The corneal contour is flatter in the eyes of patients with congenital ptosis than in eyes without it, according to research published in International Ophthalmology.
Researchers conducted a matched case-control observational study to investigate the impact of the drooping eyelid on corneal topographic and tomographic alterations in patients with unilateral congenital ptosis.
They evaluated differences in keratometric, pachymetric parameters, volumetric parameters, topometric indexes, and other metrics between eyes with ptosis and normal contralateral eyes (control eyes). They also assessed correlations between the severity of ptosis (marginal reflex distance [MRD]) and alterations in corneal topography and tomography.
The researchers included 17 patients with unilateral congenital ptosis in the study. The average patient age was 25.00±11.95 years (range, 6-47). The mean best-corrected visual acuity (BCVA) was 0.115±0.120 logMAR (range, 0.000-0.300) in the ptosis eyes and 0.017±0.038 logMAR (range, 0.000-0.100) in the control eyes. The mean spherical equivalent was -2.07±3.61 diopters (D) (range, -11.50 to +3.50) in the ptosis eyes and -1.96±3.03 D (-11.25 to +1.75) in the control eyes.
The values for anterior flat keratometry (K1), posterior steep keratometry (K2), and anterior and posterior mean keratometry (Km) were significantly decreased in the ptosis eyes compared with the control eyes (anterior K1, 42.42±1.69 vs 42.78±1.63 D [P =.010]; posterior K2, -6.39±0.32 vs -6.51±0.33 D [P =.019]; anterior Km, 43.02±1.67 vs 43.38±1.65 D [P =.003]; posterior Km, -6.24±0.27 vs -6.32±0.27 D [P =.003]).
The corneal thicknesses at the pupil center point and thinnest point were significantly thicker in ptosis eyes compared with those in control group (pupil center, 542.35±31.75 vs 534.29±34.67 μm [P =.049]; thinnest point, 535.18±30.51 vs 528.00±33.81 μm [P =.049]), the researchers report.
Among topometric indices, the team observed higher index of surface variance (ISV), index of vertical asymmetry (IVA), keratoconus index (KI), index of height decentration (IHD) values in the ptosis eyes compared with the control eyes (ISV, 23.12±9.19 vs 18.94±7.21 [P =.026]; IVA, 0.19±0.09 vs 0.14±0.07 [P =.014]; KI, 1.05±0.05 vs 1.02±0.04 [P=.004]; IHD, 0.02±0.01 vs 0.01±0.01 [P =.040]).
They demonstrated that the intergroup difference in MRD was significantly correlated with the difference in ISV (r=-0.495; P =.042).
“Remarkable alterations in corneal power and irregularity in ptotic eyes might be a consequence of corneal remodeling induced by persistent influence from drooping eyelid,” the researchers explain.
Limitations of the study included the small sample size and limitation of the study to Chinese patients at a single center.
Shen J, Li H, Chen Y, Liu L, Cui H. Clinical observations of corneal topographic and tomographic changes in congenital ptosis eyes: a study in China. Int Ophthalmol. Published online October 21, 2022. doi:10.1007/s10792-022-02557-2