Effects of monocular blur (monovision) on binocular supra-threshold performance

Session Details

Session Title: Refractive
Session Date/Time: Sunday 28/02/2016 | 08:30-11:00
Paper Time: 09:30
Venue: Skalkotas
First Author: : S.Plainis GREECE
Co Author(s): :    M. Ganga   E. Papadatou   J. Laretzaki   N. Parry     

Abstract Details

Purpose:

To explore binocular supra-threshold performance under monocular blur (monovision) conditions using pattern visual evoked potentials (pVEP) simple reaction times (RT) and visual acuity (VA) measures.

Setting:

Laboratory of Vision and Optics, University of Crete

Methods:

The effect of defocus, induced by positive powered contact lenses up to 3.00D (in 0.50D steps), on the pVEP, RT and VA was measured on 12 volunteers (average age, 29±7 years). All recordings were performed at 1m distance with best sphero-cylindrical correction under binocular viewing with monocular (dominant or non-dominant eye) or binocular defocus. VEPs were elicited using reversing 10 arcmin checks (4 reversals/s) with 100% contrast. RTs were measured to the onset of a horizontal sinusoidal grating with a spatial frequency of 4 c/deg and a contrast of 10%. VA was measured using ETDRS acuity charts.

Results:

In all conditions, the average P100 amplitude and implicit time of pVEP was greater and faster, respectively, under monocular as compared to binocular defocus. When compared to the in-focus condition, monovision correction reduced the amplitude of the P100 component of the pVEP and increased its latency, by about 5 ms. Similarly, RT was increased by ~20-25 ms in monovision correction. These effects were independent to eye dominance. In addition, pVEP P100 latency and RT were found to covary well, being more susceptible to defocus compared to VA.

Conclusions:

Supra-threshold measures of visual processing, such as pVEP and RT, form more “sensitive” procedures, compared to acuity (threshold) measures, for evaluating visual performance in monovision correction. Their high covariance with defocus reveals a common source of variability in the underlying neural responses.

Financial Disclosure:

NONE