The Posterior Pole and Papillomacular Fold in Posterior Microphthalmos: Novel Spectral-Domain Optical Coherence Tomography Findings

Abstract

To report and analyze the spectral-domain optical coherence tomography (SD-OCT) features of the posterior pole and papillomacular fold (PMF) in posterior microphthalmos (PM) in relation to axial length of the globe and corneal power. Comparative case series. Forty eyes of 20 PM patients and 70 eyes of 35 age-matched controls. All PM and control eyes underwent a full biometric evaluation, including axial length and corneal power measurements, and macular SD-OCT. In addition, a novel SD-OCT marker of the posterior pole curvature, termed the posterior pole curvature index (PPCI), was measured along both the vertical and horizontal meridians. The OCT characteristics of the PMF were analyzed and the PPCIs were compared and correlated with the axial length and corneal power in both groups of eyes, and with the PMF severity in PM eyes. We considered the SD-OCT features of the PMF, the PPCI in PM eyes and controls, and the correlations between PPCI and PMF severity and axial length. All PMFs were predominantly horizontal and partial thickness, sparing the outer retina except the outer plexiform layer. The PPCI in PM eyes (mean ± standard deviation, 145±40.3 microns; median, 144) was significantly larger than that of controls (14±12.8 microns; median, 14; P<0.0001). In addition, the vertical PPCI in PM eyes, but not in controls, was notably larger than the horizontal PPCI (mean difference, 55±30.4 microns; P<0.0001). In PM eyes, the PPCI strongly correlated with PMF height (R = 0.68; P<0.0001), inverse axial length (R = -0.71; P<0.0001), and corneal power (R = 0.49; P = 0.002), and the PMF height correlated strongly and inversely with the axial length (R = -0.62; P<0.0001). The PMF in PM eyes has characteristic morphologic SD-OCT features. The increased posterior pole curvature in PM and its significant correlation with the axial length, the PMF severity and keratometry established in this study suggest that PM eyes are not only shorter than normal, but seem to be abnormally shaped posteriorly, particularly along the vertical meridian. This factor may play a role in the pathogenesis and morphology of the PMF. The authors have no proprietary or commercial interest in any of the materials discussed in this article.