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J Tan, D Poinoosawmy, R Hitchings; Progression at the Optic Nerve Head in Ocular Hypertension and Normal Pressure Glaucoma . Invest. Ophthalmol. Vis. Sci. 2002;43(13):929.
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© ARVO (1962-2015); The Authors (2016-present)
Purpose: To apply scanning laser tomography to studying changes at the optic nerve head (ONH) in people with: 1) ocular hypertension (OHT) who developed perimetric abnormality (converters), 2) asymmetrical normal pressure glaucoma (NPG), and 3) normal controls. Methods: We used a previously described approach for studying ONH change in Heidelberg Retina Tomograph images (ARVO 2001). This method: 1) analyses rim area in 30 degree sectors, 2) uses a novel and reproducible reference plane, positioned to suit the morphology of each ONH, 3) accounts for measurement variability in each eye separately, and 4) requires that change is repeatable in at least 2/3 consecutive images. Measurement variability in each sector of each ONH was defined by statistical limits; an ONH was considered changed if at least one sector exceeded its limit of variability. We studied: for OHT converters (n=29), only the side that converted; for asymmetrical NPG (n=26), the eye with normal visual fields; and for normal controls (n=26), one randomly selected eye. Each subject had sequential images from over at least three years. Results: Confirmed change in rim area was found in 26/29 of converters (90%), 13/26 of NPG subjects (50%) and 2/26 of controls (8%). 6/26 NPG subjects (23%) developed reproducible perimetric abnormality over the follow-up; of this, rim area in 5/6 (83%) was found to have changed. The pattern of regional change in OHT converters and NPG was similar, with change in both found most often inferotemporally. Conclusion: A high proportion of eyes that progressed on visual fields were identified as having accompanying changes in rim area using this approach. Very few controls showed ONH change. Our findings also suggest that some subjects with asymmetrical NPG had progressive glaucoma in their eyes with normal visual fields.
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