As contact lens options continue to expand, I’m confident that my astigmatic patients will leave with a contact lens correction that achieves their goals. But, there is one group of astigmatic patients that can be exceptionally challenging when it comes to meeting a high degree of lens-wearing satisfaction. It’s the group that never wanted to wear correction at all…so they had refractive surgery.
Patients who have undergone refractive surgery have a strong desire for sharp and stable vision and may want correction for small astigmatic refractive errors that have emerged from treatment regression. Due to the shape of post-surgical corneas, it can be a challenge to find a lens that is both centered and stable. Thankfully, we have options in custom and frequent replacement lens designs that can help us meet the expectations of these patients and build positive patient relationships.
Frequent Replacement Torics
Soft frequent replacement toric contact lenses can be a viable option for many of these patients. The best candidates are those who had a low-to-moderate pre-treatment refractive error, as the milder changes in corneal curvature will give the lens a better chance to center and stabilize.
Be prepared to utilize the LARS (left add, right subtract) rule, as a lens may stabilize in a rotated position, especially if the axis of astigmatism is different from the pre-treatment refractive error. Use topography to verify the treatment zone location to predict the success of lens centration.
Custom Soft Lens Designs
If the corneal shape is too oblate, a soft lens will not drape evenly over the treated cornea and instead will “float” over the flat central area. This warrants a flatter, shallower lens design. Reverse geometry custom soft lenses can be a great tool for these patients, as the flatter lens base curve will align more appropriately with the treated cornea.
Custom lenses can be ordered empirically; important measurements would include refraction, corneal diameter, and corneal curvature readings. While keratometry readings can be used, topography is valuable to determine the optical zone size and the amount of reverse curvature for the lens haptics, if needed. Pre-treatment refraction and keratometry readings are also helpful, if the information is available. Custom soft toric lenses can be made in a variety of lens materials and diameters for optimum lens wettability, centration, and stability. They can also be ordered with a multifocal correction, if desired.
Another important factor to note is the location and stability of the toric marker. Like all soft toric fittings, if the lens marking is not stable, then the lens design itself should be changed; custom lenses can be designed with nearly any base curve and lens diameter to improve rotational stability and centration. Because many refractive surgery patients have worn soft lenses before, they often appreciate using a lens that is similar to their previous experiences.
If soft lenses are not yielding consistent visual acuity, GP lenses are an option. Reverse geometry corneal lenses work extremely well for patients who were previously myopic. Those who were previously hyperopic can succeed in traditional or irregular cornea designs.
Scleral and mini-scleral lenses also offer benefits for this patient group, as the fluid chamber can both correct astigmatism and protect the cornea for patients who note any post-surgical ocular surface dryness. CLS