The Use of OCT in Differential Diagnosis of Elevated Optic Discs

Abstract

Purpose: Recent papers discussed the role of optical coherence tomography (OCT) in the differential diagnosis of optic nerve head (ONH) elevation and its usefulness in detecting pathological ONH swelling. Given its use in assisting diagnosis in a range of ocular conditions, OCT should be beneficial in the differential diagnosis of optic disc swelling. In this study, we evaluated its en face value to distinguish papilloedema, other ONH pathologies, and non-pathological causes of optic disc elevation. We also assessed if short-term educational intervention on OCT improved the participants’ diagnosis.

Methods: A web-based survey was developed displaying ONH photography with or without OCT line scans of 40 patients with various types of ONH swelling. Optometrists from Australia and New Zealand were invited to participate through email by their respective professional organisations. Anonymous classifications for each case were initially recorded from ONH photography only for 197 practicing optometrists alongside basic descriptors of the participants. The respondents were subsequently randomised and repeated the assessment on ONH images with the addition of OCT line scans without (control group, n=91) of with (intervention group, n=106) a short education on OCT image interpretation. The number of correct answers for the classification papilloedema (n=5), other pathologies (n=17) and normal (n=18) were noted. Differences between groups were statistically analysed.

Results: The number of correct answers was normally distributed for all assessed groups. Participant characteristics, such as exposure to OCT scans, had no influence on results. Diagnostic accuracy showed a small but significant decrease from 66% ± 8.9 to 63% ± 10.6 in the control group with the use of OCT images. The intervention group showed a negligible improvement with availability of OCT line scans, accompanied by an overall 30% loss in correct diagnosis of papilloedema.

Conclusion(s): Our results suggest that OCT should be reserved as an adjunct clinical diagnostic tool for practitioners with appropriate training in OCT interpretation. The provision of short-term education for new modes of assessment could pose a potential danger if used in lieu of evidence based clinical markers. OCT results should be interpreted in conjunction with clinical examination of the optic disc, RNFL assessment, B-Scan ultrasound and fundus autofluorescence.