97th DOG Annual Meeting 1999
CAPILLARY DENSITY OF THE JUXTAPAPILLARY RETINA IS DECREASED IN LOW TENSION GLAUCOMA.
G. Michelson, J. Harazny, J. K. E. Welzenbach
Purpose: To estimate non-invasively capillary density of the juxtapapillary retina in eyes with Low Tension Glaucoma (LTG).
Method: Capillary density of the juxtapapillary area and rim area was studied in 93 eyes of 71 normal subjects (mean age 57±8 years, mean defect 0.8±0.23 dB, IOP 16±2mmHg) and in 29 eyes of 15 patients with LTG (mean age 60±8 years, mean defect 6.5±5.6 dB, IOP 15±3mmHg). Capillary density of the superficial capillaries of the temporal and nasal juxtapapillary retina was measured by "Automatic full-field perfusion image analyze" (AFFPIA) (Michelson et al, BJO 1998;82:1294-1300). The base of the capillary density calculation by AFFPIA was the whole perfusion-image gained by the Scanning Laser Doppler Flowmeter (HRF, Heidelberg Engineering). The capillaries and vessels of the retinal vessel tree were identified automatically by pattern-analysis. Based on the whole perfusion-image the distances of each retinal site to the next capillary or vessel were estimated in um. Intraobserver reliability was estimated by measuring 10 eyes of 10 subjects at 5 different days by one observer. Interobserver reliability of AFFPIA was evaluated by analyzing 10 perfusion maps by 5 different operators. For statistical analysis non-parametric Mann-Whitney-Wilcoxon tests were performed.
Results: The coefficient of reliability of the intraobserver reproducibility and interobserver reproducibility was 0.74, and 0.95, respectively. In LTG the mean distance to the next capillary was significantly increased with 28±11 um (control 21±6.5 um, p<0.00001). 12% of retinal sites in LTG-eyes (control 4%, p<0.0001) showed distances to the next capillary of greater than 60um.
Conclusion: Scanning Laser Doppler Flowmetry allows to evaluate the density of the capillary meshwork. We found, that LTG is associated with a decreased density of capillaries in the juxtapapillary retinal area.
Supported by DFG, SFB 539
Dpt. of Ophthalmology, University of Erlangen-Nürnberg