Purpose
To evaluate the utility of the SPOT (Welch Allyn, Inc.) and the PlusoptiX S12 (PlusOptix, Inc.) photoscreeners in detecting significant refractive error in a sample of Native American children with a high prevalence of astigmatism.
Methods
Subjects were 3rd through 8th grade students from schools on the Tohono O’odham reservation. A best estimate of refractive error was obtained through subjectively refined cycloplegic autorefraction (Retinomax K-plus2, Nikon Inc.). Non-cycloplegic photoscreenings using the SPOT and PlusoptiX S12 were conducted according to manufacturer recommendations, and testing environment (e.g., lighting) was controlled as much as possible in a school setting. AAPOS referral criteria for children > 48 months were applied to photoscreener refractive error results to determine screening pass/fail, and the same criteria were applied to cycloplegic refraction results to determine exam positive/negative results.
Results
Exams were conducted and screening was attempted on 209 students (mean age 11.89, range 8.64 to 15.55, 56% female). Exam results were positive for 116 students (55.5%), with 105 (50.2%) meeting the criterion for astigmatism (>1.50D). A screening result (estimate of refractive error) was obtained on 202 students with the SPOT (97%) and on 112 students with the PlusoptiX (54%). Most students for whom we were unable to obtain a screening measurement had an exam positive result for astigmatism (5/7 for SPOT, 76/97 for PlusoptiX). Students for whom a screening measurement was not obtained were classified as a screening “fail”. A summary of screening results are provided in Table 1.
Conclusions
Both instruments had high sensitivity and NPV, but the SPOT provided better specificity and PPV than the PlusoptiX and was more likely to provide a refractive error estimate, particularly in astigmatic students. The results provide information on the ability of these instruments to detect significant astigmatism, but may not reflect the utility of the instruments for use in populations with lower rates of astigmatism and/or higher rates of other refractive errors. Measurement success rates are also likely to differ in younger children for whom instrument-based screening is recommended and may be improved in a more controlled testing environment, particularly with regard to light levels.