Abstract
Purpose :
Glaucoma diagnosis in high myopia (HM) eyes is challenging. We tested the hypothesis that HM-glaucoma (HM-G) can be detected through disproportionate retinal ganglion cell (RGC) thinning, relative to deep retina layer (DRL) thickness.
Methods :
Cross-sectional observational study on single eyes from 110 HM no glaucoma (HM-NG) subjects, 81 HM-G (42 high tension, HM-HTG; 39 normal tension, HM-NTG) subjects. HM was defined as axial length (AL)≥26mm. HM-NG included intraocular pressure (IOP)≤21mmHg, visual field index (VFI)≥97% and glaucoma hemifield test (GHT) within normal limits on two consecutive reliable tests. HM-G included focal superior and/or inferior neuro-retinal rim thinning with corresponding VF defects and GHT outside normal limits on two consecutive reliable tests. HM-HTG and HM-NTG were based on highest IOP>21mmHg and ≤21mmHg, respectively. Exclusion criteria were chorioretinal lesions or other ocular/neurological conditions. Measurements from macula spectral-domain optical coherence tomography scans were corrected for AL, age and gender. Disproportionate thinning was based on Pearson correlation between retinal nerve fiber layer (RNFL), ganglion cell complex (GCC), or ganglion cell inner plexiform layer (GCIPL) thickness and inner nuclear layer to retinal pigment epithelial layer (DRL) thickness, comparing HM-NG with combined HM-G,HM-HTG or HM-NTG using Wald test. Area Under the Receiver Operating Characteristics Curve (AUC) using RNFL, GCC or GCIPL/DRL ratios were also estimated.
Results :
HM-G compared to HM-NG showed disproportionate RNFL thinning in the inferotemporal (IT) (-0.27vs0.03,p=0.046), and GCIPL thinning in the superior (S) sectors (-0.20vs0.13,p=0.037). HM-HTG showed significant disproportionate RGC-layer thinning in the inferior, superonasal, IT, S, inferonasal sectors and globally. HM-NTG showed significant RGC-layer thinning superiorly (Table 1). Highest AUC for RGC/DRL ratios were 0.84(0.77,0.91), 0.87(0.79,0.95), 0.81(0.72,0.89) in HM-G, HM-HTG and HM-NTG using GCIPL/DRL in IT sector. There was no difference in age, gender, VFI, mean deviation or AL between HM-HTG and HM-NTG (Table 2).
Conclusions :
HM-HTG and HM-NTG show different patterns of RGC-specific thinning. HM-NTG may contain a subgroup of myopic optic neuropathy with proportionate RGC and DRL thinning. GCIPL/DRL ratio has excellent diagnostic accuracy for all types of HM-glaucoma.
This abstract was presented at the 2023 ARVO Annual Meeting, held in New Orleans, LA, April 23-27, 2023.