[The search for electrophysiological predictors of visual comfort after presbyopia correction with contact lenses]

Starting at 40 years of age, prespyopia affects a quarter of the world population. Many techniques of presbyopia surgery have emerged in recent years. The purpose of this study was to compare monovision and multifocality and to identify clinical and electrophysiological predictive markers of visual comfort for each correction available in clinical practice. Ten presbyopic patients participated in this study. Patients received monovision and multifocal correction using contact lenses for three weeks each in a random order. A clinical evaluation (visual acuity, TNO test, binocular contrast sensitivity and quality of vision questionnaires) and an electrophysiological evaluation (monocular and binocular pattern VEP with multiple spatial frequencies: 60, 30 and 15') were performed before and after each correction modality. The P100 was significantly wider and slightly earlier after binocular compared to monocular stimulation at T0. The TNO stereopsis score decreased significantly after correction. No other significant differences, either on clinical or electrophysiological criteria, were found between the two modes of correction. Several significant correlations were found between the stereoacuity difference depending upon correction and evoked potentials by binocular pattern at T0. The larger the stereoacuity difference (better stereoacuity with multifocal compensation), the longer the latency of the P100 using 60' checks (R=0.82; P=0.004) and the greater the amplitude of the N75 using 30' (R=0.652; P=0.04). Our study found no differences between the 2 types of correction, but it highlights a benefit of VEP used in current practice and measurement of the P100 wave, the best indicator of stereopsis and the most consistent, to predict visual comfort after compensation presbyopia.