Comparative Analysis Of Anterior Segment Parameters And Lamina Cribrosa Thickness By Stages In Adult Patients Diagnosed With Keratoconus And A Control Group

To compare the nasal and temporal scleral thickness, nasal and temporal conjunctiva-tenon thickness, lamina cribrosa thickness, lamina cribrosa curvature index in keratoconus patients with different stages of the disease and the control group and to evaluate the relationship between these values ​​and corneal parameters.

Haseki Training and Research Hospital, Ophthalmology Department

A total of 356 eyes, including 156 eyes of 96 keratoconus patients from the cornea unit and 200 eyes of 100 healthy volunteers, were included. Our observational cross-sectional study classified keratoconus patients into four stages using the Amsler-Krumeich system. Lamina cribrosa thickness (LCC), curvature width (LCCW), depth (LCCD), index (LCCI), and nasal/temporal sclera and conjunctiva-tenon thicknesses were measured with Swept-Source OCT. LCC was assessed via radial scans of the optic nerve head, and the curvature index was calculated as (LCCD/LCCW) × 100. Sclera and conjunctiva-tenon thicknesses were measured at 1 mm, 2 mm, and 3 mm posterior to the scleral spur. Values were compared between groups and across stages.

Our study revealed a significantly thinner lamina cribrosa in the keratoconus group compared to controls (p<0.001), with LCC varying significantly across keratoconus stages (p<0.001). However, LCCI, LCCW, and LCCD showed no significant differences (p=0.091, p=0.001, p=0.090, respectively). LCC correlated positively with central corneal thickness (CCT) and thinnest corneal thickness (TCT) but negatively with keratometry. Scleral and conjunctiva-tenon thicknesses were markedly reduced in keratoconus patients across all measured meridians. While scleral thickness exhibited significant stage-dependent variation, conjunctiva-tenon thickness remained consistent across stages.

In keratoconus patients, LCC, nasal and temporal sclera, and conjunctiva-tenon thicknesses were significantly thinner than in controls. The correlation between LCC and CCT, along with LCC differences in keratoconus, highlights the need for careful glaucoma monitoring in these patients. Our study suggests that the cornea, sclera, lamina cribrosa, and conjunctiva-tenon, which share structural similarities, may undergo parallel alterations in keratoconus. These findings emphasize a broader impact on the ocular framework. Further histological research and standardized measurements are essential to validate our results.