Difficult Contact Lens Fittings

Why standard lenses fail

• Irregular cornea: keratoconus, scarring or post-surgical shape means a soft lens follows the irregularity and vision stays poor
• Corneal size and curvature outside the range stock lenses cover, so the lens is too tight, too loose or decentered
• High or unusual astigmatism, which stock toric lenses are not made for or do not stabilize
• Dry eye, which makes lenses uncomfortable within hours and blurs vision as the lens dehydrates
• Eyelid anatomy and blink patterns that push or rotate the lens
• Previous LASIK, PRK or RK, which flatten the center of the cornea so a standard lens rocks and moves
• Allergy or sensitivity to lens materials or solutions

Finding the cause

The fitting begins by understanding the failure. Corneal topography shows irregularity and unusual curvature. Measurement of the corneal diameter and the sclera shows size. The tear film is assessed. The old lens is examined on the eye to see how it behaves. Each finding points to a design: a scleral lens for irregularity and dryness, a custom soft or hybrid for size and astigmatism, a rigid lens for optics, or a reverse-geometry design for a post-surgical cornea.

The solutions

Scleral lenses solve the largest share of difficult fittings: they vault the cornea, so irregularity is irrelevant, and they hold fluid against it, so dryness is relieved rather than aggravated. Custom soft lenses are made to the eye's measurements in any parameter, which solves size and astigmatism problems. Hybrid lenses give rigid optics with a soft skirt for patients who could not tolerate a rigid lens. Reverse-geometry rigid and scleral designs fit the flattened center of a post-LASIK or post-RK cornea. Where dry eye is the driver, treating it alongside the fitting is what makes the lens succeed.

When surgery is the better answer

Some patients who struggle with lenses are better served by vision correction surgery, and the assessment says so honestly: a healthy eye with a regular cornea and a stable prescription may do better with LASIK, SMILE or the EVO ICL than with any lens. The practice offers both, so the recommendation follows the eye.