Keratoconus, a progressive eye disease that weakens and thins the cornea, can significantly impact vision. Fortunately, specialty contact lenses offer a valuable tool for managing keratoconus and improving visual acuity in these patients. However, fitting contact lenses for keratoconus requires a nuanced approach due to the irregular corneal shape. This blog post serves as a guide for eye care professionals (ECPs) on navigating the complexities of fitting keratoconus patients with contact lenses, maximizing comfort, and optimizing vision.
Understanding the Corneal Irregularity:
In a healthy cornea, the surface is smooth and dome-shaped, focusing light rays precisely onto the retina. Keratoconus disrupts this smooth curvature, causing the cornea to thin and bulge outward in a cone-like shape. This irregularity scatters light entering the eye, leading to distorted vision.
Specialty Lenses for Keratoconus:
Conventional soft contact lenses are not suitable for keratoconus due to their inability to vault (cover) the irregular corneal surface. Specialty contact lenses, however, are designed to address these challenges. Here’s an overview of the most common types:
- Rigid Gas Permeable (RGP) Lenses: These lenses are made of a durable, oxygen-permeable plastic material. Their rigid design vaults over the irregular cornea, creating a smooth optical surface for clear vision. RGP lenses come in various designs, including spherical, aspheric, and piggyback lenses (a combination of RGP and soft lens).
- Soft Toric Lenses: These specialized soft lenses incorporate toric correction to address astigmatism often present in keratoconus. However, their ability to correct for higher-order aberrations caused by the irregular cornea is limited.
- Hybrid Lenses: These combine a central RGP zone for optical correction with a soft peripheral skirt for comfort and improved centration.
- Scleral Lenses: These large-diameter lenses vault over the entire cornea and rest on the sclera (the white part of the eye). They are ideal for advanced keratoconus cases where other lens types struggle to provide optimal vision and comfort.
The Fitting Process:
Fitting contact lenses for keratoconus patients demands a comprehensive approach, with several key steps to ensure successful outcomes:
- Detailed History and Examination: A thorough medical history and eye examination are crucial. This includes assessing the severity of keratoconus, corneal topography (mapping the corneal shape), tear film evaluation, and overall eye health.
- Discussion of Expectations: Discussing realistic expectations with the patient is vital. Specialty contact lenses can significantly improve vision, but they may not restore perfect vision and require an adaptation period.
- Lens Selection: Based on the examination findings and the patient’s needs, the ECP can select the most appropriate lens type (RGP, soft toric, hybrid, or scleral). Factors to consider include corneal shape, severity of keratoconus, patient comfort level, and lifestyle.
- Lens Fitting and Trial Wear: The ECP will carefully fit the lenses, ensuring proper centration, movement, and tear exchange. Trial wear allows the patient to experience lens wear and identify any initial discomfort.
- Follow-up and Adjustments: Regular follow-up appointments are essential to monitor lens fit, address any discomfort, and refine lens parameters for optimal vision and comfort.
Enhancing Comfort and Optimizing Vision:
- Material Selection: Newer lens materials with higher oxygen permeability can improve comfort and corneal health.
- Lens Design Optimization: Advanced lens designs like reverse geometry or customized lenses can provide more precise corneal vaulting and aberration correction for improved vision.
- Teaching Proper Insertion and Removal Techniques: Proper lens handling techniques can minimize discomfort and ensure proper lens wear.
- Managing Dry Eye: Keratoconus patients often experience dry eye. Artificial tears and punctal plugs can help maintain lens hydration and reduce discomfort.
Conclusion:
Fitting contact lenses for keratoconus patients requires a specialized skillset and a commitment to providing exceptional care. By understanding the unique challenges posed by keratoconus, utilizing appropriate lens types, and following best practices for fitting and management, ECPs can empower their keratoconus patients to achieve optimal vision and improved quality of life. This collaborative approach, coupled with ongoing research and advancements in contact lens technology, holds immense promise for the future of keratoconus management.