Abstract
Purpose:
In a previous study, we could show that central macular thickness correlates with central retinal function in the induced components of the 2-global flash multifocal ERG (2F-mfERG) in primary open angle glaucoma (POAG) patients. Here we investigate, if a separate analysis of the segmented macular ganglion cell layer rather than the full thickness analysis of the central retina will increase structure function correlation.
Methods:
20 eyes were examined with OCT, 2F-mfERG and automated perimetry (AP): 6 preperimetric glaucoma (PPG), 10 POAG and 4 controls. OCT: fast macular thickness protocol (Cirrus SD-OCT, Carl Zeiss), AP: (Octopus 101,G2) and 2F- mfERG (VERIS 6.06TM, FMSIII): bandpass filter (BPF): 1-300Hz, 103 Hexagons, M-sequence stimulus 2^13: LMax 100cd/m^2, Lmin<1cd/m^2, global flash:200cd/m^2. For analysis: OCT: full macular thickness (mT) and macular ganglion cell thickness (mGC:GCL+IPL) as per Cirrus software. 2F-mfERG: Responses filtered at 1-200Hz. RMS was calculated for the focal flash response at 15-45ms (DC) and global flash responses at 45-75ms (IC1) and 75-105ms (IC2). AP: MS, MD and sLV values in dB. Results were analyzed for the retinal central 5° radius. Statistical analysis was performed using linear and linear mixed effects models in the statistical package R version 3.0.2.
Results:
Mean mT was 294.6µm (SD±20.05) in patients and 310.1μm (SD±13.21) in controls. Mean mGC in patients was 62.49µm (SD±9.93) and 84.02 μm (SD±3.27) in controls. In correlation to the mfERG, mT showed an overall trend (p=0.05), but the mGC correlated significantly and in all epochs. The mfERG showed a significant correlation with sLV in POAG, but not in controls. In POAG MD and MS correlated significantly with mGC. Interestingly 37.5% (6) of the analyzed patients had no AP central defect, but central mfERG and mGC alterations. Only 1 patient had a central AP defect associated with reduced mGC without detectable dysfunction on mfERG.
Conclusions:
Structure function analysis in glaucoma correlates better when mGC thickness is included rather than just mT. The mfERG correlates well with structure, which adds information on function especially in PPG where AP are normal but the mfERG may be abnormal.
Keywords: 507 electrophysiology: clinical •
758 visual fields •
552 imaging methods (CT, FA, ICG, MRI, OCT, RTA, SLO, ultrasound)