A 49-year-old patient had a history of radial keratotomy in both eyes in
1987. He developed a hyperopic shift in his right eye several years later and
had LASIK to improve distance vision in 1999. More recently, the patient
developed a cataract in the right eye. The patient desired spectacle
independence for at least distance vision.
To choose the power of the patients lens implant, in the
surgeons office we measured the effective corneal power using the average
axial powers from corneal topography. We also compared the spherical equivalent
of his manifest refraction to that of his over-refraction while wearing a
gas-permeable contact lens of known anterior curvature. These data were used to
calculate his desired IOL power (targeting emmetropia) using the Holladay II,
Hoffer Q and Haigis formulas available on the website of the American Society
of Cataract and Refractive Surgery (www.ascrs.org).
One month after uneventful surgery, the patients right eye had the
following refraction: -2.00 D, -1.00 D, axis 013 correcting to 20/25. There was
mild opacity of the posterior lens capsule. The patient complained of limited
I plan to do a PRK (with mitomycin C), and the patient is likely to do
quite well. We generally do a Nd:YAG capsulotomy prior to PRK because of the
small but real chance of the capsulotomy shifting the lens position and
Patients with prior refractive surgery deserve special consideration
when cataract surgery is being considered because of the challenge in obtaining
precise corneal power measurements in patients with previously-altered corneas.
RK is particularly difficult in this respect, and when myopic RK is combined
with subsequent hyperopic LASIK, surprises often occur. To avoid
disappointment, patients should know about the possible need for
enhancement before cataract surgery is performed.
Because this patients cornea did not have a high degree of
irregular astigmatism, photorefractive keratectomy with mitomycin was a
reasonable option, considering he had a history of multiple procedures.
In more routine cases where enhancement is needed, some surgeons prefer
to perform LASIK, implant piggyback IOLs or even perform mini-RK. All of these
can achieve a satisfactory result, and some form of enhancement is generally
necessary when residual refractive error is greater than +/-0.5 D.
- Joseph G. Heinrich, OD, can be reached at 32241 Camino Capistrano,
Suite A-101, San Juan Capistrano, CA 92675; (949) 661-3669;
- John A. Hovanesian, MD, FACS, is a member of the Primary Care
Optometry News Editorial Board. He can be reached at Harvard Eye
Associates, 24401 Calle De La Louisa, Suite 300, Laguna Hills, CA 92653; (949)
951-2020; fax: (949) 380-7856; firstname.lastname@example.org.