contact lens materials

Fitting a Challenging Case with a Custom Silicone Hydrogel

BY LYNDON JONES, PHD, FCOPTOM, FAAO, KATHY DUMBLETON, MSC, MCOPTOM, FAAO, & JILL WOODS, BSC, MCOPTOM

This final article in a three-part series on the O₂Optix Custom lens (CIBA Vision) describes a challenging patient whom we fit with the lens during recent clinical studies at the Centre for Contact Lens Research at the University of Waterloo.

High Myopia, Chronic Hypoxia

Patient VM was a 54-year-old female who presented having worn soft contact lenses for more than 30 years. She wore her lenses for seven days a week, 17 hours per day, with dryness symptoms for the last five to six hours each day. On presentation she was wearing Acuvue 2 (Vistakon) lenses in a monovision modality (OD for near), with acuities of 20/40– and 20/40 OU at near. Her spectacle prescription was OD –17.50 –1.00 x130 (20/40–) and OS –10.25 –1.25 x010 (20/40) with a +1.25D reading add. K readings were OD 45.75/46.50 and OS 46.25/47.25.

Figure 1. Extensive limbal vasculature changes in a high myope (–17.00D) wearing conventional hydrogel lenses for more than 30 years.

Slit lamp examination revealed extensive limbal hyperemia, obvious neovascularization, stromal striae and endothelial polymegethism (OD>OS) resulting from chronic hypoxia (Figure 1).

A Dramatic Change

VM was enrolled into a clinical study for O₂Optix Custom, and we ordered the following lenses: OD 8.4mm base curve, 14mm diameter –14.50D (near) and OS 8.4mm base curve, 14mm diameter, –9.00D (distance). With these lenses she had best corrected distance acuities of OD 20/40 (with the distance over-refraction in place) and OS 20/30– and she managed 20/40 OU at near.

Figure 2. Same patient as in Figure 1, one week after wearing an O₂Optix Custom lens.

At her one-week follow-up visit her acuities were OD 20/30, OS 20/20– and she managed 20/40 OU at near with ease. No striae were present and her limbal vessels appeared dramatically different, with an obvious reduction in both limbal hyperemia and neovascularization (Figure 2). Her wearing time was still 17 hours, but she reported a marked improvement in end-of-day dryness symptoms.

The improvement in her ocular appearance continued over the next three weeks, and at her one-month visit all signs of chronic hypoxia (with the exception of endothelial polymegethism, which we don't expect to recover substantially) were absent.

Benefits for Many

This case is typical of the kind of patient who will benefit greatly from the availability of custom-made silicone hydrogels. Their recent release will aid patients and practitioners alike. CLS

For references, please visit www.clspectrum.com/references.asp and click on document #139.

Dr. Jones is the associate director of the Centre for Contact Lens Research and a professor at the School of Optometry at the University of Waterloo, Ontario, Canada. Dr. Dumbleton is a senior clinical scientist at the Centre for Contact Lens Research. Jill Woods is a clinical scientist at the Centre for Contact Lens Research.