Abstract
Purpose: :
To compare the optic discs, as analyzed by CirrusTM HD-OCT, in eyes with dominant optic atrophy (DOA) and normal tension glaucoma (NTG) to those of healthy subjects.
Methods: :
Twenty-two eyes with DOA, 22 eyes with NTG and 38 healthy eyes were prospectively enrolled. For each subject, three scans were acquired on the same day with Cirrus (software version 4.0) using the Optic Disc Cube 200x200 protocol. The ONH analysis was performed on this data set using the Cirrus 5.0 pre-production software. The ONH parameters reported result from a fully-automatic algorithm that defines both the disc and cup margins within the 3d data cube. Data were compared by analysis of variance with Bonferroni post-test.
Results: :
Disc area of NTG eyes (2.06±0.30mm2) was not statistically larger than in healthy subjects (1.99±0.21mm2, p>0.05), whereas disc area of DOA eyes (1.80±0.34mm2) was smaller than in healthy (p<0.05) and NTG eyes (p<0.01). Rim area was larger in healthy eyes (1.36±0.27mm2) than in DOA eyes (1.10±0.15mm2, p<0.001) and in NTG eyes (0.77±0.27mm2, p<0.001); the difference between DOA and NTG eyes was statistically significant (p<0.001). Cup volume was larger in NTG eyes (0.49±0.15mm3) than in healthy and DOA eyes (respectively, 0.16±0.14 and 0.14±0.11mm3, both p<0.001 compared to NTG). Average retinal nerve fiber layer thickness was thinner in NTG (62.73±10.20µ) and DOA eyes (64.11±5.44µ) than in healthy subjects (90.63±10.41µ, p<0.001 for both comparisons), with no statistically significant difference between DOA and NTG.
Conclusions: :
Data from spectral-domain OCT confirmed previous studies showing that DOA feature a smaller optic disc than healthy subjects. Cirrus may help in differentiating between NTG and DOA eyes thanks to differences in area disc and cup volume (both larger in NTG) as well as in rim area (larger in DOA).
Keywords: optic nerve • imaging methods (CT, FA, ICG, MRI, OCT, RTA, SLO, ultrasound) • neuro-ophthalmology: optic nerve