Optical quality and visual performance with customised soft contact lenses for keratoconus

Area of Science:

• Ophthalmology
• Optometry
• Biomedical Engineering

Background:

• Keratoconus is a progressive eye condition characterized by irregular corneal shape, leading to higher-order ocular aberrations and reduced visual acuity.
• Conventional refractive corrections like spectacles and rigid gas-permeable lenses may not fully correct these complex aberrations.
• Customised soft contact lenses offer a potential solution for managing higher-order aberrations in keratoconic eyes.

Purpose of the Study:

• To evaluate the efficacy of aberration-controlling, customised soft contact lenses in correcting higher-order ocular aberrations.
• To compare the visual performance of these customised lenses with spectacles and rigid gas-permeable lenses in keratoconic patients.

Main Methods:

• Twenty-two keratoconic patients (16 RGP lens wearers, 6 spectacle wearers) were fitted with standard toric and customised soft lenses designed to correct 3rd-order coma.
• Ocular aberrations were measured using Hartmann-Shack aberrometry.
• LogMAR visual acuity (high- and low-contrast) was assessed with habitual and study lenses.

Main Results:

• Both habitual rigid gas-permeable (RGP) lenses and customised lenses significantly reduced 3rd-order coma and higher-order aberrations in RGP lens wearers.
• Standard toric and customised soft lenses significantly reduced aberrations in spectacle wearers.
• While aberrations were reduced, customised lenses did not improve visual acuity compared to habitual corrections in spectacle wearers, and were inferior to habitual RGP and standard toric lenses in RGP wearers.

Conclusions:

• Customised soft contact lenses effectively reduced ocular aberrations in keratoconic patients.
• Suboptimal visual performance with customised lenses suggests that on-eye decentration is a significant factor.
• Further research into lens design and fitting to minimize decentration is warranted for improved outcomes.