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Abstract #9099 Published in IGR 5-2
Vertical cup to disc ratio: Agreement between direct ophthalmoscopic estimation, fundus biomicroscopic estimation, and scanning laser ophthalmoscopic measurement
Watkins R; Panchal L; Uddin J; Gunvant POptometry and Vision Science 2003; 80: 454-459
PURPOSE: Ophthalmoscopic estimation of the vertical cup-to-disc ratio (VCDR) of the optic nerve head is important in the management of patients with glaucoma or who are glaucoma suspects. The purpose of this study was to compare the accuracy of estimation of VCDR obtained with direct ophthalmoscopy with that obtained with fundus biomicroscopy through undilated pupils. Measurements of VCDR obtained with the Heidelberg Retina Tomograph (HRT), a confocal scanning laser ophthalmoscope, were used as a standard. METHODS: Thirty young, healthy adults had their optic discs photographed and then imaged and analyzed with the HRT. Due to HRT software limitations, the VCDR could not be calculated automatically, and so a validated VCDR measurement was derived. This was used as the standard against which ophthalmoscopic estimations were compared. Two months later, the subjects had their VCDRs estimated using direct ophthalmoscopy and fundus biomicroscopy performed in random order after varying time intervals. Agreement between ophthalmoscopic VCDR estimation and HRT derived VCDR measurement was assessed by means of bias plots and the weighted kappa statistic. RESULTS: Compared with the HRT-derived VCDR measurement, both ophthalmoscopic techniques tended to underestimate VCDR. The bias with direct ophthalmoscopy was statistically significant. There were also wide variations in VCDR estimation with direct ophthalmoscopy and fundus biomicroscopy, which were more pronounced with direct ophthalmoscopy. The weighted kappa statistic indicated moderate agreement between fundus biomicroscopy and HRT derived VCDR measurement. There was poor to fair agreement between direct ophthalmoscopy and HRT derived VCDR measurement. The level of disagreement was independent of HRT derived VCDR, optic nerve head size and pupil size for both direct ophthalmoscopy and fundus biomicroscopy. CONCLUSIONS: Fundus biomicroscopy enables more accurate, less variable VCDR estimation than direct ophthalmoscopy. The clinician should record which method they used to examine the optic nerve head so that subsequent clinical decisions are not influenced by apparent VCDR changes.
Dr. R. Watkins, Department of Optometry, University of Bradford, Richmond Road, Bradford, BD7 1DP, UK. r.j.watkins@bradford.ac.uk
Classification:
2.14 Optic disc (Part of: 2 Anatomical structures in glaucoma)
6.9.1 Laser scanning (Part of: 6 Clinical examination methods > 6.9 Computerized image analysis)
6.8.2 Posterior segment (Part of: 6 Clinical examination methods > 6.8 Photography)
