Fitting effect of scleral lens for moderate and severe keratoconus

Objective

To compare the fitting effect between rig gas-permeable contact lens (RGPCL) and scleral lenses (SLs) in moderate and severe keratoconus eyes.

Methods

A cross-sectional study was performed.Fifty-two eyes of 42 keratoconus patients were recruited in Henan Eye Hospital from September 2022 to September 2023.Based on steep keratometry (Ks) value, patients were divided into moderate stage (48 D≤Ks<55 D, 28 eyes) and severe stage (Ks≥55 D, 24 eyes). RGPCL and SLs were fitted normatively in all eyes.Fluorescein staining and anterior segment optical coherence tomography were performed under a slit lamp.The distance between the central and lateral centers of the lenses and the cornea, the centering of the lenses, the mobility of the lenses and the peripheral fit of the lenses were observed.Best corrected visual acuity (BCVA) converted to logarithmic minimum angle of resolution, comfort score, wetness score and clarity score were recorded.Differences in the above parameters of each patient between RGPCL and SLs wear were compared.The improvement of the above parameters after RGPCL and SLs wear was compared in moderate and severe patients.This study adhered to the Declaration of Helsinki.The study protocol was approved by the Ethics Committee of Henan Eye Hospital (No.HNEECKY-2019[5]-04). Written informed consent was obtained from each patient before any medical examination.

Results

After RGPCL wear, the mean BCVA, comfort, wetness, and clarity score were 0.19(0.10, 0.30), 5.5(3.0, 7.0) points, 7.0(5.0, 8.0) points and 7.0(4.0, 8.0) points, respectively.After SLs wear, the mean BCVA, comfort score, wetness score and clarity score were 0.10(0.00, 0.10), 8.0(8.0, 9.0) points, 8.0(8.0, 9.0) points and 8.0(6.0, 9.0) points, respectively.Compared with RGPCL wear, the BCVA, comfort score, wetness score and clarity score of SLs were significantly improved (Z=-5.887, -6.064, -5.705, -5.516; all at P<0.001). There was a moderate positive correlation between BCVA and Kmax after SLs wearing (r_s=0.519, P<0.001), and had a moderate negative correlation with TCT (r_s=-0.535, P<0.001). There was a moderate positive correlation between the clarity score of the SLs and TCT (r_s=0.303, P=0.029). In the moderate and severe subgroup analysis, BCVA, comfort score, wetness score and clarity score were significantly improved after SLs wear compared to RGPCL (all at P<0.05). In addition, the clarity score was significantly improved in severe keratoconus compared to moderate keratoconus (Z=-3.100, P=0.002).

Conclusions

In patients with moderate to severe keratoconus, RGPCL can improve BCVA to a limited extent.SLs can significantly improve patients’ comfort, wetness and visual clarity while improving their BCVA.

Keratoconus; Therapy; Visual acuity; Scleral lens; Rig gas-permeable contact lens; Clarity