Measurement of Optic Disc Diameter and CD Ratio Using OCT Imaging and Fundus Stereobimicrosopy to Find an Agreement between the Two

Abstract

Purpose: To compare the clinician disc assessment findings with OCT estimation and to assess the agreement.

Study Design: Observational study.

Place and Duration of Study: North Devon District Hospital, UK from January 2017 and April 2017.

Material and Methods: This is an observational study of 100 eyes of 50 consecutive patients. All patients and eyes were examined by one single clinician. Vertical disc height was measured by the clinician using the slit lamp narrow beam of light. CD ratio was estimated by comparing the cupped area of the optic disc with the neuro-retinal rim of the optic disc considering the overall optic disc size. OCT was used for automated disc examination and to assess disc parameters. The agreement between the two methods was analyzed statistically by intraclass correlation coefficient (ICC).

Results: There was a good correlation seen between the two methods while assessing vertical disc diameters and CD ratio (r = 0.65, 0.66 respectively). There was a substantial strength of agreement (according to ICC agreement criteria) in both clinician and OCT estimated values in the measurement of vertical disc diameter and CD ratio. The ICC values were 0.77 (CI = 0.66, 0.84) and 0.70 (CI = 0.28, 0.85) respectively.

Conclusion: In this study, the agreement is much greater for both important disc parameters between OCT and clinician methods and clearly it is substantial but still not perfect. OCT and clinician measured observations for optic disc measurements are still not interchangeable in clinical practice.

Keywords: CD ratio; OCT; Vertical disc diameter.