Abstract
Purpose: :
To study optic nerve head (ONH) characteristics using confocal laser tomography (HRT) in a population of glaucoma patients and comparison to a normative database of 1933 healthy adults.
Methods: :
A total number of 339 patients (mean age 59.1 ±10.9 years; 193 women, 146 men) was included based on chart reviews. Patients were examined between 1994 and 2007. Inclusion criteria comprised: adult caucasian, diagnosed POAG / pseudoexfoliation glaucoma / pigment glaucoma or normal tension glaucoma according to EGS guidelines, refractive error ranging from -6 to 6 dpt, available visual field data on at least two visits. Pseudophacic and aphacic patients or patients with additional severe ocular pathology or neurological disease were excluded.The analysed data for each patient included ONH data obtained from HRT, visual acuity testing, slit lamp examination of anterior and posterior segment, Goldmann tonometry, computerised 30° field perimetry and a structured patient interview assessing peak IOP, earlier eye surgery, year of glaucoma diagnosis, IOP lowering medication, presence of systemic disease. For data evaluation the eye with the better mean-image quality was selected.
Results: :
The analysis of ONH topographies included 172 right and 167 left eyes. The mean refractive error was 0.11 ±1.88 dpt. Seventeen patients with pigmentary glaucoma, 33 with pseudoexfoliation glaucoma, 82 with NTG and 207 with POAG were included. Global HRT data displayed an overall mean disc area of 2.25 ± 0.47 mm2 , a mean cup area of 1.81 ±0.49 mm2, a mean cup to disc area ratio of 0.80 ±0.09 and a mean retinal fibre layer thickness of 0.176 ±0.082. The analysis of relative neuroretinal rim loss correlated to the loss of visual field function using the Aulhorn-Karmeyer classification. No relevant gender or age related differences were observed.
Conclusions: :
The presented data may be useful to create a larger basis for the classification of ONH characteristics in glaucomatous eyes. In comparison to other studies with smaller numbers of patients, this analysis could show the differences in global and focal HRT-parameters in relation to the actual functional damage measured with white-on-white perimetry. A significantly increased cup to disc area ratio even in patients with only mild visual field loss seems underline the existing structural damage on the optic nerve head even before a functional damage can be seen. Additionally glaucoma patients showed a significantly greater mean disc area than the healthy adults emerging from the comparison database, thereby indicating that a high disc area may be a possible risk factor for the development of glaucoma.
Keywords: optic disc • imaging/image analysis: clinical • laser