Abstract
Purpose :
Astigmatism blurs the retinal image of a spot along a particular orientation rendering an elliptical shape. The Wilkins Egg and Ball Test (WEBT) was created based on the hypothesis that.astigmatic patients encounter difficulty differentiating between oval and circular targets.In WEBT, patients are asked to identify a circle hidden in a row with nine ovals. This study examined the utility of WEBT in identifying patients requiring astigmatic correction in three cohorts; participants with astigmatism, participants with keratoconus and normal participants with induced astigmatism.
Methods :
Non-astigmatic participants (N=27, mean age:27±5, range:20-36, 8 male), participants with astigmatism (N=28, mean age:36±10, range:18-36, 9 male) with mean spherical equivalent (SE) corrections of -4.16±4.25, and mean cylindrical corrections of 2.80±0.76 DC (range: -2.00 DC to -4.00 DC), and keratoconic participants (N= 7 eyes, mean age:37±13, range:26-54, 2 female) with mean SE corrections of 0.27±2.20 DS, mean cylindrical corrections of -3.32±3.33 DC (range: -0.75 DC to -10.70 DC), were recruited. Participants detected the circle in each of the ten rows of each page, while the search time (sT) and number of errors(noE) were recorded. Non -stigmatic participants were examined under five conditions (baseline, and induced cylinder at four primary meridians) and participants with keratoconus and astigmatism were examined under corrected and uncorrected conditions, in random order. The sT and noE of varying conditions were compared using the Friedman test.
Results :
In non-astigmatic participants, sT was significantly quicker and the noE was significantly lower in the baseline condition (38±9 sec, 0.97±1.5 errors) compared with all induced cylinder conditions (approximately 54±19 sec, 2.35±2.2 errors, p<0.05 for all except for the induced 90 deg astigmatism condition). Astigmatic participants were 6 sec faster and had one less error on average in the corrected condition. Keratoconic participants were 12 sec faster and had three less errors on average in the corrected condition.However, these differences were non-significant.
Conclusions :
The potential of WEBT for detection of uncorrected astigmatism remains uncertain, though preliminary results in the clinical population are promising. More participants are being recruited to draw definitive conclusions.
This is a 2021 ARVO Annual Meeting abstract.