Spectral-domain optical coherence tomographic assessment of severity of cystoid macular edema in retinopathy of prematurity

Abstract

Objective: To investigate whether the severity of cystoid macular edema (CME) in neonates who were 31 to 36 weeks' postmenstrual age, as viewed by spectral-domain optical coherence tomography (SD-OCT)imaging, predicts the severity of retinopathy of prematurity(ROP) or is related to systemic health.

Design: Of 62 prematurely born neonates in a prospective institutional review board-approved study, 42 met the following inclusion criteria: at least 1 SD-OCT imaging session prior to 37 weeks' postmenstrual age and prior to ROP laser treatment, if a laser treatment was performed,and an ophthalmic ROP examination at or after 41 weeks' postmenstrual age, evidence of complete retinal vascularization in zone III, or documentation through telephone report of such information after transfer of care.Measures of CME severity, including central foveal thickness,retinal layer thicknesses, and foveal-to-parafoveal thickness ratio in 1 eye per subject, were compared with ROP outcomes: laser treatment, maximum plus disease,and maximum ROP stage. Systemic health factors were also correlated.

Results: Cystoid macular edema was present in 50% of neonates. Multiple elongated cystoid structures within the inner nuclear layer were most common. The presence of CME was not associated with ROP outcomes. The central foveal thickness, the thickness of the inner retinal layers, and the foveal-to-parafoveal thickness ratio were higher in eyes that required laser treatment or that developed plus disease or ROP stage 3. Cystoid macular edema was not clearly associated with systemic factors.

Conclusions: Cystoid macular edema is common in premature infants screened for ROP before 37 weeks' postmenstrual age, with the most common SD-OCT phenotype ofa bulging fovea from multiple elongated cystoid spaces. Detection of CME is not associated with ROP severity; however,tomographic thickness measurements could potentially predict a higher risk of requiring laser treatment or developing plus disease or ROP stage 3. Systemic health factors are probably not related to the development of CME.

Figures

Figure 1

Macular spectral-domain optical coherence tomographic scan segmentation to obtain quantitative measurements. Boundary lines were semiautomatically segmented. A, A foveal-to-parafoveal (FP) thickness ratio provided a quantitative measure of foveal contour and was calculated by dividing the central foveal thickness (CFT) by an average of the retinal thickness values at 1000 μm on either side of the fovea (white parafoveal vertical bars): inner retinal layer (IRL) thickness (green to magenta), inner nuclear layer (INL) thickness (yellow to magenta), and CFT (green to cyan). A premature infant with edema had a CFT of 370 μm and an FP thickness ratio of 1.35 (A), whereas a premature infant without edema had a CFT of 113 μm and an FP thickness ratio of 0.42 (B).

Figure 2

Prevalence of cystoid macular edema (CME) in the study population, as a percentage of total eyes imaged in which CME was either present (dark blue) or absent (light blue), per postmenstrual age.

Figure 3

Morphologic characteristics and phenotypes of cystoid macular edema (CME) observed by use of spectral-domain optical coherence tomography (SD-OCT). Three CME phenotypes were observed in our subjects: single central (A), parafoveal (when cystoid structures were grouped around the foveal center, as shown within the white encircled areas) (B), and multiple elongated cystoid structures when the parafoveal and central fovea contained cystoid structures (C-E). For the multiple elongated CME phenotype, severity was scored as mild (C) if the foveal pit was present, moderate (D) if the fovea was bulging but the photoreceptor layer was not affected, and severe (E) if the fovea and the photoreceptor layer had a bulging shape (white arrow). A magnified SD-OCT scan shows the morphologic characteristics found in severe CME (F). The white asterisk is located within 1 cystoid space.

Figure 4

Central foveal thickness (CFT) and foveal-to-parafoveal (FP) thickness ratio data distribution by final retinopathy of prematurity (ROP) outcome. The median CFT and the median FP thickness ratio were greater in the laser group than in the nonlaser group (A and D), in the plus disease group than in the normal vasculature group (B and E), and in maximum stage 3 group than in subjects with stages 0, 1, or 2 (C and F).

Figure 5

Correlation of control foveal thickness between study and fellow eyes. The central foveal thickness (CFT) was highly correlated in both eyes of the same subject, with a correlation coefficient of 0.989 and a mean (SD) absolute difference of 10.0 (8.8) μm.