K Pesudovs, DJ Coster
Department of Ophthalmology, Flinders Medical Centre and Flinders University of South Australia

Purpose. To examine the impact of cataract on visual disability (VDis) and whether objective tests of visual function confirm the development of VDis. To determine how cataract surgery alters VDis and what factors influence post-surgical satisfaction.

Methods. Cataract surgery was performed on 56 patients without ocular comorbidity. Pre-operatively, cataract was quantified using the Lens Opacities Classification System III (LOCS III). Visual disability was assessed with a previously validated questionnaire. A battery of tests of visual function were applied pre- (pre-op) and post-operatively (post-op). Satisfaction was also assessed by questionnaire.

Results. Visual disability score is related to LOCS III scores in the least affected eye for nuclear opacity (p=0.01) and posterior subcapsular cataract (PSC) (p=0.0004) (R2 = 0.43). The pre-op VDis score relates to several measures of visual function: peak contrast sensitivity (CS) (p=0.0001), visual acuity (p=0.01) and peak CS with glare (p=0.03) (R2 = 0.83). Visual disability score is significantly more before surgery (mean 1.81, SD 0.67) than after (mean 1.19, SD 0.21) (p<0.001). Post-op VDis is influenced by pre-op VDis (p<0.0001), the absolute value of the post-op spherical equivalent (p=0.0001) and post-op peak CS with glare (p=0.0001). The chief determinant of post-op patient satisfaction is the absolute value of the spherical equivalent (p=0.005) (R2 = 0.32).

Conclusions. In this series, nuclear and PSC cataracts cause more VDis than cortical cataracts. The development of VDis is confirmed by a test of visual function in each of three domains: acuity, CS and glare. Cataract surgery reverses this disability. However, patients with more pre-op VDis have more residual post-op VDis because some patients have bilateral disease. Post-op VDis is also greater and patient satisfaction is less for patients with greater post-op ametropia.