Optic nerve assessment with stereo photographs and ultra-widefield scanning laser ophthalmoscope images

Clinical relevance: Clinical evaluation of the optic nerve using 3-D stereo disc photographs is considered the gold standard for estimating vertical cup-to-disc ratios. Ultra-widefield retinal imaging has gained increasing popularity to document and screen the health of the retina and optic nerve.

Background: Glaucoma is often first identified or suspected based on initial optic nerve assessment. Despite technological advancements in imaging, stereo disc photography remains the gold standard of optic nerve assessment. This study compared vertical cup-to-disc ratio (VCDR) estimations using ultra-widefield scanning laser ophthalmoscopy images with estimations using paired stereo disc images.

Methods: Thirty-five healthy and 35 glaucomatous eyes were imaged using Zeiss VISUCAM® PRO NM and Optos Monaco® (optomap®) [Registered in U.S. Patent and Trademark Office] devices. Four experienced clinicians assessed each image in a masked fashion and graded the VCDR. Stereo viewers and review software tools were used to determine VCDRs. Bland-Altman plots and regression/correlation analyses were used to check VCDR agreement.

Results: Bland-Altman analyses showed low mean differences between devices with VCDR estimation for each grader (-0.03, +0.01, -0.02, and +0.03). Difference vs. means plots suggest stable differences across the range of measurement.

Conclusions: VCDR estimations were comparable using optomap® images and VISUCAM® PRO NM stereo optic disc images.