[Clinical application of a new method for the objective estimation of minimum visual acuity]

Recently, a new method for the objective estimation of the minimum visual acuity (OEM) by means of suppression of the optokinetic nystagmus has been presented (Klin Monatsbl Augenheilkd 1998;212:196-202). This study reports on the clinical use of this method.

In 120 individuals referred to our clinic either to procure an ophthalmological expert opinion or for differential diagnosis of an unclear visual impairment, an OEM was performed. The result of the OEM was compared to the clinical findings (history, biomicroscopy of anterior and posterior segments, objective refractometry, pupillary responses, binocular alignment, motility, binocular vision, colour vision, applanation tonometry, electrophysiology, fluorescein angiography, neurologic, radiologic, psychiatric findings, reproducibility of visual acuity and visual field statements under different conditions, comparison of subjective and objective visual field data, statistical prove of false visual acuity and visual field statements) which were critically interpreted concerning the credibility of the subject's statements.

As a result of the clinical examinations, the stated visual acuity of 62 individuals was credible. In one of these individuals, the OEM pointed to a slightly (1dB) better visual acuity. The statements of 7 individuals could not be categorized clinically. The OEM pointed to a better acuity in 3 cases. The stated vision of the remaining 51 individuals was not credible. In 38 of these cases, the OEM pointed to a better acuity, or false statements could be proven by the OEM.

A significant rate (75%) of the individuals whose statements were not credible was detected by the computer-aided, nystagmographic method of OEM. The method allows an estimation of the actual minimum visual acuity and yields evidence of false statements concerning the detection acuity.