Contact Lens Case Reports
Consider Thicker Soft Lenses to Manage Post-LASIK Dryness
BY PATRICK J. CAROLINE, FAAO, & MARK P. ANDRÉ, FAAO
Our patient was a 27-year-old female with a history of bilateral LASIK surgery to correct –1.75D of myopia. Her residual refractive error one year postoperatively was –0.75D in both eyes (Figure 1). She also experienced significant glare at night with spectacle lenses as well as dry eye symptoms.
Figure 1. Corneal topography following LASIK surgery.
Finding the Best Soft Lens
Numerous attempts were made to fit traditional soft contact lenses, but the thinner lens designs failed to correct the patient’s asymmetric corneas and further exacerbated her dry eye symptoms.
We ultimately fitted NovaKone T2 (Alden Optical) lenses. NovaKone is a custom soft lens with five different IT (thickness) factors designed to mask some of the irregular astigmatism created secondary to injury, surgery, or corneal disease. The design incorporates a double lenticulation that decreases lens mass and can help increase lens stability (Figure 2).
Figure 2. Anterior segment OCT image of NovaKone T2 lens.
The final contact lens prescription was OD 8.6 –0.75 15.0 T2 and OS 8.6 –0.75 15.0 T2, with visual acuity of 20/15 in both eyes (Figure 3).
Figure 3. The NovaKone T2 lenses on our patient
Benefits of Thicker Lenses
A way to quantify improvement in the surface quality at the cornea’s anterior plane is to measure the surface asymmetry index (SAI). First, perform corneal topography and have the instrument calculate the SAI without the contact lens. Next, do the same with the lens in place. Readings of less that 0.75 are considered normal, and the lower the SAI reading, the better.
Our patient’s SAI OD without the contact lens was 0.86 and with the lens was 0.56, a 35-percent improvement (Figure 4). The OS SAI without the lens was 0.71 and with the lens was 0.51, a 28-percent improvement.
Figure 4. The SAI values OD without and with the NovaKone lens.
Clinical experience has taught us that thicker contact lenses dehydrate less on-eye compared to thinner lenses. Therefore, thicker soft lens designs may serve two functions in managing patients post-LASIK: 1) they can improve the surface regularity at the plane of the cornea, and 2) they may help decrease surface evaporation, lessening dryness symptoms. CLS
Patrick Caroline is an associate professor of optometry at Pacific University. Mark André is an associate professor of optometry at Pacific University. He is also a consultant for CooperVision.