Abstract
Abstract: :
Purpose: To study the development of glaucomatous damage in patients with ocular hypertension (OHT). In eyes who had recently converted to glaucoma we specifically investigated (1) whether SLP would classify these eyes as abnormal, (2) whether SLP was able to detect the progressive nerve fiber layer (NFL) thinning that was assumed to have occurred in these eyes since baseline and (3) whether SWAP would classify these eyes as abnormal at time of conversion. Methods: 410 patients with OHT (22 mm Hg <IOP <32 mm Hg) were prospectively followed for 5 years. Of this group, 1/3 was assigned to a placebo treatment, 1/3 to topical timolol and 1/3 to topical betaxolol treatment. SLP measurements with standard corneal compensation (GDx NFA, Laser Diagnostic Technologies, San Diego, USA) and visual field tests (Humphrey Field Analyzer 24–2 full threshold program; both standard automated perimetry (SAP) and SWAP) were performed every 6 months. Conversion to glaucoma was defined as a reproducible glaucomatous visual field loss on SAP that matched any glaucomatous optic disc abnormalities. An abnormal GDx NFA scan was defined as a "The Number" parameter >30. Progressive NFL thinning was defined as a decrease of the superior maximum or inferior maximum parameter greater than their 95% limits of agreement (Colen et al. J Glau 2000). Results: After 5 years, 12 eyes of 11 patients had converted to glaucoma. The percentage of these eyes that were classified as abnormal at the time of conversion by GDx "The Number", progressive NFL thinning and SWAP was 30%, 50% and 25% respectively. In the eyes that showed NFL thinning the decrease in superior and inferior maximum parameter averaged 11.3µ. Conclusions: 1. The GDx NFA "The Number" parameter was not very sensitive to early glaucomatous damage. 2. Progressive NFL thinning could be detected by the GDx NFA in half the eyes that had developed glaucoma. 3. Most patients who had just converted to glaucoma had normal SWAP results.
Keywords: imaging/image analysis: clinical • nerve fiber layer • perimetry