Comparison of Cup-disc ratio measurement using photograph scale (FPS) and optical coherence tomography (OCT) in glaucoma and suspect glaucoma patients

Andika Prahasta Gandasubrata

Cup disc ratio may resemble the severity of the optic nerve damage. There are several ways in determining cup-disc ratio, which can be done in practices, using direct ophthalmoscopy and hand—held lens. Digital retina photograph or also known as fundus photograph can be used to examine the optic disc. To obtain a documented measurement with better result, fundus photograph scale (FPS) was made. There is presumed to be an agreement between cup-disc ratio measurement using FPS and OCT.

This was a method comparison study to accomplish an agreement between two methods in determining cup-disc ratio wth repeated measurements. The subjects included fundus photographs and OCT analysis of the optic discs of glaucoma and glaucoma suspect patients in Glaucoma Unit, Cicendo Eye Hospital, Bandung. There were 33 eyes (21 patients) who met the inclusion criteria. All subjects underwent horizontal and vertical cup-disc ratio measurement using FPS. The results were analyzed using Bland Altman.

The result showed that p value of horizontal cup-disc ratio measurement using OCT an FPS was 0.1817 (p> 0.005), with limit of agreement 0.128-0.058. The p value of vertical cup-disc ratio measurement was 0.9818 (p>0.005), with limit of agreement 0.031-0.029.
To concluded, there was an agreement of horizontal and vertical cup-disc ratio measurement between OCT and FPS. It is suggested to use vertical cup disc ratio measurement due to its narrower limit of agreement, hence its superior accuracy.

Keywords: glaucoma, cup-disc ratio, optical coherence tomography (OCT), fundus photograph scale (FPS).