothelial graft thickness from 51 to 98 microns (27 eyes) and those with the endothelial graft thickness from 102 to 121 microns (22 eyes). The dynamics of the graft thickness change after surgery was also assessed. RESULTS: The thickness of the graft gets reduced by an average of 21% over the first 2-3 weeks after UTDSAEK and by approximately 5% over 2 more months. For the next few years it remains relatively stable (the maximum follow-up period was 5 years). The study showed no statistically significant difference in visual acuity between two groups of patients with the endothelial graft thickness of less than and greater than 100 microns (p=0.7). CONCLUSION: The thickness of the endothelial graft for UTDSAEK has no statistically significant effect on postoperative visual acuity. The optimal thickness of the graft being cut out lies in the range from 100 to 150 microns. Such grafts adapt well to the posterior surface of the recipient cornea with no significant changes to its topography. Moreover, thicker grafts are easier manipulated before insertion into the anterior chamber and are associated with a lower risk of perforation during acquisition as compared to grafts of under 100 microns.

[Fuchs endothelial corneal dystrophy]. / Éndotelial'naia distrofiia rogovitsy Fuksa.

Fuchs endothelial dystrophy is a severe disease characterized by slowly progressing bilateral asymmetric corneal edema usually seen in elderly patients. The primary purpose of treatment is to minimize edema-related symptoms, such as ocular discomfort and visual acuity loss. Conservative therapy is symptomatic and has a short-term positive effect that does not lead to full functional rehabilitation of the patient, while endothelial keratoplasty is pathogenetically oriented. Intentional replacement of pathologically altered corneal layers has several advantages: preservation of corneal architectonics, rapid recovery of visual function, 'closed eye' surgery with corneal tunnel approach, and independence from expensive equipment. However, principle indications and contraindications for various modifications of endothelial keratoplasty in the presence of comorbidity are still to be defined. Further improvement of the methods and their broader implementation into clinical practice are the most pressing and promising issues of corneal transplantation.

[Risk factors, clinical presentations, prevention, and treatment of corneal graft rejection]. / Faktory riska, klinicheskie proiavleniia, metody profilaktiki i lecheniia reaktsii ottorzheniia transplantata rogovitsy.

Corneal transplantation is the most common and successful type of allotransplantation surgery. Post-transplant immune response in keratoplasty is less pronounced than that in other transplantation procedures, which is accounted for by anatomical features of the cornea and, also, its low antigenic potential and active immunosuppression. However, the immune privilege of the cornea can be violated by neovascularization, inflammation, or trauma. Patients who require keratoplasty to restore their sight and whose immune privilege is disturbed, fall into a high-risk group and are likely to demonstrate tissue incompatibility and non-transparent engraftment. Two approaches exist as to how graft rejection can be prevented. One of them involves induction of donor-specific tolerance, the other - non-specific suppression of the recipient's immune response. To avoid tissue incompatibility, measures can be taken to restore the immune privilege of the cornea as well as to induce antigen-specific tolerance, which is considered a promising, thought yet experimental, area of modern transplantology. In clinical practice, one pays most attention to improvement of non-specific immune suppression methods based on interfering in the metabolism of immunocompetent cells. Thus, timely prescriptions and proper immunosuppressive tactics with account to possible risk factors determine the outcome in high-risk patients undergoing corneal transplantation surgery.