Posters

Significantly decreased contrast sensitivity in cataract patients despite good visual acuity

Poster Details

First Author: M.Vasalaki UK

Co Author(s): E. Papavasileiou   M. Vasalaki   M. Niestrata-Ortiz   J. Tolia           

Abstract Details

Purpose:

Cataract is the most common cause of reversible blindness and results in significant morbidity. There are vast differences within the UK in the criteria for funding cataract surgery, however, they are largely based on visual acuity (VA) worse than LogMAR 0.2 or 0.3 or worse. As a result some patients with significant visual morbidity, particularly difficulty driving at night, do not qualify due to a relatively good VA. The aim of this study was to assess the contrast sensitivity of patients with cataract compared with pseudophakic controls to determine whether it should be considered in the eligibility criteria for surgery.

Setting:

The study was conducted in ophthalmic clinics in Spire Harpenden Hospital and Western Eye Hospital in London. The study group comprised 45 eyes of 25 patients and the control group 15 eyes of 15 patients.

Methods:

In addition to distance acuity, contrast sensitivity was assessed using a near contrast sensitivity chart, whereby LogMAR near VA was measured at 100%, 10% and 2.5% contrast. The study group included patients referred with cataract and the control group comprised age-matched pseudophakic patients without posterior capsule opacification. Patients with co-existing optic nerve or retinal diseases affecting contrast sensitivity were excluded. As the data distribution was not normal (verified with Shapiro-Wilk test), Mann-Whitney test was used for the comparison between the study and control group. The statistical analysis was conducted using Statistica v.12 software.

Results:

Mean VA reduction from 100% to 10% contrast was -0.30 (SD 0.14) and -0.05 (SD 0.09), in study and control group, respectively (p<0.0001), whereas from 100% to 2.5% contrast it was -0.49 (SD 0.19) and -0.11 (SD 0.10) in study and control group, respectively (p<0.0001). In cataract patients with distance VA of 0.2 or better (n=14), the near VA reduction from 100% to 10% contrast was -0.29 (SD 0.13) vs. -0.05 (SD 0.09) in control group (p<0.0001), whereas from 100% to 2.5% contrast it was -0.44 (SD 0.22) vs. -0.11 (SD 0.10) in control group (p<0.0001).

Conclusions:

There is a very significant reduction in VA in lower contrast in patients with cataract compared with the pseudophakic patients. This includes patients with good distance VA of 0.2 and better who are frequently not eligible for funding for cataract surgery. The decreased VA in low contrast conditions, such as driving at night, can cause significant visual morbidity. We advocate that contrast sensitivity and visual acuity at low contrast should be taken into account in the eligibility criteria for cataract surgery and in the assessment of fitness to drive.

Financial Disclosure:

None