Normal-Tension Glaucoma closely associated with cognitive deficits: BMJ

The results of a recent study, which were published in the British Journal of Ophthalmology, show a link between normal-tension glaucoma (NTG) status and impaired cognition, supporting the idea that NTG and dementia share patho-etiological characteristics and a disease relationship.

A diverse set of ocular neuropathies known as glaucoma include abnormal optic disc cupping, retinal ganglion cell death, and distinct patterns of permanent vision field loss. The only risk factor for glaucoma that may be modified is increased intraocular pressure (IOP). Recent studies reveal a link between dementia-causing conditions like Alzheimer's Disease and primary open-angle glaucoma (POAG) (AD). A form of POAG known as NTG is characterized by glaucomatous retinal degeneration without obvious ocular pressure. Sean Mullany and colleagues used cognitive screening within an Australiasian Glaucoma Disease Registry to examine if cognitive impairment is more strongly connected with NTG than high tension glaucoma (HTG).

In this study, 290 NTG patients and HTG controls aged 65 or older were randomly selected from the Australian and New Zealand Registry of Advanced Glaucoma to participate in a case-control cross-sectional cognitive test. The telephone version of the Montreal Cognitive Assessment was used for cognitive screening (T-MoCA). In order to account for confounding issues linked to vision loss in individuals who are blind or visually impaired, the T-MoCA leaves out items that need visual interpretation. A T-MoCA score of 11/22 was used to define cognitive impairment. Using absolute screening scores and specified criteria, cognitive abilities were compared between NTG and HTG subjects.

The key findings of this study were:

1. 290 people in all completed the cognitive evaluation. At baseline, there were no differences in the demographics or ocular characteristics of the NTG (n=144) or HTG (n=146) cohorts.

2. In comparison to the HTG group, the NTG cohort had a higher prevalence of cognitive impairment.

3. Although there was a linear trend between the NTG cohort's lower absolute T-MoCA scores and the HTG cohort's higher absolute T-MoCA scores, this connection was not statistically important (p=0.108).

In conclusion, this NTG-dementia relationship may alter how NTG is perceived and shed light on potential future treatment trajectories. To clarify this NTG-dementia link in greater detail, additional study is necessary.

Reference: 

Mullany, S., Xiao, L., Qassim, A., Marshall, H., Gharahkhani, P., MacGregor, S., Hassall, M. M., Siggs, O. M., Souzeau, E., & Craig, J. E. (2022). Normal-tension glaucoma is associated with cognitive impairment. The British Journal of Ophthalmology, 106(7), 952–956. https://doi.org/10.1136/bjophthalmol-2020-317461