[GDx-VCC NFI analysis in Lebanese glaucoma patients]

Abstract

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.