Background: The authors have developed a slit-lamp mounted digital photography system. This ensures that the patient's head is consistently positioned in the same plane in relation to the camera and generates standardized images of the eyelids, which are then analyzed using commercially available computer measurement software. The aim of this study was to assess the repeatability and reproducibility of this system compared with traditional methods of eyelid measurement.
Methods: Both eyes of 10 patients were photographed and then measured by three clinicians using a handheld ruler for five eyelid parameters (i.e., palpebral aperture, superior marginal reflex distance, inferior scleral show, levator function, and upper eyelid skin crease height). The photographs were then assessed using computer software by the same clinicians (twice by a consultant and once by a clinical fellow and a specialist registrar). At all times, each observer was masked to their colleagues' results. Data were analyzed using Bland-Altman plots.
Results: There was a good level of agreement between measurements obtained by computer analysis of digital photographs and measurements obtained by traditional methods. A higher level of reproducibility (interobserver variability) was demonstrated in all digital measurements compared with those obtained by handheld ruler. Repeatability (intraobserver variability) with the digital photograph technique was also high and consistent for each of the five eyelid parameters.
Conclusions: These results suggest that a digital photography system with computer analysis is comparable to, and offers advantages over, traditional methods of measurement. This system offers a simple, standardized, and rapid method of patient assessment with important applications in electronic patient records, audit, and research.