Anterior Segment Digital Photography Accuracy in the Evaluation of Pterygium: The Brazilian Amazon Region Eye Survey (BARES)

Abstract

Purpose : Pterygium is an eye disease that occurs more commonly in tropical regions, associated with chronic sun exposure and specifically to ultraviolet light. Our purpose was to determine agreement between anterior segment digital photography and eye exam for pterygium evaluation.

Methods : BARES is a population-based cross-sectional prospective study conducted in Parintins city. Participants were residents ≥45 years of age identified through a door-to-door interview. Eligible participants were invited for an eye exam. Pterygium occurrence and severity were assessed by ophthalmologists through slit-lamp examination considering its location (nasal - N, temporal - T or both - N&T), size (> 3 mm) and pupillary invasion. Participants from 8 urban and 4 rural clusters with pterygium had anterior segment photography obtained from each eye using a digital camera system (iCam, Optovue) with natural pupils on the same day. Images were analyzed off-line by a masked experienced ophthalmologist using the same grading system from the ophthalmic exam. The level of agreement of studied variables was determined by both percentage agreement and kappa statistic agreement. Clinical exam was used as gold-standard to determine sensitivity, specificity, positive and negative predictive values of anterior segment photography for pterygium detection.

Results : A total of 2384 persons was enumerated and 2041 were examined. Anterior segment photography was taken from 716 (35.1%) participants, 307 (42.9%) urban and 409 (57.1%) rural. Good agreement was found for pterygium location (k=0.69 N, k=0.81 T and k=0.77 N&T). Moderate agreement was found for size > 3 mm (k=0.39 N; k=0.29 T; k= 0.14 N&T) and pupillary invasion (k= 0.53). Overall, good sensitivity ranging from 59.5% to 91.6% (except for lesions >3mm), and high specificity (78.2% a 99.8%) were found. Positive predictive values ranged from 50.0% (pupillary invasion) to 92.5% (nasal > 3mm) whereas negative predictive values ranged from 76.8 (nasal lesion) to 98.8% (pupillary invasion).

Conclusions : There was moderate-to-substantial agreement between anterior segment digital photography and a comprehensive eye exam for pterygium evaluation. Anterior segment digital photography showed good accuracy and may be a useful tool for identification of pterygium and its severity in regions with limited access to eye care services.

This is an abstract that was submitted for the 2017 ARVO Annual Meeting, held in Baltimore, MD, May 7-11, 2017.