Contact Lens Case Reports
Lens Comfort, Good Vision—Even With Post-LASIK Dry Eye
BY PATRICK J. CAROLINE, FAAO, & MARK P. ANDRÉ, FAAO
Since the mid-1990s, over 1 million people a year have undergone LASIK in the United States. With the average age at surgery approximately 38, it is clear that many are now presbyopic.
Our 50-year-old female patient represents this demographic. She had successful LASIK at 37, and today her uncorrected visual acuities are 20/25 OD and OS with a manifest refraction OD of –0.50 –0.50 x 005 20/20 and OS –0.25 –0.50 x 175 20/20. Her keratometric readings are OD 36.25 @ 00/37.37 @ 097 and OS 35.87 @ 170/37.00 @ 080.
She is now interested in improving her distance and near acuities. She had tried a wide range of contemporary soft multifocal lens designs. However, every design failed to provide adequate distance or near acuity. Her best success was with the CooperVision Proclear Multifocal. However, post-LASIK dry eye limited her wearing time to six to eight hours a day.
With the assistance of the OrthoTool Contact Lens Design Software (www.orthotool.com), we designed for her a pair of reverse geometry multifocal GP lenses. The process began by having the software create the cornea shapes on which we would ultimately construct her contact lenses. This was accomplished by entering the flat simulated keratometric reading of 36.00D (9.35mm, semi cord 3.0mm) and a midperipheral radius of 40.00D (8.4mm, semi cord 4.0mm) (Figure 1). Next, a lens with a central base curve of 36.00D and an alignment curve of 40.50D (0.50D steeper than the underlying midperipheral cornea) was entered into the design program, and an 11.0mm reverse geometry lens was created.
Figure 1. Our patient’s corneal topographical maps and the OrthoTool corneal shape entry module.
The finishing touch was an anterior aspheric optic of –0.80, which in our hands consistently delivers an add power of +1.75D to +2.25D (Figure 2). The lenses were manufactured by Precision Technology Services in the highindex Paragon HDS HI material.
Figure 2. Lens design module and the subsequent simulated tear volume profile.
Successful Fits are Possible
After one change to fine tune distance powers, the patient enjoys bilateral 20/20 distance and near visual acuities with all day lens comfort (Figure 3). This case shows that with accurate corneal mapping and simple lens design software we can empirically create complex lens designs that actually work for our patients. CLS
Figure 3. The actual fluorescein patterns of the reverse geometry multifocal lenses.
Patrick Caroline is an associate professor of optometry at Pacific University. He is also a consultant to Paragon Vision Sciences. Mark André is an associate professor of optometry at Pacific University. He is also a consultant for CooperVision.