Abstract
Abstract: :
Purpose: To utilize oculokinetic, time limited, offset acuity testing to reveal pericentral scotomata undetectable by standard vision screening tests. Microsaccades allow patients with even large perifoveolar and macular defects to 'fill-in' these scotomata and achieve normal vision results on standard acuity or Amsler testing. Methods: 21 consenting patients, with and without severe pericentral scotomata by Humphrey threshold perimetry, underwent oculokinetic acuity (OKAy) testing using a moving red-dot fixation target with constant audio feedback. Computer-generated ETDRS letters corresponding to acuities of 20/20, 20/40, 20/50, 20/70, 20/100, and 20/200 were presented in each quadrant with the near corner of each optotype 1.5 degree from fixation, for time intervals of 1.0, 0.5, 0.2 and 0.1 sec. Testing proceeded from the largest to smallest optotype size, and from the longest to shortest presentation time for each optotype, in randomized quadrant series. Results: The study population included 12 age-matched patients with no pericentral defects (8 F:4 M; mean age 64.3 years) and 9 patients with dense (≷20 dB depression) pericentral defects (4 F:5M; mean age 65.9 years) as demonstrated on HVF analysis. Patients without pericentral defects had best-corrected logMar acuities at 20 ft ranging from 0.4 to 1.0 (mean 0.9 +/- sem 0.1), and those with pericentral defects had logMar acuities ranging from 0.3 to 1.0 (mean 0.7 +/-0.1). There was no statistically significant difference in LogMar acuity between the two groups. Good correlation (R=0.9) was noted between the standard time-unlimited distance acuity at 20 ft and OKAy acuities at duration 1.0 or 0.5 sec among all subjects. OKAy testing produced bimodal segregation of patients with pericentral scotomata from those without pericentral defects when offset ETDRS letters were presented for 0.2 or 0.1 sec. The best intratest segregation was obtained comparing OKAy results at 0.5 sec versus 0.1 sec, which produced consistent acuities in normal eyes, but disparate OKAy acuities (in all quadrants) among subjects with pericentral scotomata. Conclusion: This study suggests that time limited oculokinetic offset testing at 0.5 sec can rapidly document standard acuity, and when combined with 0.1 sec offset testing, can simultaneously detect pericentral visual deficits that elude standard testing strategies. Near or lane-projection OKAy testing may allow for early detection and intervention in patients with pathology leading to pericentral visual field loss from macular degeneration, diabetic retinopathy and glaucoma.
Keywords: 624 visual fields • 620 visual acuity