Recovery Of Contrast Sensitivity Research Articles

Fixation instability, astigmatism, and lack of stereopsis as factors impeding recovery of binocular balance in amblyopia following binocular therapy

Dichoptic therapy is a promising method for improving vision in pediatric and adult patients with amblyopia. However, a systematic understanding about changes in specific visual functions and substantial variation of effect among patients is lacking. Utilizing a novel stereoscopic augmented-reality based training program, 24 pediatric and 18 adult patients were trained for 20 h along a three-month time course with a one-month post-training follow-up for pediatric patients. Changes in stereopsis, distance and near visual acuity, and contrast sensitivity for amblyopic and fellow eyes were measured, and interocular differences were analyzed. To reveal what contributes to successful dichoptic therapy, ANCOVA models were used to analyze progress, considering clinical baseline parameters as covariates that are potential requirements for amblyopic recovery. Significant and lasting improvements have been achieved in stereoacuity, interocular near visual acuity, and interocular contrast sensitivity. Importantly, astigmatism, fixation instability, and lack of stereopsis were major limiting factors for visual acuity, stereoacuity, and contrast sensitivity recovery, respectively. The results demonstrate the feasibility of treatment-efficacy prediction in certain aspects of dichoptic amblyopia therapy. Furthermore, our findings may aid in developing personalized therapeutic protocols, capable of considering individual clinical status, to help clinicians in tailoring therapy to patient profiles for better outcome.

Recovery of Contrast Sensitivity After Descemet Membrane Endothelial Keratoplasty.

To study the change in contrast sensitivities in eyes with Fuchs endothelial dystrophy and bullous keratopathy after Descemet membrane endothelial keratoplasty (DMEK). In this prospective study, 50 pseudophakic eyes of 50 patients who received DMEK surgery at the Charité-Universitätsmedizin Berlin were included. Visual acuity; contrast sensitivity using OPTEC 6500 at spatial frequencies of 1.5, 3, 6, 12, and 18 cycles/degree in photopic and mesopic light with and without glare; central corneal thickness (CCT); and anterior and posterior corneal aberrations were measured preoperatively and at 3 and 12 months postoperatively. Best-corrected visual acuity (preoperative 0.67 ± 0.46 and after 12 months 0.19 ± 0.16 LogMAR, P < 0.001) and photopic and mesopic contrast sensitivities with and without glare improved significantly, whereas CCT decreased significantly (preoperative 677 ± 114 μm, after 12 months 527 ± 29 μm, P < 0.001). Preoperative CCT correlates significantly with preoperative photopic contrast sensitivity (correlation coefficient -0.462, P = 0.002), and postoperative total anterior aberrations correlates with postoperative photopic contrast sensitivity (correlation coefficient -0.361, P = 0.006). Photopic and mesopic contrast sensitivities, especially with glare, are impaired in patients with Fuchs endothelial dystrophy and bullous keratopathy. The extent of the corneal thickening seems to mainly influence the contrast sensitivity preoperatively. DMEK surgery improves the contrast sensitivity significantly. However, higher postoperative anterior corneal aberrations limit the postoperative contrast sensitivities.

25 Hz adaptation: Influence on recovery time in glaucoma

INTRODUCTION. Normal temporal contrast sensitivity is maximally influenced by pre-adaptation with 25-Hz temporal contrast flicker. The aim of this study was to investigate the effects of 25-Hz contrast adaptation on recovery of contrast sensitivity in normals, patients with ocular hypertension, preperimetric, perimetric and advanced perimetric open-angle glaucoma. MATERIALS AND METHODS. Temporal contrast sensitivity was examined after pre-adaptation with 25 Hz in the following: 43 normals, 14 ocular hypertension, 10 preperimetric primary open-angle glaucoma, and 33 perimetric open-an­gle glaucoma patients. After pre-adaptation (the time after which a test stimulus could be detected again), recovery time (RT) was measured at 3% and 5% test contrast. Additionally, 25 patients with advanced perimetric open-angle glaucoma were measured at 12%, 25%, and 35% contrast and compared to a normal group consisting of 15 subjects. RESULTS. 1. Measurements of RT are reliable (Cronbach’s a > 0.8). 2. RT was age-dependent requiring an age-correction in further analyses. 3. RT 3% and RT 5% were significantly prolonged in perimetric primary open-angle glau­coma compared to normals (3% test contrast: p = 0.007; 5% test contrast: p = 0.035). 4. Within each group, RT 3% and RT 5% were significantly different at both test contrasts (normals, perimetric open-angle glaucoma: p < 0.001; ocular hypertension: p = 0.007; preperimetric open-angle glaucoma: p = 0.035). 5. RT 3% and RT 5% were significantly correlated with mean defect (p < 0.001) and retinal nerve fibre layer thickness (p = 0.018). RT5% was correlated with loss variance (p = 0.048). 6. RT 12% , RT 25% and RT 35% were significantly prolonged in advanced perimetric glaucoma (p < 0.001), and correlated with mean defect (p < 0.001, p = 0.002, p = 0.013) and retinal nerve fibre layer thickness (p < 0.001, p = 0.003, p = 0.013). RT 12% was also correlated with loss variance (p = 0.016). CONCLUSIONS. Measurements of RT after 25-Hz pre-adaptation can be used in glaucoma diagnosis and follow-up examination, especially in monitoring glaucoma progress in advanced perimetric primary open-angle glaucoma.

The change of contrast sensitivity of myopic patients after laser in situ keratomileusis

Objective To evaluate the contrast sensitivity function before and after laser in situ keratomileusis(LASIK).Methods With test chart,contrast sensitivity was measured in randomly selected 58 subjects(112 eyes)before,1 month and 3 months after LASIK.The contrast sensitivity was measured at 1.5,3.0,6.0,12.0 and 18.0 cycles per degree(c/d)spatial frequency respectively and comparison was made.Results The patients achieved the mean uncorrected visual acuity(UCVA) of 1.07 ±0.15 and 1.10±0.20 at postoperative 1-month and 3-months respectively.Which were close to the correct preoperative visual acuity.There was a general reduction in contrast sensitivity in all spatial frequencies at postoperative 1-month when they were compared with the preoperative contrast sensitivity.The difference at 6.0,12.0 and 18.0 c/d spatial frequency was statistically significant(P<0.01).By the 3-month visit,all eyes showed a recovery of contrast sensitivity function.Near contrast sensitivity in 6.0.12.0 and 18.0 c/d spatial frequency had a decline in superhigh myopia patients at 3-month(P<0.01).Conclusion Near contrast sensitivity became worse at the early stage after LASIK.It could be recovered later on.But that in super high myopia would take a longer recover time. Key words: laser in situ keratomileusis; myopia; contrast sensitivity

Multicenter Clinical Trial for Evaluating Methylprednisolone Pulse Treatment of Idiopathic Optic Neuritis in Japan

Background: A randomized, controlled clinical trial was conducted in 1991 to compare an intravenous megadose of methylprednisolone with a control drug (mecobalamin) for treating acute idiopathic optic neuritis. Cases: Sixty-six cases from 22 clinical centers throughout Japan were examined to evaluate the treatment on visual function parameters, such as visual acuity, visual field, color vision, contrast sensitivity, and critical flicker frequency. Observations: The methylprednisolone pulse treatment group showed faster recovery of visual function, particularly the visual acuity at 1 week ( P < .05), Humphrey field analyzer mean deviation at 3 weeks ( P < .05), and color vision at 1 week ( P < .05). Recovery of contrast sensitivity at several different spatial frequencies was significant in the pulse treatment group at 1 ( P < .01), 2 ( P < .05), and 4 weeks ( P < .05) after the start of treatment. Visual function test results at 12 weeks and 1 year were essentially the same in the two treatment groups. Side effects appeared more frequently in the pulse treatment group than in the control ( P < .05). Conclusions: Pulse treatment does not appear effective for idiopathic optic neuritis even though visual function in the pulse treatment group of this trial recovered more quickly during the initial phase compared to the controls. More effective and specific treatment should be established for optic neuritis.

Recovery of contrast sensitivity during optic nerve regeneration in fish

Psychophysical experiments on goldfish and sunfish studied the recovery time course of visual contrast detection during optic nerve regeneration. The results showed delayed recovery of detection of positive as compared to negative contrasts, and of high as compared to low spatial frequencies. The findings are related to previous electrophysiological and anatomical results in the fish retinotectal system.

The Effect of Alcohol on Contrast Sensitivity

Contrast sensitivity was measured for subjects having different levels of blood alcohol content (BAC) under photopic and mesopic luminance conditions. In general, alcohol intoxication of less than 0.1% resulted in contrast sensitivity changes at all spatial frequencies tested. Most gains in contrast sensitivity occured at the higher spatial frequencies and the higher luminance levels. Losses of contrast sensitivity were perceived at all spatial frequencies. There were significant differences in the patterns of sensitivity gains and losses for individuals. For some subjects, the highest intoxication levels produced the greatest change in contrast sensitivity, while others demonstrated a delayed change in contrast sensitivity. Recovery of contrast sensitivity also varied. While some subjects returned to baseline sensitivity as BAC decreased, the contrast sensitivity of others increased or remained suppressed even after BAC returned to initial levels. These alcohol produced contrast sensitivity losses are significant when compared to previous performance-based target acquisition research. Results of this study suggest that the person who drinks alcohol, even moderately, might experience some serious loss in visibility of certain objects, especially under low luminance conditions. These results have implications for the general interpretation of tests of alcohol intoxication in visual task performance, especially for night driving. Further research is required.