contact lens case reports

Soft Lens Option For Keratoconus

BY PATRICK J. CAROLINE, FAAO, FCLSA, & MARK P. ANDRÉ, FAAO, FCLSA
October 2001

Figure 1. The Innovations in Sight keratoconus soft lens.

Practitioners have historically chosen rigid contact lenses to manage keratoconus. However, Dr. Rob Breece at Innovations in Sight in Front Royal, VA, recently developed a new keratoconus soft lens. Its 8.0mm central aspheric zone has increased thickness to mask much of the regular and irregular astigmatism associated with the condition (Figure 1). The lens has a 14.8mm overall diameter and a wide range of base curve radii that employ traditional soft lens fitting techniques. The following case history shows the versatility of the design.

	Figure 2. Photokeratocosopy OD.

Patient S.H. is a 24-year-old college student with a seven-year history of keratoconus OU. His right eye is more advanced than his left, with K readings of OD 56.00 @ 165/62.50 @ 76 (Figure 2), OS 45.75 @ 155/53.25 @ 65. His RGP lenses provided acuities of OD 20/50 and OS 20/30. The patient's chief complaint was limited wearing time (OD) of 10 hours a day despite optimization of the RGP fit. Wearing time OS was 16 hours a day.

We elected diagnostic fitting with the new keratoconus soft lens design, OD only. We selected the initial base curve by converting the mean K into millimeters and adding 1.0mm (mean K OD 59.25 diopters. (5.70mm) plus 1.0mm = 6.70mm). 

Figure 3. Photokeratoscopy OD over the Innovations in Sight soft lens.

We placed a 6.70mm ­9.00 14.8mm diagnostic lens onto the patient's right eye and allowed it to equilibrate for 30 minutes. Photokeratoscopy (performed over the soft lens) illustrates the masking capabilities of this design (Figure 3). An over-refraction of ­3.50D sphere revealed visual acuity of 20/50. We could also incorporate any cylinder component, if revealed in the over-refraction, into the anterior optics of the lens. Slit lamp examination showed the lens to be slightly decentered temporally, so we ordered a steeper base curve of 6.50mm.

	Figure 4. Keratoconus soft lens on the patient's right eye.

With time, the surface of the cornea improved beneath the soft lens. The final VA OD was 20/40 with a wearing time of 16 hours a day. This new soft lens design changes the idea that all patients with keratoconus require RGP lenses for optimum correction. While RGP lenses remain our primary choice in keratoconus, we should not forget the availability of custom soft contact lens designs when fitting irregular corneas.

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