Abstract
Purpose:
In eyes affected by optic neuropathy (ONEs) the functional impairment is associated with anatomical changes of the macula related to loss of cells involved in the disease. SD-OCT allows the segmentation of perifoveal ganglion cells layer (PGCL). Our study is aimed to compare the PGCL thickness with flicker sensitivity (FS) evaluated by means frequency-doubling perimetry in different type of ONEs
Methods:
Thirty-six ONEs of 36 patients, mean age 54.33±16.82 years, 20 F and 16 M, were studied. The ONEs group consisted of: 11 glaucoma (GEs), 12 early-glaucoma (EGEs), 6 compressive optic neuropathy (CEs) and 7 multiple sclerosis optic neuritis eyes (MSEs). All subjects had ametropia <3D and underwent clinical examination including VA evaluation using ETDRS chart, slit-lamp biomicroscopy with +90D lens and visual field testing with frequency doubling technology (FDT). The PGCL was studied with a SD-OCT (Cirrus 4000, Carl Zeiss Meditec, Inc) using the 512×128 scan pattern where a 6×6 mm area on the retina is scanned. The software (ver. 6.0) performed the segmentation of PGCL and calculated the mean thickness of 6 perifoveal sectors, supero-nasal (SN), supero-central (SC), supero-temporal (ST), infero-nasal (IN), infero-central (IC), infero-temporal (IT). The FS of the corresponding visual field areas was evaluated with a FDT perimeter (Humphrey Matrix, Carl Zeiss Meditec, Inc), to elicit a more selective response from GC, using the threshold test 10-2 . Data from sectors underwent to linear regression analysis. A level of p<0.05 was accepted as statistically significant
Results:
A significant correlation between PGCL thickness and FS was found. The correlation in each sector was as follows: SN R=0.51, p=0.001; SC R=0.38, p=0.020; ST R=0.54, p<0.000; IN R=0.72, p<0.000; IC R=0.58, p<0.000; IT R=0.64, p<0.000. Overall correlation for all sectors was R=0.72, p<0.000. Subgroup analysis showed no overall correlation in MSEs (R=0.24, p=0,603), whereas the other subgroups showed significant correlation (GEs R=0.73, p=0,010; EGEs R=0.82, p<0.000; CEs R=0.96, p<0.000)
Conclusions:
These data are consistent with the hypothesis that in ONEs the functional defects are related to cell loss in the PGCL. However, probably the pattern of GC loss depends on the type of ON. In MSEs the thickness of PGCL does not correlate with FS; it is possible that in MSEs most of the GC lost were not involved in the FS response
Keywords: 552 imaging methods (CT, FA, ICG, MRI, OCT, RTA, SLO, ultrasound) •
629 optic nerve