25 Hz adaptation: Influence on recovery time in glaucoma

Abstract

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). RT 5% 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.

Temporal contrast adaptation in the analysis of visual function in primary open-angle glaucoma

“…Horn et al [ 33 ] found that in the control group, there was no significant age relationship with the temporal contrast threshold. However, Brehmer et al [ 23 ] showed that both RT 3% and RT 5% were significantly correlated with age. Cursiefen et al [ 34 ] found that although the RT increased 0.55 s per decade, there was no significant correlation between RT and age.…”

“…This might be related to the temporal contrast adaptation and stimulation threshold of M-cells [ 21 , 22 , 35 ]; that is, for 100% contrast adaptation stimuli at 25 Hz frequency, magnocellular cells protect themselves by preventing overstimulation, while lower contrast test stimuli might not be able to be perceived by damaged RGCs. Brehmer et al[ 23 ] found that RT 3% and RT 5% in the early glaucoma group (mean MD = 6.33 dB) were significantly prolonged compared with the control group, but there was no significant difference between the preperimetric POAG group and the control group. The study also found that in the control group, RT 3% was greater than 10 s and RT 5% was greater than 8 s, while in the early glaucoma group, RT 3% was greater than 20 s and RT 5% was greater than 10 s. It showed that RT 3% and RT 5% could distinguish glaucoma patients from normal people and could be used as auxiliary indicators for glaucoma diagnosis.…”

“…The contrast and the frequency of the stimuli could be set variably [ 25 ]. The adaptation frequency was 25 Hz, and the average luminance was 49.5 cd/m 2 [ 23 ]. The test was performed with one eye at a time, with the contralateral eye covered by an eye patch.…”

“…Due to the self-protection mechanism of optic nerve cells, after high-contrast stimulation, low-contrast stimulation can be perceived only after a certain time. The interval in which the lower-contrast can be perceived between two consecutive stimulations is defined as the recovery time (RT), that is, the time interval in which the ganglion cells can sense the next stimulation, which can be used to reflect glaucomatous optic nerve damage [ 23 ]. The purpose of this study is to investigate the efficacy of the EFT in detecting the visual function of POAG patients and its ability to further classify glaucoma, especially in advanced or end-stage glaucoma patients who have severe visual field defects.…”

Trabecular Meshwork and Intraocular Pressure Dynamics: Oxidative Stress‐Induced Changes

“…Next to perimetric visual field defects, morphological alterations of the optic nerve and an increased intraocular pressure (IOP) occur. Additionally, special examinations were investigated in the last years for glaucoma diagnosis and follow-up [1][2][3][4].…”