Disc Ratio Research Articles

A Constraint on the Amount of Hydrogen from the CO Chemistry in Debris Disks

The faint CO gases in debris disks are easily dissolved into C by UV irradiation, while CO can be reformed via reactions with hydrogen. The abundance ratio of C/CO could thus be a probe of the amount of hydrogen in the debris disks. We conduct radiative transfer calculations with chemical reactions for debris disks. For a typical dust-to-gas mass ratio of debris disks, CO formation proceeds without the involvement of H2 because a small amount of dust grains makes H2 formation inefficient. We find that the CO to C number density ratio depends on a combination of n H Z 0.4 χ −1.1, where n H is the hydrogen nucleus number density, Z is the metallicity, and χ is the far-UV flux normalized by the Habing flux. Using an analytic formula for the CO number density, we give constraints on the amount of hydrogen and metallicity for debris disks. CO formation is accelerated by excited H2 when either the dust-to-gas mass ratio is increased or the energy barrier of chemisorption of hydrogen on the dust surface is decreased. This acceleration of CO formation occurs only when the shielding effects of CO are insignificant. In shielded regions, the CO fractions are almost independent of the parameters of dust grains.

CORRELATION BETWEEN ASSESSMENT OF CUP DISC(CD) RATIO USING OPTIC NERVE HEAD PHOTOGRAPHY AND OPTICAL COHERENCE TOMOGRAPHY(OCT)

Background: Various types of modalities exist for examination of the Optic nerve head. As changes in the optic disc are a major indicator of glaucoma it is vital to establish which among the modalities correlate best with each other. In this study the cup to disc ratio was assessed using optical coherence tomography and optic nerve head photography and the ndings were compared A Methods: n observational study was conducted. Group I consisted of 50 patients of primary open angle glaucoma and Group II consisted of 50 non-glaucomatous patients. ONHP and OCT were done to assess the average cup to disc ratio CDR. Average CDR as calculated by the 2 methods was compared by Pearson correlation. Correlation value of +1 is total positive correlation, 0 is no correlation and −1 is negative correlation. The correlation value in the case Results: group was 0.86 for CDR. The correlation value in the control group was 0.72 for CDR. The study fo Conclusion: und OCT ndings and ONHPndings have weak correlation

Association between Myopia and Glaucoma; A Cross-sectional Study

Myopia is a major cause of worldwide avoidable blindness and its prevalence increasing rapidly. Objective: To investigate the prevalence of glaucomatous optic nerve damage with various myopia levels as well as the relationship between myopia and glaucoma. Methods: A multi-centered cross-sectional study was conducted from January 2022 to July 2022. 250 individuals between the ages of 40 and 65 were recruited using non-probability purposive sampling technique. Mild, moderate and severe degree of myopia who had never had any surgery were included. All subjects underwent refraction and the optic disc ratio was assessed by slit lamp biomicroscopy, perimetry was performed to evaluate the visual field defects and IOP was determined using air puff tonometer. Frequency of glaucoma indicated by presence of visual field defects, glaucomatous optic disc. SPSS software was used for data analysis. Results: 145 (58%) of the 250 total subjects were female and 105(42%) were male. 67 (26.8%) people had refractive errors of mild myopia up to 3D. While 85 (34%) had a severe degree of myopia (refractive error greater than 6D) and 98 (39.2%) had a moderate degree. No intragroup's intraocular pressure showed a significantly distinct configuration. Age-related VF anomalies (a larger blind region, a vertical cup to disc ratio, and an unjustified defect) were associated with both glaucoma and high myopia. Findings from the study indicated that glaucoma risk increased for those with high myopia (p=0.001). Conclusion: High myopia is strongly associated with glaucomatous changes and a high prevalence of optic disc damage.

Time course study of optical coherence tomography angiography in patients with methanol induced optic neuropathy

IntroductionIn countries where alcoholic beverages are legally prohibited, methanol toxicity usually occurs due to ingesting homemade alcoholic drinks. The initial ophthalmologic symptoms of methanol toxicity typically appear 6–48 h after ingestion, and the severity of symptoms varies widely from mild and painless decreased vision to no-light perception vision.MethodsThis prospective study examines 20 patients with acute methanol poisoning within 10 days of use. Patients underwent ocular examinations, BCVA (Best Corrected Visual Acuity) recording, and OCTA (Optical Coherence Tomography Angiography) of the macula and optic disc. BCVA measurement and imaging were repeated one month and three months after intoxication.ResultsThere was a statistically significant reduction in superficial parafoveal vascular density (P-value = 0.026), inner retinal thickness (P-value = 0.022), RNFL (Retinal Nerve Fiber Layer) thickness (P-value = 0.031), and an increase in cup to disc ratio (P-value < 0.001), and central visual acuity (P-value = 0.002) in this time course. However, there was no statistically significant difference in FAZ (Foveal Avascular Zone) area (P-value = 0.309), FAZ perimeter (P-value = 0.504), FD-300 (Foveal density, vascular density within a 300 μm wide region of the FAZ) (P-value = 0.541), superficial vascular density (P-value = 0.187), deep foveal vascular density (P-value = 0.889), deep parafoveal vascular density (P-value = 0.830), choroidal flow area (P-value = 0.464), total retinal thickness (P-value = 0.597), outer retinal thickness (P-value = 0.067), optic disc whole image vascular density (P-value = 0.146), vascular density inside the disc (P-value = 0.864), or peripapillary vascular density (P-value = 0.680) at different times.ConclusionOver time, methanol poisoning can cause changes in retinal layers thickness, vasculature, and optic nerve head. The most important changes include cupping of the optic nerve head, reduction in RNFL thickness, and inner retinal thickness.

Mesoscale modeling to study isolated asphaltene agglomerates

The mesoscopic behavior of asphaltene plays a significant role in the formation of microstructures and agglomerates. In this study, a new coarse-grained model is developed to investigate the formation of aggregated microstructures in asphaltene. Disk-like building block is adopted as the basic unit in the coarse-grained model. The forcefield parameters based on Gay-Berne potential are derived from the full atomistic simulations and applied in the coarse-grained simulations. The results show that randomly orientated asphaltene disks gradually adjust their positions and orientations during equilibrium process, and reach the jammed state with different columnar structures containing packed asphaltene disks. The packing fraction and the microstructures of agglomerates are affected by the aspect ratio of asphaltene disks, temperature and pressure. The developed coarse-grained model can characterize the evolution of asphaltene microstructures and help understand the formation mechanism of asphaltene agglomerates. The in-depth analysis reveals the influencing factors on asphaltene agglomerates, which can enlighten the solutions to aggregation problems of asphaltene system.

PY-Net: Rethinking segmentation frameworks with dense pyramidal operations for optic disc and cup segmentation from retinal fundus images

Glaucoma is one of the leading causes of irreversible blindness across the globe. Early diagnosis is therefore essential for the provision of timely treatments and reducing the loss of vision. From the retinal fundus images, the calculation of the cup to disc ratio (CDR) is an efficient indicator to distinguish between glaucomatous and non-glaucomatous cases. Therefore, precise segmentation of optic disc and cup from the retinal images are important steps for improved diagnosis of the disease. This paper presents a robust segmentation pipeline for optic disc and cup segmentation utilizing the U-Net architecture. In the upsampling half of the model, a spatial pyramid based decoder cascaded with an intermediate decoder is introduced. To incorporate channel-wise attention throughout the framework squeeze and excite blocks are incorporated. To enhance the relevant spatial features in the feature representations of the fundus images, spatial attention module is utilized. Furthermore to achieve multi-scale context extraction modified receptive field blocks (MRFB) are added to the encoding layers of the network. In addition, the MRFBs are also introduced in the auxiliary decoder for fine-tuning of the feature representation. The performance of the proposed model has been evaluated on three publicly available retinal fundus databases, DRISHTI-GS, RIM-ONE, and REFUGE and the model has achieved a dice score of 97.10, 96.12, 96.48 respectively on the optic disc and 93.38, 92.92, 93.85 on optic cup segmentation, outperforming the state-of-the-art methods.

Technical difficulties of adequate assessment of intraocular pressure in a patient with glaucoma in the long term after corneal refractive surgery (clinical case)

PURPOSE. To demonstrate a clinical case involving difficulties in adequate assessment of intraocular pressure (IOP) in a patient with glaucoma in the long term after LASIK.METHODS. The study describes the case of patient M. of 58 years old with complaints about decreased distance vision in the right eye during the last year. In 2004 the patient underwent LASIK for moderate myopia. In 2018, asymmetry in the parameters of optic nerve head (size of the optic cup to the optic disc ratio (C/D ratio) was revealed: in the right eye — up to 0.7, narrowing of the visual field from nasal to fixation point; in the left eye — 0.5, visual fields without abnormalities. The IOP measured using the Maklakov method in both eyes corresponded to the average statistical norm — 22 mm Hg. The following diagnosis was established: IIA primary open-angle glaucoma in the right eye, IA primary open-angle glaucoma in the left eye. One-time instillations of latanoprost 0.005% eye drops solution was indicated for both eyes. In subsequent years the IOP was 18–20 mm Hg. After 4 years, the IOP according to the Maklakov method: OD — 18 mm Hg; OS — 21 mm Hg (on the hypotensive regimen — instillations of latanoprost 0.005% eye drops solution). In the right eye: C/D ratio 0.85–0.9 with absolute scotoma in the Bjerrum area 5–15° from fixation; in the left eye: C/D ratio 0.9 with neuro retinal rim loss from below, with absolute scotoma in the blind spot area. The stages of primary open-angle glaucoma were ascertained: IIIA in the right eye, IIA in the left eye.RESULTS. Selective laser trabeculoplasty was performed. Brimonidine 0.1% solution was added due to the lack of complete stabilization of the IOP level on a single instillation of latanoprost 0.005%, after that IOP decreased to 19 mm Hg in both eyes.CONCLUSION. It is necessary to carefully assess the condition of the structures of the optic nerve head in patients after LASIK, regardless of the statistically normal IOP values.

Glaucoma Detection Using Fundus Images of the Retina

In the paper that we are proposing we make use of the image processing technique that can be further used to detect or predict whether the eye is glaucomatic which leads to increase in the size of the optic cup in turn affecting the optic disc. Glaucoma being the second major reason for blindness was very difficult to detect in the early stages. Here in this paper, we make use of the retinal fundus images and glaucoma is being detected using the features that we extract from the fundus images. The first feature that we extract includes one of the basic physiological parameters which is the Cup to Disc ratio (CDR) and the second feature that we extract is the neuro retinal rim which has the inferior, superior, nasal and the temporal quadrants often called the ISNT quadrants which can be used to detect glaucoma in the fundus image of the eye.

Correlation between visual field and retinal nerve fiber layer thickness in adult north Indian population from Gurugram region with glaucoma suspect

: To find the correlation between visual field and retinal nerve layer thickness in adult North Indian population from Gurugram region with glaucoma suspect. Correlative and quantitative study was carried between the visual field and retinal nerve fiber layer (RNFL) thickness of 400 adult eyes. The age of subjects participating in the study ranged between 18 to 80 years with mean age 45 ± 14years. The standard automated perimetry was acquired by Humphrey visual field analyser using 24-2 SITA standard strategy. Retinal nerve fiber layer thickness was measured by Spectral Domain OCT (3D OCT2000FA). Visual field was performed on the same day or within ± three months of OCT acquisition. Statistical analysis was performed using MS Excel, SPSS (ver.20) and other descriptive statistical tools.: The mean MD and PSD were -2.79 dB ±2.21 and 2.52 dB ±1.49, respectively. The average thickness of RNFL of the four quadrants calculated was 98.40 µm±10.70. RNFL thickness in an inferior and superior quadrant was 122.49µm ± 16.71 and 118.86 µm ±15.21 respectively. The mean cup to disc area ratio (CDAR) in the glaucoma suspect subject was 0.60± 0.10, and the vertical cup to disc ratio (VCDR) was 0.74± 0.074. Correlation of the average RNFL thickness, Inferior RNFL thickness and superior RNFL thickness with GHT was 0.245(P=0.011), 0.19 (P=0.094) and 0.27, (P=0.004), respectively. Superior RNFL thickness showed a more significant Correlation (r= 0.193, P&amp;#60;0.01) with mean deviation (MD) of the visual field. Retinal nerve fiber layer thickness demonstrated a weak to mild and statistically significant correlation with the visual field. The correlation of average RNFL thickness with Visual field global indices and parameters were significant but weaker. Correlation between superior RNFL thicknesses was highest with GHT in adult North India Gurugram subjects with glaucoma suspect. Superior RNFL thickness showed a higher Correlation with Mean deviation (MD) and VFI of the visual field

Evaluation of Cup Disc Ratio and RNFL Thickness Based on Goldmann Visual Field Test

Introduction and Objective : To assess the relationship between the cup-disc ratio of the optic nerve head and peripapilarry RNFL thickness to the visual field loss in glaucoma patients. Methods : Visual field from Goldmann kinetic perimerty and Ocular Computed Tomography (OCT) records from Yap Eye Hospital, Yogyakarta are used to examine the figure of visual field loss in glaucoma patient. Result: Broad spectrum of glaucoma-related visual field defects were observed from 73 eyes. The most common visual field defects are arcuate defect (23.3%) and followed by general depression. Arcuate defects can already observable in some patients with cup-disk ratio of 0.5 (30%).Arcuate defect occurs in the average RNFL thickness of 69.90 ?m (46.93-118.77). It appears that the pinhole vision appeared on the average RNFL thickness of 44.23 ?m (25.33-63.13), and temporal RNFL thickness remnant occured at 48.64 ?m (46.22-51.06). RNFL thickness with normal visual field was on the thickness of 107.78 ?m (100.27-115.29). Conclusion: Visual field defect that may be observed in glaucoma with Goldmann kinetic perimetry are arcuate defect, and general visual field depression. RNFL thickness may be correlated longitudinally with the worsening of visual field defect.

Clinical outcomes in children and adolescents referred for increased cup:disk ratio at a tertiary referral center

To report clinical outcomes and risk factors for glaucoma in children and adolescents referred for increased cup:disk ratios (CDRs) to a tertiary referral center. This retrospective, single-center study examined all pediatric patients evaluated for increased CDR at Wills Eye Hospital. Patients who had previous known ocular disease were excluded. Demographic data, including sex, age, and race/ethnicity were recorded, as were baseline and follow-up ophthalmic examination findings, including intraocular pressure (IOP), CDR, diurnal curve, gonioscopy findings, and refractive error. Risks of glaucoma diagnosis based on these data were analyzed. A total of 167 patients were included, of whom 6 were found to have glaucoma. Despite more than 2 years' follow-up on 61 patients, all glaucoma patients were identified within the first 3 months of evaluation. Baseline IOP was statistically significantly higher in glaucomatous patients than nonglaucomatous patients (28 ± 7 vs 15 ± 4, resp. [P = 0.0002]), as was maximum IOP on diurnal curve (24 ± 3 vs 17 ± 3 [P = 0.0005]). In our study cohort, diagnosis of glaucoma was apparent in the first year of evaluation. Baseline IOP and maximal IOP on diurnal curve were found to be statistically significantly associated with glaucoma diagnosis in pediatric patients referred for increased CDR.

Dual Consistency Enabled Weakly and Semi-Supervised Optic Disc and Cup Segmentation with Dual Adaptive Graph Convolutional Networks.

Glaucoma is a progressive eye disease that results in permanent vision loss, and the vertical cup to disc ratio (vCDR) in colour fundus images is essential in glaucoma screening and assessment. Previous fully supervised convolution neural networks segment the optic disc (OD) and optic cup (OC) from color fundus images and then calculate the vCDR offline. However, they rely on a large set of labeled masks for training, which is expensive and time-consuming to acquire. To address this, we propose a weakly and semi-supervised graph-based network that investigates geometric associations and domain knowledge between segmentation probability maps (PM), modified signed distance function representations (mSDF), and boundary region of interest characteristics (B-ROI) in three aspects. Firstly, we propose a novel Dual Adaptive Graph Convolutional Network (DAGCN) to reason the long-range features of the PM and the mSDF w.r.t. the regional uniformity. Secondly, we propose a dual consistency regularization-based semi-supervised learning paradigm. The regional consistency between the PM and the mSDF, and the marginal consistency between the derived B-ROI from each of them boost the proposed model's performance due to the inherent geometric associations. Thirdly, we exploit the task-specific domain knowledge via the oval shapes of OD & OC, where a differentiable vCDR estimating layer is proposed. Furthermore, without additional annotations, the supervision on vCDR serves as weakly-supervisions for segmentation tasks. Experiments on six large-scale datasets demonstrate our model's superior performance on OD & OC segmentation and vCDR estimation. The implementation code has been made available 1.

Distribution of the Retinal Microcirculation Based on the Morphology of the Optic Nerve Head in High Myopia

ABSTRACT Purpose To explore the retinal microvasculature of the optic nerve head and macula and their associations with the optic nerve head deformation in high myopia. Methods One hundred sixty-seven eyes from patients with high myopia (HM) were enrolled in a cross-sectional study. We have evaluated and measured characteristics like the tilt ratio of the optic disc, interpupillary vascular density (IVD), peripapillary vascular density (PVD), macular vascular density (MVD), subfoveal choroidal thickness (SFCT) and foveal avascular zone (FAZ). The subjects were classified as a non-tilt group (control group) and a tilt group based on the tilt index. The above parameters were utilized to compare the two groups. In addition, we collected the data from the subjects’ right eyes to analyze variance, the Kruskal-Wallis test, and the least significant difference. Results The patients were divided into the non-tilt group of ninety-one eyes and the tilt group of seventy-six eyes. We found that the IVD in the tilt group was more significant than in the non-tilt group (t = −2.794, P = .006). On the other hand, the PVD was less in the tilt group than in the non-tilt, especially in the NS, NI and IN directions (tNS = 3.782; tNI = 3.07; tIN = 2.086; P < .05). Interestingly, the values of PVD were the highest in temporal, second in superior and inferior and lowest in nasal. Concerning the fovea-DMVD (including fovea, parafovea and perifovea), we characterized them as more minor in the tilt group when compared to those in the non-tilt group (P < .05). Conclusion Herein, we discovered that the retinal microvasculature differed significantly in patients with HM according to the ONH morphology. In this population, lower PVD and thinner SFCT were associated with higher odds of the tilted optic disc. In addition, the other two characteristics, the IVD and DMVD, were affected by the ONH deformation. Finally, we showed that PVD demonstrated better predictability of rapid myopic progression than MVD.

Differentiating stages of functional vision loss from glaucoma using the Disc Damage Likelihood Scale and cup:disc ratio

BackgroundGlaucoma staging is critical for treatment planning but has rarely been tested in severe/end-stage disease. We compared the performance of the Disc Damage Likelihood Scale (DDLS) and cup:disc ratio (CDR)...

Multi-Parameter Optimization Analysis of Hydrodynamic Performance for Rim-Driven Thruster

The efficiency of rim-driven thrusters (RDT) has always been the focus of attention in the context of energy conservation and environmental protection. A multi-parameter collaborative optimization framework is proposed to improve the efficiency of RDT based on the response surface method (RSM). The common structural parameters of RDT, including pitch ratio, disk ratio and rake angle, are selected as design variables to carry out the Box–Behnken experimental design combined with the simulation data obtained through CFD calculations. The response surface second-order model is employed to evaluate the extent to which different parameters can affect the target variable and obtain the optimal hydraulic efficiency. The results show that the established model has high precision, good reproducibility and strong anti-interference ability. The influence of the pitch ratio, rake angle and disk ratio on open water efficiency decreases in sequence. Compared with the prototype RDT, the maximum efficiency of the optimized RDT is increased by 13.8%, and the surface pressure distribution and flow field characteristics are also significantly modified.

On the crown formation and cavity dynamics of free-falling thick disks

The water entry, crown formation, and cavity dynamics of gravity-driven thick solid and annular disks were studied by conducting a series of detailed laboratory experiments. Three different release conditions were examined to study the fully guarded and partially guarded release conditions on the cavity dynamics. The effects of aspect ratio, geometry, and density of disks on crown formation, interface impact, seal development, and air entrainment were investigated. Four crown shapes were identified, and the crown structure was classified based on the dimensionless moment of inertia, I*, and the impact Froude number, Fro. The effects of controlling parameters on variations of crown dimensions were investigated. It was found that the normalized crown diameter decreased with I* and crown geometries were found to be smaller in annular disks. Experimental observations have shown that high-density disks have larger pinch-off depth and form a deep seal in the ambient water. The normalized pinch-off depth increased with Fro and the normalized pinch-off depth in cylindrical thick disks were smaller than thin disks and spherical objects. The temporal variations of cavity indicated a non-linear correlation between the growth rate of normalized pinch-off depth and time. The disk's velocities in three different stages were measured, it was found that the settling velocities followed a linear relationship with I*, and it was affected by the release conditions. The velocity and vortex fields were extracted from the particle image velocimetry data. The velocity fields showed that the solid disks affected a greater surrounding ambient in comparison to the annular disks due to their higher initial momentum. Periodic vortex shedding was formed in the wake of annular disks, and the frequency of the vortex field was found to be proportional to the disk density.

Extreme intraocular pressure and steroid-dependent iritis.

A 50-year-old ophthalmic technician was referred by her retina specialist for urgent consultation due to markedly elevated intraocular pressure (IOP) unresponsive to medical therapy. Her history included chronic polyarticular juvenile rheumatoid arthritis and chronic uveitis requiring ongoing topical steroid therapy. She had a sub-Tenon injection of Kenalog (triamcinolone) 18 months prior to referral. Chronic topical anti-inflammatory therapy included nepafenac (Ilevro) and prednisolone acetate 2 times a day. Attempts to discontinue topical steroid resulted in worsening inflammation. The patient was referred when the IOP measured 44 mm Hg in the left eye despite aggressive medical therapy, including acetazolamide. The IOP improved slightly when loteprednol was substituted for prednisolone acetate. Current medications in the left eye include brimonidine 3 times a day, loteprednol 2 times a day, nepafenac 2 times a day, and fixed combination latanoprost + netarsudil at bedtime. Her only medication in the right eye was travoprost. She is intolerant to dorzolamide. She was also taking acetazolamide 500 mg 2 times a day. She was not taking any anticoagulants. Past surgical history included cataract surgery in each eye. She has not had laser trabeculoplasty in either eye. Examination revealed uncorrected visual acuity of J1+ in the right eye (near) and 20/30 in the left eye (mini-monovision). There was no afferent pupillary defect. There was mild band keratopathy in each eye while the central cornea was clear in both eyes without keratic precipitates. Here angles were open to gonioscopy without peripheral anterior synechia. There was mild to moderate flare in each eye with trace cells. The IOP was 17 mm Hg in the right eye and 31 mm Hg in the left. Central corneal thickness measured 560 μm and 559 μm in the right and left eye respectively. There was a well-positioned intraocular lens within each capsule with a patent posterior capsulotomy. There was mild vitreous syneresis but no vitreous cell. The cup to disc ratio was 0.5 in each eye with a symmetrical neural rim. The retina was flat without macular edema. Visual field was normal in both eyes (Figures 1 and 2). Optical coherence tomography of retinal nerve fiber layer (RNFL) is shown in Figure 3 and retinal ganglion cell layer is shown in Supplemental Figure 1 (http://links.lww.com/JRS/A756).JOURNAL/jcrs/04.03/02158034-202301000-00020/figure1/v/2022-12-26T045736Z/r/image-tiffJOURNAL/jcrs/04.03/02158034-202301000-00020/figure2/v/2022-12-26T045736Z/r/image-tiffJOURNAL/jcrs/04.03/02158034-202301000-00020/figure3/v/2022-12-26T045736Z/r/image-tiff Please comment on your management of this patient's left eye.

Presumptive discerning of the severity level of glaucoma through clinical fundus images using hybrid PolyNet

PurposeGlaucoma is the major leading cause of non-curable visual defects and blindness across the world. Glaucoma is one of the eye diseases which cause an optic nerve, due to increased pressure called intraocular pressure. If the damage gets worse, it causes permanent vision loss within a few years. Timely diagnosis, early and accurate prediction are the most important factors for the prevention of visual blindness. For experts, it is uncompromising task for detecting glaucoma manually. In most of the retinal images, different investigations are carried out for identifying an automated detection tool for diagnosing glaucoma. MethodsThe main aim of this paper is to build a machine learning model for predicting glaucoma and its severity level. To predict the severity level of glaucoma, firstly, the segmentation of the blood vessel is performed and classification is accomplished using proposed U-Net model. Secondly, the segmentation of the Optic Disc (OD) and the Optic Cup (OC) is performed to determine the Cup to Disk Ratio (CDR). The proposed hybrid PolyNet classifies the severity of the glaucoma disease. The earlier detection of glaucoma disease is important for preventing the severity of the eye disease. ResultsThe segmentation of blood vessels is implemented using the U-Net model, the sensitivity and the specificity are measured as 97% and 88% respectively. The accuracy and the F1 score have been measured as 96% and 98% respectively. Hence, the proposed deep learning architecture with hybrid PolyNet models is implemented for OD and OC separately to produce an appropriate result. By increasing the number of layers, more features are identified. The current work deals with the retinal fundus images and achieves the highest accuracy of 96.21% in the ACRIMA dataset with sensitivity and specificity of about 97.32% and 94.26% respectively. ConclusionBlood vessel segmentation is achieved with U-Net and the segmentation of the optic disc and the optic curve have been achieved and the severity level of glaucoma has been identified using hybrid PolyNet with high accuracy.

Clinical Profile and Intraocular Pressure Control of Medically Treated Glaucoma Patients Seen in a Tertiary Hospital in Enugu, Nigeria

Background: Glaucoma is the second most common cause of blindness and the leading cause of irreversible blindness worldwide. It is a chronic optic neuropathy with characteristic optic disc changes and corresponding visual field defect. Aim: The aim of this study was to determine the clinical profile and intraocular pressure control of Primary Open Angle Glaucoma (POAG) patients on medical treatment at the glaucoma clinic of Enugu State University of Science and Technology Teaching Hospital Parklane (ESUTTHP), Enugu with a view for better patient management. Methods: The study was a hospital based cross sectional study on POAG patients on medical treatment attending the eye clinic of ESUTTHP, Enugu. Patients were selected by simple random sampling. Their eyes were examined which included visual acuity assessment, follow-up clinic intraocular pressure measurement, gonioscopy, anterior and posterior segments examination. Water Drinking Test (WDT) and modified phasing were carried out on them. WDT was done over 2 hours after intake of 1 liter of water with intraocular pressure measured every 15 minutes. Modified phasing was done over 8 hours with intraocular pressure measured at 2 hourly intervals. Data analysis was done using SPSS version 20 (U.S.A). The mean follow-up clinic intraocular pressure (IOP), IOP peak and fluctuation during WDT and phasing were determined and compared using T-test. Results: A total of 130 primary angle glaucoma patients on medical treatment were examined comprising of 43.1% males and 56.9% females with mean age of 62.25±9.002. Few of the patients were blind (3.8%) while 66.2% had normal vision. Their mean vertical cup disc ratio was 0.78±0.13. Majority of the patients had thin central cornea and uncontrolled intraocular pressure. The mean follow-up clinic IOP, mean IOP peaks during WDT and phasing were 16.2±4.3, 22.9±5.7, 18.0±4.4mmHg, respectively. There was a significant correlation between central corneal thickness and IOP peaks in WDT and modified phasing as well as follow-up clinic IOP but there was no significant correlation between central corneal thickness and IOP fluctuations in WDT and modified phasing. There was a significant correlation between vertical cup disc ratio and IOP peaks in WDT as well as vertical cup disc ratio and follow-up clinic IOP (p&lt; 0.01). Conclusion: Few patients are blind from glaucoma but greater percentage still have uncontrolled IOP despite being on medical treatment. Therefore, other treatment options should be explored to bring their IOP under control to avoid further glaucomatous progression and consequent blindness.

Optical coherence angiography of optic disc in eyes with primary open‐angle glaucoma and normal tension glaucoma with equal levels of structural damage

AbstractPurpose: To compare visual field (VF), nerve fibre and ganglion cell loss and changes in peripapillary vasculature in age matched patients with normal‐tension (NTG) and high tension glaucoma (HTG) at an equal level of glaucomatous structural damage of the optic nerve head (ONH).Methods: For the present study a retrospective analysis of patients with NTG and HTG was performed. One eye of each patient was randomly assigned for further analysis. To provide a reliable case by case match of HTG and NTG eyes, an equal optic disk size as measured by available spectral‐domain OCT system (RTVue XR OCT Avanti System; Optovue Inc., Fremont, CA) and an equal estimated excavation of the optic disk were chosen. Optic nerve head parameters, retinal nerve fibre layer (RNFL) ganglion cell (GCC) thickness and vessel densities (VD) in the peripapillary area were measured automatically by OCT with a respective software. Forty eyes with NTG, were matched according to the same glaucomatous ONH damage based on cup to disc ratio rim area and disc size with 40 eyes with HTG.Results: Mean age of patients was 68.5 ± 12 (27–84) years. The visual field index, RNFL, GCC thickness and peripapillary VDs in the HTG eyes were similar to those in the NTG eyes (mean VFI 79.6 vs. 78.8 p = 0.84, mean RNFL thickness 71.5 vs. 72.05 μm p = 0.87, mean GCC thickness 76.2 vs. 74.5 μm p = 0.62, mean peripapillary VD 43.6 vs. 43.8% p = 0.87). There was no difference in sectoral RNFL thickness and peripapillary VDs between HTG and NTG. In both groups, univariate regression analysis using the Pearson correlation coefficient showed VFI significantly correlated with RNFL thickness (NTG r = 0.423 p = 0.006 HTG r = 0.514 p = 0.002), and peripapillary VD (NTG r = 0.793 p &lt; 0.001 HTG p = 0.534 p = 0.001) in both groups but with GCC thickness (NTG r = 0.585 p &lt; 0.001) only in eyes with NTG.Conclusions: At an equal level of glaucomatous structural damage of the ONH indicated by cup to disk ratio and RNFL thickness, NTG patients seem to have same losses of peripapillary vasculature. Visual field index correlated with RNFL thickness and peripapillary vessel density in both groups.