No abstract

Purpose To evaluate the efficacy of using optokinetic nystagmus (OKN) suppression and induction method as an objective measurement of visual acuity at near and distance. Methods Eighty‐three eyes of 83 patients were examined from December 2007 to February 2008. The visual stimuli were presented on a 17‐inch monitor screen located 40cm from subject for measuring visual acuity at near and on a 127‐inch projector screen located 3m for visual acuity at distance. Eye movement were recorded by infrared oculography and analyzed. The correlation between objective visual acuities at near and distance and subjective visual acuities at near and distance were evaluated. And the reproducibility of objective visual acuity measurement was also investigated. Results Linear regression identified that objective visual acuities measured by using OKN suppression and induction methods were found to be correlated with subjective visual acuities(r2; induction method at near: suppression method at near: induction method at distance: suppression method at distance = 0.641:0.685:0.566:0.724, P<.05). And the objective visual acuity measurement showed high reproducibility(intraclass correlation; induction method at near: suppression method at near: induction method at distance: suppression method at distance = 0.963:0.994:0.945:0.988, P<.05). The suppression method is useful in patient with visual acuities better than 20/120 while the induction method is useful in patient with visual acuities worse than 20/120. Conclusion The objective near and distance visual acuities measured by presenting optokinetic stimuli on 17‐inch monitor screen located 40cm from subject and on a 127‐inch projector screen located 3m were highly correlated with subjective near and distance visual acuities.