Subjective Visual Acuity Research Articles

Comparative study of pterygium excision with suture and sutureless conjunctival autograft

Introduction and aim. This is a prospective interventional study to compare corneal astigmatism before and after pterygium excision with conjunctival autograft, to determine the difference in mean corneal curvatures before and after pterygium excision, to evaluate the safety and efficacy of autologous blood technique, and sutured conjunctival autograft for primary pterygium. Material and methods. Patients were divided into group A – pterygium excision+sutured conjunctival limbal autograft and group B – pterygium excision+autologous conjunctival limbal autograft under local anesthesia. The preoperative and post operative K1 and K2 values and BCVA were noted. Results. There was statistically significant reduction in mean astigmatism at each post operative follow up in group A at 1 week (p=0.0249), 2 weeks (p=0.004), 1 month (p=0.0031) and at 3 months (p=0.0009) and similarly in group B post operative follow up at 1 week (p=0.0011), 2 weeks (p=0.0021), 1 month (p=0.0009) and at 3 months (p=0.0003). Conclusion. Pterygium surgery decreases the cylindrical error and reverts corneal curvatures to normal, thus improving subjective visual acuity. Astigmatism produced by the pterygium is reduced after surgery We found autologous conjunctival autograft is superior than sutural conjunctival autograft. Pterygium causes astigmatism depending upon the size of pterygium it should be surgically removed to prevent obstruction in the vision.

Prediction of Visual Acuity in Pseudophakic Cataract Population Based on Residual Refraction

Purpose The purpose of the study was to design a simple, handy prediction for the effect of spherical and cylindrical refractive error on the visual acuity degradation at different distances and validate this model on a clinical dataset. Methods This study examined 70 eyes from 35 patients’ post-cataract surgery with aberration-free intraocular lenses. Biometric and corneal data were analysed, and subjective refraction and visual acuity were evaluated by two experienced optometrists. The study computed the spherical equivalent (SEQ), and defocus equivalent via vector addition (DEQ vec), as the sum of absolute values (DEQ abs). Predictive models were developed using univariate regression, with confidence intervals (BCa 95%) calculated through non-parametric bootstrapping (10,000 cycles). Results Various calculated equivalents included −0.44 D for spherical equivalent (SEQ), 0.70 D for defocus equivalent based on vector calculation (DEQ vec), and 0.89 D for defocus equivalent based on absolute values (DEQ abs). Uncorrected and corrected visual acuity averaged 0.07 logMAR and −0.04 logMAR, respectively. The absolute defocus equivalent (DEQ abs) exhibited the smallest confidence interval (BCa 95%) at 0.07. Conclusion The defocus equivalent based on the addition of absolute values (DEQ abs) emerged as the most practical predictor for the described applications. Notably, it offers the advantage of easy calculability through a simple equation: VA loss = DEQ abs ⋅ 0.23. In 95% of cases, this predicted loss would have an accuracy of ±0.03 lines.

Comparing 2-dimensional macular pigment optical density with objective and subjective perimetry and visual acuity in age-related macular degeneration

PurposeTo compare diagnostic power for different severities of age-related macular degeneration (AMD) of two-dimensional macular pigment optical densities (2D-MPOD) and spatially matched objective perimetry, with standard perimetry and best-corrected visual acuity (BCVA).MethodsThe ObjectiveField Analyser (OFA) provided objective perimetry, and a Heidelberg Spectralis optical coherence tomography (OCT) measured 2D-MPOD in AMD patients, both completed twice over 0.99 ± 0.16 years. From each 2D-MPOD image, we extracted 20 regions/macula, matched to the 20 OFA stimuli/macula. For each region, we calculated 7 measures from the 2D-MPOD pixel values and correlated those with OFA sensitivities and delays. We quantified 2D-MPOD changes, the ability of 2D-MPOD and OFA to discriminate AMD stages, and the discriminatory power of Matrix perimetry and BCVA using percentage area under receiver operator characteristic plots (%AUROC).ResultsIn 58 eyes of 29 subjects (71.6 ± 6.3 years, 22 females), we found significant correlations between 2D-MPOD and OFA sensitivities for Age-Related Eye Disease Studies (AREDS)-3 and AREDS-4 severities. Delays showed significant correlations with AREDS-2. For AREDS-4, correlations extended across all eccentricities. Regression associated with the Bland–Altman plots showed significant changes in 2D-MPOD over the study period, especially variability measures. MPOD per-region medians discriminated AREDS-1 from AREDS-3 eyes at a %AUROC of 80.0 ± 6.3%, outperforming OFA, Matrix perimetry, and BCVA.ConclusionsMPOD changes correlated with central functional changes and significant correlations extended peripherally in later-stage AMD. Good diagnostic power for earlier-stage AMD and significant change over the study suggest that 2D-MPOD and OFA may provide effective biomarkers.

Vitrectomy for the Management of Vitreous Hemorrhage : Clinical Characteristics and Surgical Outcomes

Purpose: Vitreous hemorrhage (VH) can cause sudden loss of vision. Conservative management is sometimes employed, yet potential risk due to delayed diagnosis and definitive treatment is concerning. Vitrectomy for VH can reduce such risk by confirming the etiology and providing surgical treatment. This study was conducted to evaluate the clinical characteristics and surgical outcomes of vitrectomy for VH in our center.
 Methods: A descriptive study was conducted. Data were collected retrospectively from patient’s medical records who underwent vitrectomy for VH from January to December 2020, including pre-operative clinical characteristics, surgical and adjunctive intervention, and postoperative findings. Statistical analysis was conducted. Comparison of final visual acuity to baseline visual acuity was analyzed.
 Results: There were 164 eyes from 164 subjects who underwent vitrectomy due to VH included in this study. The mean age of the subjects was 55,2 ± 9,8 years. Most of the subjects had severe VH pre-operatively (84,7%). Diabetic retinopathy was the most common etiology (45,1%), followed by breakthrough from submacular hemorrhage (29,9%) and retinal vein occlusion (10,3%). Most of the subjects (87,2%) underwent early vitrectomy. Final visual acuity in all subject groups improved significantly compared to baseline visual acuity (p = 0,00; p < 0,05). Final visual acuity in subjects with breakthrough from submacular hemorrhage was lower compared to other etiology. Complications after vitrectomy were recurrent VH (10,3%) and increased intraocular pressure associated with silicone oil (1,82%).
 Conclusion: Early vitrectomy appears to be beneficial for VH. Visual acuity varies regarding the etiology, nevertheless, was maintained or improved in most subjects.

Multifocal electroretinography in the diagnosis and monitoring of early and intermediate stages of age-related macular degeneration

Multifocal electroretinography is a valuable diagnostic method for the objective localization and quantitative assessment of functional disorders of the central retina in age-related macular degeneration. It is used to detect early changes, monitor the course of the disease and treatment outcomes. In many cases, multifocal electroretinography is a more sensitive method for detecting functional disorders at the early/intermediate stage of age-related macular degeneration compared to morphological (optical coherence tomography) and subjective (visual acuity, perimetry) testing methods.

Actual issues of secondary prevention of liver cancer in Kazakhstan

Liver cancer is characterized by high mortality and low survival rates in most countries of the world. According to the WHO data, more than 1.3 million people with liver cancer die annually in the world and according to the data of the 9th volume of "Cancer on five continents" - the highest standardized incidence rates are in Korea - 44.9 per 100 thousand population as well as in Thailand, Japan, China. Low rates were in Algeria, India, Belgium and the Netherlands. In Russia 61.5% of patients die of liver cancer progression in the first year after diagnosis [1,2].<br /> Information on the global burden of cancer in 2018 showed that the specific weight of liver cancer in the structure of malignant neoplasms (MN) is 8.2%, and in 2020 - 8.3% [3].  <br /> The worldwide peculiarity of liver cancer is its late diagnosis. Several evidence-based treatment options for liver cancer are currently available: liver transplantation for hepatocellular liver cancer (HCC) (according to the Milan criteria), radiofrequency ablation as a radical treatment option (RFA), chemoembolization for intrahepatic cholangiocarcinoma (TACE), and the administration of Sorafenib as systemic therapy [4].<br /> Current approaches for the treatment of early-stage primary liver cancer are represented by hepatic RFA, and the efficacy of this approach depends on the subjective attentiveness and visual acuity of the clinician. The latest technique used in liver RFA is the hyperspectral imaging which utilize objective assessment [2].<br /> Ultrasound is usually used to detect liver lesions, but the detection rate is low for many reasons, such as clinician skills and technical capabilities. Modern approaches of diagnostic capabilities, such as contrast-enhanced ultrasound integrated imaging (CEUS) and comprehensive ultrasound imaging - contrast-enhanced CT (CECT) or contrast-enhanced MRI (CEMRI) for visualization of focal liver lesions (FLL) - increase the confidence of the interventional physician so it should be recommended for use as a routine procedure [5-6].<br /> The ratio of morbidity and mortality in many countries reaches 91.6%, which represents the third most important cause of cancer deaths [7-9].

Optical characterization and through-focus performance of two advanced monofocal intraocular lenses

PurposeTo compare the refractive power profile, subjective depth-of-field and objective optical quality of two advanced monofocal intraocular lenses (IOLs) designed to improve intermediate vision.MethodsThis prospective study evaluated forty-six eyes of twenty-three patients, aged 54–68 years, binocularly implanted with two monofocal enhanced intraocular lenses (IOLs), the Tecnis Eyhance and the Physiol Isopure. Subjective through-focus visual acuity curves were obtained by placing trial lenses in front of the eye while wearing its best spherical-cylindrical correction for distance. Objective optical quality was defined as the area under the modulation transfer function, calculated from the wavefront maps measured with a high-resolution aberrometer. The optical design of both lenses was compared based on their refractive power profiles measured with the lenses immersed in saline solution.ResultsBoth lenses have progressive aspherical geometries, in which the sagittal power decreases rapidly from the center to the edge of the optical zone. Mean monocular through-focus curves show a best corrected distance visual acuity of − 0.02 logMAR with both lenses. Through-focus visual acuity was marginally higher for the Eyhance, with a difference of 1 letter at the defocus position of − 0.5D and 3 letters between − 1.0D and − 2.0D. Objective assessment of optical quality revealed only a difference of about 2 points in MTF area at distance.ConclusionBoth IOLs use a similar approach to improve intermediate vision. The Eyhance showed marginally better subjective performance than the Isopure at the target vergences between − 1.00D and − 2.00D, although these results did not reach statistical significance and were not replicated by the objective findings.

Evaluation of Agreement Between Sweep Visual Evoked Potential Testing and Subjective Visual Acuity.

The primary objective of this study was to evaluate the agreement of visual acuity (VA) obtained with the sweep visual evoked potential (sVEP) method with the VA obtained with the Snellen chart. The secondary objective was to examine the effect of age and gender on agreement. Best corrected VAs of subjects were recorded with the Snellen chart, and sVEP testing was performed according to the recommendations of the International Society for Clinical Electrophysiology of Vision (ISCEV). Snellen VAs and sVEP measurements were analyzed using logMAR conversion for statistical analysis. Agreement was evaluated with Bland-Altman analysis. The study included 49 subjects with a mean age of 53.5±17.3 years (range: 19-75 years) and mean Snellen VA of 0.31±0.32 logMAR (range: 1.3-0.0 logMAR). In the Bland-Altman analysis, the mean differences between the VA and sVEP measurements (VA-sVEP) were significantly different and outside the limits of agreement (p=0.035). A significant proportional bias (p=0.0007) was found in the regression analysis performed between VA-sVEP and the mean VA. According to the Bland-Altman analysis of sex subgroups, there was a significant difference between VA and sVEP measurements in female subjects (p=0.006). The difference between VA and sVEP measurement increased significantly with older age (R2: 0.306, p<0.001, β: 0.05 [0.03, 0.08]). In conclusion, sVEP measurements and VAs did not show statistical agreement. Cranial anatomy and endocrine differences of the subjects may affect their sVEP measurements. The difference between the methods varies according to VA level. Directly using sVEP results instead of VA would not be appropriate.

Increasing depth of focus with allogeneic presbyopic inlays: 3-year results.

To demonstrate the safety and efficacy of allogenic corneal inlays designed to increase the depth of focus (DoF) in treated eyes. Medipol University Hospital, Istanbul, Turkey. Prospective case series. This study includes 50 eyes of 25 patients with a follow-up of 3 years. Emmetropic patients with presbyopia had implantation of allogenic corneal inlays in the nondominant eye. The uncorrected distance visual acuity (UDVA), corrected distance visual acuity (CDVA), and uncorrected near visual acuity (UNVA) were evaluated in all eyes. A subjective visual acuity test system (Multifocal Lens Analyzer 3.0 application) was used to analyze the DoF by measuring the defocus curves. No significant difference between the treated and fellow eyes in UDVA and CDVA was found, whereas UNVA was significantly better in the treated eyes ( P = .20, P = .07, P < .01, respectively). Comparing to the preoperative CDVA, there was a 1-line decrease in CDVA in 6 (%24) patients. The mean defocus curves reveal a DoF of 1.1 diopters (D) for the untreated eye at the logMAR = 0.2 threshold. By contrast, the mean DoF of the treated eye and binocularly was 2.8 D. The areas under the curve were significantly better in the near, intermediate, and total distances in the treated eyes, whereas it was better for the far distances in the untreated eyes. All values were significant ( P = .023 total, P < .01 others). Allogenic presbyopic inlay implantation may be safe and provided a clinically and statistically significant increase in the DoF leading to good far, intermediate, and near-visual acuity in emmetropic presbyopic patients.

Accuracy of Artificial Intelligence in Estimating Best-Corrected Visual Acuity From Fundus Photographs in Eyes With Diabetic Macular Edema

Best-corrected visual acuity (BCVA) is a measure used to manage diabetic macular edema (DME), sometimes suggesting development of DME or consideration of initiating, repeating, withholding, or resuming treatment with anti-vascular endothelial growth factor. Using artificial intelligence (AI) to estimate BCVA from fundus images could help clinicians manage DME by reducing the personnel needed for refraction, the time presently required for assessing BCVA, or even the number of office visits if imaged remotely. To evaluate the potential application of AI techniques for estimating BCVA from fundus photographs with and without ancillary information. Deidentified color fundus images taken after dilation were used post hoc to train AI systems to perform regression from image to BCVA and to evaluate resultant estimation errors. Participants were patients enrolled in the VISTA randomized clinical trial through 148 weeks wherein the study eye was treated with aflibercept or laser. The data from study participants included macular images, clinical information, and BCVA scores by trained examiners following protocol refraction and VA measurement on Early Treatment Diabetic Retinopathy Study (ETDRS) charts. Primary outcome was regression evaluated by mean absolute error (MAE); the secondary outcome included percentage of predictions within 10 letters, computed over the entire cohort as well as over subsets categorized by baseline BCVA, determined from baseline through the 148-week visit. Analysis included 7185 macular color fundus images of the study and fellow eyes from 459 participants. Overall, the mean (SD) age was 62.2 (9.8) years, and 250 (54.5%) were male. The baseline BCVA score for the study eyes ranged from 73 to 24 letters (approximate Snellen equivalent 20/40 to 20/320). Using ResNet50 architecture, the MAE for the testing set (n = 641 images) was 9.66 (95% CI, 9.05-10.28); 33% of the values (95% CI, 30%-37%) were within 0 to 5 letters and 28% (95% CI, 25%-32%) within 6 to 10 letters. For BCVA of 100 letters or less but more than 80 letters (20/10 to 20/25, n = 161) and 80 letters or less but more than 55 letters (20/32 to 20/80, n = 309), the MAE was 8.84 letters (95% CI, 7.88-9.81) and 7.91 letters (95% CI, 7.28-8.53), respectively. This investigation suggests AI can estimate BCVA directly from fundus photographs in patients with DME, without refraction or subjective visual acuity measurements, often within 1 to 2 lines on an ETDRS chart, supporting this AI concept if additional improvements in estimates can be achieved.

Pituitary Adenoma Presenting with True Bitemporal Hemianopsia: A Case Report

Pituitary adenomas grow from the anterior pituitary gland and can cause compression of surrounding structures, including the optic chiasm, leading to visual field defects such as bitemporal hemianopia, visual acuity or color perception reduction. In this case report, we present the case of a 45-year-old male patient who presented with long-lasting headaches and visual disturbances, including diplopia and a decline in visual acuity. Despite being initially diagnosed with migraine by a neurologist, a thorough ophthalmological examination revealed visual field defects consistent with true bitemporal hemianopsia. MRI results confirmed the presence of sellar mass, and the patient was referred to the neurosurgery department for immediate intervention. The patient underwent surgical removal of the mass, which was identified as a pituitary adenoma upon histological examination. Three months later, the patient experienced significant improvements in subjective and objective visual acuity, with no diplopia or scotomas in the visual field. In conclusion, this case report highlights the importance of considering pituitary adenoma as a potential cause of visual disturbances, even in the absence of bitemporal hemianopsia. Thorough ophthalmological examination, including visual field testing, can aid in the early detection of chiasmal involvement and prompt referral for further investigation. Early intervention, including surgical removal of the tumor, can prevent other complications and significantly improve visual acuity and overall quality of life for patients.

Objective Prediction of Human Visual Acuity Using Image Quality Metrics

This work addresses the objective prediction of human uncorrected decimal visual acuity, an unsolved challenge due to the contribution of both physical and neural factors. An alternative approach to assess the image quality of the human visual system can be addressed from the image and video processing perspective. Human tolerance to image degradation is quantified by mean opinion scores, and several image quality assessment algorithms are used to maintain, control, and improve the quality of processed images. The aberration map of the eye is used to obtain the degraded theoretical image from a set of natural images. The amount of distortion added by the eye to the natural image was quantified using different image processing metrics, and the correlation between the result of each metric and subjective visual acuity was assessed. The correlation obtained for a model based on a linear combination of the normalized mean square error metric and the feature similarity index metric was very good. It was concluded that the proposed method could be an objective way to determine subjects’ monocular and uncorrected decimal visual acuity with low uncertainty.

Characteristics of visual function in children with autism complicated with mental retardation

Objective: To explore the characteristics of visual function and eye diseases in children with autism spectrum disorder (ASD) and mental retardation. Methods: It was a cross-sectional study. Two hundred and ninety-two cases (584 eyes) of children with ASD combined with mental retardation from 7 special education schools in Chaoyang District of Beijing, including 235 males (80.48%) and 57 females (19.52%); The age ranged from 2 to 18 years old. Subjective far and near vision, near stereoacuity, objective vision, diopter, anterior segment and fundus were examined. In addition, 300 students with normal intelligence level, aged 2 to 18 years, were included as controls. LogMAR was used to record vision examination. Subjective, objective vision and diopter were examined. Mann Whitney U test or Kruskal Wallis H test was used for the data of children with different genders, different age. Results: Among 584 eyes of children with ASD and mental retardation, 272 eyes (47.22%) were ametropia, 260 eyes (45.14%) were astigmatism, 29 eyes (5.03%) were hyperopia, 10 eyes (1.74%) were myopia, and 47 eyes (8.16%) were amblyopia risk factors. Among 292 children, there were 20 cases of strabismus (6.85%), 3 cases of color weakness (1.03%), and 4 cases of external eye abnormalities (1.37%). Two hundred and eleven children completed near stereopsis examination, of which 54 (25.59%) were within 100″ and 157 (74.41%) were within 200″ to 900″. Two hundred and seventy-two eyes with ametropia, 157 eyes (57.72%) needed correction but did not. The median and quartile of subjective and objective logMAR visual acuity were 0.22(0.10, 0.35), 0.10(0.00, 0.22), respectively; There were no significant differences in far visual acuity, near visual acuity, objective visual acuity, diopter, and near stereoacuity between different genders of ASD children with mild or moderate mental retardation (all P>0.05); There was a statistically significant difference in ASD children with mild mental retardation at different age rangs (H=21.453, P<0.001). There was a statistically significant difference in subjective tests such as far visual acuity and near visual acuity, for children with moderate mental retardation (Z=-3.508, -4.503; P<0.001). There was no statistically significant difference in objective visual acuity, diopter and near stereo acuity(all P>0.05). There are 300 healthy children as the control group, with LogMar's subjective far vision is 0.10(0.00, 0.22), and the objective vision is 0.00(0.00, 0.10), diopter 0.25 (-0.25, 0.50) D. Compared with healthy children, ASD children with mental retardation had a significant difference in subjective far vision and objective vision (Z=-8.527, -10.393; P<0.001). There was no significant difference in diopter (Z=-1.274, P=0.203). Conclusions: The subjective and objective visual acuity of children with ASD combined with mental retardation was lower than that of healthy children. The prevalence and uncorrected rate of refractive errors, strabismus, amblyopia and other eye diseases were significantly higher than those of healthy children. Their refractive errors were mainly astigmatism, and the rates of correction and treatment were low.

Evaluating the effect of ocular aberrations on the simulated performance of a new refractive IOL design using adaptive optics.

Adaptive optics (AO) visual simulators are excellent platforms for non-invasive simulation visual performance with new intraocular lens (IOL) designs, in combination with a subject own ocular aberrations and brain. We measured the through focus visual acuity in subjects through a new refractive IOL physically inserted in a cuvette and projected onto the eye's pupil, while aberrations were manipulated (corrected, or positive/negative spherical aberration added) using a deformable mirror (DM) in a custom-developed AO simulator. The IOL increased depth-of-focus (DOF) to 1.53 ± 0.21D, while maintaining high Visual Acuity (VA, -0.07 ± 0.05), averaged across subjects and conditions. Modifying the aberrations did not alter IOL performance on average.

Early Detection of Refractive Errors by Photorefraction at School Age

Early detection and treatment of refractive defects during school age are essential to avoid irreversible future vision loss and potential school problems. Previously, vision screening of preschool children used methods based on subjective visual acuity; however, technologies such as photorefraction have promoted the detection of refractive errors quickly and easily. In this study, 1347 children from 10 schools in Madrid aged 4 to 12 years participated in a program of early detection of visual problems, which consisted of visual screening composed of anamnesis and photorefraction with a PlusOptix A12R. The prevalence of refractive errors was analyzed in terms of spherical equivalent, cylinder and its orientation, and potential cases of development of high myopia or amblyopia. Hyperopia predominates in the early years, but the number of myopic subjects is higher than that of hyperopic subjects from the age of ten onwards. At all ages, the predominant orientation of astigmatism was with-the-rule. On average, 80% of the myopic subjects were uncorrected. Potential high myopia increased with age, from 4 to 21% of the measured population. Potential amblyopia cases decreased across age groups, from 19 to 13.7%. There is a need to raise awareness of the importance of vision screening at school age to address vision problems.

Ophthalmic findings in marginally housed women in a Canadian city

ObjectifÉvaluer la prévalence et les principales causes de pathologies oculaires chez des femmes vulnérables en situation de logement marginalisé et/ou qui ont des antécédents de maltraitance, de violence ou de traite de personnes. MéthodesOn a recruté, grâce à un échantillonnage aléatoire stratifié, 93 femmes vivant dans 10 refuges pour femmes choisis au hasard à Toronto, au Canada, entre mai et novembre 2018. Toutes les femmes anglophones d'au moins 18 ans étaient admissibles. On a recensé les données démographiques et médicales de même que les données sur les antécédents oculaires, l'acuité visuelle subjective et l'accès aux soins oculaires. Chaque participante a fait l'objet d'un examen oculaire complet et d'un examen dilaté du fond d’œil. RésultatsL’âge médian était de 40 ans (intervalle interquartile : 30,5–54 ans), et la durée médiane de l'itinérance se chiffrait à 8 mois (intervalle interquartile : 2,25–20,5 mois); 63,4 % des participantes ont signalé avoir subi de la maltraitance, tandis que 44,9 % d'entre elles ont subi un traumatisme crânien et 15,9 % d'entre elles, un traumatisme oculaire. Enfin, 22,5 % des patientes s'identifiaient comme réfugiées et 2,17 % (2 sur 92) avaient été victimes de traite de personnes. L'analyse univariée n'a mis au jour aucune corrélation significative entre ces variables et la gravité des troubles visuels. Si l'on se fie à l'acuité visuelle des participantes au moment de l'examen, 27,8 % d'entre elles (intervalle de confiance à 95 % : 18,9–38,2) présentaient effectivement un trouble visuel, qui relevait surtout d'une erreur de réfraction (54,8 % [51 sur 93]), bien que des atteintes oculaires non réfractives aient également été observées. De plus, 64,5 % des participantes présentaient au moins une anomalie pendant l'examen de dépistage, et 40,9 % d'entre elles ont eu besoin d'un suivi auprès d'un ophtalmologiste. La très grande majorité des participantes (96,7 %) ont manifesté un intérêt envers des examens de la vue gratuits. ConclusionsLa prévalence des troubles visuels est très élevée chez les femmes en situation d'itinérance à Toronto. Les programmes de dépistage des troubles oculaires de routine représentent une occasion d'améliorer la santé oculaire de cette population vulnérable.

The Relationship Between Diabetic Retinopathy Degree With Visual Acuity And Retinal Nerve Fiber Layer Thickness In Type 2 Diabetes Mellitus Patients

Introduction: Diabetic retinopathy is an ocular complication of diabetes mellitus (DM), and is one of the leading causes of visual impairment and blindness worldwide.. More than one third of people with diabetes have signs of diabetic retinopathy.&#x0D; &#x0D; Methods: This was an analytic observational study with cross-sectional design. The sample was type 2 diabetes mellitus patients with diabetic retinopathy who visited the eye clinic at the University of Sumatera Utara General Hospital from September 2021-December 2021. The sample were then analyzed with the Mann-Whitney and Kruskal Wallis test to find the relationship between diabetic retinopathy degree with visual acuity and retinal nerve fiber layer thickness in type 2 diabetes mellitus patients.&#x0D; &#x0D; Results: The sample of this study were 20 subjects with diabetic retinopathy and 20 subjects without diabetic retinopathy as the control group. The mean visual acuity in subjects with mild diabetic retinopathy was 0.65+0.48. Average visual acuity in subjects with the degree of moderate diabetic retinopathy was 0.83+0.46. The mean visual acuity in subjects with a proliferative degrees diabetic retinopathy was 0.77+0.64. Mann Whitney test revealed no statistically significant relationship between the degree of diabetic retinopathy and visual acuity (p=0.734). Using the Kruskal Wallis test revealed that there was no significant relationship between the degree of retinopathy diabetic with Avg RNFL (p=0.495), superior RNFL (p=0.385), inferior RNFL (p=0.111), temporal RNFL (p=0.064), nasal RNFL (p=0.535).&#x0D; &#x0D; Discussion: Controlling blood glucose levels becomes more important than the duration of diabetes in preventing the development of retinopathy. Most patients are advised to have an HbA1c of 7% or lower, and for certain patients it is recommended to be lower than6.5%. Diabetic retinopathy slowly damages the retinal blood vessels or the optic nerve layer, leading to leakage, thus resulting in accumulation of fluid containing lipid and blood in the retina which will gradually lead to visual impairment, and even blindness.&#x0D; &#x0D; Conclusion: There is no significant relationship between diabetic retinopathy degree with visual acuity and retinal nerve fiber layer thickness in type 2 diabetes mellitus patients.

Comparison of CRT and LCD monitors for objective estimation of visual acuity using the sweep VEP

PurposeTo investigate the applicability of liquid crystal displays (LCD) as suitable replacement for cathode ray tube monitors (CRT) as stimulator for the sweep VEP for estimating visual acuity.MethodsIn a first experiment, sweep VEPs were recorded in 13 healthy volunteers with best-corrected visual acuity with an LCD and a CRT monitor, respectively. Time-to-peak after stimulus and peak-to-trough amplitudes as well as the visual acuity, estimated using a second-order polynomial and the modified Ricker model, were compared between both monitor types. In a second experiment, sweep VEPs were recorded in six healthy volunteers with two levels of stimulus contrast using artificially reduced visual acuities as well as best-corrected with the same monitors as in the first experiment and additionally, a modern LCD gaming monitor with a response time of 1 ms. Time-to-peak after stimulus and peak-to-trough amplitudes were compared between the different combinations of monitors and contrasts. Finally, visual acuities estimated using the modified Ricker model were compared to subjective visual acuities determined using the Freiburg Visual Acuity and Contrast Test (FrACT).ResultsIn the first experiment, the time-to-peak after stimulus presentation was statistically significantly delayed for LCD displays (mean difference [confidence interval]: 60.0 [54.0, 65.9] ms; t(516) = 19.7096, p < 0.0001). Likewise, peak-to-trough amplitudes were statistically significantly smaller for the LCD stimulator, however, not clinically relevant (mean difference [confidence interval]: − 0.89 [– 1.59, − 0.20] µV; t(516) = − 2.5351, p = 0.0115). No statistically significant effect of the monitor type on the estimated visual acuity was found for neither method, second-order polynomial, nor the modified Ricker model. In the second experiment, statistically significant delays of the time-to-peak after stimulus onset were found for all combinations of monitor and contrast compared to the CRT monitor. A statistically significant, but not clinically relevant, difference of the peak-to-trough amplitudes was only found between the CRT monitor and the LCD gaming monitor (mean difference [confidence interval]: 2.6 [1.2, 4.0] µV; t(814) = 4.66, p < 0.0001). Visual acuities estimated from LCD stimulation significantly underestimated the subjective visual acuity up to 0.2 logMAR using the conversion formula of the first experiment. No statistically significant difference was found when using conversion formulas adjusted for each combination of monitor and contrast.ConclusionsBased on the results of this study, LCD monitors may substitute CRT monitors for presenting the stimuli for the sweep VEP to objectively estimate visual acuity. Nevertheless, it is advisable to perform a calibration and to collect normative data of healthy volunteers using best-corrected and artificially reduced visual acuity for establishing a conversion formula between sweep VEP outcome and the subjective visual acuity before replacing a CRT with an LCD stimulator.

The Effect of Monochromatic Aberrations of the Cornea on Contrast Sensitivity under Photopic and Mesopic Conditions

Purpose: Vision is one of the most important senses. The first stage of vision is the creation of the observed object’s image on the retina. The quality of the retinal image is affected by several factors, such as diffraction, sampling on the retina, chromatic aberration, scattering and higher order aberrations. The measurement of the quality is achieved both with subjective (visual acuity, contrast sensitivity) and objective methods (PSF, MTF, Strehl ratio, RMS). The purpose of this project is the measurement of higher order aberrations of the anterior corneal surface (with a Placido corneal topographer) and of the contrast sensitivity (with a Pelli Robson optotype). Then, we will try to find if there is a correlation between them.&#x0D; Methods and Materials: 20 persons participated in this survey, divided in two groups of 10 persons each. The first group (group 1) included subjects up to 39 years old and the second group (group 2) from 40 years and up. The participants didn’t have any pathological problems, except lower order refractive errors. Both eyes of each individual were included in the procedure. First, the higher order aberrations of the anterior corneal surface were measured, with the implementation of a Placido corneal topographer. This was followed by a measurement of the contrast sensitivity. The whole procedure took place under two lighting conditions, both photopic and mesopic. The examination presentation of the higher order aberrations is performed with the use of Zernike polynomials.&#x0D; Results: The results of the measuring procedure showed that for the first group, under photopic conditions (luminance 32.70 cd/m2) the mean value (± standard deviation) for the higher order aberrations RMS and decimal logarithm contrast sensitivity was 0.073 ± 0.018μm and 1.54 ± 0,16 (contrast 2.88 ± 1.24%) respectively. For the second group the corresponding values were 0.080 ± 0.036μm and 1.59 ± 0.16 (contrast 2.57 ± 1.24%). Accordingly, under mesopic conditions (luminance 1.14 cd/m2) the values for the first group were 0.252 ± 0.064 μm and 1.27 ± 0.15 (contrast 5.37 ± 2.06%), while for the second were 0.253 ± 0.069μm and 1.32 ± 0.12 (contrast 4.79 ± 1.35%). Spherical aberration and coma (horizontal and vertical) were also measured for both groups under photopic and mesopic conditions. The results showed that for the first group, under photopic conditions, RMS for coma and spherical aberration is 0.033 ± 0.014 μm and 0.022 ± 0.011 μm respectively, while for the second group 0.041 ± 0.027 μm and 0.024 ± 0.008 μm. Under mesopic conditions, the relevant results are 0.139 ± 0.065 μm and 0.124 ± 0.035μm for the first group and 0.149 ± 0.066 μm and 0.107 ± 0.038 μm for the second group.&#x0D; Finally, we should mention here that the equivalent defocus error corresponding to the higher order aberration RMS was estimated. The results for all the participants (without age separation), are 0.23 ± 0.09D (photopic conditions) and 0.28 ± 0.07D (mesopic conditions).&#x0D; Conclusions: From the statistical analysis of the results we conclude that there exists a symmetry between left and right eyes regarding higher order aberrations. Furthermore, it seems that age is not a significant factor for differences on the magnitude of higher order aberrations both under photopic and mesopic conditions as well. Similar conclusions are also reached for the contrast sensitivity measurements. In addition, we have observed that a correlation exists between the higher order aberrations of the anterior corneal surface and the contrast sensitivity, for both photopic and mesopic conditions. Correlation also exists between coma and contrast only under photopic conditions. But there is no significant correlation between spherical aberration and contrast. The age difference of these two groups has not an effect on the results. Finally, the equivalent defocus is too small, both for photopic and mesopic conditions and between each other, in order to be clinically significant.

Morphology of foveal hypoplasia: Hyporeflective zones in the Henle fiber layer of eyes with high-grade foveal hypoplasia.

Foveal hypoplasia is characterized by the persistance of inner retinal layers at the macular center. We evaluated using spectral-domain optical coherence tomography (SD-OCT) morphological parameters of the macular center of eyes with foveal hypoplasia and describe the presence of hyporeflective zones in the Henle fiber layer (HFL) of eyes with high-grade foveal hypoplasia. Eyes with foveal hypoplasia were classified into two groups: high-grade foveal hypoplasia with thick inner retinal layers at the macular center (thickness above 100 μm; 16 eyes of 9 subjects) and low-grade foveal hypoplasia with thinner inner retinal layers at the macular center (thickness below 100 μm; 25 eyes of 13 subjects). As comparison, SD-OCT images of normal control eyes (n = 75) were investigated. Eyes with foveal hypoplasia displayed shorter central photoreceptor outer segments (POS), a thinner central myoid zone, and a thicker central HFL compared to control eyes. Eyes with high-grade foveal hypoplasia also displayed a thinner central outer nuclear layer (ONL) compared to eyes with low-grade foveal hypoplasia and control eyes. There was a negative correlation between the thicknesses of the central ONL and HFL in eyes with foveal hypoplasia; however, the total thickness of both ONL and HFL was similar in all eye populations investigated. Visual acuity of subjects with foveal hypoplasia was negatively correlated to the thickness of the central inner retinal layers and positively correlated to the length of central POS. In contrast to central POS, the length of paracentral POS (0.5 and 1.0 mm nasal from the macular center) was not different between the three eye populations investigated. The paracentral ONL was thickest in eyes with high-grade foveal hypoplasia and thinnest in control eyes. Hyporeflective zones in the HFL were observed on SD-OCT images of eyes with high-grade foveal hypoplasia, but not of eyes with low-grade foveal hypoplasia and control eyes. OCT angiography images recorded at the level of the HFL of eyes with high-grade foveal hypoplasia showed concentric rings of different reflectivity around the macular center; such rings were not observed on images of eyes with low-grade foveal hypoplasia and control eyes. It is suggested that the hyporeflective zones in the HFL of eyes with high-grade foveal hypoplasia represent cystoid spaces which are surrounded by Henle fiber bundles. Cystoid spaces are likely formed because there are fewer Henle fibers and a thinner central ONL despite an unchanged thickness of both ONL and HFL. Cystoid spaces may cause the concentric rings of different reflectivity around the macular center in the HFL of eyes with high-grade foveal hypoplasia.