Comparison of contrast sensitivity, visual acuity, and Humphrey visual field testing in patients with glaucoma.

BACKGROUND: Despite their normal or near-normal Snellen visual acuity, patients with glaucoma often complain of "poor" vision. OBJECTIVE: To investigate the relationship between large-letter contrast sensitivity, high-contrast visual acuity, and visual field defects in patients with glaucoma who have 20/40 or better visual acuity. DESIGN: Prospective, cross-sectional case series. PATIENTS AND METHODS: We evaluated 250 eyes of 144 subjects from the Glaucoma Service at the University of Illinois at Chicago College of Medicine. Subjects with a diagnosis of glaucoma, suspected glaucoma, or ocular hypertension who met the 20/40 or better vision requirement were recruited. Visual acuity was measured using the rear-illuminated Lighthouse Visual Acuity Chart at 4 m. Contrast sensitivity was measured using the Pelli-Robson Chart in a front-illuminated box with even luminance across the chart. Visual fields of the patients were measured using the 24-2 full-threshold program on the Humphrey Visual Field Analyzer. RESULTS: A significant correlation (r = 0.57, P < 0.001, n = 127) was found between the visual field mean deviations and the contrast sensitivity scores. The correlation (r = -0.322, P < 0.001, n = 127) was less between the visual field mean deviation and the log MAR visual acuity values, as was the correlation between the contrast sensitivity scores and log MAR visual acuity values (r = -0.370, P < 0.001, n = 127). In the subgroup of patients with chronic open-angle glaucoma, the correlation between the mean visual field deviation and the contrast sensitivity score was higher at 0.689 (P < or = 0.001, n = 62). CONCLUSIONS: Reduced contrast sensitivity is significantly correlated with visual field losses in patients with glaucoma and a visual acuity of 20/40 or better. The study data support the conclusion that, compared with visual acuity, the disease process preferentially affects contrast sensitivity. In our previous work, contrast sensitivity was shown to be more related than visual acuity to real-world function in patients with early glaucomatous changes.

Predictors for success of needle revision of failing filtration blebs.

OBJECTIVE: To assess the factors that can predict the success of external needle revision of failing blebs. DESIGN: Retrospective, nonrandomized, comparative case series. PARTICIPANTS: Forty-nine eyes of 43 patients who underwent a needle revision of a filtration bleb with 5-fluourouracil (5-FU) by one physician (SVLB) between August 1993 and December 1994. INTERVENTION: Needle revision of a failing filtration bleb using 5-FU. MAIN OUTCOMES: The intraocular pressure, glaucoma medications, and any complications. RESULTS: The risk ratio of fornix-based trabeculectomies compared with limbus-based trabeculectomies was 3.781; P = 0.047. The risk ratios for gender, race, type of glaucoma, lens status, previous surgery, antimetabolite used for the initial trabeculectomy, and preoperative bleb characteristics were not statistically different for any one group. CONCLUSIONS: Fornix-based trabeculectomies were more likely to fail the needle revisions compared with limbus-based trabeculectomies. None of the five preneedling bleb characteristics showed a propensity toward success or failure. Other demographics such as gender, race, type of glaucoma, previous surgery, antimetabolite used for the initial trabeculectomy, and lens status were also not predictive for success.