Glaucoma worsens faster in longer eyes

Glaucoma tends to be more severe and to progress quicker in the longer eye when there is an axial length difference of >1.0 mm, reveals a study. 

Between 2010 and 2020, 95 patients (mean age 51.2 years) with a diagnosis of glaucoma in both eyes with an axial length difference of >1.00 mm at Seoul National University Hospital, Seoul, Korea, were included in this long-term observational study. 

A total of 190 eyes were analysed and classified into longer and shorter eyes. The research team then used the paired T-test and McNemar test to examine the baseline and follow-up clinical data of the participants. Differences in clinical characteristics in patients with asymmetric axial length served as the primary endpoint. 

Over a mean follow-up of 10.1 years, no difference was observed in baseline intraocular pressure (IOP) or central corneal thickness between longer and shorter eyes. 

Longer eyes tended to have larger ovality index, β-zone, and γ-zone parapapillary atrophy (PPA) area (p<0.001) among the baseline disc parameters. Longer eyes also showed thinner retinal nerve fibre layer (RNFL) thickness (p=0.009) and ganglion cell–inner plexiform layer (GCIPL) thickness (p<0.001) in the baseline OCT data. 

Moreover, the results of a baseline visual field (VF) test showed significantly lower mean deviation (p<0.001) and VF index (VFI) values (p=0.034) in the longer eyes. 

Analysis of glaucoma progression revealed a greater rate of change of superior GCIPL (longer eyes: –0.65 μm/year; shorter eyes: –0.40 μm/year; p=0.006), mean deviation (longer eyes: –0.40 dB/year; shorter eyes: –0.21 dB/year; p=0.005), and VFI (longer eyes: –0.92 percent/year; shorter eyes: –0.46 percent/year; p<0.001) in the longer eyes. 

“Additionally, the greater the difference in IOP fluctuation, the greater the difference in the rate of change between mean deviation and VFI,” the researchers said.