The Effect of Loss of Contrast and Distortion on Vision and Mobility Tasks

Abstract

Purpose : The effects of distortion caused by uncorrected astigmatism and loss of contrast due to cataracts has on balance during routine mobility tasks have not been fully investigated. Implantation of toric IOLs may offer more than an increased unaided visual acuity for the patients. A prospective observational study was performed using a novel technique to monitor centre of mass (COM) during routine mobility tasks.

Methods : The stability of 15 healthy presbyopic subjects (47.8 ± 4.9 years) was assessed while walking up and down stairs and stepping over an obstacle. Each task was carried out under 6 visual conditions: plano, moderate and high astigmatism, each with and without cataracts. Bangerta foils (grade 0.4) were used to simulate the effect of cataract and contact lenses (CLs) were worn provide moderate and high levels of oblique astigmatism. A sensor (Pro-Move system, Inertia Technology B.V, Netherlands) was placed over the L3 spinous vertebrae to monitor COM mean peak angle, velocity and acceleration in three planes of movements: rotational, forwards/ backwards and side tilt.

The study aimed to determine the effect cataracts and uncorrected astigmatism has on balance during routine daily tasks.

Results : When stepping over an obstacle, the mean peak side–tilt angle for both moderate and high astigmatism were significantly different to the other conditions (p<0.001). Additionally, in the high astigmatism with cataracts group both forward bending and rotational acceleration were also significantly different from plano and plano cataract (p<0.01). During the stairs task, there was only one change indicated among the whole data set. The high astigmatism altered side tilt angle movement going downstairs indicated by a bit of a larger peak in sideways movement compared to all other visual conditions in this task (p<0.002). There were no changes indicated when walking up the stairs.

Conclusions : A patient with blurred vision due to cataract or uncorrected astigmatism (or both) may experience reduced stability during obstacle negotiation. However, they may not notice balance problems when walking up or downstairs. The correction of astigmatism at the time of cataract surgery could potentially improve balance as well as visual acuity.

This is an abstract that was submitted for the 2016 ARVO Annual Meeting, held in Seattle, Wash., May 1-5, 2016.