The papilla as screening parameter for early diagnosis of glaucoma

Abstract

Introduction: In the industrialized countries 67 million people suffer from glaucoma, which represents the third most common cause of blindness and thus has a high economic impact. Early diagnosis of glaucoma, which does not necessarily involve raised intraocular pressure, is essential because by the time the patient notices functional impairment the damage is irreversible. Early treatment can decrease the rate of blindness 20 years later by about 50%.

Methods: Selective literature review and clinical investigation of early glaucoma detection and of screening methods.

Results: Currently, no evidence-based recommendations for glaucoma screening can be found in the literature. No single method or combination of screening procedures can be recommended unambiguously on economic grounds.

Discussion: From the clinical perspective sensitive, specific, and cost-effective glaucoma screening seems feasible. The high-risk group would need to be defined on the basis of age and family history. A two-stage screening process would then have to be established with initial computer-supported telemedical sorting followed by telemedical ophthalmological diagnosis of cases selected for clarification.

Keywords: early detection of disease; glaucoma; ophthalmology; prevention; telemedicine.

Figure 1

Prevalence of glaucoma as a function of age. Calculations of the incidence and prevalence of open-angle glaucoma are based on the glaucoma model of Quigley and Vitale (2). Data from 14 different population based studies went into this model. The model calculations relate to white (Caucasian) people. Mean prevalence rates from different publications are also shown. The values were taken from publications as follows: 1 from (3), 2 from (e5), and 3 from (e6).

Figure 2

Color papillary images showing different phases of glaucoma disease; a) healthy with regular margin, b) narrow, clearly visible nerve fiber defects in 2 h and 7 h, c) discrete focal nerve fiber defect in 12 h, d) wide nerve fiber defect in 6 h to 8 h, nerve fiber loss from 6 to 12 h, f) complete nerve fiber loss with deep papillary excavation. With permission from

Figure 3

Image processing steps of healthy and glaucomatous papillary: - color image, normalized color image with automatic vascular recognition (only green channel), green channel image focusing on papilla, with vascular segmentation and green channel image focused on papilla excluding vessels