Abstract
Purpose:
To determine the intra- and interobserver reproducibility of non-mydriatic, monoscopic optic disc photo grading and to determine the sensitivity and specificity of optic disc photos in diagnosing patients with glaucoma and glaucoma suspects, in a large, community-based, CDC-funded, glaucoma detection program.
Methods:
As part of the detection program, patients underwent slit-lamp examination by an ophthalmologist, who then graded each patient’s optic discs using two methods: cup-to-disc (CD) ratio and Disc Damage Likelihood Scale (DDLS). Following an automated visual-field test, patients were diagnosed as having “glaucoma,” “glaucoma suspect,” or “no glaucoma”. Non-mydriatic, monoscopic optic disc photographs were then taken by an ocular technician using the Volk Pictor fundus camera (Volk Optical Inc, Mentor, Ohio), a novel, portable digital imaging device. On a different day, in a masked fashion, the same examiner and a second observer graded the disc photos and determined a diagnostic impression based only on the disc photos. For disc grading, intra-class correlations for intra- and interobserver reproducibility were calculated for both CD ratio and DDLS. Sensitivity and specificity of the disc photos’ diagnostic impression were also determined.
Results:
One thousand one hundred and eight patients (1108) were examined between 1/3/13 - 11/8/13. Of those, patients were randomly selected according to three groups of diagnoses: “glaucoma” (n=36), “glaucoma suspect” (n=50), and “no glaucoma” (N=33). For CD ratio, the intraobserver agreement was 0.71 and the interobserver agreement, 0.69. For DDLS, the intraobserver agreement was 0.65 and the interobserver agreement, 0.67. The sensitivity of diagnosing glaucoma or glaucoma suspect based on disc photos alone was 66% and the specificity was 85%.
Conclusions:
Non-mydriatic, monoscopic disc photos had little value as a screening technique for glaucoma, with moderate intra- and interobserver disc grading reproducibility. Possible reasons include a high percentage of patients with significant cataracts that were examined, as well as the photography technique through small pupils, both of which reduced the quality of the images and made interpretation more challenging for the reviewer
Keywords: 627 optic disc •
550 imaging/image analysis: clinical •
460 clinical (human) or epidemiologic studies: health care delivery/economics/manpower