Reduced Contrast Sensitivity Research Articles

Invited Session V: GABAergic function and dysfunction in visual perception: Abnormal processing of visual context in schizophrenia

People with schizophrenia (SZ) exhibit persistent deficits in visual processing including reduced contrast sensitivity and poor detection of complex image structure, such as contours. Over recent years accumulating psychophysical evidence indicates that vision in SZ is associated with a reduced influence of spatial context which in turn has been attributed to reduced spatial suppression in visual cortex. Compared to controls, people with SZ do not experience the same reduction in perceived contrast that occurs when targets are embedded in a high contrast background. This appears to be a cortical phenomenon: reduced influence of context is not limited to contrast but carries over to other image attributes (such as orientation) but not others (such as luminance). Finally, although patients poor processing of higher-order image structure has been attributed to differences in perceptual grouping, work from my lab indicates that abnormal processing of context may also contribute to patients' poor sensitivity for contours. It does this by (a) reducing their sensitivity to local orientation and (b) reducing their ability to discount irrelevant background structure. Taken together these results suggest that abnormal processing of context contributes to a range of visual processing deficits in SZ.

Longitudinal Impact of Vision Impairment on Concern About Falling in People With Age-Related Macular Degeneration.

PurposeTo explore the longitudinal impact of central vision loss on concern about falling (CF), over a 12-month period, in people with age-related macular degeneration (AMD).MethodsParticipants included 60 community-dwelling older people (age, 79.7 ± 6.4 years) with central vision impairment due to AMD. Binocular high-contrast visual acuity, contrast sensitivity, and visual fields were assessed at baseline and at 12 months. CF was assessed at both time points using the Falls Efficacy Scale–International (FES-I). Sensorimotor function (sit to stand, knee extension, postural sway, and walking speed) and neuropsychological function (reaction time, symptoms of anxiety and depression) were also assessed at both time points using validated instruments. Falls data were collected using monthly diaries during the 12 months.ResultsCF increased by a small but significant amount over the 12-month follow-up (2.1 units; P = 0.01), with increasing prevalence of high levels of CF (FES-I score ≥ 23), from 48% at baseline to 65% at 12 months. Linear mixed models showed that reduced contrast sensitivity was significantly associated with increased concern about falling (P = 0.004), whereas declines in both visual acuity and contrast sensitivity during the follow-up period were associated with increases in CF over the 12-month follow-up (P = 0.041 and P = 0.054, respectively), independent of age, gender, falls history, or number of comorbidities.ConclusionsHigher levels of CF are common in older people with AMD, and levels increase over time; this increase is associated with declines in both visual acuity and contrast sensitivity. These findings highlight the need for regular assessment of both visual acuity and contrast sensitivity to identify those at greatest risk of developing higher CF.Translational RelevanceRoutine assessment of visual acuity and contrast sensitivity in older people with AMD will assist in identifying those at risk of developing high CF.

Differential effects of experimental glaucoma on intrinsically photosensitive retinal ganglion cells in mice.

Glaucoma is a group of eye diseases characterized by retinal ganglion cell (RGC) loss and optic nerve damage. Studies, including this study, support that RGCs degenerate and die in a type-specific manner following the disease insult. Here we specifically examined one RGC type, the intrinsically photosensitive retinal ganglion cell (ipRGC), and its associated functional deficits in a mouse model of experimental glaucoma. We induced chronic ocular hypertension (OHT) by laser photocoagulation and then characterized the survival of ipRGC subtypes. We found that ipRGCs suffer significant loss, similar to the general RGC population, but ipRGC subtypes are differentially affected following chronic OHT. M4 ipRGCs, which are involved in pattern vision, are susceptible to chronic OHT. Correspondingly, mice with chronic OHT experience reduced contrast sensitivity and visual acuity. By comparison, M1 ipRGCs, which project to the suprachiasmatic nuclei to regulate circadian rhythmicity, exhibit almost no cell loss following chronic OHT. Accordingly, we observed that circadian re-entrainment and circadian rhythmicity are largely not disrupted in OHT mice. Our study demonstrates the link between subtype-specific ipRGC survival and behavioral deficits in glaucomatous mice. These findings provide insight into glaucoma-induced visual behavioral deficits and their underlying mechanisms.

Photopic and Mesopic Contrast Sensitivity Function in the Presence of Glare and the Effect of Filters in Young Healthy Adults.

Purpose: The aim of this study was to evaluate the effect of four different filters on contrast sensitivity under photopic and mesopic conditions with and without glare.Methods: A forced choice algorithm in a Bayesian psychophysical procedure was utilized to evaluate the spatial luminance contrast sensitivity. Five different spatial frequencies were evaluated: 1.5, 3, 6, 12, and 18 cycles per degree (cpd). The measurements were performed under 4 settings: photopic and mesopic luminance with glare and no glare. Two long pass filters (LED light reduction and 511nm filter) and two selective absorption filters (ML41 and emerald filter) and a no filter condition were evaluated. The measurements were performed in 9 young subjects with healthy eyes.Results: For the no filter condition, there was no difference between glare and no glare settings for the photopic contrast sensitivity measurements whereas in the mesopic setting, glare reduced the contrast sensitivity significantly at all spatial frequencies. There was no statistically significant difference between contrast sensitivity measurements obtained with different filters under both photopic conditions and the mesopic glare condition. In the mesopic no glare condition, the contrast sensitivity at 6 cpd with 511, ML41 and emerald filters was significantly reduced compared to no filter condition (p = 0.045, 0.045, and 0.071, respectively). Similarly, with these filters the area under the contrast sensitivity function in the mesopic no glare condition was also reduced. A significant positive correlation was seen between the filter light transmission and the average AULCSF in the mesopic non-glare condition.Conclusion: The contrast sensitivity measured with the filters was not significantly different than the no filter condition in photopic glare and no glare setting as well as in mesopic glare setting. In mesopic setting with no glare, filters reduced contrast sensitivity.

21 Long-Term Ophthalmologic Outcome of Young Adults Born Extremely Preterm

Abstract Primary Subject area Ophthalmology Background Retinopathy of prematurity (ROP) remains the dominant cause of severe visual impairment in childhood in North America and Europe. With the salient improvement in neonatal care since the 1980s, more and more very/extremely premature infants survived and are now reaching adulthood. Premature birth interferes with the critical period of retinal maturation and foveal development. The development of ROP further damages the retina and its vasculature. So far, outcome studies on visual functions and ocular structure in adults born preterm remain scarce. Objectives The first aim of this study is to describe the visual function and retinal structure in a cohort of young adults who were born prematurely. With the recognition of the insidious nature of ROP, we also aimed to investigate if ROP could exert a “second hit” beyond prematurity. Design/Methods This cross-sectional observational study compared visual function of young adults (18-29 years old) born prematurely (< 30 weeks of gestational age [GA]) versus full-term controls. Participants were categorized into three groups: preterm without ROP, preterm with ROP, and term. Comprehensive ophthalmologic examination was performed with blinding to preterm and ROP status. Best corrected visual acuity (BCVA) was assessed with a standardized linear Snellen chart and contrast sensitivity (CS) with the Vistech system. When analyzing BCVA, refractive errors, and contrast sensitivities, we further grouped data based on the strong eyes (better BCVA) and the weak eyes (worse BCVA). Area-under-the-curve (AUC) analysis was performed to gauge the overall CS. Group comparisons were done using ANOVA. Results In this study, 88 individuals born prematurely and 86 individuals born full-term were recruited. Among the strong eyes of the 3 groups, there was no significant difference for BCVA or refractive errors (see image). Among the weak eyes, the preterm with ROP group had the worst BCVA and refractive outcomes, compared to the preterm without ROP and term groups. In the strong eyes, the CS AUC of the preterm with ROP group (16.22 ± 2.69 p<0.0001) was significantly lower than both the preterm without ROP (18.13 ± 2.01) and term (19.55 ± 2.48) groups. In the weak eyes, the AUC of the 3 groups showed a significant and progressive decline from the term group (18.9 ± 2.84) to the preterm without ROP group (18.29 ± 2.14), then to the preterm with ROP group (15.24 ± 2.21). Conclusion In our cohort of young adults born preterm, prematurity alone did not affect their BCVA and refractive errors. However, ROP was independently associated with a lower BCVA, higher refractive errors, and a reduced contrast sensitivity. Our data have shown that prematurity and ROP have independent effects on contrast sensitivity. This study highlights the necessity of long-term ophthalmologic follow-ups for adults who were born prematurely.

Effect of Contact Lenses on Contrast Sensitivity under Various Lighting Conditions.

PurposeTo assess contrast sensitivity in clear and colored soft contact lenses under different lighting conditions.MethodsThis study was performed on 34 medical students. Visual acuity was measured using a tumbling E chart at a distance of 6 m, and contrast sensitivity was determined by Pelli Robson chart at a distance of 1 m. These tests were repeated in mesopic (3 lux) and glare (2000 lux) conditions. Then, a clear contact lens was applied to one eye and a colored contact lens was applied to the other. After 2 hr, visual acuity and contrast sensitivity were measured for each individual. The results were compared with and without contact lenses under normal, mesopic, and glare conditions.ResultsThe mean refractive error was 0.44 0.20 diopters. Repeated measures ANOVA showed a decline in contrast sensitivity with colored and clear contact lenses as compared to no-lens condition (P 0.001). Additionally, lighting conditions had a significant impact on contrast sensitivity (P 0.001); contrast sensitivity was lower in mesopic and glare conditions than under normal lighting condition.ConclusionIn addition to the drop in contrast sensitivity under unusual lighting conditions (e.g., glare and mesopic), wearing soft contact lenses can further reduce contrast sensitivity in different lighting conditions. Therefore, people who wear contact lenses should be aware of this reduction in visual performance in conditions like driving at night or in the fog.

Vision through Healthy Aging Eyes.

As life expectancy grows, so too will the number of people adversely affected by age. Although it is acknowledged that many conditions and diseases are associated with age, this mini-review will present a current update of the various visual changes that generally occur in healthy individuals disregarding the possible effects of illness. These alterations influence how the world is perceived and in turn can affect efficiency or the ability to perform ordinary daily tasks such as driving or reading. The most common physical developments include a decreased pupil size and retinal luminance as well as changes both in intercellular and intracellular connections within the retina along the pathway to the visual cortex and within the visual cortex. The quantity and the physical location of retinal cells including photoreceptors, ganglion and bipolar retinal cells are modified. The clarity of intraocular organs, such as the intraocular lens, decreases. These all result in common visual manifestations that include reduced visual acuity, dry eyes, motility changes, a contraction of the visual field, presbyopia, reduced contrast sensitivity, slow dark adaptation, recovery from glare, variation in color vision and a decreased visual processing speed. Highlighting these prevalent issues as well as current and possible future innovations will assist providers to formulate treatments and thereby conserve maximum independence and mobility in the modern mature population.

Intraocular lens optic edge design for the prevention of posterior capsule opacification after cataract surgery.

Intraocular lens optic edge design for the prevention of posterior capsule opacification after cataract surgery.

Clinical, Morphological, and Optical Correlates of Visual Function in Patients With Fuchs Endothelial Corneal Dystrophy.

The purpose of this article was to study the clinical, optical, and morphological correlates of visual function in patients with Fuchs endothelial corneal dystrophy (FECD). The case records were analyzed for patients diagnosed with FECD between September 2019 and March 2020. The best-corrected visual acuity (BCVA) was recorded as decimal visual acuity and converted to the logarithm of the minimum angle of resolution units. Contrast sensitivity was measured with the Pelli-Robson contrast sensitivity test. Corneal alterations, including central corneal thickness, depression of the posterior cornea, and corneal densitometry values, were evaluated using Scheimpflug images. Corneal epithelial thickness was measured by spectral-domain optical coherence tomography. A total of 107 eyes of 61 patients (18 male and 43 female) with FECD were retrospectively investigated. The Spearman rank correlation coefficient showed moderate correlation between BCVA and contrast sensitivity (ρ = -0.66, P < 0.001), with some patients maintaining relatively good BCVA but having reduced contrast sensitivity. Logistic regression analysis demonstrated that age, central corneal thickness, depression of the posterior cornea, and epithelial thickening were negatively associated with contrast sensitivity but not with BCVA. Contrast sensitivity is a useful tool for assessing visual dysfunction and should be incorporated into the assessment protocol of patients with FECD. Alterations in the cornea, including central corneal thickness, depression of the posterior cornea, and epithelial thickening, might be objective parameters that can help the clinician in grading the severity of the disease and tracking its progression.

Contrast sensitivity and higher-order aberrations in Keratoconus subjects

This study analyzes the relationship between contrast-sensitivity and higher-order aberrations (HOA) in mild and subclinical-keratoconus in subjects with good visual-acuity (VA). Keratoconus group (including subclinical-keratoconus) and controls underwent autokeratometry, corneal-tomography, autorefraction and HOA measurement. Contrast-sensitivity was tested using a psychophysical two-alternative forced-choice Gabor patches in three blocks (6, 9, 12 cycles/deg). Controls were compared to the keratoconus group and to a keratoconus subgroup with VA of 0.00 LogMar group ("keratoconus-0.00VA"). Spearman correlation tested association between HOA and contrast-sensitivity. Twenty-two keratoconus subjects (38 eyes: 28 keratoconus, 10 subclinical-keratoconus, 20 keratoconus-0.00VA) and 35 controls were included. There was a significant difference between control and keratoconus, and between control and keratoconus-0.00VA, for keratometry, cylinder, thinnest and central corneal thickness (p < 0.001). Controls showed lower HOA and higher contrast-sensitivity for all spatial-frequencies (p < 0.001). Most HOA were negatively correlated with contrast-sensitivity for all spatial-frequencies for keratoconus group and for 9 and 12 cycles/deg for keratoconus-0.00VA. Keratoconus subjects with good VA showed reduction in contrast-sensitivity and increased HOAs compared to controls. HOA and contrast-sensitivity are inversely correlated in subjects with mild keratoconus despite good VA. This suggests that the main mechanism underlying the decreased vision quality in keratoconus is the increase of HOA.

No Evidence of Reduced Contrast Sensitivity in Migraine-with-Aura for Large, Narrowband, Centrally Presented Noise-Masked Stimuli.

Individuals with migraine aura show differences in visual perception compared to control groups. Measures of contrast sensitivity have suggested that people with migraine aura are less able to exclude external visual noise, and that this relates to higher variability in neural processing. The current study compared contrast sensitivity in migraine with aura and control groups for narrow-band grating stimuli at 2 and 8 cycles/degree, masked by Gaussian white noise. We predicted that contrast sensitivity would be lower in the migraine with aura group at high noise levels. Contrast sensitivity was higher for the low spatial frequency stimuli, and decreased with the strength of the masking noise. We did not, however, find any evidence of reduced contrast sensitivity associated with migraine with aura. We propose alternative methods as a more targeted assessment of the role of neural noise and excitability as contributing factors to migraine aura.

Future Trends in Presbyopia Correction.

Presbyopia affects 1.8 billion people worldwide. This reduction in distance corrected near visual acuity impacts quality of life, which prompts patients to seek treatment. Presbyopia is an early manifestation of the "crystalline lens optical dysfunction through aging," or dysfunctional lens syndrome, and appropriate management of presbyopia is dependent on coexisting factors such as increased higher order aberrations, reduced contrast sensitivity, light scatter, and lenticular opacification. This review of published literature (PubMed and MEDLINE) is presented in narrative format and discusses medical and surgical treatments available to patients who experience presbyopia, while highlighting future therapies. Numerous strategies exist for the management of presbyopia. These strategies include pharmacological therapy, glasses and contact lenses, corneal, scleral, and lenticular procedures. This article discusses the role of several new and existing presbyopia treatments, as well as which patients are candidates for these novel therapies. Although no single treatment is ideal for all patients with presbyopia, new medical and surgical strategies increase the number of options available when addressing different stages of presbyopia and dysfunctional lens syndrome. [J Refract Surg. 2021;37(6 Suppl):S28-S34.].

Profile of vision function amongst learners with low vision attending inclusive schools in Kakamega County, Kenya

Background: The quality of vision function of low vision (LV) children determines their ease and success in performing activities of daily living including academic activities undertaken whilst at school.Aim: The aim of this study was to determine the vision function of LV learners attending inclusive schools in Kakamega County, Kenya.Setting: This study was designed at public primary inclusive schools in Kakamega County, with LV placements by the County Educational Assessment and Resource Center.Methods: This was a school-based cross-sectional study. A census survey identified 21 LV learners, who met the World Health Organization (WHO) classification of LV and had been assessed and placed in 11 public primary inclusive schools in Kakamega County. Participants underwent standard LV assessment tests. Data were entered into Statistical Package for the Social Sciences (SPSS) version 25 software and analysed using descriptive and inferential statistics. Data were summarised and presented using tables, figures and percentages.Results: Out of the 21 LV learners who were selected, 19 (90.5%) were assessed. The best recorded visual acuity (VA) was 0.33 decimal notation at far and 0.02 and 0.01 in the right eye and the left eye, respectively, at near. The vast majority, 94.7%, had reduction in stereopsis, whilst 42.1% had defects in colour vision, 20.0% reduced contrast sensitivity (CS) and 15.8% had visual field impairment within the central 20 degrees.Conclusion: There is an overall decrease in vision function amongst LV learners attending inclusive schools in Kakamega County. The most affected parts of vision function are VA and stereopsis.

The cover photo shows different neovascularization types from the paper by Smid et al.

The cover photo shows different neovascularization types from the paper by Smid et al.

Loss of visual function in diabetes mellitus

Background: Diabetes mellitus being a well-known cause for peripheral neuropathy, this study aims to detect visual pathway dysfunction in diabetics using contrast sensitivity as a subjective measure and visual-evoked potential (VEP) as an objective measure of visual pathway function. Aims: To compare contrast sensitivity and VEP in patients with type 2 diabetes mellitus as compared with control and to find the correlation with glycemic level. Materials and Methodology: This was a comparative study conducted at a tertiary eye care center. After detailed ophthalmological evaluation, contrast sensitivity and VEP of 40 patients with diabetes (20 with retinopathy and 20 without retinopathy) were compared with suitable control. Data were analyzed using the SPSS (Statistical Product and Service Solutions) version 18 using the independent sample t-test and ANOVA. Results: There was reduction of mean contrast sensitivity in diabetics as compared to nondiabetics. Contrast sensitivity was better in diabetics without retinopathy as compared to diabetics with retinopathy. There was prolongation of P100 latencies and reduction of P100 amplitudes among diabetics as compared to non-diabetics and among those with diabetic retinopathy as compared to those with normal fundus. Reduced contrast sensitivity and reduction of P100 amplitudes were seen among those with poor glycemic control. Conclusion: There was evidence of reduction of contrast sensitivity and alteration of VEP in patients with diabetes even before reduction in visual acuity giving evidence of visual pathway dysfunction in diabetes mellitus. This may also be affected by the glycemic status of the patient.

Побочное действие психотропных препаратов на орган зрения

Any antipsychotics provoke more or less ocular complications. Some of them are relatively harmless (i.e., dark eyelids, conjunctival and corneal pigmentation, mydriasis, nystagmus, dry eye etc.). These adverse effects are resolved spontaneously after treatment discontinuation, drug switching, or prescribing additional therapy. However, the intake of both typical and atypical neuroleptics, lithium salts, some anticonvulsants (e.g., topiramate) is associated with high risks of vision loss. Moreover, in some patients these medications may result in blindness. The use of psychotropic drugs (e.g., tricyclic antidepressants or serotonin reuptake inhibitors) in patients with higher risk of acute angle closure is of particular concern. The association between phenothiazines and anticonvulsants and retinopathy, chlorpromazine and cataract, anticonvulsants and poor color vision and reduced contrast sensitivity is also important. Psychiatrists and ophthalmologists should consider potential ocular side effects in patients receiving psychotropic drugs. Knowing management algorithm for these conditions is also important. The number of recent publications on this issue is limited. Therefore, articles older than 10 years are sometimes used. Keywords: eye, visual organ, adverse effects, psychotropic drugs, neuroleptics, tricyclic antidepressants, selective serotonin reuptake inhibitors, glaucoma, retinopathy, cataract. For citation: Petukhova A.A., Panov A.A., Malygin Ya.V., Kazanfarova M.A. Side effects of psychotropic drugs on eye. Russian Journal of Clinical Ophthalmology. 2021;21(1):29–33. DOI: 10.32364/2311-7729-2021-21-1-29-33.

Determinants of concern about falling in adults with age-related macular degeneration.

To investigate the prevalence and level of concern about falling (CF) among older people with vision impairment due to age-related macular degeneration (AMD) compared to a visually normal control group, and to identify determinants of CF for the AMD group. Participants included 133 older people: 77 with AMD (mean age=80.5±6.2years), and 56 controls (mean age=75.4±5.3years). Binocular visual acuity, contrast sensitivity and visual fields were measured, and CF was assessed using the Falls Efficacy Scale - International (FES-I). Data were also collected for sensorimotor function (postural sway, sit-to-stand, knee extensions, walking speed, proprioception), and neuropsychological function (reaction time, symptoms of anxiety and depression) using validated tests and scales. Concern about falling scores were higher for AMD participants compared to control participants (mean±S.D. 24.6±8.0 vs 21.6±5.7, p=0.02, respectively), although these findings failed to reach significance when adjusted for age (p=0.16). Among AMD participants, multivariable models showed that greater CF was associated with reduced contrast sensitivity (p=0.02), slower sit-to-stand times (p<0.001) and higher anxiety scores (p<0.001); these factors explained 40% of the variance in CF (p<0.01). Levels of CF in older people with AMD were not found to be elevated by their disease status alone, but rather by the extent of vision loss. Levels of CF in those with AMD were associated with various visual, sensorimotor and neuropsychological factors. These findings will assist clinicians in identifying those at greatest risk of developing high CF and inform the design of future intervention programmes for this population.

Stimuli Characteristics and Psychophysical Requirements for Visual Training in Amblyopia: A Narrative Review.

Active vision therapy using perceptual learning and/or dichoptic or binocular environments has shown its potential effectiveness in amblyopia, but some doubts remain about the type of stimuli and the mode and sequence of presentation that should be used. A search was performed in PubMed, obtaining 143 articles with information related to the stimuli used in amblyopia rehabilitation, as well as to the neural mechanisms implied in such therapeutic process. Visual deficits in amblyopia and their neural mechanisms associated are revised, including visual acuity loss, contrast sensitivity reduction and stereopsis impairment. Likewise, the most appropriate stimuli according to the literature that should be used for an efficient rehabilitation of the amblyopic eye are described in detail, including optotypes, Gabor’s patches, random-dot stimuli and Vernier’s stimuli. Finally, the properties of these stimuli that can be modified during the visual training are discussed, as well as the psychophysical method of their presentation and the type of environment used (perceptual learning, dichoptic stimulation or virtual reality). Vision therapy using all these revised concepts can be an effective option for treating amblyopia or accelerating the treatment period when combining with patching. It is essential to adapt the stimuli to the patient’s individual features in both monocular and binocular training.

A STUDY TO ASSESS THE CONTRAST SENSITIVITY OF THE HUMAN VISUAL SYSTEM IN PATIENTS WITH OR WITHOUT DIABETES IN A TERTIARY CARE HOSPITAL

Objective: The objective of our study was to assess the variations in contrast sensitivity values of normoglycemic subjects and that of type II diabetic subjects of the same age group. It was also aimed at finding the visual acuities and study the associations of it with contrast sensitivity if any.&#x0D; Methods: It was a hospital-based comparative cross-sectional descriptive study conducted in the out-patient department of the Department of Ophthalmology, Saveetha Medical College, Hospital, Chennai. Visual Acuity and Contrast Sensitivity of 50 Type II Diabetic individuals and 50 age-equivalent control group subjects were measured using the Snellen’s chart and Pelli-Robson chart, respectively, during the months of January to March 2020.&#x0D; Results: Contrast Sensitivity measurements from 50 subjects with Non-Insulin dependent Diabetes Mellitus (NIDDM) were obtained. The subjects were the ones who had minimal or no diabetic retinopathy. It was observed that there is a significant association between reduced contrast sensitivity and Diabetes (P value&lt;.00008). We also noted that CS may be reduced without corresponding loss of Visual Acuity. Hence, both visual acuity and contrast sensitivity measurements are helpful in the assessment of visual impairment due to diabetic eye disease.&#x0D; Conclusion: The contrast sensitivity can be seen as an early marker for visual impairment in diabetic eye care.

Disorganisation of retinal inner layers is associated with reduced contrast sensitivity in retinal vein occlusion

Background/AimsTo determine if disorganisation of retinal inner layers (DRIL) is associated with reduced contrast sensitivity (CS) in patients with retinal vein occlusion (RVO) with a history of macular oedema (ME).MethodsProspective,...