Effect of interocular differences on binocular visual performance after inducing forward scattering

Abstract

To assess binocular visual performance by means of binocular summation on visual function after inducing monocular forward scattering, and to study the influence of interocular differences on ocular parameters. Methods:Seven young healthy subjects were recruited. Four Bangerter foils and five fog filters were used to induce monocular forward scattering. To analyse the impact of the scatter, visual acuity, contrast sensitivity, visual discrimination capacity and distance stereoacuity were measured binocularly with the filter placed over the dominant eye. Additionally, interocular differences were calculated for four ocular parameters: the Objective Scatter Index (OSI), Strehl ratio (SR), modulation transfer function cut-off (MTF cut off) and straylight (log[s]). Binocular summation was determined for these visual functions.Results: A statistically significant deterioration in visual acuity, contrast sensitivity and stereoacuity was seen for all of the filter conditions with respect to the natural state (baseline), with the largest change being recorded for the Bangerter foils.Similarly, the interocular difference for the three retinal image quality parameters (OSI, SR and MTF cut-off) and log(s) increased significantly for the Bangerter foil condition, but not for the fog filters (except log(s)). Binocular summation declined gradually with the Bangerter foils, but not for the fog filters. Statistically significant correlations were found, that is, the greater the interocular differences, the lower the binocular summation of the visual functions and the greater the distance stereoacuity. Conclusion:Increased forward scattering in the dominant eye resulted in interocular differences, which reduced the overall binocular visual performance, including the binocular summation of several visual functions and distance stereoacuity. The results suggest that marked interocular differences in ocular parameters should be avoided in cases of ocular pathology, amblyopia and emmetropisation procedures (such as refractive surgery) or a monovision correction for presbyopia.

Mesopic conditions optimise the detection of visual function loss in drivers with simulated media opacity

“…This was consistent with results from a study by Castro-Torres et al 27 which showed no difference between participants’ mean baseline photopic HCVA and when Hoya filters (Fog A, B & A + B) and B + W Fog_1 filter were used. This trend was also in line with another study by Martino et al 28 in which they assessed VA binocularly wearing different Fog filters in the dominant eye and reported that on average, VA reduced by only one line.…”

Neural binocular summation and the effect of defocus on the pattern electroretinogram and visual evoked potentials for different pupil sizes

“…For low‐ and high‐contrast VA, the BS ratio (BS VA ), which characterises the binocular visual performance, 8,17,23 was calculated by dividing the binocular VA value by the best monocular finding following Equation 24 : The conversion from logMAR to decimal VA values was as follows:where corresponds to the value of binocular VA and to the best monocular finding (the highest of the two monocular values).…”

Effects of alcohol consumption on driving performance in the presence of interocular differences simulated by filters

“…The latter is defined as the capacity of the visual system to see the surrounding environment in depth. This binocular visual performance is influenced by several other factors including refractive error 19 , pupil size 20 , ocular pathologies 21 , 22 , and interocular differences 23 , 24 . An interocular difference is the difference between the two eyes for a determined ocular parameter.…”

“…On the other hand, an important phenomenon known as intraocular scattering may be responsible for an increase in these interocular differences. When this phenomenon affects one eye more than the other, interocular differences cause a deterioration in binocular visual performance 18 , 24 , 29 . An increase in intraocular scattering results in a veiling luminance on the retina which worsens the retinal image quality 24 , 30 .…”

“…When this phenomenon affects one eye more than the other, interocular differences cause a deterioration in binocular visual performance 18 , 24 , 29 . An increase in intraocular scattering results in a veiling luminance on the retina which worsens the retinal image quality 24 , 30 . Intraocular scattering is also implicated in visual disturbances such as disability glare, which reduces contrast sensitivity 31 , 32 , and night vision disturbances such as halos 33 – 35 .…”