Significant Loss Of Contrast Sensitivity Research Articles

Microglia Prevent the Loss of Visual Function in the Aging Retina by Maintaining the Health of Retinal Pigment Epithelial Cells

Even in healthy individuals, aging leads to the progressive deterioration of visual function that coincides with increasing cellular dysfunction in retinal neurons and retinal pigment epithelial (RPE) cells. Interestingly, aging also coincides with the migration of microglia from the inner to the outer retina where they reside in the subretinal space between photoreceptor outer segments and the apical surface of RPE. Healthy young microglia act as the immune sentinels of the retina, and thus are protective and maintain retinal homeostasis. However, age alters cellular functions and the role of aging subretinal microglia is not known. Here we investigated whether aged microglia residing in the subretinal space are either preventing or promoting loss of visual function.Microglia were depleted in 33‐month‐old C57/BL6 mice fed for 6 weeks with a chow containing PLX5622, a small molecule inhibitor of colony‐stimulating factor‐1 receptor (Csf1r) which is expressed by microglia and is required for their proliferation, differentiation, and survival. As a negative control, age‐matched mice received a control diet. Following microglia depletion, the optomotor reflex (OMR) was used to assess visual acuity and contrast sensitivity and electroretinogram (ERG) assessed retinal function. Morphological analysis was determined by immunohistochemical staining and TEM.To distinguish microglia from infiltrating macrophages, retinas from old mice were stained with P2RY12, a microglia‐specific marker. The vast majority of cells residing between the photoreceptor outer segments and RPE layer in old mice were P2RY12+ microglia. These cells displayed a highly amoeboid and activated morphology and were filled with autofluorescence droplets similar to lipofuscin. PLX5622 treatment depleted up to 90% of the microglia. Microglia preserved visual function, and in the absence of microglia, there was a significant loss of contrast sensitivity and ERG c‐wave, as compared with untreated controls. Loss of microglia coincided with a loss of RPE cells and increased RPE swelling indicating that microglia support RPE in aged animals. TEM indicates that subretinal microglia actively phagocytize shed photoreceptor outer segments, thereby compensating for the known age‐related decline of RPE phagocytosis.We conclude that microglia in aging mice migrate to the subretinal space of the outer retina to support and maintain RPE cell functions that preserves vision.

Longitudinal study of visual function in patients with relapsing-remitting multiple sclerosis with and without a history of optic neuritis

IntroductionThe contrast sensitivity test determines the quality of visual function in patients with multiple sclerosis (MS). The purpose of this study is to analyse changes in visual function in patients with relapsing-remitting MS with and without a history of optic neuritis (ON). MethodsWe conducted a longitudinal study including 61 patients classified into 3 groups as follows: (a) disease-free patients (control group); (b) patients with MS and no history of ON; and (c) patients with MS and a history of unilateral ON. All patients underwent baseline and 6-year follow-up ophthalmologic examinations, which included visual acuity and monocular and binocular Pelli-Robson contrast sensitivity tests. ResultsMonocular contrast sensitivity was significantly lower in MS patients with and without a history of ON than in controls both at baseline (P=.00 and P=.01, respectively) and at 6 years (P=.01 and P=.02). Patients with MS and no history of ON remained stable throughout follow-up whereas those with a history of ON displayed a significant loss of contrast sensitivity (P=.01). Visual acuity and binocular contrast sensitivity at baseline and at 6 years was significantly lower in the group of patients with a history of ON than in the control group (P=.003 and P=.002 vs P=.006 and P=.005) and the group with no history of ON (P=.04 and P=.038 vs P=.008 and P=.01). However, no significant differences were found in follow-up results (P=.1 and P=.5). ConclusionsMonocular Pelli-Robson contrast sensitivity test may be used to detect changes in visual function in patients with ON.

Visual Acuity and Contrast Sensitivity Depending from Keratoconus Apex Position

Abstract Various studies have demonstrated that patients with keratoconus have significant loss of contrast sensitivity while its value varies in different studies. None of these studies has analysed reduced contrast sensitivity depending on the position of apex of corneal conus. Visual acuity and contrast sensitivity were evaluated for patients with keratoconus using the FrACT software. Contrast sensitivity was assessed at the following frequencies: 1, 3, 5, 7, 9, 11, 13, and 15 cycles per degree (cpd). Twenty-four eyes with keratoconus were analysed. Contrast sensitivity was significantly lower for patients with the apex at the centre compared with apex on the periphery both with (p = 0.0078) and without (p = 0.0078) spectacle correction. For patients with the apex at the centre, contrast sensitivity was significantly different with and without correction (0.02); however, there was no difference for patients with apex on the periphery (p = 0.06). The results showed that if the keratoconus apex is at the centre, then spectacle correction improves contrast sensitivity at lower spatial frequencies (1, 3, and 5 cpd), while it remains unchanged at medium and high spatial frequencies. If the keratoconus apex is on the periphery, spectacle correction does not improve contrast sensitivity.

Estudio longitudinal de la función visual en pacientes con esclerosis múltiple remitente-recurrente con y sin antecedentes de neuritis óptica

IntroductionThe contrast sensitivity test determines the quality of visual function in patients with multiple sclerosis (MS). The purpose of this study is to analyse changes in visual function in patients with relapsing-remitting MS with and without a history of optic neuritis (ON). MethodsWe conducted a longitudinal study including 61 patients classified into 3 groups as follows: a) disease-free patients (control group); b) patients with MS and no history of ON; and c) patients with MS and a history of unilateral ON. All patients underwent baseline and 6-year follow-up ophthalmologic examinations, which included visual acuity and monocular and binocular Pelli-Robson contrast sensitivity tests. ResultsMonocular contrast sensitivity was significantly lower in MS patients with and without a history of ON than in controls both at baseline (P=.00 and P=.01, respectively) and at 6 years (P=.01 and P=.02). Patients with MS and no history of ON remained stable throughout follow-up whereas those with a history of ON displayed a significant loss of contrast sensitivity (P=.01). Visual acuity and binocular contrast sensitivity at baseline and at 6 years was significantly lower in the group of patients with a history of ON than in the control group (P=.003 and P=.002 vs P=.006 and P=.005) and the group with no history of ON (P=.04 and P=.038 vs P=.008 and P=.01). However, no significant differences were found in follow-up results (P=.1 and P=.5). ConclusionsMonocular Pelli-Robson contrast sensitivity test may be used to detect changes in visual function in patients with ON.

Low-level processing deficits underlying poor contrast sensitivity for moving plaids in anisometropic amblyopia

Many studies using random dot kinematograms have indicated a global motion processing deficit originated from extrastriate cortex, specifically middle temporal area (MT) and media superior temporal area (MST), in patients with amblyopia. However, the nature of this deficit remains unclear. To explore whether the ability of motion integration is impaired in amblyopia, contrast sensitivity for moving plaids and their corresponding component gratings were measured over a range of stimulus durations and spatial and temporal frequencies in 10 control subjects and 13 anisometropic amblyopes by using a motion direction discrimination task. The results indicated a significant loss of contrast sensitivity for moving plaids as well as for moving gratings at intermediate and high spatial frequencies in amblyopic eyes (AEs). Additionally, we found that the loss of contrast sensitivity for moving plaids was statistically equivalent to that for moving component gratings in AEs, that is, the former could be almost completely accounted for by the latter. These results suggest that the integration of motion information conveyed by component gratings of moving plaids may be intact in anisometropic amblyopia, and that the apparent deficits in contrast sensitivity for moving plaids in anisometropic amblyopia can be almost completely attributed to those for gratings, that is, low-level processing deficits.

Myopia and contrast sensitivity function

Purpose. to measure the contrast sensitivity function of varying degrees of myopia with two types of optical correction (spectacle lens and contact lens). Methods. One hundred and five myopic eyes and twenty-eight emmetropic eyes were collected. The myopic group included 105 eyes corrected with spectacle lenses and 71 eyes of them corrected with contact lenses, too; all had corrected vision acuity of 20/20 or better. The myopic eyes were divided into four groups: group 1 (-1D to -3D), low myopia; group 2 (-3.25D to -6D), medium myopia; group 3 (-6.25D to -12D), high myopia; and group 4 (> -12D), severe myopia. Spatial contrast sensitivity was measured using the OPTEC 2000 Contrast Sensitivity System. Results. In groups 1 and 2, no statistically significant difference was found between myopes and emmetropes. In group 3, statistically significant loss of contrast sensitivity at higher spatial frequencies was found for myopic subjects corrected with spectacle lens, but not for myopes corrected with contact lens. In group 4, myopic subjects corrected with spectacle lenses showed significantly reduced contrast sensitivity function at all spatial frequencies; subjects corrected with contact lenses showed statistical sensitivity losses at 6, 12, 18 cycle/degree spatial frequencies. Conclusions. 1. We may suppose that low and medium myopes (groups 1 and 2), who showed normal contrast sensitivity functions, had no retinal dysfunction. 2. For high myopes, contact lens correction could reduce optical defocus and improve contrast sensitivity function in high spatial frequencies. 3. As retinal function disturbances occurred in severe myopes, the diminished contrast sensitivity was not fully compensated by contact lens correction. 4. Loss of contrast sensitivity might be interpreted as evidence for early retinal function disruption before retinal pathological events occur in severe myopes.

Good subjective presbyopic correction with newly designed aspheric multifocal contact lens.

Many people of the so-called 'baby-boom' of 1945, nowadays require presbyopic correction. A lot of them choose for multifocal contact lenses, but this is not the perfect solution. Decreased visual acuity and contrast sensitivity, and appearance of haloes, 'ghosting' and glare are a problem. In this pilot study, with ten randomly, selected, consecutive patients, a newly designed soft aspheric multifocal contact lens was tested for visual performance and comfort on day 1 and after six months' wear. Success rate was 80% after six months. Visual acuity was good with exception for near vision under low illumination conditions. Two patients mentioned haloes. A statistical significant loss of contrast sensitivity was recorded on day 1 for the spatial frequencies 6.0, 12.0 and 18.0 cpd (cycles per degree) under high and low illumination. As well as for the spatial frequencies 12.0 and 18.0 cpd under high illumination and 6.0 cpd under low illumination (p = 0.05) after six months' wear. Mean overrefraction was limited. All patients recorded good comfort.

Contrast sensitivity and glare in patients with a diffractive multifocal intraocular lens

Contrast sensitivity was measured in 25 patients who had a multifocal diffractive intraocular lens and in 23 control patients with a monofocal lens in four simulated light conditions: (1) daylight, (2) daylight with peripheral glare, (3) twilight, (4) twilight with central glare. In normal daylight and twilight, contrast sensitivity of the multifocal group was significantly lower than the control group's (P < .05). The difference was 0.13 log units for the multifocal group and 0.17 log units for the control group (mean value across the tested frequency from 1.5 to 18 cycles/deg). Peripheral glare reduced contrast sensitivity under daylight conditions in both groups (P < .05), but the loss did not differ significantly between the two (P >.05). Central glare reduced contrast sensitivity under twilight conditions in both groups (P < .05), with the greatest loss in the multifocal patients (P < .001). We conclude that the most significant loss of contrast sensitivity in patients with the diffractive multifocal intraocular lens is found with central glare under twilight conditions.

Binocular Visual Impairment in Glaucoma

AbstractMonocular and binocular vision was assessed in patients with glaucoma (n = 21), in patients with ocular hypertension (n = 20), and in agematched visual control subjects (n = 20) using three tests: color vision with the Lanthony Desaturated D-15 test, low spatial frequency contrast sensitivity with the Pelli-Robson chart, and stereoacuity with the RANDOT test. No significant differences were found among the groups in the severity or type of color vision loss. Monocular contrast sensitivity testing showed considerable overlap among groups but a significant loss of contrast sensitivity in the glaucoma patients relative to ocular hypertensives and control subjects. Binocular testing also showed a significant loss of contrast sensitivity in the glaucoma patients compared with both the ocular hypertensives and the control subjects. Stereoacuity also was significantly impaired in the glaucoma patients. These results indicate that two tests of binocular function, stereoacuity and binocular contrast sensitivity testing, may have utility in identifying early glaucomatous damage.

Influence of high ambient temperature and humidity on visual sensitivity.

Abstract The visibility of sinusoidally modulated gratings was measured psychophysically during 3 hours of exposure to either (i) a control, (ii) a warm-humid or (iii) a hot-dry atmosphere. No significant loss of contrast sensitivity in the heat conditions could be demonstrated for low spatial frequencies (≤ 3·0 c/deg) but an increasing loss with increasing frequencies (maximal above 10 c/deg). The heat-induced performance change appeared within 30min of exposure.