Les lasers diagnostiques dans le glaucome : la polarimétrie à balayage laser (GDx VCC) et la tomographie confocale par balayage laser (HRT)

[GDx-VCC NFI analysis in Lebanese glaucoma patients]

PURPOSE

To describe the Nerve Fiber Indicator (Nerve Fiber Index; NFI) parameter findings and progression in Lebanese glaucoma patients or suspects.

STUDY DESIGN

Retrospective, observational study.

PATIENTS AND METHODS

A review was conducted of the GDx VCC examinations performed between January 2003 and December 2008 in an ophthalmological diagnostic center, in 1063 Lebanese subjects referred for this testing by their ophthalmologists. This group of subjects included confirmed glaucoma patients and glaucoma suspects. GDx VCC examination was repeated one or more times, at a one-year interval, in only 136 patients. Since we only had access to their GDx VCC examinations, the number of subjects in each category was unknown prior to the exam. After GDx VCC examination, we divided the subjects into three categories according to their NFI score. Subjects were considered to be normal when the NFI score was below 30, glaucoma suspects when the score was between 30 and 40, and confirmed glaucoma patients when the score was above 40.

RESULTS

Among the 1063 patients studied, 525 were female and 538 male, with a mean age of 56.8 ± 14.2 years at the time of examination. The mean NFI score was 27.01 ± 14.23, higher in males than females in the various age groups, and higher in older than in younger subjects, the greatest difference being between the 11- to 20-year and the 81- to 90-year age groups (P=0.015). Eight hundred and eighty patients had an NFI score within normal limits, the score was consistent with glaucoma suspect in 280 patients and with confirmed glaucoma in 103 patients. Among the 136 patients who underwent multiple GDx VCC examinations, 69 were initially classified as normal. Upon repeat GDx VCC examinations over a five year period, 24 of these 69 patients (34.78%) presented with scores consistent with glaucoma suspect or confirmed glaucoma.

CONCLUSION

This study demonstrates that glaucoma was detected or suspected in at least one of three subjects referred for GDx VCC examination (383/1063). NFI scores were higher in males than females and in older compared to younger subjects.

Comment s′assurer de la stabilité d′un glaucome ?

Exam of the optic nerve head and retinal nerve fibers is essential to firmly establishing whether glaucoma is stable. Stereoscopic examination of the optic disc (qualitative analysis) looks for modifications of the neuroretinal rim and of the cup, vascular modifications, and alterations of the retinal nerve fibers and of the peripapillary area. It can be usefully completed by photos. Although automatic analyzers (quantitative analysis) are clearly advantageous in the analyze of the retinal nerve fiber layers, they do not yet replace photographs or the clinical exam. In advanced stages of glaucoma, functional analysis is the most appropriate for assuring that the neuropathy is stable.

Glaucomes. Imagerie de la structure : HRT, GDx et OCT

Confocal scanning laser tomography (HRT), scanning laser polarimetry (GDx VCC), and optical coherence tomography provide quantitative data of the retinal fiber layer and optic nerve head. They have become good complementary evaluation tools for glaucomatous optic neuropathy and their results should be analyzed with clinical data. Good knowledge of the parameters they analyze and their limitations are indispensable. To monitor progression of structural involvement, the analysis programs used need to be validated with prospective clinical studies.