Management of Pediatric Aphakia with Silsoft Contact Lenses

Nancy MacDougall -

Centre for Contact Lens Research, University of Waterloo

Nancy MacDougall is currently a Research Associate at the Centre for Contact Lens Research at the University of Waterloo in Ontario, Canada, where she is responsible for conducting clinical research in the areas of contact lenses and refractive surgery. She graduated with honours in Optometry from the University of Waterloo and is currently working towards her PhD in Vision Science on a part-time basis.

Aasuri MK, Venkata N, Preetam P, Rao NT.

CLAO J. 1999 Oct; 25(4):209-12.

When choosing the most appropriate form of correction for a pediatric aphakic child, many factors need to be considered. Glasses, intraocular lens implants (IOLs), and contact lenses (soft or rigid gas permeable (RGP)) each have their own list of strengths and limitations.

The paper published by Murali Krishnamachary Aasuri et al in the October 1999 issue of the CLAO journal investigates the performance of silicone elastomer lenses in pediatric eyes with aphakia. This study is a retrospective analysis of 74 children (106 eyes) fitted with Silsoft lenses (elastofilcon A, Bausch & Lomb) at the L.V. Prasad Eye Institute in India. The median age was 9.0 months (range 1 month to 12 years). Reasons for lens fitting, lens parameters chosen, the mode and duration of lens wear, grounds for discontinuation, visual recovery and complications were evaluated.

The most commonly used base curves were 7.5mm (n=46 eyes), 7.7mm (n=39 eyes) and 7.9mm (n=20 eyes). An 11.3mm diameter was required for 103 eyes, whereas only 3 eyes required a 12.5mm diameter. In this study the mean lens power was 24.3 ± 6.1D (range: 12-32D) and children up to two years of age were given a +2.00D add to account for their "near world".

The most commonly prescribed mode of lens wear was one week extended wear. Visual acuity improved in 45.2% of the eyes. Patching and operating at an earlier age were found to improve visual outcomes, particularly for the children with monocular aphakia.

The median duration of lens wear in this study was 9.5 months. At the last follow-up visit, 27 eyes were still wearing the Silsoft lenses, 27 eyes were lost to follow-up and 52 eyes discontinued lens use. Of these 52 eyes, the majority (43 eyes) shifted to alternate forms of aphakic correction, including spectacles (n=21), RGP (n=10) or soft (n=4) contact lenses, and IOLs (n=4). Reasons for switching the form of correction included non-availability of the Silsoft lens with eye care practitioners, recurring cost, difficulty with regular follow-up, and attainment of an age where the child could tolerate alternate forms of correction. This article stated that lens-related complications, noncompliance, and reluctance of the parents to handle lenses did not appear to be limiting factors.

Adverse events occurred in 32 eyes, 23 of which were lens-related. Epithelial compromise secondary to lens drying and deposition occurred most commonly (n=11). Two eyes had lenses that were "sucked-on" and there were two cases each of infectious keratitis and peripheral corneal ulcers, both of which resolved with treatment and temporary discontinuation of lens wear. Only three eyes were required to discontinue lens wear permanently due to an adverse event.

Results of this study indicate that silicone elastomer lenses are an excellent option for fitting pediatric aphakic eyes and the benefits are clear. These lenses are successful because they allow a significant amount of oxygen to reach the eye, which is particularly important when such a high plus power is required on a continual basis. Silicone elastomer lenses are also easy to handle and don't pop-out of the eye like an RGP can. They also provide superior optical performance and improved cosmesis over spectacle lenses, especially for monocular aphakia. Good outcomes with silicone elastomer lenses include improved vision as a result of constant visual correction with continuous wear and minimal adverse events. Lens drying, surface deposition and lens adherence, however, are limitations of this material and scheduled follow-up care is important as infectious and inflammatory events can still occur.

What's very exciting to me is that silicone hydrogel lenses have the potential to exceed the performance of silicone elastomer lenses. Silicone hydrogel lenses have excellent handling capabilities and are very breathable; yet they are significantly more wettable and have a greater resistance to deposit formation. Silicone hydrogel lenses also move better and provide greater tear exchange. Subsequently, they would be easier to remove and there would be fewer problems with lens binding. In theory, this could reduce epithelial compromise and minimize lens-related complications, including infection and inflammation, making this form of correction even safer. Wouldn't it be nice one day if silicone hydrogel lenses were available in the necessary parameters to correct our aphakic children.