Stereopsis evaluation in patients under pharmacological treatment for presbyopia

Abstract

ABSTRACT
Objective: Stereopsis is the binocular perception of depth, which has been associated to the improvement in near visual acuity. Presbyopia is the progressive weakening of accommodation, which could be modulated by an eye-drop pharmacological treatment (Benozzi’s method). The purpose of this work was to evaluate stereopsis in patients treated with Benozzi's method for presbyopia.
Methods: A non-randomized case-series prospective study was developed. Twenty emmetropic patients were included, in the range from 40 to 55 years old. Different parameters were measured, such as spherical equivalent refraction (SE), uncorrected and corrected distance and near visual acuity (UDVA-CDVA/UNVA-CNVA), ocular motility and stereopsis. Measurements were performed in three situations: at baseline, with optical correction (eyeglasses) and, after 30 minutes of treatment (eye-drops instillation).
Results: The mean SE refraction in the right eye was 0.34 ± 0.32D and in the left eye it was 0.23 ± 0.22D. Orthophoria was found in 85% of patients while 15% had exophoria. The mean UNVA was 0.197 ± 0.02 LogMAR; with optical correction achieved J1 (0 LogMAR) and after treatment, the mean UNVA was 0.02 ± 0.06 LogMAR (18 cases with J1 and 2 with J2). Pre-treatment mean stereopsis was 200.5 ± 190.85 s of arc, which improved to 52.5 ± 19.70 s of arc (p<0.0018) after the optic correction and to 58±22.38 s of arc (p<0.002) after pharmacological treatment. Both methods exhibited similar results by Titmus stereoscopic tests showing no statistically significant difference (p>0.41).
Conclusions: This study demonstrates that pharmacological treatment for presbyopia not only re-established near and distance visual acuity but restored stereopsis.