PURPOSE:Short-wavelength automated perimetry (SWAP) has been claimed to predict conversion to glaucoma 3 to 4 years before standard automated perimetry (SAP) defects occur. This study compared the moment of glaucomatous conversion between SWAP and SAP. DESIGN:Prospective, longitudinal follow-up study. PARTICIPANTS:Four hundred sixteen subjects with ocular hypertension (intraocular pressure >/=22 and </=32 mmHg and normal visual fields). METHODS:A Humphrey Field Analyzer (24-2 program; Carl Zeiss Meditec, Dublin, CA) was used to perform both SWAP and SAP. All participants were tested once every half year during 7 to 10 years or until the onset of conversion (study end point). The conversion to glaucoma was defined as a reproducible glaucomatous visual field defect in SAP. MAIN OUTCOME MEASURES:The moment of onset of a reproducible defect in SAP was compared with that in SWAP. RESULTS:Of the 416 initial participants, 24 eyes of 21 subjects showed conversion in SAP. Of these eyes, 22 did not show earlier conversion in SWAP than in SAP. Standard automated perimetry even showed earlier conversion than SWAP in 15 cases. In only 2 eyes did SWAP show earlier conversion by up to 18 months. CONCLUSIONS:These results do not support the notion that SWAP generally predicts conversion to glaucoma in SAP. Instead, SAP appears to be at least as sensitive to conversion as SWAP in a large majority of eyes. FINANCIAL DISCLOSURE(S):The author(s) have no proprietary or commercial interest in any materials discussed in this article.

textabstractGlaucoma is the second leading cause of irreversible blindness worldwide. When left untreated, glaucoma results in visual field loss and eventually in blindness. In considering the diagnosis of glaucoma, the physician will evaluate the intraocular pressure, the optic nerve head and the visual field. This seems to be a straightforward diagnostic process, but, surprisingly, there is still no consensus on the criteria for the signs on which the diagnosis is based. Glaucoma is a progressive optic neuropathy characterized by death of retinal ganglion cells. The course of events that eventually leads to death of these cells is not exactly known, but the retinal nerve fiber layer, which is made up of the axons of the retinal ganglion cells, thins. Scanning laser polarimetry is an imaging technique that can detect glaucoma by assessing the thickness of the retinal nerve fiber layer. Scanning laser polarimetry came onto the market in 1993. The working principle is based on the fact that in the nerve fiber layer a phase shift occurs in polarized laser light that is sent through the nerve fiber layer. This so called retardation is thought to be linearly correlated with nerve fiber layer thickness. In the past, scanning laser polarimetry has shown to discriminate well between normal and glaucomatous eyes. The goal of this thesis was to investigate the clinical performance of the GDx (a revised version of the first scanning laser polarimeter, the Nerve Fiber Analyzer). In summary, the GDx provides fast, objective and quantitative data on nerve fiber layer thickness. The applicability and reproducibility of measurements are high and the image acquisition is user and patient friendly. The GDx yields useful sensitivity and specificity values for the detection of glaucoma, whereas its role in follow-up remains to be investigated. As it stands, the GDx holds insufficient validity to serve as a single test for glaucoma. It does, however, provide a very useful addition to the existing tests we run in patients to make the correct diagnosis.

Purpose: To compare the visualization of localized retinal nerve fiber layer (RNFL) defects in GDx images with fixed and with individualized compensation of anterior segment birefringence (FC and IC, respectively) with their visualization in red-free fundus photographs.Design: Observational case series.Participants: Eight eyes of six glaucoma patients with localized, wedge-shaped RNFL defects in red-free fundus photographs with matching visual field defects.Methods: We imaged all eyes with a GDx equipped with a variable corneal compensator (VCC). The VCC replaced the standard fixed compensator and could be set to compensate for birefringence of up to 120 nm at any axis. Individual anterior segment birefringence was estimated from a macular retardation profile that resulted from the interaction between birefringence of the anterior segment and that of Henle's fiber layer. Measurements of RNFL retardation were made with the GDx with FC (60 nm of retardation with a slow axis of 15degrees nasally downward) and with IC. Maps of retardation measurements with FC and IC were superimposed on red-free fundus photographs.Main Outcome Measures: Visualization of localized RNFL defects.Results: Localized RNFL defects were visible in GDx retardation maps obtained with IC. The defects closely matched those observed in red-free fundus photographs. With FC, however, the GDx retardation images did not correlate well with red-free fundus photography.Conclusions: An individualized anterior segment compensation in the GDx improves the visualization of localized glaucomatous loss. (C) 2003 by the American Academy of Ophthalmology.