Manifest refraction versus autorefraction for patients with subfoveal choroidal neovascularization.

PURPOSE: To compare the results from manifest refraction using trial lenses and a standard visual acuity protocol to results from autorefraction for obtaining refractive error and best corrected visual acuity in patients enrolled in a randomized clinical trial. METHODS: During a 4-month period, 29 patients with subfoveal choroidal neovascularization (CNV), who were enrolled in the Submacular Surgery Trials (SSTs) Pilot Study at the Wilmer Ophthalmological Institute, gave verbal consent to participate in this study. Best corrected visual acuity was obtained using Early Treatment Diabetic Retinopathy Study (ETDRS) visual acuity charts and standardized room lighting after performance of manifest refraction, according to the SST protocol, and autorefraction. Refractive error (spherical equivalent) and visual acuity scores were obtained in both eyes of all patients. RESULTS: On average, manifest refraction gave a spherical equivalent that was 1.04 D more plus than autorefraction (95% limits of agreement = 0.74, 1.34). On average, the visual acuity score was 1.5 letters better after manifest refraction than after autorefraction (95% limits of agreement = 0, 3.0). The comparison of the two methods of refraction was subdivided according to visual acuity level and eye disease (age-related macular degeneration or ocular histoplasmosis syndrome). CONCLUSIONS: Despite large differences in spherical equivalent between manifest refraction and autorefraction, the visual acuity scores were close (mean difference, 1.5 letters). Other studies comparing subjective refraction and autorefraction have shown similar results. Autorefraction in patients with subfoveal CNV may be a satisfactory alternative to manifest refraction in clinical trials and field studies in which best corrected visual acuity is of interest.

Patient and clinic factors predictive of missed visits and inactive status in a multicenter clinical trial. The Macular Photocoagulation Study Group.

Obtaining complete patient follow-up in clinical trials is important for the analysis of treatment results and for good patient care. Incomplete data can introduce bias into study results and can alter conclusions concerning treatment efficacy. The purpose of this study was to explore in a case-control design patient and clinic factors that may be associated with missed visits or inactive status within three clinical trials conducted as part of the Macular Photocoagulation Study. All inactive patients, all patients with any missed visits, and a random sample of patients with no missed visits were selected for interview. A total of 175 patients (60% of 292 selected) participated in the study. Two factors were found to be significantly associated (P less than .05) both with inactive status and with having any missed visits: health problems and travel costs. Several patient and clinic factors were found to be associated only with inactive status. These included change in marital status since joining the study, retirement since study entry, unsatisfactory interactions with the study physician or clinic coordinator, too little time spent with the study physician, and patient's belief that participants should be paid to participate in clinical trials. Distance from the clinic greater than 100 miles, in addition to health problems any time during follow-up and problems with travel costs, was found to be associated only with having any missed visits. This study emphasizes the importance of maintaining good patient-staff interactions and sensitivity to the events in a patient's life in order to obtain complete patient follow-up.