[Optical properties of the cornea after different modifications of penetrating keratoplasty]. / Opticheskie svoistva rogovitsy posle razlichnykh modifikatsii skvoznoi keratoplastiki.

PURPOSE: Comparative analysis of optical properties of the cornea after different modifications of penetrating keratoplasty. MATERIAL AND METHODS: The study included 56 patients (56 eyes) divided into three study groups according to the surgery technique. Group I included 17 patients (17 eyes) after one-piece mushroom keratoplasty, group II - 21 patients (21 eyes) after two-piece mushroom keratoplasty and group III - 18 patients (18 eyes) after penetrating keratoplasty. In addition to standard examination methods, before surgery and in the course of the follow-up all patients underwent software-powered corneal densitometry on the anterior segment analyzer (Pentacam HR, "Oculus", Germany), as well as an assessment of the degree and regularity of postoperative astigmatism. RESULTS: Comparison of the obtained results revealed with a high degree of confidence higher values of the total specific light scattering after two-piece mushroom keratoplasty throughout the entire observation period (p<0.05). At the same time, there was no statistically significant difference in visual acuity between the three study groups (p>0.05). A statistically significant increase in the level of induced astigmatism was revealed after penetrating keratoplasty. CONCLUSION: The observed increase in light scattering after two-piece mushroom keratoplasty does not lead to a decrease in visual acuity. The interface in the optical zone of the cornea formed by a microkeratome does not affect the degree and regularity of induced astigmatism.

[Modern prerequisites for creating a collagen-based artificial analogue of the corneal stroma]. / Sovremennye predposylki sozdaniya iskusstvennogo analoga stromy rogovitsy na osnove kollagenovogo materiala.

Despite the fact that various collagen biomaterials have been actively used in ophthalmology for more than 30 years, the problem of creating a material that could replace the donor cornea have not been solved. Recent advances in the field of tissue engineering and regenerative medicine have shifted the focus of approaches to solving the problem of creating an artificial cornea towards laying conditions for the restoration of its specific layers through mechanisms of its own cellular regeneration. In this regard, extracellular matrices based on collagen are gaining popularity. This review discusses general limitations and advantages of collagen for creating an artificial cornea.

[The impact of the position of toric intraocular lenses on the functional outcomes of phaco surgery]. / Vliyanie polozheniya toricheskikh intraokulyarnykh linz na funktsional'nye rezul'taty fakokhirurgii.

The article reviews data on the impact of the position (orientation) of toric intraocular lenses on the functional outcomes of cataract phacoemulsification surgery, discusses the algorithm of astigmatism correction with intraocular lenses including preoperative determination of the size and position of main meridians, calculation of lens parameters, marking of corneal meridians, intraoperative positioning, as well as rotation and/or repositioning of the lens when necessary.

[Clinical and morphological characteristics of corneal epithelial dystrophy (clinical observations)]. / Kliniko-morfologicheskie kharakteristiki epitelial'noi distrofii rogovitsy (klinicheskie nablyudeniya).

This paper presents clinical observations that can be regarded as degeneration of the basement membrane of the corneal epithelium. Difficulties in identifying such forms of corneal dystrophies, on the one hand, are associated with limitation and polymorphism of the clinical picture, and, on the other hand, with insufficient information content of the basic diagnostic methods (i.e. the methods used during the initial examination). The presented clinical cases allow singling out the alarming and pathognomonic signs of the disease in the diagnostic algorithm. In the first case, attention should be paid to biomicroscopic changes in the superficial layers of the cornea and the optical defects, which can be regarded as a manifestation of an irregularity of corneal refraction. Identification of pathognomonic signs of the disease is possible on the basis of a detailed, close-to-morphological study of the structure of superficial corneal layers using confocal microscopy and optical coherence tomography. At the same time, the localization of the detected changes at the level of epithelial basement membrane and its basal sections is of crucial significance for substantiating the diagnosis. In addition, according to the literature data, recurrent erosions of the cornea of unclear etiology should be attributed to presumptive signs of degenerative changes in the basement membrane of the epithelium.

[Morphological characteristics of Descemet's membrane removed during endothelial keratoplasty (case study)]. / Morfologicheskie osobennosti udalennoi pri endotelial'noi keratoplastike destsemetovoi membrany (klinicheskie nablyudeniya).

The two most used modifications of endothelial keratoplasty (EK) are Descemet's membrane endothelial keratoplasty (DMEK) and Descemet's stripping automated endothelial keratoplasty (DSAEK). The leading complication of EK surgeries is graft detachment in the early postoperative period. This article reports on two cases of endothelial graft adhesion depending on morphological characteristics of the Descemet's membrane (DM) removed during EK. In the first case, complete graft attachment to the recipient's posterior stroma was observed after DMEK. Morphological analysis of the DM showed clean stromal surface. In the second case there was a false chamber between the endothelial transplant and the posterior stroma of the patient. OCT scans revealed separate stromal fibers protruding into the false chamber; morphological analysis of the removed DM showed stromal fragments fixed to the anterior surface of the DM. The revealed changes indicate damage to the posterior stroma the suffered received during descemetorhexis, which may be the cause for incomplete graft attachment. Complete attachment after repeated EK (DSAEK) in this case was due to a thin stromal layer on the graft that provided high degree of adhesion to the posterior corneal surface. DSAEK can be indicated as a repeated EK surgery in cases of persistent endothelial graft non-attachment after DMEK.

[Precorneal tear film after corneal collagen cross-linking in keratoconus (preliminary report)]. / Sostoyanie prekorneal'noi sleznoi plenki posle krosslinkinga rogovichnogo kollagena pri keratokonuse (predvaritel'noe soobshchenie).

PURPOSE: To study the condition of precorneal tear film in keratoconus patients after corneal collagen cross-linking (CXL). MATERIAL AND METHODS: The study enrolled 24 patients (30 eyes) with stages I-III progressive keratoconus. All study patients underwent standard (Dresden) protocol CXL. Patients were examined before the surgery and 1 week, 1 month, and 3 months postoperatively. The condition of precorneal tear film was evaluated based on the results of Norn test (the tear film break-up time), Schirmer test, Jones test, optical coherence tomography based lacrimal meniscometry, and improved tearscopy. RESULTS: One month after CXL, patients with keratoconus experienced transient changes in the precorneal tear film condition - the tear film break-up time was reduced, the tear secretion was elevated, the lacrimal meniscus biometry parameters were increased, and the thickness of the tear film lipid layer was decreased. CONCLUSION: Corneal changes resulting from CXL lead to transient disorders of the mucin and lipid layers of the precorneal tear film, which requires adequate tear substitute therapy in the postoperative period.

[Results of optical coherence tomography of the retina and optic nerve in keratoconus]. / Rezul'taty opticheskoi kogerentnoi tomografii setchatki i zritel'nogo nerva pri keratokonuse.

The article reviews the results of optical coherence tomography (OCT) of the retina and optic nerve in patients with keratoconus (KC). This research direction is premised by the possibility that changes in the retina and optic nerve are associated with KC, as well as the potential influence of significant changes in axial eye length, disorders of corneal refraction and increased level of aberrations on the quality of visualization of these ocular structures. Results of the conducted studies were conflicting, but in all they indicated a possibility of OCT findings to be altered in KC patients. Therefore, the question of changing the parameters for OCT of the retina and optic nerve requires further investigation. The main problem that needs solving with evidence based medical research can be phrased as follows: are the changes in OCT findings observed in KC patients the consequence of changes in the retina and optic nerve associated with this disorder, or potential effect of aberrations and irregular astigmatism on the quality of visualization of the studied structures?

[Possibilities of increasing contact lens tolerance in keratoconus (a clinical case study)]. / Vozmozhnosti povysheniya perenosimosti kontaktnoi korrektsii pri keratokonuse (klinicheskoe nablyudenie).

Optical correction of keratoconus (KC) is intended to simultaneously solve two tasks: elimination of myopic defocus and irregular astigmatism. In terms of the latter, hard contact lenses (HCL) should be considered as the first-choice method for optical correction of KC. HCL are currently the most effective means of optical correction of refractive errors induced by KC. Despite this, it should be noted that adherence of patients to this method of correction does not always correspond to results. Most often, limitations of HCL use in KC are associated with the so-called intolerance of correction. The term «correction intolerance¼ should be considered as a general complex of potential subjective symptoms and clinical manifestations that limit the possibility of using a particular method of optical correction. In this clinical observation, subjective discomfort when wearing lenses was practically eliminated by changing the design of the lens and switching from corneal to scleral HCL. The second problem was caused by clinical manifestations of corneal hypoxia (growth of newly formed vessels in the limbal region of the cornea) and attempts to solve it were associated with improved tear production and increased oxygen permeability of the material HCL are made of. The observed stabilization of the growth of newly formed vessels should be considered as a positive (although in need of dynamic evaluation) result of these therapeutic measures.

[Comparative assessment of functional outcomes of different endothelial keratoplasty techniques]. / Sravnitel'naya otsenka funktsional'nykh rezul'tatov razlichnykh tekhnologii endotelial'noi keratoplastiki.

PURPOSE: Comparative analysis of the higher-order aberrations (HOA) of the cornea after endothelial keratoplasty (EK) using DSAEK and DMEK techniques; evaluation of the correlation between higher-order corneal aberrations and functional outcomes of the treatment. MATERIAL AND METHODS: The study included 47 patients (59 eyes). The main group consisted of 35 patients (35 eyes) with bullous keratopathy and Fuchs' endothelial dystrophy; among them, 19 patients underwent endothelial keratoplasty using the DSAEK technique and 16 - DMEK technique. The control group included 12 patients (24 eyes) of corresponding age without corneal pathology. Standard and special examination tests were performed before, as well as 6 and 12 months after the operation, including computed tomography and aberrometry of the cornea using the Pentacam HR system. Same tests were performed in the control group. RESULTS: The values of the main HOA of the anterior corneal surface: RMS coma (Z3±1, Z5±1), RMS spherical aberration (SA; Z40, Z60) and RMS HOA (Z3-6) 6 months after different EK techniques were statistically significantly higher than in the control group. A statistically significantly lower induction of aberrations of the posterior corneal surface after DMEK technique was revealed. Analysis of the final aberration pattern 6 months after surgery did not reveal any statistically significant differences in the values of the main (RMS coma, RMS SA, RMS HOA) total corneal aberrations after DSAEK and DMEK. A negative correlation was revealed between the best corrected visual acuity (BCVA) and HOA; however, it was statistically significant only for individual aberration values: RMS HOA (Z3-6) of the posterior corneal aberrations after DMEK (r= -0.634, p=0.049), and RMS coma (Z3±1, Z5±1) of the cornea after DSAEK (r= -0.57, p=0.042). CONCLUSION: Comparative analysis of total corneal HOA did not reveal a statistically significant difference in the main parameters: RMS coma, RMS SA, RMS HOA in patients after DSAEK and DMEK surgeries. Correlation analysis did not reveal any statistically significant effects of most aberrations on the functional outcomes of the treatment.

[Differentiated method of surgical prophylaxis against anterior capsular contraction syndrome during phacoemulsification]. / Differentsirovannaya metodika khirurgicheskoi profilaktiki kapsulyarnogo kontraktsionnogo sindroma v khode fakoemul'sifikatsii.

Prevention of the anterior capsular contraction syndrome (ACCS) in the late postoperative period in patients with lens subluxation is a current problem of phacoemulsification (PE). PURPOSE: To develop and clinically evaluate a differentiated method of surgical prophylaxis against ACCS during PE in patients with lens subluxation. MATERIAL AND METHODS: Phacoemulsification surgery with in-the-bag IOL implantation and postoperative follow-up were carried out in 192 patients (192 eyes) with cataract and lens subluxation. In all patients, complete anterior capsulorhexis at the beginning of the surgery was not possible. A differentiated approach was used for capsulorhexis extension at the final stage of the operation after in-the-bag IOL implantation. Three groups of patients were formed according to the three most common clinical situations. RESULTS: There were no signs of ACCS development in as many as 189 (98.4%) cases. In 3 (1.6%) cases, slight narrowing of the anterior capsulorhexis opening was noted, however, with no effect to the IOL position and functional results of the operation. CONCLUSION: The differentiated approach to anterior capsulorhexis in patients with lens subluxation allowed to perform phacoemulsification with in-the-bag IOL implantation and to avoid ACCS development in the late postoperative period.

[Methods of surgical treatment of keratectasia and analysis of postsurgical quality of vision]. / Metody khirurgicheskogo lecheniya keratektazii i analiz posleoperatsionnogo kachestva zreniya.

Keratectasias are non-inflammatory dystrophic diseases of the cornea characterized by progressive bilateral thinning of the cornea that lead to deterioration in the quantitative and qualitative characteristics of vision reducing patient's quality of life. The changes can be asymmetrical and destructive. A number of surgeries have been proposed to reduce the negative effects of keratectasia including penetrating keratoplasty and its modifications, implantation of corneal ring segments, corneal cross-linking - alone and in combination with other methods, intrastromal keratoplasty. These methods can improve visual acuity to a certain degree and help slow the progression of keratectasia. This article studies various surgical methods used for treating keratectasia and analyses possible assessment of the quality of vision before and after the treatment.

[Morphological and functional features of bilateral avascular retinal pigment epithelium detachment (a case report)]. / Morfofunktsional'nye osobennosti bilateral'noi avaskulyarnoi otsloiki pigmentnogo epiteliya setchatki (klinicheskoe nablyudenie).

Detachment of the retinal pigment epithelium (RPE) is a manifestation of a number of degenerative, vascular, inflammatory processes in the eye. The most common cause of RPE detachment in older individuals is the neovascular form of age-related macular degeneration (AMD). Only in 10% of cases the detachment is transudative (avascular), characterized by high domed serous RPE detachment. The article presents an analysis of a case of idiopathic bilateral avascular pigment epithelium detachment - clinical, morphological and functional features of the disease, its impact on the visual functions and the quality of life.

[Comparative evaluation of positional stability of the «capsular bag + intraocular lens¼ complex in patients with lens subluxation]. / Sravnitel'naya otsenka stabil'nosti polozheniya kompleksa «kapsul'nyi meshok + intraokulyarnaya linza¼ u bol'nykh s podvyvikhom khrustalika.

Prevention of decentration and dislocation of the "capsular bag + intraocular lens" (IOL) complex in the late postoperative period is an actual problem of surgical treatment of patients with pronounced lens subluxation. PURPOSE: To conduct a comparative clinical study of positional stability of the "capsular bag + IOL" complex in the late postoperative period after application of a combined technique of capsular bag fixation in patients with subluxation of the lens. MATERIAL AND METHODS: Phacoemulsification (PE) with in-the-bag IOL implantation and postoperative observation was performed in 213 patients (234 eyes) with cataract and pronounced lens subluxation. The 1st group consisting of 138 patients (153 eyes) underwent capsular bag fixation of the combined technique with simultaneous use of 4 modified iris-retractors and one or two capsular tension rings (CTRs). The 2nd group included 75 patients (81 eyes) who in the course of PE had their capsular bag fixed beyond the edge of capsulorhexis with only 4 modified iris-retractors. Preoperative state of the lens and the evaluation of the frequency and degree of decentration of the «capsular bag + IOL¼ complex in the postoperative period were performed using data acquired with ultrasound biomicroscopy (UBM). RESULTS: Significant (more than 1 mm according to UBM) IOL's optic decentration was observed in the 1st group after applying the combined capsular bag fixation technique in 12 (7.8%) cases, and in the 2nd group after isolated use of modified iris-retractors in 48 (59.3%) cases. CONCLUSION: The use of the combined capsular bag fixation technique not only improves the conditions for carrying out PE with in-the-bag IOL implantation in patients with pronounced lens subluxation, but also contributes to a substantial (an average of 8 times) reduction in the incidence of significant decentration of the «capsular bag + IOL¼ complex in the late postoperative period.

[Iris shape change and risk of anterior chamber angle closure]. / Izmenenie formy raduzhki i risk zakrytiya ugla perednei kamery.

Potential obstruction of the anterior chamber angle by iris root is a key factor of the pathogenesis of angle-closure glaucoma. Development and adoption of ultrasound biomicroscopy and optical coherence tomography in clinical practice have significantly expanded the capabilities of studying the structures of the anterior eye segment in terms of angle closure risk factors through improving visualization depth and quality of examination, including different variants of iris structure and potential changes of its shape in mydriasis. The article reviews various studies dedicated to the progression of primary angle-closure glaucoma and its dependence on the biometric parameters of the eye and changes in pupil size.

[Energy load and state of corneal endothelium in hybrid (femtosecond laser-assisted) and torsional phacoemulsification]. / Énergeticheskaia nagruzka i sostoianie éndoteliia rogovitsy pri gibridnoi (femtolazernoi) i torsionnoi fakoémul'sifikatsii.

Postoperative state of the corneal endothelium is the most important criterion for evaluating the safety of cataract phacoemulsification. PURPOSE: To compare the intraoperative energy load and postoperative state of corneal endothelium in hybrid (femtosecond laser-assisted) and torsional phacoemulsification. MATERIAL AND METHODS: The study analyzed surgical outcomes of 603 patients (714 eyes) divided into 3 groups: 225 patients (267 eyes) underwent modified femtosecond laser-assisted phacoemulsification (1st group), 237 patients (278 eyes) underwent standard femtosecond laser-assisted phacoemulsification (2nd group), and 141 patients (169 eyes) who underwent torsional phacoemulsification (3rd group). The follow-up period lasted up to 2 years. RESULTS: In patients with grade II lens density (here and further - L. Buratto classification is used), effective ultrasound time was 0.56±0.11 s in the 1st group, 0.83±0.17 s in the 2nd group, and 2.78 ± 0.51 s in the 3rd group (p(1-2)<0.05; p(1-3)<0.05; p(2-3)<0.05). In patients with grade III lens density effective ultrasound time was 2.04±0.37 s in the 1st group, 2.97±0.53 s in the 2nd group, and 4.59±0.91 s in the 3rd group (p(1-2)<0.05; p(1-3)<0.05; p(2-3)<0.05). In patients with grade IV lens density, effective ultrasound time was 3.95±0.81 s in the 1st group, 5.11±1.03 s in the 2nd group, and 8.37±1.73 s in the 3rd group (p(1-2)<0.05; p(1-3)<0.05; p(2-3)<0.05). In patients with grade II lens density, loss of endothelial cells was 3.3±1.1% in the 1st group, 3.7±1.2% in the 2nd group, and 4.3±1.2% in the 3rd group (p(1-2)>0.05; p(1- 3)<0.05; p(2-3)<0.05). In patients with grade III lens density, loss of endothelial cells was 5.1±1.4% in the 1st group, 5.7±1.5% in the 2nd group, 7.2±1.7% in the 3rd group (p(1-2)>0.05; p(1-3)<0.05; p(2-3)<0.05). In patients with grade IV lens density, loss of endothelial cells was 8.9±2.1% in the 1st group, 10.1±2.3% in the 2nd group, and 13.3±2.5% in the 3rd group (p(1-2)>0.05; p(1-3)<0.05; p(2- -3)<0.05). CONCLUSION: Both techniques of femtosecond laser-assisted phacoemulsification significantly reduce the effective ultrasound time (p<0.05) and the degree of corneal endothelial cells loss (p<0.05) compared with torsional phacoemulsification.

[Prevention of intraoperative miosis in femtosecond laser-assisted phaco surgery]. / Preduprezhdenie intraoperatsionnogo mioza v fakokhirurgii c primeneniem femtosekundnogo lazera.

INTRODUCTION: Prevention of intraoperative miosis in hybrid (femtosecond laser-assisted) phacoemulsification is a relevant problem of cataract surgery. PURPOSE: Development and clinical study of an effective method for preventing intraoperative miosis in hybrid (femtosecond laser-assisted) phacoemulsification. MATERIAL AND METHODS: Hybrid phacoemulsification was performed in 300 patients (300 eyes). The first group (100 eyes) 3 days prior to the surgery was prescribed instillations of 0.1% indomethacin 3 times a day and 3 times in 2 hours before surgery at 30 minute intervals. The second group (100 eyes) 3 days prior to the surgery was prescribed instillations of 0.1% indomethacin 3 times a day, 3 times in 2 hours before the surgery at 30 minute intervals, and 1 hour before the surgery an additional intramuscular injection of diclofenac. The third group (control, 100 eyes) 2 hours before the operation was prescribed instillations of 0.1% indomethacin, 3 times at 30 minute intervals. The diameter of the pupil was evaluated before the beginning of femtosecond laser stage and before the opening of anterior chamber during the second stage of the operation. RESULTS: When the interval between the femtosecond laser stage and emulsification of the nucleus fragments was maintained at less than 15 minutes, pronounced decrease of the pupil (more than 2 mm) was noted in 8.2% of cases in the first group, 6.7% in the second group and 14.1% in third (control) group; mean values of pupil narrowing were 0.68±0.27 mm in the 1st group, 0.63±0.25 mm in the 2nd group, and 0.93±0.39 mm (p<0.05) in the third group. CONCLUSION: The clinical study showed high efficiency of the proposed methods for prevention of intraoperative miosis in hybrid (femtosecond laser-assisted) phaco surgery. An important factor affecting intraoperative narrowing of the pupil is the time interval between the femtolaser stage of the operation and emulsification of the nucleus fragments, which should not exceed 15 minutes.

[Changes in biomechanical properties of the cornea after keratorefractive surgery]. / Izmeneniia biomekhanicheskikh svoistv rogovitsy posle keratorefraktsionnykh vmeshatel'stv.

Biomechanical properties of the cornea are important for the functioning of the ocular optical system. They affect such qualities of the system as correct diffraction and resistance to different external action. Keratorefractive surgery widely used in clinical practice nowadays significantly upsets corneal biomechanics, which introduces a margin of error for IOP measurements done by different methods. The article reviews literature devoted to the problem of changes of corneal biomechanical properties after refractive surgeries.

[Antibiotic resistance in patients after serial intravitreal injections]. / Rezistentnost' k antibiotikam u patsientov na fone mnogokratnykh intravitreal'nykh in''ektsii.

Despite the lack of convincing data on the effectiveness of antibiotic therapy in the prevention of Post-Injection Endophthalmitis (PIE), the use of topical antibiotics for intravitreal injections is still a common practice. Frequent, monthly use of antibiotics results in changes of the composition of conjunctival flora and spontaneous mutations of bacteria, and leads to selective survival of resistant and virulent strains that can cause serious damage inside the eye.

[Compensating the Descemet's membrane defect (a clinical case study)]. / Kompensatsiia defekta destsemetovoi membrany (klinicheskoe nabliudenie).

The article describes a clinical case of Descemet's membrane detachment that occurred during cataract phacoemulsification with implantation of intraocular lens. Significant corneal edema developed in the early post-op period. Considering the ability of endothelium to close its own defects even with large injury area, the patient was followed-up for 2 years. Corneal edema was treated during 4 months and concluded with instillations of osmotic and anti-inflammatory drugs. At 1.5-2 months of therapy, the edema was gradually decreasing, and by the 4th month of the follow-up the cornea was practically transparent. Density of endothelial cells in central cornea, where the Descemet's membrane was absent, comprised 1000 cells/mm2. Further observation revealed cornea staying transparent for 2 years after the surgery. Complete optical recovery of patients with Descemet's membrane defect in this case study is supported by similar clinical cases briefly described in the article, and evidence that structural functional recovery of the corneal endothelial layer is possible even when it has large defects (more than 2.5 mm in diameter).

[Methods of preserving donor corneas]. / Metody konservatsii donorskikh rogovits.

Corneal transplantation is the most successful and frequently performed allotransplantation procedure. Benign outcome of penetrating and posterior keratoplasty depends on viability of the corneal tissue and presence of the proper endothelial layer, which retaining is one of the main objectives of preservation of donor material. Methods designed to reach this goal may be classified according to storage duration as short-term (storage in a moist chamber), medium-term (hypothermia), long-term (organ cultivation) and unlimited (cryopreservation). While there are reports of successful application of cryo-conserved corneas for penetrating keratoplasty, its use for this type of transplantation is limited due to complexity of the method and very high requirements for the quality of donor material. However, being a method of unlimited storage, it still attracts the attention of researchers. Taking into account the ongoing development of innovative keratoplasty technologies and the tendency for predominant use of layered grafts that in some cases do not need viable endothelium, methods of preservation of such material for anterior lamellar and intralamellar keratoplasties become relevant. In this context, cryopreservation without the use of cryoprotective agents is promising because it allows simple and fast accumulation of large amount of material with long storage time. Further research on the development of preservation methods of the corneal endothelial layer at sub-zero temperatures may allow storing the material by cryopreservation that will be suitable for penetrating and posterior keratoplasty.