Evaluation Of Eyelid Morphometry With A Renovated Slit Lamp Photography System In High Astigmatism And Keratoconus

To evaluate eyelid morphometry in patients with high astigmatism (HA), keratoconus (KC), and low astigmatism (LA) using a renovated slit lamp photography system, and to explore associations between eyelid morphology and corneal tomographic parameters.

A certain number of publications have focused on the association between keratoconus and eyelid abnormalities like eyelid laxity. An aberrant posterior elevation was observed in KC eyes after forced eyelid closure.  To date, there has been no publications focusing on the eyelid morphology in KC eyes. 

A total of 130 patients (84 males, 46 females; mean age 23.56 ± 7.23 years) were enrolled, including 43 KC patients, 44 HA patients (cycloplegic astigmatism >2.00 D), and 43 LA controls (astigmatism <2.00 D). Eyelid photographs were captured using a slit lamp microscope, and five morphometric indices (horizontal/vertical palpebral fissure width/height, palpebral fissure slant [PFS], upper/lower eyelid angles [UEA/LEA]) and second-order polynomial parameters (eyelid position, slope, curvature) were analyzed via custom software. Corneal tomography was performed using Pentacam HR, and associations between eyelid and corneal parameters were assessed via multiple linear regression.

Significant intergroup differences were observed in PFS (ANOVA, P<0.001), LEA (P=0.023), lower eyelid slope (P=0.023), and lower eyelid curvature (Kruskal–Wallis, P=0.001). HA patients exhibited less slanted PFS and UEA, while KC patients showed greater lower eyelid slant and flatter lower eyelid curvature. In KC, corneal astigmatism (KA) correlated positively with lower eyelid position (β=0.428, P=0.003) and slope (β=0.441, P=0.002). In HA, KA J45 (45° astigmatic vector) correlated positively with upper eyelid curvature (β=0.416, P=0.007). Lower eyelid position also associated with corneal elevation (FE, BE), pachymetric progression index (PPIavg), and normality deviation indices (Df, Dp) in KC.

Eyelid morphology differs significantly among KC, HA, and LA patients. Lower eyelid position and slope may influence corneal astigmatism in KC, while upper eyelid curvature correlates with oblique astigmatism in HA. These findings suggest eyelid morphometry could serve as a potential biomarker for corneal disorders.