Increased IOP closely associated with retinal microvascular loss

Increased intraocular pressure (IOP) measurements were linked to quicker rates of total retinal microvascular loss, says an article published in British Journal of Ophthalmology.

Elevated IOP is the most major risk factor for glaucoma, and epidemiological research shows that normal ocular pressure ranges between 10 and 21 mmHg. However, the threshold IOP level at which glaucoma damage starts differs from person to person. In order to assess the link between intraocular pressure and the rate of macula whole image vascular density (wiVD) loss and whole image ganglion cell complex (wiGCC) thinning in glaucoma, Golnoush Mahmoudinezhad and peers undertook this study.

The Diagnostic Innovations in Glaucoma Study included 62 patients, with 59 having primary open-angle glaucoma and 27 having glaucoma suspect eyes, with a mean follow-up of 3.2 years. The vascular density and structural thickness of the same 6 mm GCC scan slab were assessed using optical coherence tomography angiography (OCT-A). To explore the influence of IOP factors on the rate of wiVD and wiGCC change, univariable and multivariable linear mixed models were done for all eyes and a selection of those with peak IOP of 18 mm Hg.

The key findings of this study were:

1. The mean baseline deviation in the visual field (95% CI) was 3.3 dB (4.4 to -2.1).

2. Higher mean IOP (0.07%/year per 1 mm Hg (0.14 to -0.01), p=0.033), peak IOP (0.07%/year per 1 mm Hg (0.13 to -0.02), p=0.004), and IOP fluctuation (IOP SD) (0.17%/year per 1 mm Hg (0.32 to 0.02), p=0.026) were linked to quicker retinal vascular density reduction.

3. Higher mean IOP (0.05 m/year per 1 mm Hg (0.10 to -0.01), p=0.015), peak IOP (0.05 m/year per 1 mm Hg (0.08 to -0.02), p=0.003), and IOP variation (0.112 m/year per 1 mm Hg (0.22 to -0.01), p=0.032) were related with faster wiGCC thinning.

4. Faster wiVD development was linked with higher mean IOP in eyes with a peak IOP of 18 mm Hg (p=0.042).

5. In these eyes, faster wiGCC development was linked with higher mean IOP (p=0.025).

Reference:

Mahmoudinezhad, G., Moghimi, S., Nishida, T., Micheletti, E., Du, K. H., Mohammadzadeh, V., Wu, J.-H., Kamalipour, A., & Weinreb, R. N. (2022). Intraocular pressure increases the rate of macular vessel density loss in glaucoma. In British Journal of Ophthalmology (p. bjo-2022-322261). BMJ. https://doi.org/10.1136/bjo-2022-322261