Abstract
Purpose::
Aim of the study was to examine the dynamics of the RNFL-loss after AION over 10 weeks using GDxVCC.
Methods::
21 eyes of 21 patients (mean age 65) with AION and resulting inferior visual field defect were examined with the GDxVCC one to four days after first symptoms of visual dysfunction (baseline, BL). Follow up examinations were 2,4,6,8 and 10 weeks after baseline. 12 patients reached the end point after 10 weeks. The other patients left the study for unknown reasons and were excluded. After 10 weeks visual acuity and visual field (Humphrey Field Analyzer 30-2) were also obtained.
Results::
GDx-parameters (in % to baseline except NFI after 2,4,6,8 and 10 weeks) ± SD:RNFL average: 91±10, 86±13, 77±10, 73±9, 74±7; RNFL superior: 78±10, 70±9, 64±7, 61±9, 63±10; RNFL inferior: 103±15, 97±17, 85±18, 80±13, 77±11; RNFL SD.: 102±21, 95±21, 85±30, 78±23, 70±20; NFI (BL=19±10): 29±4, 39±13, 44±19, 52±13, 52±15Mean visual acuity at BL was 0.7±0.3 and MD was -24±9 dB. After 10 weeks mean visual acuity was 0.6±0.4 and MD=-21±8 dB. Only two patients had a decrease of visual acuity, 10 had an increase.
Conclusions::
In this pilot study the loss of RNFLT during AION was well detectable using GDxVCC. The greatest loss appeared between baseline and the second week. This shows a very early decrease of microtubules in the retinal nerve fibers. Loss in the superior hemisphere (opposite of the affected side in the visual field) was much higher than in the unaffected inferior part. We found a maximum loss of 61 % to the baseline RNFLT. The subjective impression of RNFL-loss was much higher. Anyhow, most of the patients had an increase of visual acuity and MD of visual field. One explanation for this difference could be that the base of measurement of GDxVCC is only the number of microtubules and not the number of axons or their functionality.
Keywords: nerve fiber layer • imaging/image analysis: clinical • optic nerve