Purpose : Both the increase of intraocular scattering due to cataracts and the reduction of central foveal vision associated with age-related macular degeneration (AMD) may occur with aging and are often developed simultaneously. We performed a study to better characterize the impact of induced scatter on the quality of vision in the near periphery, where functional areas of the retina are usually still present in patients with AMD.
Methods : We used a realistic cataract simulator based in projecting at the eye’s pupil plane phase masks with controlled spatial properties generated with a liquid crystal on silicon spatial light modulator. The phase wavefronts were designed to accurately replicate the angular distribution of light intensity in the retina found in cataractous eyes with different severities. The induced amount of scatter ranged from values of straylight (S) from 10 to 85 degree2/sr, that corresponds from normal aging eye to advanced cataract stages. The field of view of the instrument was 27 degrees that allowed peripheral testing. Visual Acuity (VA) and Contrast Sensitivity (CS) at 3 cycles per degree were measured at the fovea and two retinal eccentricities (5 and 10 degrees in the nasal visual field). The measurements were performed in the dominant eye of a group of ten normal subjects (32±8 years old). An effective artificial pupil of 1.33 mm diameter was used with subjects under their best focus correction.
Results : We found a linear decrease of the VA (expressed in LogMAR) for increasing amounts of induced scatter (values of straylight parameter S) both at the fovea and periphery. There was an average VA reduction of 0.18 (LogMAR) at the fovea for each S increment of 25 degree2/sr, while at 10 degrees this value was reduced to 0.06 (LogMAR). A similar qualitative behaviour was found for the CS.
Conclusions : The effect of induced scattering on VA and CS at the fovea and the near periphery was successfully evaluated. We found a relatively lower impact of scatter in the periphery. That may explain the modest improvement in vision often found after cataract surgery in patients with AMD.
This is an abstract that was submitted for the 2017 ARVO Annual Meeting, held in Baltimore, MD, May 7-11, 2017.