Faster Rates of GCIPL, cpRNFL Thinning Associated With Higher Risks of Glaucoma

Perimetric glaucoma had a higher risk of developing when rapid rates of ganglion cell/inner plexiform layer (GCIPL) and circumpapillary retinal nerve fiber layer (cpRNFL) thinning occurred, according to a study published in JAMA Ophthalmology.

Glaucoma, a progressive optic neuropathy caused by loss of retinal ganglion cells, is best detected through macular optical coherence tomography (OCT) that helps evaluate central retinal ganglion cells. This study aimed to predict glaucoma development by using the rates of change that are measured by macular OCT in eyes with suspected glaucoma.

This study collected data on patients who had enrolled in the University of California, San Diego–based Diagnostic Innovations in Glaucoma Study (DIGS) and the multicenter African Descent and Glaucoma Evaluation Study (ADAGES).

All participants had baseline gonioscopy, an annual comprehensive ophthalmologic evaluation, and pachymetry. Race and ethnicity data were collected due to glaucoma progression being linked to those factors.

Participants were included if they were older than 18 years, had a best-corrected visual acuity of 20/40 or better, and had open angles defined by gonioscopy. Participants were excluded if they had a history of intraocular surgery, had other intraocular diseases, had systemic diseases, had an axial length of 27 mm or greater, or had secondary causes of elevated intraocular pressure (IOP).

Participants with suspected glaucoma needed to have an elevated IOP of 22 mm Hg or higher or glaucomatous-appearing optic discs without visual field damage. They were also required to have 2 or more years of follow-up with 3 or more macular spectral domain (SD)–OCT scans.

A total of 658 eyes that had suspected glaucoma were included in this study. The mean number of OCT imaging tests was 5.5 and there was a mean follow-up of 3.2 years. A total of 153 eyes (23%) developed perimetric glaucoma in the follow-up period. The baseline age of patients with eyes without glaucoma was 62.2 years and the age of those with glaucoma was 66.6 years; 29% of patients who did not develop glaucoma and 35% of patients with eyes that did were African American.

The mean number of IOP-lowering medications that were being taken for eyes with suspected glaucoma was 0.72 (95% CI, 0.66-0.79) for eyes that did not develop glaucoma and 1.08 (95% CI, 0.95-1.21) for eyes that did.

Global GCIPL thickness was 76.4 μm (95% CI, 75.7-77.0) for eyes that had suspected glaucoma but did not develop glaucoma and 72.1 μm (95% CI, 70.7-73.6) for eyes that did develop glaucoma. Mean minimum GCIPL thickness for eyes that did not develop glaucoma was 73.5 μm (95% CI, 72.7-74.3), compared with 67.9 μm (95% CI, 66.3-69.6) for eyes that did.

Rates of GCIPL thinning were found to be faster in eyes with suspected glaucoma that did develop perimetric glaucoma. Mean rates of global GCIPL thinning were –0.38 μm/year (95% CI, –0.49 to –0.27) for eyes that did not develop glaucoma and –0.73 μm/year (95% CI, –0.92 to –0.53) for eyes that did; mean rates of minimum GCIPL thinning were –0.66 μm/year (95% CI, –0.91 to –0.40) and –1.28 μm/year (95% CI, –1.65 to –0.90), respectively.

A 1 μm/year faster rate of minimum GCIPL thinning was associated with 2.4 times higher risk of developing perimetric glaucoma (HR, 2.48; 95% CI, 1.87-3.28). A higher risk of developing perimetric glaucoma was found in participants who were African American (HR, 1.56; 95% CI, 1.05-2.34), were male (HR, 1.47; 95% CI, 1.02-2.15), had 1-dB higher baseline visual field pattern standard deviation (HR, 1.73; 95% CI, 1.56-1.91), and had 1-mm Hg higher mean IOP at follow up (HR, 1.11; 95% CI, 1.05-1.17).

The 24-2 visual field test was used to define the criteria for conversion to perimetric glaucoma, which may have led to underestimation of the development of perimetric glaucoma.

The researchers concluded that a faster rate of thinning in the GCIPL and cpRNFL led to a higher risk of the development of perimetric glaucoma in eyes that had suspected glaucoma.

Reference

Mohammadzadeh V, Moghimi S, Nishida T, et al. Association rates of ganglion cell and inner plexiform thinning with development of glaucoma in eyes with suspected glaucoma. JAMA Ophthalmol. Published online March 2, 2023. doi:10.1001/jamaophthalmol.2023.0005