RNFL Thickness Associated With Pseudophakic Cystoid Macular Edema

The retinal nerve fiber layer (RNFL) was found to be thicker in patients’ eyes with pseudophakic cystoid macular edema (PCME) compared with their healthy eye, according to a study published in the European Journal of Ophthalmology.

PCME is a leading cause of reduced vision after having surgery for cataracts and vitreoretinal surgery. Incidence of clinical CME, which decreases visual acuity, ranges from 0.1% to 2.35% whereas angiographic CME, which is CME without vision loss, can occur in up to 20% of surgeries. PCME can be detected through optical coherence tomography (OCT), but is unknown how assessing the RNFL can be beneficial for determining changes in PCME. The current study aimed to “investigate the effects of PCME on RNFL thickness before and after medical treatment using spectral-domain OCT.”

Female eye with long eyelashes close-up | Image credit: Vladimir Voronin - stock.adobe.com

Patients were observed in a retrospective observational study from February 2015 to April 2021. All patients were recruited from Meir Medical Center in Kfar Saba and Rabin Medical Center in Petach Tikva, both in Israel. PCME was identified by using OCT, and fluorescein angiography was performed for all patients to rule out any other pathologies. OCT was performed for both a patient’s study eye, which had PCME, and the patient’s other eye, serving as a healthy control eye. All patients were treated using nonsteroidal anti-inflammatory drugs, topical steroids, dorzolamide, or an injection of triamcinolone.

Patients who were treated with anti–vascular endothelial growth factor injections or had high myopia, a history of retinal detachment, central serous chorioretinopathy, diabetic retinopathy, macular telangiectasias, central or branch retinal vein occlusions, glaucoma, optic neuropathy of any kind, tractional and degenerative lamellar macular holes, central or branch retinal artery occlusion, any inability to perform OCT, or a nonreadable OCT were excluded from this study.

There were 40 eyes from 40 patients included in this study. The mean (SD) age of the patients was 71.1 (8.1) years and 45% were men. Patients were diagnosed with PCME a mean (SD) 4.1 (5.7) months after surgery.

The PCME eye was found to have significantly higher central thickness when compared with the healthy eye (515.7 [127.9] μm vs 238.1 [41.8] μm). Greater global, superonasal, and superotemporal thickness values were found in the PCME eyes compared with the healthy eyes. Temporal, inferotemporal, inferonasal, and nasal thickness had no significant differences between the 2 eyes.

Visual acuity was 0.59 (0.23) logMAR, equivalent to Snellen 20/78, at presentation and 0.34 (0.22) logMAR, or Snellen 20/44, at follow-up 6 months later. Resolution of CME prompted a significant decrease in thickness in all macular and RNFL parameters in edematous eyes. This reduction was greater in PCME and edematous eyes compared with healthy eyes. RNFL thickness was similar in PCME and healthy eyes after the resolution of PCME; this included a mean (SD) thickness of 91.9 (19.6) in PCME eyes and 92.8 (21.1) in the healthy eyes.

A binary logistic regression analysis found that global thickness (odds ratio [OR], 1.12; 95% CI, 1.01-1.24) and inferotemporal thickness (OR, 0.97; 95% CI, 0.95-0.99) were significantly associated with CME at baseline.

There were some limitations to this study. The study had a retrospective design and a small sample size, and macular ganglion cell thickness, which could also indicate loss of RNFL, was not measured.

The authors concluded that eyes with PCME had greater macular thickness as well as global, superotemporal, and superonasal RNFL thickness when compared with healthy eyes. Thinning in regions of RNFL also occurred when PCME was resolved.

Reference

Rabina G, Shtayer C, Shemesh R, et al. Peripapillary retinal nerve fiber layer thickness as a diagnostic tool for pseudophakic cystoid macular edema. Eur J Ophthalmol. Published online September 28, 2023. doi:10.1177/11206721231199119