Abstract
Purpose: :
To evaluate the changes in the classification results of HRT III optic disc topography with small modifications of the contour line.
Methods: :
Cross sectional study. Consecutive evaluation of the optic nerve of 113 eyes with diagnosis of normality, ocular hypertension (OHT) or glaucoma were included in this study. All subjects were examined with Humphrey perimetry (24-2 SITA standard), disc photographs, and Confocal Scanning Laser Ophthalmoscopy (HRT-III, Heidelberg Engineering). Only eyes with good quality images (SD < 25µ) and reliable fields were included.
Results: :
Modifications in the global MRA classification occurred in 49 images (10%) of 452 images with modified contour line and in 27 eyes (23%). Changes were found in 23 images (5%), 52 (11%), 61 (13%), 12 (2%), 63 (13%) and 58 (12%) of MRA temporal, superior-temporal, inferior temporal, nasal, superior nasal, and inferior nasal MRA classification, respectively. Changes in Global MRA tended to be more frequent in eyes glaucoma (27%) and OHT (30%) than in normal eyes (18%) but the difference was not significant. Smaller disk size was related to a greater frequency of classification changes (p<0.05)
Conclusions: :
Slight modifications of the contour line can alter the classification of the HRT-III. Careful placement of the contour line is recommended.
Keywords: imaging/image analysis: clinical • clinical (human) or epidemiologic studies: systems/equipment/techniques • optic nerve