When a patient experiences acute primary angle closure, it’s an urgent situation. Even if they’re able to make it to a doctor for timely treatment, angle closure patients still aren’t out of the woods. They’re prone to progressing glaucomatous damage for which they’ll require continued disease monitoring. A new study in the British Journal of Ophthalmology shows a more precise timeline of what optometrists can monitor and how they can predict progression.

The study noted early reductions of vessel density and long-term decrease in retinal nerve fiber layer (RNFL) thickness in the first eight months following acute angle closure. Reduced vessel density at two months was the best predictor of conversion to an abnormal RNFL thickness, according to the investigators.

The researchers used OCT and OCT angiography to evaluate the RNFL thicknesses of 26 patients who were successfully treated for acute angle closure. The patients were evaluated two and eight months after their initial episode. All subjects experienced their angle closures unilaterally, leaving the unaffected eye as a control.

The team found that, at a mean of 94µm, RNFL thicknesses were significantly thinner in the affected eye than in the unaffected fellow eye, which had a mean of 103.1µm after two months. After eight months, the affected eyes thinned even more, to 89.5µm, but the unaffected eyes stayed the same. Although vessel density was significantly lower in affected eyes after two months, no significant change was noted between two and eight months. In the multivariate analysis, the only factor that was associated with RNFL progression was lower vessel density at two months.

Glaucomatous progression should be suspected in eyes with lower vessel density even after remission of an episode of acute primary angle closure, the investigators concluded in their paper.