Collaborative Case #011: Treating Irregular Astigmatism After Laser Vision Correction

Due to cost of the ICL procedure and the findings of the normal BAD score, the patient opted for corneal laser refractive surgery. Because the patient had 8.00 D of myopia and a slightly thin cornea, he and surgeon chose PRK (along with 12 seconds of mitomycin C exposure to the cornea at the end of the procedure) using the iDesign Refractive Studio (Johnson & Johnson Vision). PRK for higher levels of myopia typically provides very good vision, and because there is no flap, there is a lower risk for developing ectasia as compared with LASIK.

The procedure was uneventful. The epithelium was removed manually (no dilute alcohol was used) and a bandage contact lens was placed at the completion of the procedure. The patient started his postoperative drop regimen, which included prednisilone acetate 1% four times daily for 1 week, then three times daily for 3 weeks, plus polymyxin B/trimethroprim (Polytrim, various) and moxifloxacin drops four times daily for 1 week, and bromfenac ophthalmic solution 0.07% (Prolensa, Bausch + Lomb) once daily for 5 days. There was a slight delay in epithelial healing of 1 to 2 days. Many patients can have complete epithelial healing in 3 to 4 days after PRK when dilute alcohol is not used to help with epithelial removal. In this patient’s case, the epithelium had healed by day 6, at which point the bandage contact lens was removed.

Once healed, the patient was happy overall with his vision, but was concerned that the quality of vision was not as crisp as he expected. This is not uncommon to hear from patients after PRK or even LASIK, and typically, interventions that optimize the tear film are helpful with improving their vison. In this case, corneal topography was again performed with the Pentacam, and the central corneal shape was not as expected. When performing PRK or LASIK for high mopes, one typically expects to see postoperative topography with a central flat circle-shaped zone surrounded 360˚ by a steeper area (Figure 2).

In this case, the patient presented with some degree of steepening in the central part of the cornea (Figure 3), called a central island. This irregularity in the corneal shape can cause blurring of vision, as the central steep area has a higher refractive power than the rest of the central cornea, which is flatter. Patients may complain of monocular diplopia, ghosting, and may also experience night vision issues. The cause of central islands is multifactorial and can stem from issues with epithelial healing or may be related to the laser treatment itself, where the central cornea did not flatten as much as expected. Fortunately, this patient's symptoms were mild, and his UCVA at 1 month was 20/20 OD and 20/30 OS.

The patient was maintained on topical cyclosporine and returned at 6 months postoperatively with UCVA of 20/20 OU. He also noted minimal issues with his quality of vision. The corneal maps show some improvement in the shape of his cornea (Figure 4).

The patient returned for his 5-year postoperative visit and noted that his quality of vision was significantly better (Figure 5). His UCVA was 20/20 OU, and the corneal maps showed significant improvement in corneal shape OU.