Detection of optic disc change with the Heidelberg retina tomograph beforeconfirmed visual field change in ocular hypertensives converting to early glaucoma

Aim-To determine whether analysis of sequential optic disc images obtained with the Heidelberg retina tomograph (HRT) is able to demonstrate optic dis c change before the development of reproducible field defects in a group of ocular hypertensive (OHT) patients converting to early glaucoma. Methods-Two groups were analysed: (1) 13 eyes of 13 OHT patients who subseq uently developed reproducible field defects (converters); and (2) 13 eyes o f 11 normal control subjects. Two sequential optic disc images were obtaine d using the HRT (median separation between images was 12 months for the con verters and 13 months for the normals). The second image in the converter g roup was obtained before confirmed visual field loss. The optic disc variab les were analysed both globally and segmentally using HRT software version 1.11. The Wilcoxon signed rank test was used to determine if there were any significant differences between the variables of the two image sets. Results-Significant optic disc change was demonstrated in the group of conv erters: (1) global variables: the cup area increased by 9.7%, the CID area ratio increased by 10.5%, and the rim area decreased by 6.9%; (2) segmental variables: the superonasal cup area increased by 11.0%, the superonasal CI D area ratio increased 11.7%, and the inferonasal cup volume increased by 2 8.4%. The temporal rim volume decreased by 15.6%, the inferotemporal rim vo lume decreased by 23.6%, and the rim area in the superonasal and superotemp oral segments decreased by 6.6% and 6.9% respectively. Conclusion-Analysis of sequential optic disc images on the HRT allowed the detection of glaucomatous change before confirmed visual field change in a group of OHT patients converting to early glaucoma.