Therapeutic wavefront treatment used after LASIK

Issue: January 15, 2004

ByRobert K. Maloney, MD

ByFarid Eghbali, MD

Figure 1. This post-LASIK topography map of the left eye shows a central area of the myopic ablation without obvious topographic irregularity.

Figure 2. The post-LASIK Wavescan map of the left eye reveals minimal residual refractive error (upper left map) but significant higher-order aberrations (lower left map). The RMS value of the higher-order aberration was 0.55. The visually significant aberration was mostly spherical aberration (lower right graph).

Figure 3. The Wavescan map of the left eye after custom therapeutic wavefront treatment. The RMS value decreased to 0.45. Refractive error (upper left) was close to emmetropia.

Corneal laser treatment can sometimes result in irregular astigmatism. This can be caused by a decentered ablation, irregularity in the laser energy applied on the cornea or irregular healing of the cornea postoperatively. This results in higher-order aberrations, which cannot be corrected by conventional spherical or astigmatic corrections.

Wavefront-guided laser treatments are showing promise in treating such irregularities. We present a case in which therapeutic wavefront-guided LASIK was used to treat a reduction in best-corrected visual acuity caused by conventional laser treatment.

History

A 43-year-old man presented with a complaint of reduced quality of vision in his left eye after a LASIK procedure in 1999. His postoperative refraction in his right eye was –5.5 D, correcting the eye to 20/20, and the left eye was –5.75 D, correcting to 20/20. He had a LASIK procedure in both eyes with LASIK enhancement in the left eye.

Preoperative examination

Uncorrected visual acuity: Right eye: 20/20–2; left eye: 20/40
Manifest refraction: Left eye: 0.50 –0.25 3 070
BCVA: Left eye: 20/40

Corneal topography of the left eye (Figure 1) revealed a centered laser treatment without obvious topographic abnormalities. However, the waveprint map of the left eye (Figure 2) showed greater-than-average higher-order aberrations, with RMS value of 0.55. The normal value is usually less than 0.35.

The patient was enrolled in our Food and Drug Administration trial of wavefront-guided treatment after previous laser surgery. The information from the waveprint map was transferred to the Visx Wavescan System for a custom therapeutic ablation.

Postoperative examination

Manifest refraction: Left eye: +1.00 –0.50 3 180
BCVA: Left eye: 20/25

Postoperatively, the patient’s complaint of glare at night was dramatically improved. The postoperative waveprint map showed a reduction in higher-order aberrations, with a RMS value of 0.45 (Figure 3).

Discussion

Patients who suffer from induced irregular astigmatism, a reduction in BCVA or a loss of quality of vision from previous laser procedures can be helped by wavefront-guided re-treatments.

Therapeutic wavefront treatment utilizes the Visx Wavescan System to map out the entire optical system of the eye and measure lower-order aberrations (sphere and cylinder) and higher-order aberrations, such as spherical, aberration or coma. This information is programmed into the laser to reduce corneal aberrations, improving quality of vision.

For Your Information:

Robert K. Maloney, MD, and Farid Eghbali, MD, can be reached at 10921 Wilshire Blvd., Suite 900, Los Angeles, CA 90024; 310-208-3937; fax: 310-208-0169; e-mail: drmaloney@maloneyvision.com or dreghbali@maloneyvision.com. Drs. Maloney and Eghbali have no financial interest in the products mentioned in this article. Dr. Maloney is a paid consultant for Visx.