Performing corneal tunnel incision with keratotomy scars intersection in patients after radial keratotomy during phacoemulsification

Purpose. A clinical study of safety and changes of refraction during intersection of a keratotomy scar while performing the corneal tunnel incision in phacoemulsification with IOL implantation. Material and methods. The clinical study included 11 patients (19 eyes) suffering from cataract and patients with previously performed anterior radial keratotomy. A tunnel incision 2.2 mm wide was performed with the location of the scar in its center. In case of insufficient area of the corneal tissue between the scars to involve only one keratotomy scar into the tunnel incision, the adjacent scar was transected at the final stage of tunnel formation when entering the anterior chamber. The other stages of phacoemulsification were carried out in a standard way. During the operation, the state of the keratotomy scar was assessed. A day, a week and a month later after the operation, the patients underwent biomicroscopy, autorefractokeratometry, visometry with an assessment of the values of subjective and objective cylindrical correction. In order to assess the postoperative state of the keratotomy scar and the incision zone, OCT of the cornea was performed using an RTVue 100 optical coherence tomograph (Optovue, Inc, USA) in Line, Crossline, 3D cornea modes. Results. In all cases, during the operation and also the next day, biomicroscopically the cornea was transparent, there was no keratotomy scar dehiscence. There is a dynamic of the best corrected visual acuity value by 1 month after surgery and the difference between the value for subjective and objective cylinder correction as well. The next day after the operation, in all cases the keratotomy scar on the OCT scans is uniform, comparable in width, the architectonics of the tunnel incision does not differ from that of standard phacoemulsification. Conclusion. Performing a corneal tunnel incision with the beginning of the formation outside the zone of the keratotomy scar and with further intersection of the scar with the plane of the blade so that most of it is in the projection of the center of the tunnel incision, as well as the intersection of the adjacent keratotomy scar at the end of the formation of the tunnel incision when entering the anterior chamber in case of insufficient the area of the corneal tissue between the incisions is safe at all stages of phacoemulsification and in the postoperative period. Changes in the values of best corrected visual acuity over time and the difference between the values of subjective and objective cylinder correction require further study on a larger sample and using various keratometry methods. Key words: radial keratotomy, phacoemulsification, tunnel incision, intersection of the keratotomy scar, cornea optical coherence tomography.

Certain chorioretinal parameters of the eye in congenital and acquired myopia and their relationship with anatomical and optical parameters

Purpose: to assess the thickness of the central region of the retina and choroid, the layer of nerve fibers in the macular and peripapillary regions, the density of the superficial and deep plexus of the retina and the choroid in congenital and acquired myopia and see how they are related with the refraction and axial length of the eye.Material and methods. 33 patients aged 6 to 16 (averagely, 12.07 ± 3.09 years) were divided into 3 groups: 1) with congenital myopia (23 eyes), 2) with acquired myopia (9 eyes), and 3) the control group with emmetropia (20 eyes). Chorioretinal and hemodynamic parameters were determined using an RS-3000 Advance 2 spectral optical coherence tomograph (Nidek, Japan). Correlation analysis was performed using Pearson’s linear correlation coefficient (r).Results. Structural changes in the sensory and vascular membranes of the eye were revealed in both myopic groups as compared to the control group. Of the two clinical groups, more severe structural disorders were found in congenital myopia. Hemodynamic parameters revealed abnormalities in the deep retinal layers, as well as in the choriocapillary layer. The comparative analysis showed that morphological changes in the posterior pole have a stronger correlation with anatomical parameters as compared to optical ones.Conclusion. Optical coherence tomography is an informative method of differential diagnosis, monitoring, and prognostication of changes in the posterior pole in myopia.

A Fast Lightweight Based Deep Fusion Learning for Detecting Macula Fovea Using Ultra-Widefield Fundus Images

Macula fovea detection is a crucial prerequisite towards screening and diagnosing macular diseases. Without early detection and proper treatment, any abnormality involving the macula may lead to blindness. However, with the ophthalmologist shortage and time-consuming artificial evaluation, neither accuracy nor effectiveness of the diagnose process could be guaranteed. In this project, we proposed a deep learning approach on ultra-widefield fundus (UWF) images for macula fovea detection. This study collected 2300 ultra-widefield fundus images from Shenzhen Aier Eye Hospital in China. Methods based on U-shape network (Unet) and Fully Convolutional Networks (FCN) are implemented on 1800 (before amplifying process) training fundus images, 400 (before amplifying process) validation images and 100 test images. Three professional ophthalmologists were invited to mark the fovea. A method from the anatomy perspective is investigated. This approach is derived from the spatial relationship between macula fovea and optic disc center in UWF. A set of parameters of this method is set based on the experience of ophthalmologists and verified to be effective. Results are measured by calculating the Euclidean distance between proposed approaches and the accurate grounded standard, which is detected by Ultra-widefield swept-source optical coherence tomograph (UWF-OCT) approach. Through a comparation of proposed methods, we conclude that, deep learning approach of Unet outperformed other methods on macula fovea detection tasks, by which outcomes obtained are comparable to grounded standard method.

A Fast Lightweight Based Deep Fusion Learning for Detecting Macula Fovea Using Ultra-Widefield Fundus Images

Macula fovea detection is a crucial prerequisite towards screening and diagnosing macular diseases. Without early detection and proper treatment, any abnormality involving the macula may lead to blindness. However, with the ophthalmologist shortage and time-consuming artificial evaluation, neither accuracy nor effectiveness of the diagnose process could be guaranteed. In this project, we proposed a deep learning approach on ultra-widefield fundus (UWF) images for macula fovea detection. This study collected 2300 ultra-widefield fundus images from Shenzhen Aier Eye Hospital in China. Methods based on U-shape network (Unet) and Fully Convolutional Networks (FCN) are implemented on 1800 (before amplifying process) training fundus images, 400 (before amplifying process) validation images and 100 test images. Three professional ophthalmologists were invited to mark the fovea. A method from the anatomy perspective is investigated. This approach is derived from the spatial relationship between macula fovea and optic disc center in UWF. A set of parameters of this method is set based on the experience of ophthalmologists and verified to be effective. Results are measured by calculating the Euclidean distance between proposed approaches and the accurate grounded standard, which is detected by Ultra-widefield swept-source optical coherence tomograph (UWF-OCT) approach. Through a comparation of proposed methods, we conclude that, deep learning approach of Unet outperformed other methods on macula fovea detection tasks, by which outcomes obtained are comparable to grounded standard method.

Characteristic of the central cornea thickness in healthy children and in patients with congenital glaucoma

Background. Ophthalmic hypertension is one of the most important diagnostic criteria for congenital glaucoma. The «gold standard» for measuring intraocular pressure (IOP) is the applanation tonometry (Maklakov and Goldmann methods). However, the thickness of the central corneal zone has a significant effect on the value of IOP measured by these methods. The aim of this study was to compare the central corneal thickness (CCT) in children with congenital glaucoma and in healthy children. Material and methods. We examined 15 children aged from 7 months to 14 years (22 eyes) with congenital glaucoma. In the healthy children group, 26 subjects from 7 to 17 years old (51 eyes) were examined. CCT was measured in all subjects using the optical coherence tomograph Carl Zeiss Cirrus HD-OCT 5000 with an external lens for cornea scanning. The examination was carried out in pachymetry mode; the average thickness of the central ring having a diameter of 2 mm was evaluated. Results. Central corneal thickness in children with glaucoma ranged from 471 to 771 microns, the average value was 561.5±72.26 microns. In the group of healthy children, CCT was in the range of 480-597 microns with an average value of 529.88±29.33 microns. Thus, we noted a higher average value of the central corneal thickness and its higher variability in children with glaucoma in comparison with the group of healthy children. Conclusion. All children with glaucoma and suspected glaucoma should routinely perform pachymetry prior to applanation tonometry. One should consider the central corneal thickness when assessing intraocular pressure. Key words: congenital glaucoma, pachymetry, optical coherence tomography, central corneal thickness, applanation tonometry, intraocular pressure.

Morphometric assessment of the state of the choroid in patients with anterior uveitis associated with the HLA-B27 Antigen

Purpose. To assess the state of the choroid in patients with anterior uveitis associated with the HLA-B27 Antigen, without ophthalmoscopically detectable lesions of the macular zone. Material and methods. 24 patients with acute anterior uveitis associated with HLA-B27 Antigen, without ophthalmologically detectable changes in the macular zone. The average age of the patients was 39.02±13.76 years. There were 16 men and 8 women. Maximum corrected visual acuity ranged from 0.1 to 0.5. The level of intraocular pressure according to Maklakov varied from 15 to 22 mm Hg. The subfoveal choroidal thickness (SCT) was determined using an optical coherence tomograph in comparison with paired intact eyes before treatment and 2 weeks after its initiation. Results. The initial values of the SCT index in the main group varied from 337 to 371 µm, averaging 354±8 µm. This is statistically significantly higher than in intact paired eyes (255±7 µm; from 246 to 268 µm; p<0.001). 2 weeks after the start of treatment, the SCT index in the main group was 268±10 µm, which was statistically significantly lower than the initial values in this group (p<0.001). Conclusion. A statistically significant increase in SCT was revealed in the eyes of patients with acute anterior uveitis. 2 weeks after the start of treatment, the SCT index statistically significantly decreased to 268±10 µm, which did not statistically significantly differ from that of the intact eye. Key words:anterior uveitis, HLA-B27 Antigen, subfoveolar thickness of the choroid.

Correlation analysis of some functional and anatomical parameters of the visual analyzer in nystagmus and amblyopia of various origins

Aim: To conduct a correlation analysis of the parameters of visual fixation, light sensitivity of the retina in the central region, and the thickness of the central region of the retina and choroid with the best corrected visual acuity (BCVA), refraction (SER), and axial length of the eye (AL) in nystagmus and amblyopia of various origins. Material and methods: The study included 45 patients aged 544 years (mean 11.26.14 years). All patients were divided into six groups depending on the type of amblyopia and associated conditions (with nystagmus). The retinal photosensitivity and fixation parameters were studied using an MP-3 Nidek microperimeter (Japan). Chorioretinal parameters were studied using an RS-3000 Advance 2 spectral optical coherence tomograph (Nidek, Japan). The axial length of the eye was measured using a Galilei G6 Scheimpflug analyzer. Correlation analysis was performed using the linear Pearson correlation coefficient (r). Results: In nystagmus, refractive and dysbinocular amblyopia, a strong direct correlation was found between the indicators of BCVA and the characteristics of fixation. In the groups associated with congenital myopia, relationships were found between BCVA, retinal thickness, and light sensitivity of the retina in the central region. There was no relationship between the subfoveal choroidal thickness and functional parameters of the eyes. Conclusions: In nystagmus and amblyopia associated with strabismus and hyperopic refraction, the primary amblyogenic factor is a decrease in the density and amplitude of fixation. In relative amblyopia due to congenital myopia, the decrease in visual acuity correlates with the photosensitivity of the retina and does not correlate with fixation parameters, which indicates the partially organic nature of relative amblyopia. No relationship was found between the choroidae thikness and the degree of amblyopia, which does not cofine its participation in the pathogenesis of the disease.

Mathematical modeling in diabetic retinopathy

The problem of digital medicine in ophthalmology arose in connection with the increase in the incidence of diabetes mellitus in the world. The issue of preventing blindness and early diagnosis in diabetic retinopathy with a forecast of its course using mathematical modeling is especially acute. A system for assessing the prognosis of the risk of developing diabetic retinopathy was created based on interdisciplinary research in three areas: ophthalmology, biochemistry and mathematics. The studies were conducted in ophthalmology with the analysis of the condition of the retina in the macular area using digital ophthalmic equipment (optical coherence tomograph, fundus microperimeter). Biochemical studies consisted in the analysis of tear fluid with the determination of the level of the pathogenetic biomarker VEGF-A and the analysis of blood serum with the determination of the level of glycated hemoglobin HbA1c. Mathematical research consisted in the presentation of digital material in the form of mathematical criteria based on the method of standardizing the indicator under study. The result of the research was a computer program based on the developed mathematical formulas. The program gives the opportunity to automatically enter the data of a specific patient with diabetic retinopathy and give a prognosis of the disease.