Abstract
Purpose:
In eyes affected by optic neuropathy (ONEs) visual field defects are due to dysfunction of neural elements of the retina; functional impairment is associated with macular thinning related to loss of cells involved in the disease. A software of spectral domain (SD) OCT allows the segmentation of perifoveal ganglion cells layer (PGCL). Our study is aimed to evaluate by means of SD-OCT and frequency-doubling technology (FDT) perimetry the correlation between anatomical and functional changes occurring in different type of ONEs
Methods:
Twenty-eight ONEs of 28 patients, mean age 56.28±14.52 years, 14 F and 14 M, was studied. The ONEs group consisted of: 9 glaucoma, 11 early-glaucoma, 4 compressive optic neuropathy and 4 multiple sclerosis optic neuropathy eyes. 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. 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 macula is scanned. The software (ver. 6.0) performs the segmentation of PGCL with an automated algorithm and produces a map with the mean thickness of 6 radial sectors, supero-nasal (SN), supero-central (SC), supero-temporal (ST), infero-nasal (IN), infero-central (IC), infero-temporal (IT). The flicker sensitivity (FS) of the corresponding visual field areas was evaluated using a FDT perimeter (Humphrey Matrix, Carl Zeiss Meditec, Inc) using the test 10-2, threshold strategy, to elicit a more selective response of ganglion cells. The data from homologous 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 in each homologous sector was found. The correlation in each sector was as follows: SN r=0.62, p=0.0004; SC r=0.46, p=0.0134; ST r=0.57, p=0.0017; IN r=0.77, p=1.97 10-6; IC r=0.62, p=0.0004; IT r=0.64, p=0.0002
Conclusions:
These data show that functional defects in ONEs are related to thinning of the PGCL. We believe that PGCL maps could have an important role in the diagnosis and the follow-up of optic neuropathies
Keywords: 531 ganglion cells •
642 perimetry •
612 neuro-ophthalmology: diagnosis