Contact Lens Case Reports
Custom Silicone Hydrogel for High Hyperopic Astigmatism
By Patrick J. Caroline, FAAO, & Mark P. André, FAAO
Our patient is a 12-year-old male with a history of congenital high hyperopia and astigmatism OD and OS. The patient presented with a history of right eye strabismus and amblyopia. His only remarkable systemic condition was that of asthma, which he controls with Advair (GlaxoSmithKline).
The patient had a two-year history of soft contact lenses but reported a significant decrease in his visual acuity compared to that with his glasses. Additionally, he had experienced two episodes of sterile peripheral corneal ulcers (one in each eye) while wearing his traditional 59-percent water HEMA custom toric soft lenses. At the time of his visit, the patient had not worn lenses for six weeks. It was his strongest desire to continue with some form of contact lens correction.
A Silicone Hydrogel Solution
On presentation to our clinic, the patient's best-corrected spectacle prescription was OD +8.00 −2.50 x 002 20/40, OS +7.75 −2.75 x 176 20/20. Simulated keratometric readings were OD 39.87 @ 006/43.50 @ 096 and OS 40.25 @ 174/43.50 @ 084. His corneal topography demonstrated flatter than normal corneal radii with normal, naturally occurring, with-the-rule corneal astigmatism in both eyes (Figure 1).
Figure 1. The patient's corneal topography, demonstrating his high with-the-rule corneal astigmatism.
Because of the patient's past history of sterile peripheral infiltrates with his habitual HEMA lenses, we considered two contact lens options: GP lenses or a custom, high-DK silicone hydrogel soft lens. After some discussion, the patient and his parents elected to go with the custom silicone hydrogel lenses, with the understanding that if the peripheral infiltrates returned, we'd need to investigate the GP modality.
Because of the patient's requirement for a toric, high-plus lens design, we elected to have the lenses manufactured by Art Optical in the Intelliwave Toric Design. They were manufactured in the new Contamac Definitive material, which is a latheable (made-to-order), non-surface treated, daily wear, silicone hydrogel material with a Dk of 60 and a 74-percent water content. The final parameters were OD base curve 8.4mm, power +9.75 −3.00 x 002, diameter 14.5mm and OS base curve 8.4mm, power +8.50 −2.75 x 176, diameter 14.5mm (Figures 2 and 3). His visual acuity was stable in both eyes at OD 20/40 and OS 20/20.
Figure 2. The Intelliwave Toric Design on the patient's right eye.
Figure 3. The Intelliwave Toric Design on the patient's left eye.
This case describes an individual whose history with soft contact lenses was perhaps compromised by the limited transmissibility of traditional HEMA materials. Only time will tell if the higher Dk of the silicone hydrogel material proves adequate for his ocular physiology. CLS
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.