Diagnosing and monitoring open-angle glaucoma. Pupillometry and other novel techniques

Abstract

Aim:To investigate the ability of a custom-built pupillometer and other novel diagnostic instruments to detect and monitor optic nerve damage in glaucoma.Methods:In the first two studies we investigated pupillary reactions to light in patients with glaucoma and in healthy persons using a custom-built pupillometer. In the first study, comprising 32 subjects, light reflexes were studied with five different sets of stimulus-pause combinations in order to find the optimum stimulus parameters. Using these parameters we examined 65 participants in the second study. In the third study frequency doubling technology perimetry (FDT) was compared with high-pass resolution perimetry (HRP) in 162 eyes. In the fourth study we conducted a long-term follow-up study of 25 persons with glaucoma and 34 with ocular hypertension in which we analyzed glaucomatous optic disc changes using Heidelberg Retina Tomography (HRT). Results:Study I-II: Alternating light stimulation with 0.5 sec stimulation and 1 sec darkness was shown to be optimum for detection of relative afferent pupillary defect (RAPD) in glaucoma. Quantification of RAPD based on calculations of pupil area ratio (PAR) was found to be the most sensitive for glaucoma detection. Study III: A strong correlation was found between FDT and HRP. Sensitivity and specificity of the FDT screening test for glaucoma detection were 92% and 88%, respectively.Study IV: Several HRT parameters showed significant difference between baseline and follow-up examination in a group of patients with progressive glaucomatous neuropathy. A well-defined distinction between the progressive and the stable group was found by comparing digitally processed HRT change images.Conclusions:Both pupillometry and FDT screening perimetry could distinguish eyes with glaucoma from normal eyes with a good sensitivity and specificity. HRT proved useful for long-term follow-up of glaucomatous optic neuropathy and is an important adjunct to optic disc photography and visual field test for the monitoring of glaucoma progression.