The impact of central foveal thickness and integrity of the outer retinal layers in the visual outcome of uveitic macular edema

Abstract

Background: To analyze the relationship between the central foveal thickness (CFT) and the integrity of the ellipsoid portion of inner segments (EPIS) and interdigitating zone (IZ) retinal layers in the visual outcome of uveitic macular edema (UME).

Methods: Prospective, observational, and cross-sectional study of eyes with UME. Spectral-domain optical coherence tomography (SD-OCT) macular morphological pattern, CFT, and integrity of the outer retinal layers were analyzed. We arranged the data by EPIS or IZ integrity and contrasted it with student t-test (quantitative variables) and Fisher exact test or χ² distribution (categorical variables) to evaluate visual impairment and retinal measures. Receiver operator curve (ROC) estimation and logistic regression (probit) assessed if the sample´s variance could be associated with IZ or EPIS integrity.

Results: We included 145 SD-OCT macular scans from 45 patients at different stages of UME. Cystoid macular edema (CME) increased the risk of severe (P ≤ 0.0162) and moderate visual loss (P ≤ 0.0032). The highest CFT values occurred in patients with moderate (478.11 ± 167.62 μm) and severe (449.4 ± 224.86 μm) visual loss. Of all morphological patterns of macular edema, only CME showed a statistically significant relationship with severe visual impairment (44.92%, p = 0.0035, OR 4.29 [1.62-11.4]). Likewise, an increased probability of severe visual loss correlated negatively with both, IZ (37.93%, P ≤ 0.001, OR 10.02) and EPIS (38.98%, P ≤ 0.001, OR 13.1) disruption. A CFT > 337 μm showed a higher probability of IZ (AUROC = 0.7341, SEN 77.59%, ESP 65.52) and EPIS (AUROC = 0.7489, SEN 76.37%, ESP 65.12%) loss of integrity. Moreover, when BCVA reached 0.44 LogMAR (≤ 20/50 Snellen eq.), it was more likely to have IZ (AUROC = 0.8706, ESP 88.51%, SEN 77.59%) and EPIS (AUROC = 0.8898, ESP 88.3%, SEN 76.27) disruption.

Conclusions: Significantly increased CFT has a higher probability for EPIS and IZ disruption, which significantly increases the risk for irreversible visual loss in eyes with UME. Evaluating these layers' integrity by optical coherence tomography helps predict the visual outcome and make the right therapeutic decisions. Trial registration The study was registered on April 13, 2020, at the Instituto Tecnologico y de Estudios Superiores de Monterrey Research Committee (License No. COFEPRIS 20 CI 19 039 002), project registration No. P000338-CAVICaREMU-CI-CR002, and the Ethics Committee (License No. CONBIOETICA 19 CEI 011-2016-10-17), project registration No. P000338-CAVICaREMU-CEIC-CR002.

Keywords: Central foveal thickness; Cystoid macular edema; Diffuse macular edema; EPIS, interdigitation zone; Macular edema; SD-OCT; Subretinal fluid; Uveitis; Visual loss.

Fig. 1

Relationship between central foveal thickness with the grade of visual loss in uveitic macular edema

Fig. 2

Probability of severe visual loss as a function of the CFT and the integrity or disruption of EPIS and IZ outer retinal layers. The logistic regression model predicts increased risk and a higher probability of severe visual impairment (3.74 OR with CI 95% = 2.07–6.77) (P = 0.001) when there is EPIS disruption (a), and a low risk of severe visual loss when this retinal layer is preserved (b). In the same manner, the logistic regression model predicts an increased risk (3.26 OR with CI 95% = 1.85–5.74) (P = 0.001) of visual impairment if IZ gets disrupted (c), and a low risk of severe visual loss when this retinal layer is preserved (d). EPIS ellipsoid portion of inner segments, IZ interdigitating zone

Fig. 3

Initial macular SD-OCT (a) of a 43-year-old female diagnosed with idiopathic retinal vasculitis, revealing CME with a CFT of 493 μm (b) and a BCVA of 20/20. After four years of combined systemic immunosuppressive/biologic therapy and three sustained-release 700mm dexamethasone phosphate intravitreal implantations, CME (c) with a CFT of 607 μm (d) and a BCVA of 20/30 persist. The white arrowheads identify the integrity of EPIS and IZ retinal layers in both crossline SD-OCT images. SD-OCT spectral-domain optical coherence tomography, CME cystoid macular edema, CFT central foveal thickness, BCVA best corrected visual acuity, EPIS ellipsoid portion of inner segments, IZ interdigitating zone

Fig. 4

Initial macular SD-OCT (a) of a 68-year-old female diagnosed with idiopathic chronic anterior uveitis, revealing CME with a CFT of 686 μm (b) and a BCVA of 20/200. After four years of systemic immunosuppressive therapy, periocular and intravitreal corticosteroid injections, there is complete resolution of the CME (c) with a CFT of 218 μm (d), but with persistent visual loss (BVCA = 20/100). The white arrowheads identify the disruption of both EPIS and IZ retinal layers in the initial and final crossline SD-OCT images, along with subfoveal retinal pigment epithelium (RPE) atrophy in the final image. SD-OCT spectral-domain optical coherence tomography, CME cystoid macular edema, CFT central foveal thickness, BCVA best corrected visual acuity, EPIS ellipsoid portion of inner segments, IZ interdigitating zone