An assessment of the orthogonal astigmatism test for the subjective measurement of astigmatism.
The orthogonal astigmatism test (OAT) is a newly developed method for assessing ocular astigmatism. This study compares the OAT with the Jackson crossed-cylinder (JCC), Raubitschek arrow (RA) and the fan and block (FB) (fan chart). Fifty emmetropes or corrected spherical ametropes (<0.25 DC of astigmatism) were recruited, with a visual acuity of at least 6/5 in both eyes. Pseudo-astigmatism was induced by placing a +0.75 DC lens in front of the right eye at a random axis. With the left eye occluded, each subjective test was performed in a random order and the correcting lens power and axis noted. No significant difference was found in the ability of the OAT to locate the power and axis of the induced astigmatism over the JCC, RA and FB. In conclusion, the OAT offers the clinician an alternative method for locating and correcting ocular astigmatism. It has a similar but not superior accuracy to the other three subjective tests assessed.
Murphy
Paul J
PJ
Department of Optometry and Vision Sciences, Cardiff University, UK. murphypj@cf.ac.uk
Beck
Alan J
AJ
Coll
Eunan P
EP
D000328:Adult; D000704:Analysis of Variance; D001251:Astigmatism / Q000175:diagnosis*; D006801:Humans; D015203:Reproducibility of Results; D014787:Vision Tests / Q000379:methods*; D014792:Visual Acuity