Purpose:
To assess the spatial pattern of decline in rim area (RA) in ocular hypertension as measured with the Heidelberg Retina Tomograph (HRT).
Methods:
198 ocular hypertensive (OHT) were examined prospectively with the HRT from 1993-2001. One eye per subject was selected for analysis, with a median 10 (range 5-16) HRT mean topographies available for each eye, processed using the 320 µm reference plane. Linear regression analysis of RA over time was performed for each of the HRT Explorer pre-defined sectors; Temporal (T), Superotemporal (ST), Inferotemporal (IT), Nasal (N), Superonasal (SN) and Inferonasal (IN).The mean slope of RA loss (mm2/Year) in each sector was compared, as was the frequency of significant slopes in each sector.
Results:
IT slopes were greater than T, SN and IN slopes (p = 0.03, 0.01 and 0.03, respectively, paired t-test) and ST slopes were greater than SN slopes (p = 0.005, paired t-test).
Conclusions:
Although there are significant differences in the rate of RA loss between some sectors, the differences are small, when considered as a percentage of total RA. A similar frequency of significant RA loss occurs in each sector with the exception of the temporal which may have greater localised variability. Our results indicate that a ‘typical’ pattern of glaucomatous RA loss with ST/IT damage occurring first, may be over-emphasised; such patterns may represent an extreme phenotype, rather than the norm.
Keywords: imaging methods (CT, FA, ICG, MRI, OCT, RTA, SLO, ultrasound)