Topcon 3D Research Articles

Application of optical coherence tomography in neurodegenerative diseases: a focus on Parkinson’s, Alzheimer’s, and Schizophrenia in Bulgarian patients

This study investigates retinal alterations in patients with Alzheimer’s disease (AD), Parkinson’s disease (PD), and schizophrenia (SZ) using Optical Coherence Tomography (OCT). The primary objective was to determine whether these neurodegenerative diseases manifest in measurable retinal changes and to assess the impact of disease duration, medication use, and cognitive decline on these alterations. A cross-sectional observational design was employed, including 132 patients and age- and gender-matched controls. OCT imaging was performed using the Topcon 3D OCT-1 Maestro 2, focusing on the retinal nerve fibre layer (RNFL), ganglion cell complex (GCC), and macular thickness. Significant retinal thinning was observed in the AD and PD groups, correlating with disease severity and cognitive decline, and was more pronounced with longer disease duration. In contrast, no significant retinal changes were identified in the SZ group. The study also explored the effects of different drug classes, revealing correlations between specific medications and retinal parameters, particularly in the AD and PD cohorts. To our knowledge, this is the first study of its kind conducted with Bulgarian patients. These findings suggest that OCT may serve as a non-invasive biomarker for neurodegeneration in AD and PD, though its utility in SZ remains limited. Future research should aim to standardize OCT protocols, further investigate the potential of retinal imaging in tracking neurodegenerative disease progression, and explore its integration with other neuroimaging techniques for a more comprehensive diagnostic and monitoring approach.

Values of peripapillary retinal nerve fibre layer thickness are different in children and adults

ABSTRACT Clinical relevance The detection of abnormal values of peripapillary nerve fibre layer (pRNFL) thickness measured with optical coherence tomography (OCT) is important for detecting optic nerve disease in children. Background To evaluate the level of agreement between the adult reference database supplied with an OCT device and the present paediatric study database for the measurement of pRNFL thickness in children. This study also aimed to provide reference values for pRNFL thickness according to the spherical equivalent in the paediatric population. Methods This was a cross-sectional study. One hundred and twenty-six healthy children were included, who had undergone a full ophthalmological examination including cycloplegic refraction and examination of pRNFL thickness using the Topcon 3D OCT 2000 device (Topcon Corporation, Tokyo, Japan). Values equal to or below the fifth percentile (≤p5) and above the 95th percentile (>p95) were considered abnormal. Observed agreement and specific agreement were investigated between OCT measurements classified with paediatric and adult reference values for normality. Results Values ≤ p5 in the adult database were recorded for 2 of the 30 values (6.6%) of the pRNFL values by quadrants ≤p5 in the paediatric database and 17 of the 88 (19.3%) values by sectors ≤p5. For values >p95 in the adult database, 88% by quadrants and 72% by sectors would have been classified as being within the normal range using the paediatric database. Conclusion The use of adult reference values currently available in OCT devices can lead to classification errors concerning the normal range of pRNFL thickness in a large proportion of paediatric patients. The use of normative paediatric databases, such as the one discussed in this study, should be taken into consideration.

Optic disc morphology and interocular symmetry in children.

The purpose of the study was to obtain a pediatric reference database for optic disc parameters and interocular symmetry. To ascertain factors that modify these parameters (age, spherical equivalent [SE], and sex). This was a cross-sectional study. 90 patients aged 5-17 years fulfilled all the inclusion criteria. After a full examination including cycloplegic refraction, all patients underwent optical coherence tomography (OCT) of the papilla using the three-dimensional (3D) scan protocol of the Topcon 3D 2000 OCT device. We provide reference values for optic disc parameters in the pediatric population. We also retrieved interocular symmetry reference values for these parameters. The multivariate regression analysis did not reveal variations in any of the optic disc parameters associated with age, sex, or SE (all P ≥ 0.126). The 95th percentile limit for absolute interocular differences for the cup-to-disc area ratio was 0.24. The multivariate regression analysis revealed the absence of a correlation between asymmetry of the optic disc parameters and age, sex, and the interocular difference in SE (all P ≥ 0.105). Pediatric reference databases for optic disc parameters and ranges of normality for interocular symmetry provide key diagnostic support in diseases that affect the optic nerve.

TESTING THE EXCAVATOR PERFORMANCE (USING TOPCON 3D EXCAVATOR X63 SYSTEM) ESPECIALLY FOR NAVIGATION AND EARTHWORK

Construction sites commonly utilize bulldozers, wheel loaders, excavators, scrapers, and graders. Among these, excavators are versatile hydraulic heavy-duty equipment operated by humans. They are employed for various tasks like digging, levelling the ground, transporting and dumping loads, as well as providing straight traction. However, certain hazardous environments, such as nuclear disasters or earthquakes, are not suitable for human on-site work. To enhance productivity, accuracy, and profitability in excavation projects, the adoption of 3D machine control is recommended. The Topcon 3D Excavator X63 System offers advanced and precise GNSS positioning technology, coupled with Hidromek with Assist and an intuitive software interface, to significantly improve excavation operations. In this study, the accuracy of the coordinates of the route followed by the Excavator was checked by using RTK GNSS method by using P1 reference point. While the differences obtained in horizontal coordinates are 2–2.5 cm and 4–6 cm in vertical coordinates. In addition, excavation calculations of the earthwork area were performed and checked with the number of bucket of the excavator. The differences obtained from the earthwork were calculated as 0.8 cubic meters for each bucket.

Low tensor train and low multilinear rank approximations of 3D tensors for compression and de-speckling of optical coherence tomography images

Objective. Many methods for compression and/or de-speckling of 3D optical coherence tomography (OCT) images operate on a slice-by-slice basis and, consequently, ignore spatial relations between the B-scans. Thus, we develop compression ratio (CR)-constrained low tensor train (TT)—and low multilinear (ML) rank approximations of 3D tensors for compression and de-speckling of 3D OCT images. Due to inherent denoising mechanism of low-rank approximation, compressed image is often even of better quality than the raw image it is based on. Approach. We formulate CR-constrained low rank approximations of 3D tensor as parallel non-convex non-smooth optimization problems implemented by alternating direction method of multipliers of unfolded tensors. In contrast to patch- and sparsity-based OCT image compression methods, proposed approach does not require clean images for dictionary learning, enables CR as high as 60:1, and it is fast. In contrast to deep networks based OCT image compression, proposed approach is training free and does not require any supervised data pre-processing. Main results. Proposed methodology is evaluated on twenty four images of a retina acquired on Topcon 3D OCT-1000 scanner, and twenty images of a retina acquired on Big Vision BV1000 3D OCT scanner. For the first dataset, statistical significance analysis shows that for CR ≤ 35, all low ML rank approximations and Schatten-0 (S 0) norm constrained low TT rank approximation can be useful for machine learning-based diagnostics by using segmented retina layers. Also for CR ≤ 35, S 0-constrained ML rank approximation and S 0-constrained low TT rank approximation can be useful for visual inspection-based diagnostics. For the second dataset, statistical significance analysis shows that for CR ≤ 60 all low ML rank approximations as well as S 0 and S 1/2 low TT ranks approximations can be useful for machine learning-based diagnostics by using segmented retina layers. Also, for CR ≤ 60, low ML rank approximations constrained with S p , p ∊ {0, 1/2, 2/3} and one surrogate of S 0 can be useful for visual inspection-based diagnostics. That is also true for low TT rank approximations constrained with S p , p ∊ {0, 1/2, 2/3} for CR ≤ 20. Significance. Studies conducted on datasets acquired by two different types of scanners confirmed capabilities of proposed framework that, for a wide range of CRs, yields de-speckled 3D OCT images suitable for clinical data archiving and remote consultation, for visual inspection-based diagnosis and for machine learning-based diagnosis by using segmented retina layers.

Assessment of the Effectiveness of Different Variants of Frequency Doubling Technology Perimetry in Monitoring the Glaucoma Process

Purpose: To compare the diagnostic effectiveness of non-standard perimetry and standard automated perimetry (SAP) during earlystage monitoring of primary open-angle glaucoma (POAG).Patients and methods. The study involved 30 patients (46 eyes) with early-stage of POAG, aged 30 to 65 years (54.9 ± 1.3), who were under ongoing monitoring for 3 to 4 years (3.50 ± 0.68 years). All subjects, in addition to the standard ophthalmological examination, performed the threshold program “24-2” perimetry using the Humphrey II, the own modification of Frequency Doubling Technology (FDT) Perimetry, in the form of 2 threshold strategies: the wellknown “FDT-16” and the new “FDT-64”. The condition of the optic nerve head (ONH) was assessed using HRT 3 (Heidelberg Retina Tomograph, Germany) and OCT — Topcon 3D OCT- 2000 (TOPCON, Japan). During monitoring, RTVue FD-OCT (Optovue, USA) was additionally performed, evaluating the parameters of the retinal ganglion cell complex (GCC).Results. Regular follow-up, the implementation of the prescribed treatment contributed to the stabilization of glaucoma, as evidenced by the stability of the average MD index values according to all 3 threshold strategies, but reliably (p = 0.000) only according to SAP data. According to the criterion of the number of scotomas, there was a weakly expressed, but statistically significant negative dynamics for all the compared strategies. According to the results of the structural assessment of the ONH (the size of the excavation), a weakly pronounced negative dynamics was obtained in dynamics according to both HRT and OCT data. The average MD index values, the number of scotomas according to the three perimeter strategies and the excavation size based on HRT and OCT in patients with early-stage of POAG turned out to be stronger and more significant using the “FDT-16”, and the correlation characteristics with the results of “24-2” HFA II, “FDT-64” largely coincided.Conclusion. A reliable correlation between structural and functional parameters indicates the feasibility of using “FDT-64” in combination with SAP not only in for the diagnosis of the early-stage of glaucoma, but also in assessing its course. The sensitivity level of the results of “FDT-64” (100 %) compared to “FDT-16” (88 %) in patients with POAG was higher, therefore, “FDT-64” is advisable to use in complex diagnostic cases and in monitoring glaucoma.

Macular Thickness- An Early Predictor of Diabetic Macular Oedema

Introduction: Diabetic Macular Oedema (DME) accounts for visual morbidity in about three fourth of Diabetic Retinopathy (DR) patients. Traditional examination on 90D slit lamp or stereoscopic fundus photograph may not be able to identify early maculopathy. Optical Coherence Tomography (OCT) is a sensitive, non invasive modality which may detect early retinal thickness changes in DME. Aim: To identify any increase in macular thickness in diabetic patients with early DR without any clinically detectable macular oedema. Materials and Methods: This cross-sectional analytical study was conducted from September 2018 to July 2020 in the Ophthalmology Department at Bharati Vidyapeeth Medical College and Hospital, Pune, Maharashtra, India. A total of 277 eyes of 184 subjects were evaluated. Of these 182 eyes were of diabetic patients (124 patients) and 95 eyes belonged to controls (60 subjects). Amongst the diabetic eyes evaluated, group I consisted of 100 eyes with no evidence of DR and group II consisted of 82 eyes with mild Non Proliferative Diabetic Retinopathy (NPDR). Group III included 95 eyes of non diabetic age matched controls. Macular thickness was measured using the Topcon 3D OCT-1 Maestro System. The central 1mm macular thickness of the three groups was analysed and compared using student's t-test. Results: The mean Central Macular Thickness (CMT) showed no statistically significant difference (p-value<0.7) between group III (222.4±10.8) and group I (223.0±13.7 μm). However, a significant increase in CMT (p-value<0.0001 and, p-value<0.0006) was noted in group II (230.7±15.6 μm) when compared with group III (222.4±10.8 μm) and group I (223.0±13.7 μm). Macular thickness amounting to Subclinical Macular Oedema (SCME) was seen in only in 6.09% of eyes in group II, five eyes of the total number of 82 eyes with mild NPDR. Conclusion: Increased CMT was detected in mild NPDR patients on Optical Coherence Topography (OCT) even without any clinical evidence of macular oedema. Since eyes with SCME, diagnosed at base line assessment, are at a higher risk of developing clinical macular oedema subsequently, it is recommend that a base line OCT be performed in all patients detected to have mild NPDR irrespective of the absence of clinical findings suggestive of DME.

Use of Teleophthalmology for Evaluation of Ophthalmic Emergencies by Ophthalmology Residents in the Emergency Department

Background: Utilizing telemedicine is one approach to reduce the ever-increasing burden of patients on emergency departments (EDs) and consulting physicians. Utilization of telemedicine services in the ED may also benefit resident education. Materials and Methods: Ten first-year ophthalmology residents were trained to use a Topcon 3D Optical Coherence Tomography (OCT)-1 Maestro to capture OCT images and fundus photos in patients presenting to the ED with urgent ophthalmic concerns. Findings were communicated to the supervising ophthalmologist. Retrospective chart review was conducted to obtain patient characteristics and final ophthalmologist diagnosis. Residents rated ease of use, technical reliability, and educational value through a survey. Results: From December 1, 2019, to December 1, 2020, the device was used in 109 patient encounters, capturing 887 images (average 8.1 images per encounter). Patients on whom the device was used were on average 48.5 years old (±17.2, range 17-90) and 59.6% were female. The imaging device was utilized most commonly for evaluating papilledema (n = 21, 18.6%), new-onset visual acuity/visual field defects (n = 12, 10.6%), retinal detachment/tear (n = 8, 7.1%), and ophthalmic trauma workup (n = 8, 7.1%). Eight residents completed the survey and most (n = 7) agreed or strongly agreed that the device helped them diagnose patients more accurately. Technical issues such as machine malfunction, image artifacts, and problems syncing with the electronic health record and computer were noted by survey respondents. Conclusions: The most common use of teleophthalmology in the ED setting was evaluation of papilledema; the majority of residents perceived an educational benefit from this tool. Efforts should be made to address the technical challenges to increase the utility of this device.

Evaluation of Corneal Stromal Demarcation Line Depth in Epithelium-Off Standard, Epithelium-Off Accelerated and Transepithelial Cross-Linking in Keratectasia

Background: Corneal collagen cross-linking (CXL) has been increased to moderate and halt the development of keratoconus and LASIK ectasia as a viable method. This research is intended to research the corneal current demarcation line (DL) and to compare the depth of the Corneal Strom Demarcation Line utilising anterior segment epithelial, epithelial, accelerated, and transepithelial interconnection (AS-OCT). Methods: Methods: 24 Eyes that match the criteria for inclusion of Cross-Linking patients split evenly into three interventions throughout the last 6 months were included in this research. Topcon 3D spectral domain OCT 2000 was used to measure the demarcation line depth. Outcomes: The DL depth indicated an overall significant difference in the conventional epi-off group (340 microns) across analysed groups, which is much greater than the accelerated epi-off (267 microns) and the accelerated epi-on (190 microns). In the accelerated epi-off it was also much greater than the accelerated epi-on. Conclusion: stromal demarcation line revealed a larger depth in the standard epidemic than rapid epidemic, which depth is higher than that of transepithelial cross-linking, meaning that standard epidema, accelerated epidemic and transepitude techniques are used to determine a larger depth of treatment.

Optic disc morphometry using spectral domain optical coherence tomography in a Nigerian population.

To assess morphological optic disc dimensions using spectral-domain optical coherence tomography (OCT) in a Nigerian population. Good quality SD-OCT scans of the optic disc of 147 eyes of 88 participants were selected, enrolled, and retrospectively reviewed. All subjects had optic nerve head and retinal nerve fibre layer OCT imaging, as well as analysis, done using the Topcon 3D OCT-1 Maestro®. The age, sex, and some OCT-generated optic disc dimensions namely disc area (DA), vertical disc diameter (VDD), horizontal disc diameter (HDD) were retrieved from the database and analyzed. The mean age of the study subjects was 52.6±20.9 years with a range of 8-90 years; male to female ratio was 1:1.3. The right eye and left eye accounted for 75 and 72 of the 147 scans respectively. The mean DA, VDD, and HDD were 2.54 ± 0.48 mm2, 1926.5 ± 189.6 μm and 1673.9 ± 173.9 μm, respectively. Males had significantly larger DA than females (2.56 ± 0.53 mm2 vs 2.51 ± 0.44 mm2, p = 0.043). The mean DA and VDD of eyes of subjects aged 21-40 years were significantly higher compared to subjects aged 60 years and more (p = 0.008 and 0.001, respectively). The mean optic disc area and diameters are larger than those reported in similar studies involving blacks and other races. The mean disc area reduces with increasing age.

Efficacy and safety of Ziv-aflibercept in patients with central retinal vein occlusion

Background Retinal vein occlusion is one of the most common vascular disorders that can cause visual loss. It is classified into central retinal vein occlusion (CRVO) and branch retinal vein occlusion. The most common cause of visual loss in CRVO is cystoid macular edema. Intravitreal injection of many antivascular endothelial growth factor agents can treat cystoid macular edema that occur owing to CRVO.Purpose The aim of the present study was to evaluate the efficacy of a new drug (Ziv-aflibercept) in the management of patients with CRVO.Patients and methods This is a prospective interventional study that was conducted on 15 eyes of 15 patients of recently diagnosed nonischemic CRVO of less than 2-month duration. Three loading doses of 1.25 mg of Ziv-aflibercept were given 1 month apart for each patient and then continued as needed in a pro re nata regimen. Complete ophthalmic evaluation was done at the Ophthalmology Department of Tanta University, including best-corrected visual acuity (BCVA), fundus examination, intraocular pressure measurement, and anterior segment examination. Optical coherence tomography (TOPCON 3D optical coherence tomography machine) was done for all patients at presentation and 1 month after each injection and then monthly during the follow-up period, which persisted for 6 months.Results The intraocular pressure did not show a statistically significant increase after intravitreal injection of Ziv-aflibercept. The BCVA improved significantly from 0.87±0.10 to 0.32±0.12 LogMAR after injection (P=0.001). The central macular thickness decreased significantly from a baseline value of 771±141.87 μm before injection to 306.67±91.51 μm after the three loading doses and to 208.07±12.97 μm after 6 months (P=0.001). There was no statistically significant correlation between the final BCVA and the final central macular thickness after 6 months (r=0.054, P=0.848). No serious complications were reported, such as endophthalmitis, vitreous hemorrhage, retinal detachment, or stroke.Conclusion Ziv-aflibercept is a highly effective drug in cases of nonischemic CRVO with a high safety profile and a relatively low cost.

Role of Optical Coherence Tomography (OCT) in Early Detection of Subclinical Cystoid Macular Edema after Nd-YAG Laser Capsulotomy

Purpose: To determine role of optical coherence tomography (OCT) in early detection of subclinical cystoid macular edema (CME) after Nd-YAG laser capsulotomy in patients with posterior capsular opacification (PCO).
 Study Design: Descriptive case-series.
 Place and Duration of Study: Department of Ophthalmology Unit 1, Dow University of Health Sciences and Civil Hospital Karachi from 1-July-2015 to 31-Dec-2015.
 Methods: A total of 72 eyes with unilateral or bilateral visually significant PCO following uncomplicated cataract surgery with posterior chamber intraocular lens implantation were included in the study. Patients with corneal opacities, glaucoma, retinopathy, maculopathy, optic neuropathy, complicated cataract surgery, previous ocular surgery other than cataract surgery and High refractive errors were excluded from the study. Best-corrected visual acuity (BCVA), Slit lamp examination, posterior segment examination and macular thickness was measured using spectral domain (TOPCON 3D OCT) optical coherence tomography before laser and at 1 week and at 1 month after laser.
 Results: Mean age was 55.76 ± 5.28 with Confidence interval of 55.02 – 56.49 years. Eighty-one were males and 122 were females. Subclinical cystoid macular edema (CME) was found in 10 (14%) patients. Out of the patients who had CME, 3 were in age group of 40-55 years and seven were in age group of 56-70 years. P value was found to be significant i.e. (P = 0.039).
 Conclusion: Optical coherence tomography OCT is a non invasive and useful tool for early detection and management of subclinical cystoid macular edema after Nd-YAG laser capsulotomy in patients having posterior capsular opacification (PCO).
 Key Words: Cystoid Macular Edema, Nd-YAG laser, Posterior Capsular Opacification. Optical Coherence Tomography (OCT).

Interobserver reproducibility and interocular symmetry of the macular ganglion cell complex: assessment in healthy children using optical coherence tomography

BackgroundAssessment of interobserver reproducibility and interocular symmetry using optical coherence tomography (OCT)–based measurements of the macular ganglion cell complex (GCC) in healthy children facilitates interpretation of OCT data. We assessed the interobserver reproducibility and interocular symmetry of GCC and evaluated candidate determinants.MethodsThis was a cross-sectional study performed in a primary and tertiary health-care setting. A total of 126 healthy participants aged 5 to 18 years were eligible. GCC scans were performed by 4 operators using the Topcon 3D OCT-2000 device. Intraclass correlation coefficients (ICCs) were used to estimate reproducibility and symmetry. Cut-off points for symmetry were defined as the 95th percentile of the absolute interocular difference for 6 GCC parameters. Percentile distributions of interocular difference were generated based on age and difference in absolute interocular spherical equivalent (SE).ResultsThe reproducibility ICC ranged from 0.96 to 0.98 for all 6 GCC parameters. Cut-off points for interocular symmetry of the superior and inferior quadrants and total macular retinal nerve fibre layer thickness (mRNFL) and macular ganglion cell layer-inner plexiform layer thickness were 3.5, 4.5, 3.0, 3.0, 2.5, and 2.5 μm respectively. A positive association was observed between the absolute interocular difference of SE and superior and total mRNFL symmetry values (p = 0.047 and p = 0.040, respectively).ConclusionsOCT measurements of GCC in healthy children show excellent reproducibility. Interocular differences in SE should be assessed when mRNFL differences exceed the 95% cut-off. These findings can contribute to establish reference values for interocular symmetry in paediatric GCC parameters.

Evaluation of glaucoma cases with gonioscopy and optical coherence tomography

Glaucoma is the second leading cause of blindness in the adult population of India. Diagnosis and management depends on categorization of Glaucoma into open or closed angle. : To compare the accuracy of Gonioscopy and Anterior Segment Optical Coherence Tomography (ASOCT) in studying the structures of anterior chamber angle of the eye and find out the agreement between them in detecting angle closure. Cross -sectional observational study. The present study is a hospital based cross-sectional study of patients between 20 to 80 years of age with Glaucoma attending the outdoor patient department in a tertiary care government hospital (New civil hospital), Surat. Patients having Corneal Opacity, and anti-Glaucoma surgeries done were excluded. All diagnosed cases of Glaucoma were evaluated by Gonioscopy in the dark with a Goldman 3 mirror lens Gonioscope at high (16x) magnification for static assessment (without indentation). A narrow slit beam, 2mm* 1mm, was cast during Gonioscopy, avoiding direct illumination over the pupil. The angle in each quadrant was graded with the Shaffer grading system. Anterior Segment OCT was done by TOPCON 3D OCT-1 MAESTRO machine. Imaging was performed in dark room conditions. Patients were imaged gazing straight ahead. Imaging of a single meridional section of the Anterior Chamber Angle at superior, inferior, temporal and nasal quadrants were performed. Grading of Anterior Chamber Angles on AS-OCT is termed as Closed if there is no visualization of Scleral Spur and/or any degree of irido-trabecular contact. kappa value, sensitivity & specificity, positive & negative likelihood ratio. Total 50 Glaucoma patients were examined by Gonioscopy and AS OCT. Total number of Angles examined were 400. Total number of Angles closed on Gonioscopy were 136 (34%). Total number of Angles closed on AS OCT were 190 (47.5%). Agreement between Gonioscopy and AS OCT in detecting angle closure in all 4 quadrants was ‘Moderate to Good’ by Kappa Value.

OUR EXPERIENCE OF USING AUTOLOGICAL BLOOD SERUM IN COMPLEX TREATMENT OF BACTERIAL CORNEAL ULCERS IN PATIENTS WITH DIABETES MELLITUS DEPENDING ON THESEVERETY OF DIABETIC POLYNEUROPATHY

Summary. Diabetic keratopathy, which develops against the background of diabetic corneal neuropathyshould be taken into account when choosing tactics for the treatment of bacterial corneal ulcers in patients with diabetes mellitus.
 The aim of the study was to determine the effectiveness of treatment of bacterial corneal ulcers with the help of additional local use of autological serum eye drops in patients with type 1 diabetes depending on the severity of diabetic polyneuropathy (DPN).
 Materials and methods. The results of observation of 10 patients (10 eyes) with bacterial corneal ulcer and type 1 diabetes mellitus, in which delayed healing of corneal ulcer defect were noted and the absence of microorganisms ware confirmed by repeated bacteriological examinations of corneal smears and scrapings,were analyzed. In addition to standard therapy, all patients 2 weeks after the start of treatment were additionally prescribed eye drops with autologous serum. Patients were divided into 2 groups according to the stage of severity of DPN: the first group consisted of 5 patients with symptomatic stage, the second - 5 patients with a stage of severe complications. In addition to standard, ophthalmic examination methods included bacteriological examination, fluorescein test, OCT of the anterior segment of the eye on the device TOPCON 3D OCT-2000, non-contact examination of corneal sensitivity.
 Results and discussion. It was found that the threshold of corneal sensitivity in patients with bacterial corneal ulcer at the stage of severe complications of DPN was higher than that in symptomatic DPN by an average of 16.6 % during the observation. The degree of pericorneal injection and infiltration of the cornea, as well as the size and depth of the ulcerative defect of the cornea at the stage of severe complications exceeded the corresponding indicators of patients with symptomatic DPN during the observation. Normalization of conjunctival color and reepithelialization of the cornea in all patients with severe complications occurred 3 days later than in patients with symptomatic DPN.
 Conclusions. The course of bacterial keratitis in patients with diabetes mellitus depends on the severity of DPN: a pronounced violation of corneal innervation at the stage of severe complications of DPN, manifested by a decrease in its sensitivity, leads to prolongation of treatment, even with additional use of eye drops with autologous serum.

Functional and Structural Changes of the Retinal Nerve Fiber Layer and Ganglion Cell Complex in Heavy Smokers.

PurposeTo assess the functional and structural changes in the retinal nerve fiber layer (RNFL) and the ganglion cell complex (GCC) in heavy smokers using pattern electroretinogram (PERG), photopic negative response(PhNR) and spectral domain optical coherence tomography (SD-OCT).Patients and MethodsSixty eyes of 30 heavy smokers (at least 15 cigarettes/day for 10 years) (study group) and 60 eyes of 30 age and gender-matched healthy non-smoker subjects (control group) were included. After full ophthalmologic examination (PERG), (PhNR) using RETI-port/scan 21 (Roland Consult, Brandenburg, Germany) and (SD-OCT using Topcon 3D OCT model 2000 FA version.8.30) were tested for all participants. Statistical analysis was performed to compare GCC, RNFL thicknesses, PERG and phNR values between groups.ResultsThe mean age was 36.67±4.13 years in the study group and 36.0±4.76 years in the control group. There were no statistical significant differences between the two groups regarding intraocular pressure (p=0.43), axial length (p=0.37), and central corneal thickness (p=0.86). There were significant differences of GCC thickness values between the study group (88.4±6.6 µm) and control group (94.83±5.25 µm) (p<0.001). The mean RNFL values of study and control groups were 97.87±5.88 and 106.43±6.59 µm, respectively (p<0.001). In the study group the superior and inferior quadrants of RNFL were significantly thinner, but there were no significant differences between the two groups in nasal and temporal quadrants. There were no significant differences of PERG-P50 amplitude (p=0.49) and latency (p=0.71); however, PERG-N95 amplitude and latency showed significant differences between the two groups (p<0.001).There were significant differences of phNR amplitude and latency between the two groups (p<0.001). Multiple regression analyses demonstrated that the PhNR, PERG amplitude and latency are the most important determinants for both RNFL and GCC thicknesses.ConclusionIn heavy smokers RNFL thickness was decreased, the PhNR, PERG-N95 amplitudes were diminished and the implicit times were prolonged compared to non-smokers. PhNR and PERG reflect both dysfunction and loss of ganglion cells and their axons.

New morphometric criteria in the study of pathogenesis of normal-tension glaucoma

Studying the factors that contribute to the disturbance of transmembrane pressure gradient is a topical task in the research of pathogenesis of normal-tension glaucoma (NTG). To measure and compare the thickness and depth of lamina cribrosa (LCT and LCD), as well as optic nerve subarachnoid space width (ONSASW) in patients with NTG and healthy individuals. The first group included 12 patients (23 eyes) aged from 58 to 74 years (average age 66.8±3.2 years) with NTG who all had normal intraocular pressure and arterial hypotension. The second (control) group consisted of 11 healthy individuals (22 eyes) aged from 51 to 69 years (average age 56.2±4.2 years). All patients underwent structural and functional assessment of the optic nerve head using OCT RTVue-100 (Optovue, USA), as well as Humphrey Visual Field Analyzer (HFA II 745i, Germany-USA) and our modification of Frequency Doubling Technology perimetry. In all subjects the central corneal thickness (CCT) was measured by Pentacam HR (Oculus, Germany), the LCT and LCD were measured by EDI (Enhanced Depth Imaging) mode of Topcon 3D OCT 2000 (Japan). To measure the ONSASW we used a cross-sectional image of the optic nerve taken 3 mm behind the eyeball with Magnetic Resonance Imaging (Siemens Magnetom Symphony 1.5 T, Germany). Statistically significant difference was found between the 1st and 2nd groups in the average LCT (217.60±36.92 and 345.86±33.29 μm respectively; p=0.0000), LCD (435.00±86.31 and 367.31±87.00 μm, respectively; p=0.014) and ONSASW (1.27±0.13 and 1.44±0.19 mm respectively; p=0.004); the difference wasn't significant in the average CCT (543.26±31.52 and 557.50±24.92 μm respectively; p=0.11). Patients with NTG had significantly higher value of the LCD with significantly lower values of the LCT and ONSASW compared with healthy individuals, which confirms the importance of these morphometric criteria in the study of NTG pathogenesis.

ReLayer: a Free, Online Tool for Extracting Retinal Thickness From Cross-Platform OCT Images.

PurposeTo describe and evaluate a free, online tool for automatically segmenting optical coherence tomography (OCT) images from different devices and computing summary measures such as retinal thickness.MethodsReLayer (https://relayer.online) is an online platform to which OCT scan images can be uploaded and analyzed. Results can be downloaded as plaintext (.csv) files. The segmentation method includes a novel, one-dimensional active contour model, designed to locate the inner limiting membrane, inner/outer segment, and retinal pigment epithelium. The method, designed for B-scans from Heidelberg Engineering Spectralis, was adapted for Topcon 3D OCT-2000 and OptoVue AngioVue. The method was applied to scans from healthy and pathological eyes, and was validated against segmentation by the manufacturers, the IOWA Reference Algorithms, and manual segmentation.ResultsSegmentation of a B-scan took ≤1 second. In healthy eyes, mean difference in retinal thickness from ReLayer and the reference standard was below the resolution of the Spectralis and 3D OCT-2000, and slightly above the resolution of the AngioVue. In pathological eyes, ReLayer performed similarly to IOWA (P = 0.97) and better than Spectralis (P < 0.001).ConclusionsA free online platform (ReLayer) is capable of segmenting OCT scans with similar speed, accuracy, and reliability as the other tested algorithms, but offers greater accessibility. ReLayer could represent a valuable tool for researchers requiring the full segmentation, often not made available by commercial software.Translational RelevanceA free online platform (ReLayer) provides free, accessible segmentation of OCT images: data often not available via existing commercial software.

Performance of Topcon 3D optical coherence tomography-2000 in re-analyzing OCT-1000 raw data.

The aim of the present study was to evaluate the accuracy of the Topcon 3D optical coherence tomography (OCT)-2000 built-in algorithm in analyzing OCT data acquired using the Topcon 3D OCT-1000 instrument. Raw data of 3D macular 512×128 scans acquired using the Topcon 3D OCT-1000 instrument were analyzed using the Topcon 3D OCT-2000. The occurrence and severity of segmentation error (SE) were compared between the built-in algorithms of the two instruments. Agreement in retinal thickness measurement between the two systems was evaluated in normal and abnormal eyes. A total of 87 eyes from 87 patients were included. The image quality score evaluated by Topcon OCT-2000 software was lower than that of OCT-1000. No statistically significant difference was identified in the SE rate (77.01 vs. 74.71%; P=0.864) or mean SE score (15.97 vs. 16.30; P=0.763) of the total scan area between the two algorithms. Intraclass correlation coefficient values for retinal thickness were high (0.951–0.995). The mean paired difference in retinal thickness was 3.72–5.77 µm (P<0.05) in normal and 0.61–9.52 µm (P<0.05) in abnormal eyes. No significant difference in retinal segmentation performance was identified between OCT-2000 and OCT-1000 when analyzing OCT-1000 raw data. In conclusion, retinal thickness measurements analyzed by the two OCT algorithms may be used interchangeably in normal eyes. Abnormal eyes required investigations as big differences in retinal thickness measurements may occur due to severe SEs.

Optical Coherence Tomography Angiography of Optic Disc Perfusion in Primary Open Angle Glaucoma

AbstractBackground: Glaucoma is a major disease that potentially results in irreversible blindness. Optical coherence tomography angiography (OCTA) is a novel technique for evaluation of retinal vascular changes. Using OCTA have provided useful information about the papillary and peripapillary microvas-culature. Optic nerve head perfusion measurements.Aim of Study: To investigate optic disc perfusion differ-ences between normal and primary open angle glaucoma eyes using optical coherence tomography angiography (OCTA).Methods: This prospective comparative cross-sectional selective pilot study was performed on 15 eyes of 15 primary open angle glaucoma (POAG) patients and 20 eyes of 20 healthy age-matched controls. OCT and OCTA were performed using swept source TOPCON 3D OPTICAL COHERENCE TOMOGRAPHY DRI OCT Triton. The optic nerve head (ONH) was imaged with a 4.5x4.5mm scan and assessed in 4 different levels of segmentation; the superficial Papillary, deep papillary, outer retina level and choroidal level. Density map images gave qualitative data and quantitative assessment, these images were processed using Image J program (IJ 1.46 r edition) for determining vascular density index (VDI). The Central corneal thickness, retinal nerve fiber layer thickness (RNFLT), ganglion cell layer thickness (GCLT), stereometric parameters cup/disc area, rim area, cup volume and visual field parameters [mean deviation (MD), pattern standard deviation (PSD) were tested for correlation with vascular density.Results: The vascular density index in the OCT angi-ograms, as a quantitative assessment, of the optic nerve head (ONH) perfusion was significantly lower in the glaucoma group when compared with the normal age matched control groups. This reduction was significant in POAG with average VDI was reduced by 6.29%. However, in qualitative assessment the dense microvascular network that was visible on OCTA in normal discs, was visibly attenuated with marked capillary drop out in subjects with glaucoma. This reduction in vascular density i.e. ischemia may have a primary element as detected by decreased VDI at choroidal level POAG that reduced by 17.37%. In addition, it may be secondary to elevated IOP that has direct impact with decrease VDI at superficial papillary level that is marked in cases with high IOP. The vascular density index was correlated significantly with all functional and structural parameters and the rate of disease progression and severity.Conclusions: OCTA may offer insights into the patho-physiology of glaucomatous damage and understanding the role of vascular factors in the pathogenesis of the disease. Hence, it may be a promising technology in glaucoma man-agement.