EFFICACY AND BINOCULAR SUMMATION OF MICRO-MONOVISION WITH SMILE IN PATIENTS WITH PRESBYOPIA

To evaluate the efficacy of SMILE combined with different levels of micro-monovision in presbyopic patients and to assess the binocular summation effect on contrast sensitivity defocus curves.

Ophthalmology Departments, Qvision (VITHAS Almería, Spain) and Tecnolaser Clinic Vision (Sevilla, Spain)

A pilot study (case series) of seven patients prospectively followed up for 6-month after inducing different levels of micro-monovision according to the surgeon’s decision based on patient needs. Efficacy was evaluated for binocular contrast sensitivity defocus curve (CSDC) and visual acuity/stereopsis at distance (4 m) intermediate (67 cm) and near (40 cm), comparing preoperative results with the best distance correction and postoperative results without correction. Monocular uncorrected contrast sensitivity defocus curves were measured at 6-month to correlate with the binocular uncorrected CSDC. Patient-reported outcomes were evaluated preoperatively and at 6 months using the Convergence Insufficiency Symptoms Survey (CISS), Vision and Night Driving Questionnaire (VND-Q), Patient-Reported Spectacle Independence Questionnaire (PRSIQ), and single questions about satisfaction, bothersome to dysphotopsia, and the decision to undergo the same surgery.

Five patients completed the follow-up. Micro-monovision levels of 0 D, 0.5 D, 0.75 D, 1 D, and 1 D were achieved in these patients. At 6 months the median VA was 0 logMAR at the three evaluated distances [ranging from 0.1 to -0.3], the stereopsis was not impaired in any patient achieving a median of 119’’, 40’’ and 79’’ at far, intermediate and near distances, respectively. The CSDC range generally increased after surgery with the micro-monovision value, but patients resulted in different patterns of binocular summation. No clinically relevant changes were generally observed in the CISS and VND-Q scores. All patients achieved total spectacle independence (1 after PRK re-treatment), only one was bothered by dysphotopsia, and all answered that they were likely or very likely to be submitted to the same surgery.

Patients were satisfied, achieving spectacle independence without increasing clinical symptoms or driving difficulties. However, non-uniform patterns of binocular summation were manifested through contrast sensitivity defocus curves. Future studies with larger sample sizes are required to elucidate the patterns of binocular summation using the micro-monovision technique.