Ultrastructural and Immunohistochemical Characteristics of Corneal Lenticule Extracted during Correction of Residual Myopia in the Long-Term Period after SMILE

Purpose: To evaluate ultrastructural characteristics of lenticule surface extracted during correction of residual myopia in patients after small-incision lenticule extraction (SMILE). Methods and material: This study had a prospective, consecutive, comparative design. Sixteen patients (16 eyes) underwent additional intervention for residual myopia correction after SMILE. 16 specimens of removed lenticules underwent morphological examination. Markers and reagents were used to determine actin microfilaments, neutral fats and cell nuclei. The tissue was analyzed in layers in 2D slices form, volumetric Z-stacks, or selected areas were formed in orthogonal projections. The surface of the extracted lenticule was analyzed using scanning electron microscopy. Patients’ refractive outcomes were measured postoperatively (1 day;1 and 3 months). Results: Postoperatively uncorrected distance visual acuity (20/20 or better) was in 100% cases 3 months after surgery. Ultrastructural studies have shown the difference in surfaces of the newly formed lenticule. Structural changes of the posterior lenticule surface were characterized by ruptures of collagen fibers on its surface, degenerative changes in keratocytes with signs of colliquation necrosis, cell apoptosis and F-actin in cell cytoplasm. Conclusion: Collagen fibers are immersed in the stroma on the anterior surface of the lenticule. There is no complete structure restoration of collagen fibers explaining the lack of tight adhesion of anterior and posterior surfaces of the intrastromal space even in the long-term postoperative period. There are no degenerative changes of keratocytes on the anterior lenticule surface, that is, their changes in SMILE are reversible in most cases.

Scheimpflug Imaging of the Anterior Eye Segment during Standardized Accommodation Stimulation in Patients with Emmetropia, Myopia and Hypermetropia

Understanding of the biomechanics of the accommodative apparatus in the eyes with different refraction is important for solving the problems of theoretical and practical ophthalmology. Purpose: To determine the changes of anterior eye segment dimensions during accommodation response in normal eyes and in patients with myopia, hypermetropia. Methods and Material: 116 eyes (56 patients aged from 18 to 30 years, refraction from -2.0 to + 2.0 D) were examined. All the patients underwent a full ophthalmological examination. The ocular anterior segment was imaged using a rotational Scheimpflug camera Pentacam HR (Oculus, Wetzlar, Germany) under non- and 3.0 D of accommodative demands. The statistical data were represented as the mean value ± standard deviation (M ± SD). The Shapiro-Wilk test was used to assess the normality distribution. Wilcoxon test was used for comparison. Results: Results showed an increase in the optical density of the crystalline lens, a pupil diameter decrease and changing of the iris profile during accommodation in all patients. An increase in the total corneal aberrations and decrease in the corneal spherical aberration were revealed only in emmetropic eyes. Conclusions: The accommodative response is a multicomponent process. Scheimpflug visualization revealed the differences in the accommodative response in normal and ametropic eyes.

Diagnostics and Prediction of Glaucoma in Patients with Familial Congenital Iris Hypoplasia

Purpose: To identify the clinical features of the syndrome Frank-Kamenetsky and determine the criteria of early formation of glaucoma. Materials and Methods: We observed 52 patients. Follow up period was from 5 to 22 years. The first group (juvenile) consisted of males who had the first signs of glaucoma diagnosed before the age of 12 (n = 22). The average age of the group was 10.1 ± 2.4 years. The control group included healthy males (n = 30) in the same age range (average age 7.2 ± 1.6 years). The second group (adults) consisted of patients who had the first signs of glaucoma diagnosed after the age of 18 and elder. The average age of the group was 32.44 ± 6.28 years. The control group had males (n = 30) in the same age range (average age 26.59 ± 4.12 years). The inclusion criterion was: the presence of congenital bilateral mesodermal iris leaf hypoplasia, tra-becular dysgenesis signs, the presence of blood relatives on the maternal line (grandfather, uncle) male with similar changes iridociliary zone and glaucoma. Criteria of glaucoma formation were: increased IOP more than 21 mmHg with accompanying it expansion of the cup/disc ratio, reducing the thickness of the nerve fiber layer (RNFL) according to OCT. Results: It was found that Frank-Kamenetsky Syndrome had an X-linked with sex, recessive inheritance and was characterized by bilateral congenital irisdysgenesis and goniodysgenesis with the accession glaucoma. Predictors of glaucoma formation in early childhood are a combination of: 1) congenital subtotal atrophy of iris mesodermal layer (from 0 to 30 mkm) with signs of progressive dystrophy;2) nonprogressive congenital megalocornea (cornea diameter 12 - 14 mm);3) iridotrabecular dysgenesis of II-III degree;4) hyperopic refraction in axial myopia.

DEVELOPMENT MECHANISMS OF PIG-MENTARY DISPERSION SYNDROME AND PIGMENT GLAUCOMA

In our series of 55 patients with pigmentary dispersion syndrome and pigment glaucoma we revealed: 1. Pathogenesis of pigmentary dispersion syndrome and pigment glaucoma includes reverse pupil block forming, lipid hyperoxidation in intraocular fluid, damage of trabecular meshwork by melanin granules, resulting in eye hydrodynamics disturbance, are basic parts; 2.

FRANK -KAMENETSKI GLAUCOMA

This rare form of glaucoma is endemic for East Siberia region. This pathology is hereditary, it is transmitted through x-associat-ed recessive type by women-conductors to sick sons. Typical manifestation of this glaucoma is characteristic hypoplasia of iris stroma with its pigment layer uncovering. Pupil zone is always light gray, iris periphery is in the form of wide contrast ring of darker color. This two-colored hue is revealed in all patients

Fundamentals of Presbyopia: visual processing and binocularity in its transformation

Background:The accommodation has considerable interactions with the pupil response,vergence response and binocularity.The transformation of visual reception processing and the changes of the binocular cooperation during the presbyopia development are still poorly studied.So,the regularities of visual system violation in the presbyopia formation need to be characterized.This study aims to reveal the transformation of visual reception processing and to determine the role of disturbances in binocular interactions in presbyopia formation.Methods:This study included 60 people with emmetropic refraction,uncorrected distance visual acuity 1.0 or higher(decimal scale),normal color perception,without concomitant ophthalmopathology.The first group consisted of 30 people(from 18 to 27 years old)without presbyopia,the second cohort comprised 30 patients(from 45 to 55 years old)with presbyopia.The eyeball anatomy and optics were evaluated using ultrasound biomicroscopy,aberrometry,and pupillometry.The functional state of the visual system was investigated under monocular and binocular conditions.The registration of the disparate fusional reflex limits was performed by the original technic using a diploptic device which facilitated investigation of the binocular interaction under natural conditions without the accommodation response,but with the different vergence load.The disparate fusional reflex was analyzed using the proximal and distal fusion borders,and the convergence and divergence fusion borders.The calculation of the area of binocularity field was performed in cm2.Results:The presbyopia formation is characterized by a change in an intraocular anatomy,optics,visual processing,and binocularity.The processes of binocular interaction inhibition make a significant contribution to the misalignment of the visual perception.The modification of the proximal,distal and convergence fusion borders was determined.It was revealed that 87%of the presbyopic patients had binocularity shortage,whereas the reduction of binocularity field area in extreme grade was seen in 6%of cases.Conclusions:The presbyopia formation is accompanied by a significant reorganization of the visual system activity and by the creation of the new visual processing interactions.These data may be useful in presbyopia surgery.