contact lens case reports

Soft Bifocals Correct LASIK Overcorrection

BY PATRICK J. CAROLINE, FAAO, & MARK P. ANDR�, FCLSA
May 1999

Recent studies have shown that the average age of patients who undergo refractive surgery is 38. This means that a significant number of postoperative individuals fall into the presbyopic age range. Often, these patients elect to pursue contact lens options after surgery to accommodate any under or over

range. These patients often elect to pursue contact lens options after surgery to accommodate any under or overcorrection in conjunction with their presbyopia.

T.D. is a 50-year-old female with a 34-year history of rigid lens wear and most recently, daily wear soft lenses. Her pre-surgical refractive error was OD -7.50
-0.50 x 175, OS -7.75 -0.75 x 10 with visual acuities of 20/20 OU. Keratometric readings were OD 44.00 @ 180 / 44.25 @ 90 and OS 43.75 @ 10 / 44.50 @ 100. She was instructed to discontinue lens wear for 3 weeks prior to surgery and was scheduled for LASIK on the left eye, followed by surgery on the right eye 3 weeks later.

Six months post-operatively, her uncorrected visual acuities were OD 20/70 and OS 20/30. Manifest refraction was OD +2.75 -0.50 x 45 20/20 and OS +1.00 sphere 20/20. Keratometric readings were OD 37.75 @ 90 x 38.25 @ 180 and OS 39.50 @ 90 x 39.75 @ 180. T.D. expressed an interest in managing the overcorrection with a contact lens (Fig.1).

FIG. 1: The post operative corneal map of the patient's OD.

Options

Patients in this age group frequently benefit from the use of lenses to correct their newly acquired hyperopia, as well as their presbyopia. Post-surgical contact lens options include: standard or reverse geometry single vision RGP lenses with reading eyeglasses for near, standard soft lenses or custom single-vision soft lenses for distance with reading eyeglasses for near, and monovision or bifocal lenses.

In this case, the patient chose a trial of Acuvue Bifocal contact lenses (OD +2.50 and OS +1.25, both with a +1.50 add OU), and was very pleased with their performance. Distance visual acuities were 20/20 OU with a binocular near acuity of 20/25 (Fig.2).

FIG. 2: The Acuvue Bifocal lens on the patient's left eye.

Profile of the Chosen Lens

The Acuvue Bifocal is a 58 percent water content lens available in a base curve of 8.5mm and a diameter of 14.2mm. Powers range from +4.00D to -6.00D, in 0.25D steps with add powers of +1.00 to +2.50 in 0.50D steps. It is a concentric ring, simultaneous vision design with five alternating optical zones, beginning with a distance zone in the center. It has a center thickness of 0.075mm, which allows it to drape over the flatter central cornea while accommodating a wide range of peripheral corneal topographies.

For us, the Acuvue Bifocal lens has proven to be a surprisingly simple and inexpensive way to fit complex corneal topographies while effectively managing both the distance and near requirements of presbyopic patients.

Patrick Caroline is an associate professor of optometry at Pacific University and an assistant professor of ophthalmology at the Oregon Health Sciences University. Mark Andr� is director of contact lens services at the Oregon Health Sciences University.