Descemet Tears In Keratoconus Versus Congenital Glaucoma

Keratoconus eyes develop corneal decompensation more often, compared to eyes with primary congenital glaucoma (PCG) following Descemet’s Membrane (DM) tears. This study was conducted to compare the posterior corneal morphology in areas having undergone DM breaks with regards to DM and Pre-Descemets layer (PDL) between the two.

Anterior segment optical coherence tomography (ASOCT) scans for posterior cornea of keratoconus eyes with hydrops (n=12), PCG eyes with Haab’s striae (n=15) and healthy control eyes (n=14) were compared for  DM-PDL morphology. These were corroborated on histopathology of corneal buttons from keratoconus (n=14) and PCG (n=13) cases obtained following penetrating keratoplasty and compared with controls (enucleated retinoblastoma globes, n= 6) on light microscopy and Collagen IV immunostaining. 

Cross-sectional comparative study

ASOCT showed a thicker median DM/PDL complex in PCG (80µm) vs keratoconus eyes (36µm,p=0.01; Kruskal Wallis test). The median height and length of detached DM-PDL was significantly more in keratoconus vs PCG (145μm, 1766.1±1320.6μm vs 26.5μm, 453.3±303.2μm respectively, p=0.012; Kruskal Wallis test). A type 1 DM/PDL detachment (seen as a characteristic taut chord) in keratoconus (90%) was the most common morphological pattern vs intracameral twin protuberance (92%) following DM breaks in PCG. Histopathology confirmed thicker DM in PCG (median of 63.4μm) vs keratoconus eyes (median of 33.2µm) or controls (27.1μm) (p=0.001; Kruskal Wallis test).

Greater height/length of DM/PDL detachment compounded by poor healing response (lower DM/PDL thickness) probably causes more frequent corneal decompensation in keratoconus versus PCG eyes following DM tears.