Anatomic Relationship Among Descemet's Membrane, Trabecular Meshwork, Scleral Spur, and Ciliary Muscle

The purpose of this study was to examine anatomic relationships between Descemet's membrane (DM) and neighboring tissues.

Human eyes enucleated due to malignant uveal melanoma were histomorphometrically examined.

In all 50 eyes included in the study (age = 59.2 ± 13.3 years), a cellular tissue (mean thickness at the DM end = 14.2 ± 19.5 µm), originating in the transitional zone, extended into the space between the peripheral DM and corneal stroma for a length of 142 ± 71 µm. This length decreased with the longer part of the DM covered with Hassall-Henle-bodies (beta = -0.30, B = -0.28, 95% confidence interval [CI] = -0.54 to -0.03, P = 0.03) and was not related with age (P = 0.84), axial length (P = 0.94), transitional zone length (P = 0.51), and the DM-scleral spur distance (P = 0.72). The DM thinned toward its end and the DM-like components appeared getting together and merging with transitional zone tissue fibers. The transitional zone length (mean = 267 ± 115 µm) varied from 82 µm to 586 µm, increased with longer DM-scleral spur distance (beta = 0.80, B = 0.67, 95% CI = 0.52 to 0.82, P < 0.001), and was not related with axial length (P = 0.74) or age (P = 0.18). The DM-scleral spur distance (mean = 660 ± 136 µm, range = 302 µm-979 µm) was not related with axial length (P = 0.60) or age (P = 0.06). The scleral spur dimensions (basis = 193 ± 103 µm, height = 151 ± 46 µm, length = 231 ± 75 µm) were not related with the DM-scleral spur distance (all P > 0.35), axial length (all P > 0.07), and age (all P > 0.25). In all eyes, the scleral spur tip was orientated anteriorly, with the longitudinal ciliary muscle inserting at its posterior side.

DM is firmly connected with the transitional zone tissue, and indirectly through the corneoscleral TM, with the scleral spur. With the latter connected through the longitudinal ciliary muscle and Bruch's membrane with the optic disc, the DM is part of an anatomic spherical unit of the globe.