Several OCT Parameters Ruled Out As Indicator of Baseline Glaucoma Severity

Ophthalmology office.
Ophthalmology office. Masked patient and doctor – Covid 19. Scan of the retina, an examination that allows you to precisely visualize the different parts of the eye. This imaging makes it possible to observe the retina in order to detect, for example, a retinal uplift with edema or a diabetic retinopathy. It is used to monitor wet AMD about every two months and complements the fundus to see if an injection of treatment is needed. OCT is also used to examine the optic nerve, and therefore screen for or monitor glaucoma. (Photo by: Pascal Bachelet/BSIP/Universal Images Group via Getty Images)
Only GCL thickness was deemed a useful parameter for monitoring structural progression throughout the course of the disease.

Baseline glaucoma severity is not significantly associated with longitudinal rates of minimum rim width (MRW), peripapillary retinal nerve fiber layer (RNFL), or macular ganglion cell layer (GCL) thickness changes according to a prospective cohort study, published in the American Journal of Ophthalmology. However, the report shows that GCL thickness was “able to statistically contrast the rate of change between healthy [patients] and glaucoma patients throughout the disease spectrum.”

This study was carried out at 2 centers in Nova Scotia, Canada. Patients (n = 132) with glaucoma and healthy controls (n = 57) were assessed by optical coherence tomography (OCT) at least 5 times at 6-month intervals. The rate of change in MRW, RNFL, and GCL thickness were estimated and the change in these parameters was used to predict glaucoma severity.

Patients and controls were aged median 74.3 (IQR, 67.7-80.2) and 67.2 (IQR, 63.4-74.8) years, they had been evaluated by OCT 9 (IQR, 8-10) and 8 (IQR, 7-9) times, baseline MRW was 173 (IQR, 146-204) and 290 (IQR, 259-319) μm, RNFL thickness was 66 (IQR, 57-74) and 93 (IQR, 88-99) μm, and GCL was 37 (IQR, 32-41) and 49 (IQR, 46-51) μm, respectively.

During follow-up, the glaucoma and control cohorts had a similar proportion of individuals with significant reduction to MRW (52.3% vs 42.1%; P =.26), RNFL (46.2% vs 35.1%; P =.21), and GCL (51.5% vs 43.9%; P =.42) thickness.

After adjusting for covariates, the glaucoma cohort had a significantly faster rate of GCL thickness change compared with controls (mean group difference, -0.17 μm/year; P =.03) but not RNFL thickness (mean group difference, -0.09 μm/year; P =.54) or MRW change (mean group difference, -0.16 μm/year; P =.74).

Age was a significant covariate for GCL thickness change (-0.07 μm/year/year of age; P =.03).

This study may have been limited due to underrepresentation of patients with severe disease at baseline (9.8% had baseline visual field of -12 dB or worse).

In this longitudinal study, the investigators found that OCT monitoring of GCL thickness change over time may be a useful parameter for monitoring structural glaucoma progression but that longitudinal MRW, RNFL, or GCL thickness changes were not indicative of baseline disease severity.

Disclosure: Multiple authors declared affiliations with industry. Please refer to the original article for a full list of disclosures.

Reference

Kim YW, Sharpe GP, Hutchison DM, et al. Impact of glaucoma severity on rates of neuroretinal rim, retinal nerve fiber layer, and macular ganglion cell layer thickness change. Am J Ophthalmol. 2022;S0002-9394(22)00039-3. doi:10.1016/j.ajo.2022.01.019