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). 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.