The illuminated high contrast macular grid: a pilot study

Analysis of visual disturbances in the central 10 degrees provides valuable data for the low vision clinician. Amsler grid testing in the visually impaired can be poorly visible and it can be difficult to transcribe results. Automated perimeters will accurately map retinal defects, but the equipment is expensive and this technique is time consuming. An Amsler grid was modified using principles of luminance and contrast to improve its accuracy, and its efficacy was compared to an automated perimeter.

Eighteen visually impaired patients (28 eyes) were prospectively evaluated at the Emory Low Vision Laboratory. Each patient had three central threshold visual field tests: automated perimetry (Humphrey model 690), conventional Amsler Grid, and Illuminated High Contrast Macular Grid (IHCMG). The Humphrey central 10-2 threshold automated visual field examination was performed to map the patient's retinal function.

The Humphrey analysis identified (mean +/- one standard deviation) 2.4 +/- 1.4 defects per patient with an average percent defect area of 33.4 +/- 14.8 degrees. The IHCMG technique was not significantly different from the Humphrey technique for identifying the number of defects (2.25 +/- 1.5) (p > 0.05) or the percent defect area (26 degrees +/- 20 degrees) (p > 0.05). The conventional Amsler grid technique significantly under-evaluated the retinal defects compared to the Humphrey analysis of the number of defects (p < 0.01) and percent area of defects (p > 0.001).

The IHCMG technique can be used as a simple, rapid and accurate analysis of the central 10 degrees visual field in the low vision patient.