Retinal arcades in posterior microphthalmos: biometric correlation.

CLINICAL RELEVANCE: Posterior microphthalmos (PM) is a rare developmental disorder characterised by high hyperopia, short axial length, presence of retinal papillomacular fold and relatively normal anterior segment findings.

BACKGROUND: The purpose of the study was to compare the retinal arcade distance from fovea between PM cases and to correlate axial shortening in PM eyes with imaging findings.

METHODS: This retrospective, comparative case series included 24 eyes of 12 patients with PM as cases and an equal number of age- and sex-matched controls. Retinal findings on optical coherence tomography (OCT), OCT-angiography, Multicolour® image, axial length and corneal biometry were computed, compared and correlated between two groups.

RESULTS: Retinal papillomacular fold was noted in all 24 PM eyes. Retinal arcade narrowing was noted in PM (p < 0.001). The central retina (p < 0.001) and choroid (p = 0.003) was thick in PM. Corneal biometry showed shorter axial length (p < 0.001), high keratometry readings (p < 0.001) and small corneal diameters (p = 0.011) in PM. Vessel density (p = 0.031) on OCTA was denser and foveal avascular zone area (p = 0.033) reduced in PM. Strong negative correlation of axial length with spherical equivalent (r = > -0.804;p < 0.001), vessel density (r = > -0.803; p = <0.001) and K1 (r = > -0.76; p < 0.001) and K2 (r = > -0.67; p = 0.001) keratometry readings was noted in PM. Significant positive correlation was noted between axial length and anterior chamber depth (r = 0.75; p < 0.001), foveal avascular zone area (r = 0.56; p = 0.033) and corneal diameter (r = 0.65; p = 0.001). Vessel density on OCT-angiography correlated positively with central corneal thickness (r = 0.552;p = 0.005) and corneal powers K1 (r = 0.709; p = 0.001) and K2 (r = 0.56; p = 0.004) and negatively with corneal diameter (r = > -0.521; p = 0.033).

CONCLUSION: Increased choroidal thickening and retinal vascular arcade narrowing were two important, interesting observations noted with PM. Intercorrelation between the axial length, OCT, OCT-angiography and corneal biometry helped in understanding the pathogenesis and the structural and vascular changes in PM eyes.