Significant Improvement in Dynamic Visual Acuity after Cataract Surgery: A Promising Potential Parameter for Functional Vision

Mingxin Ao,Zhiqiang Hou,Xuemin Li,Chen Huang,Weiqiang Qiu,Wei Wang,Chen-Wei Pan

doi:10.1371/journal.pone.0115812

Abstract

PurposeDynamic visual acuity (DVA) is a relatively independent parameter for evaluating the ability to distinguish details of a moving target. The present study has been designed to discuss the extent to which age-related cataract impacts DVA in elderly individuals and to determine whether it could be restored after bilateral phacoemulsification combined with intraocular lens implantation surgery.MethodsTwenty-six elderly cataract patients scheduled for binocular cataract surgery and 30 elderly volunteers without cataract were enrolled in the study. DVA at 15, 30, 60 and 90 degree per second (dps) was assessed, and velocity-dependent visual acuity decreases between consecutive speed levels were calculated.ResultsCompared with the control group, the patient group exhibited significantly worse DVA performance at all speed levels (p<0.001), and the decreases in velocity-dependent visual acuity were more serious in the patient group at the intervals of 0–15 dps (p<0.001), 15–30 dps (p = 0.007) and 30–60 dps (p = 0.008). Postoperatively, DVA performance at every speed level in the patient group clearly improved (p<0.001) and recovered to levels compatible to the control group. The decrease in visual acuity with increasing speed was less pronounced than during the preoperative phase (p0–15 dps = 0.001, p15–30 dps<0.001 and p30–60 dps = 0.001) and became similar to that of the control group. The postoperative visual benefit regarding DVA was more pronounced than the improvement in static visual acuity (p15 dps = 0.001 and p<0.001 at 30 dps, 60 dps and 90 dps).ConclusionsThe impact of age-related cataract on DVA was more severe than its effects on static visual acuity. After cataract surgery, not only static vision of the patients was restored markedly, but also the dynamic vision. DVA could be an important adjunct to the current evaluation system of functional vision, thereby meriting additional attention in clinical assessment.

Highlights

Dynamic visual acuity (DVA) refers to the ability to resolve a target visually when there is relative motion between the target and the observer [1, 2]
The observer must rely on saccades and smooth pursuits to maintain foveal fixation on the image [1], and the DVA signal is transmitted by the magnocellular (M) pathway [3, 4]
The monocular static visual acuity (SVA) of the right eye and the left eye remained comparable in the patient group (0.021¡0.010 and 0.011¡0.005, p50.203)

Summary

Introduction

Dynamic visual acuity (DVA) refers to the ability to resolve a target visually when there is relative motion between the target and the observer [1, 2]. The observer must rely on saccades and smooth pursuits to maintain foveal fixation on the image [1], and the DVA signal is transmitted by the magnocellular (M) pathway [3, 4]. Relying on these mechanisms, DVA is a relatively independent visual parameter and is different from static visual acuity (SVA) [5] or contrast sensitivity [6], the stimuli of which are captured by highfrequency tremors of the eye [1] and are transmitted by the parvocellular (P) pathway [7, 8].

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Results

Conclusion