CustomVue used to enhance results of LASIK performed with early-generation laser

The patient, a 39-year-old man, was very dissatisfied with the results of his initial LASIK procedure.

Issue: March 15, 2004

ByDavid R. Shapiro, MD

Wavefront-guided LASIK is mostly known for its ability to correct higher-order aberrations in a primary procedure. Some have expanded its use for therapeutic enhancements of decentered or irregular ablations from LASIK complications. I have found wavefront-guided LASIK also to be useful for customized therapeutic enhancements of otherwise uneventful LASIK procedures performed with earlier generation lasers that produced suboptimal ablation profiles by today’s standards. This opens up a new use for CustomVue (Visx), albeit an off-label one.

In one recent case, an unhappy patient was able to achieve excellent vision with CustomVue customized ablation. The procedure enhanced his well-centered, small optical zone, improving his visual quality.

History

The patient, a 39-year-old man, had uneventful LASIK surgery in August 2000 at a high-volume discount laser center. Preoperatively, his cycloplegic refractive error was –5.50 +1.00 X 165 = 20/20 –2 in the right eye and –6.00 +1.00 X 001 = 20/20 in the left eye. Laser ablation was performed with a Nidek laser.

On the first postoperative day, uncorrected visual acuity measured 20/25 +2 in the right eye and 20/25 +1 in the left eye, but visual quality was subjectively poor. By 4 months, the uncorrected visual acuity was 20/25 +1 in the right eye and 20/20 in the left eye, but the patient still complained of extremely poor visual quality, especially in dim light, and induced headaches.

One year later, despite a residual cycloplegic refractive error of only –0.25 D in the right eye, a –0.75 D enhancement was performed at the same surgical center to improve low-light vision. Postoperatively, the patient was 20/20 –2 in the right eye and 20/20 in the left eye without correction. He still complained of very poor visual quality and headaches, especially under dim lights. The patient was placed on Alphagan (brimonidine tartrate, Allergan), which offered only mild improvement of his symptoms.

Frustrated with his result, the patient came to see me 3 years after his original LASIK. Despite the good visual acuity measurements, he complained of disabling levels of glare, haloing and ghosting under dim lighting conditions. He described his low-light vision as being “washed out” and of terrible quality. He noted that his depth perception, particularly under dim light, was dramatically reduced. These symptoms had been present since his initial LASIK surgery. He also complained of photophobia after surgery, even in mild lighting conditions. He was wearing –0.5 D glasses for both eyes, which did not offer much help. He was so upset that he had contacted a lawyer about a possible lawsuit against his original surgeon.

Examination

On examination, the patient had relatively good uncorrected visual acuity of 20/25 in the right eye and 20/25 in the left eye. Manifest refraction was –0.75 + 0.25 X 160 = 20/20 in the right eye and –0.50 sphere =20/20 in the left eye. Cycloplegic refraction with 1% Cyclogel (cyclopentolate HCl, Alcon) was unchanged from the manifest refraction. Slit lamp examination revealed nicely centered, well-healed, nasal-hinged flaps of approximately 9 mm in diameter and a clean, clear interface. Pupils were 7.5 mm.

Corneal topography revealed a well-centered, even zone of corneal flattening in each eye. The optical zones, however, were quite small. Surface regularity indices and surface asymmetry indices were normal for both the right and left eyes, consistent with an otherwise good postoperative result.

Preoperative WaveScan testing was the most revealing test. Wavefront analysis revealed a rather high RMS value of 0.54 in the right eye (6-mm pupil) and 0.67 in the left eye (6-mm pupil), with a pattern predominated by large amounts of spherical aberration and lesser amounts of trefoil and coma in each eye.

Most interesting, however, was the WaveScan refraction. If the simulated pupil size was decreased to 3 mm, the WaveScan refraction was nearly plano in both eyes. As the simulated pupil size was enlarged, however, the degree of myopia increased, and at a maximal pupil setting (6 mm of wavefront data), the refraction had changed to –1.80 +0.64 3 164 in the right eye and –1.69 +0.22 X 175 in the left eye — a huge increase in myopia as the pupil enlarged in each eye.

After reviewing the topography and the WaveScan results, it was clear the patient had a very small optical zone with a rapid fall-off of correction to higher degrees of myopia. WaveScan analysis was the only test that quantitatively demonstrated that the patient was looking through a multifocal cornea with very poor optical quality. The ability to calculate refractions with simulated variations in pupil size is a powerful diagnostic feature of the WaveScan and was highly illustrative in this case. Under bright lights and with a small pupil, the patient had a misleadingly good postoperative result, but under dim lights, he had a dramatically worse refraction and significant amounts of higher-order aberrations. Presumably, a conventional enhancement would not solve this problem.

PreVue lenses were created to simulate a wavefront-based therapeutic enhancement. Confirming an improvement in visual quality with the lens was reassuring not only to the patient, but also to me, considering that this patient had already sought legal counsel regarding his previous surgeon and was, at least on paper, 20/25 in each eye.

Figure 1 [chart]
Figure 1: Corneal topography of the right eye after the initial LASIK but before CustomVue therapeutic enhancement shows a small optical zone. Topography is otherwise unremarkable, showing a well-performed LASIK procedure.

Treatment, results

The non-dominant left eye underwent surgery first, and no physician adjustment was made. The dominant right eye underwent surgery 1 month later, and a –0.2 D physician offset was used. The 3-year-old flaps were lifted in both cases. The patient developed epithelial cell ingrowth in the right eye, but this was successfully removed.

On the first postoperative day, vision was 20/15 in each eye. The patient reported that all of his visual problems were eliminated the day after surgery. While awaiting surgery on his right eye, he said he was amazed at the difference in visual quality between the two eyes.

By 1 month after all surgery (including the removal of epithelial ingrowth), uncorrected visual acuity was 20/15+ in the right eye, 20/10 –3 in the left eye and 20/10 –2 in both eyes. The patient again stated that all of his visual complaints had been eliminated across all light levels, including the photophobia and headaches. He said his vision was “perfect.”

Corneal topography conducted 1 month after all surgery showed an increase in the zone of central flattening in each eye consistent with an enlargement of the optical zone with customized therapeutic enhancement.

WaveScan imaging 1 month after all surgery was interesting. It showed no significant improvement in RMS values or degrees of spherical aberration despite the dramatic subjective improvement in the patient’s vision. Manipulation of the simulated pupil, however, was again the most revealing feature in interpreting the wavefront mapping. In the right eye, the spherical equivalent of the WaveScan refraction at 6 mm went from –1.48 D at preop to +0.14 D at postop. In the left eye, the spherical equivalent went from –1.58 D to –0.46 D.

Presumably, the patient’s visual improvement was due to the improvement in the higher-order aberration profile. Even though the total RMS value was not significantly changed, there was apparently enough change, particularly in spherical aberration, in a critically close optical zone to eliminate his problems.

Figure 2 [chart]
Figure 2: Corneal topography of the right eye after customized therapeutic enhancement with CustomVue shows enlargement of the optical zone.

It is interesting that his postoperative photophobia also resolved. Postoperative photophobia, an enigmatic complication we rarely see from LASIK, may in some cases be based on a particular pattern of higher-order aberrations.

This case demonstrated how a wavefront-based customized correction can improve visual quality not only in primary cases, but also in older-generation LASIK procedures with small optical zones and associated suboptimal visual quality. It also showed the diagnostic power of the WaveScan in helping to understand difficult cases. WaveScan diagnostic imaging and CustomVue treatments open up the possibility of helping those patients who had surgery in the past and now wish for the best possible uncorrected vision we can provide.

For Your Information:

David R. Shapiro, MD, is a teacher and author of refractive surgery. He has a private practice specializing in refractive surgery at the Shapiro Laser Eye Center with offices in Ventura, Montecito and San Luis Obispo, Calif. He can be reached at 1280 S. Victoria Ave, Suite 260, Ventura, CA 93003; 805-339-0566; fax: 805-339-0133; e-mail: dshapiro1@cox.net. Dr. Shapiro has no financial interest in any companies mentioned in this article.