Validation of a portable, non-mydriatic fundus camera compared to gold standard dilated fundus examination using slit lamp biomicroscopy for assessing the optic disc for glaucoma

Purpose To evaluate the sensitivity and specificity of a portable non-mydriatic fundus camera to assess the optic disc for glaucoma. Methods We conducted a single-site, cross-sectional, observational, instrument validation study. Non-mydriatic fundus photographs centred at the optic disc were obtained from 276 eyes of 68 glaucoma and 70 normal patients, using a portable fundus camera (Smartscope, Optomed, Oulu, Finland). A senior Glaucoma consultant, masked to the patient's study participation, performed a gold standard dilated fundus examination to make the diagnosis of glaucoma. Following this, a mydriatic photograph was taken by a standard table-top fundus camera. All the images were digitalized and de-identified by an independent investigator and presented to two remote graders, masked to the patients, their diagnoses, and photographic modality. Based on individual disc characteristics, a diagnosis of screening positive or negative for glaucoma was made. In the end, the independent investigator re-identified the images. Sensitivity and specificity to detect glaucoma with the undilated Smartscope camera was calculated compared to dilated fundus examination. Results Grading remote images taken with the portable non-mydriatic fundus camera showed a sensitivity of 96.3% (95% confidence interval (CI): 91.6-98.8%) and 94.8% (95% CI: 89.7-97.9%) and a specificity of 98.5% (95% CI: 94.9-99.8%) and 97.8% (95% CI: 93.9-99.6%) for the two graders respectively as compared to gold standard dilated fundus examination. Conclusion The non-mydriatic Smartscope fundus images have high sensitivity and specificity for diagnosing glaucoma remotely and thus may be an effective tool for use in community outreach programs.