Rates of RNFL Thinning in Patients with Suspected or Confirmed Glaucoma Receiving Unilateral Intravitreal Injections for Exudative AMD

Abstract

Purpose: This study evaluated whether the rate of retinal nerve fiber layer (RNFL) thinning is faster in eyes receiving intravitreal injections than in fellow uninjected eyes among patients suspected of having or confirmed to have glaucoma and exudative age-related macular degeneration (AMD).

Design: Retrospective comparative cohort study.

Methods: Patients with a diagnosis of unilateral exudative AMD and confirmed to have or suspected of having glaucoma in both eyes receiving unilateral intravitreal injections were identified. Those with ≥3 RNFL optical coherence tomography scans and ≥6 injections were included in the study. Rates of RNFL thinning in the injected eye versus the uninjected eye were estimated using linear mixed models. The main outcome measurement was the differences in rates of RNFL thinning in the injected versus the fellow uninjected eye. The effects of postinjection elevation of intraocular pressure (IOP), injection frequency, and number of injections were also evaluated.

Results: A total of 53 patients met the inclusion criteria, receiving 26.4 ± 15.9 intravitreal injections. The average rate of RNFL thinning in uninjected eyes was -0.620 μm/year (P = .029). Injected eyes had an additional incremental loss of -0.385 μm/year, but this value was not statistically significant (95% confidence interval [CI]: -1.147 to 0.379 μm/year; P = .324). Subgroup analysis with only glaucoma patients (n = 33) also demonstrated a nonsignificant effect of injections (-0.568 μm/year; 95% CI: -1.454 to 0.319 μm/year; P = .212). Postinjection IOP elevation, injection frequency, and total number of injections were not associated with faster RNFL loss.

Conclusions: Among exudative AMD patients with glaucoma or suspected of having glaucoma, the rate of RNFL thinning in eyes receiving intravitreal injections did not significantly differ from that of fellow uninjected eyes.

Figure 1.

Retinal nerve fiber layer (RNFL) thickness versus time in injected and fellow uninjected eyes with mean regression slopes of the two groups.

Figure 2.

Differences between the rates of retinal nerve fiber layer (RNFL) thinning (injected eye minus uninjected eye) versus (A) injection frequency (number of injections per year), and (B) total number of injections.

Figure 3.

Differences between the rates of retinal nerve fiber layer (RNFL) thinning (injected eye minus uninjected eye) versus mean of differences in intraocular pressure after intravitreal injection.

Figure 4.

Comparison of retinal nerve fiber layer (RNFL) thickness over time in two patients receiving unilateral intravitreal injections. (A) Patient 1 is a 60-year old female with mild primary open-angle glaucoma (POAG) who received 50 total injections at a rate of 7.6 injections per year. The patient had intraocular pressures (IOPs) of 14 and 12 mmHg in the injected and uninjected eyes respectively on two glaucoma medications in both eyes at the beginning of the study period. (B) Patient 2 is an 80-year old female with POAG (indeterminate stage) who received 41 total injections at a rate of 4.6 injections per year. The patient had IOPs of 17 and 15 mmHg in the injected and uninjected eyes respectively on two glaucoma medications in both eyes at the beginning of the study period. Lines represent regressions from the linear mixed model for the uninjected (orange) and injected (turquoise) eyes.