contact lens case reports

Soft Lens Helps RGP-Intolerant Keratoconus Patient

contact lens case reports
Soft Lens Helps RGP-Intolerant Keratoconus Patient

Historically, RGP lenses have been the modality of choice for the correction of keratoconus. Recently, however, a number of soft contact lens designs have emerged into the marketplace that have challenged this traditional thinking. An excellent case-in-point is patient MA, a 32-year-old female with a longstanding history of keratoconus.

Figure 1. Corneal mapping clearly demonstrates the unilateral keratoconus OS.

The patient originally presented to our clinic with a manifest refraction of OD ­2.50­0.50 x 5, 20/20; OS ­6.50­1.75 x 150, 20/40. K readings were OD 44.25@12/45.37@105, with an apical radius of 44.87 diopters; OS 49.75@156/51.87@66 (2+ distortion), with an apical radius of 58.87 diopters (Figure 1).

Our initial management began with an RGP lens fitting in both eyes. The patient reported excellent visual acuity and comfort in the right eye with a wearing time of 14 hours a day. The left eye, however, was significantly more symptomatic with a maximum wearing time of four hours a day. Numerous design modifications were attempted and, despite an acceptable fitting relationship, the left eye remained essentially intolerant.

Figure 2. Schematic dual curve keratoconus design.

The patient's left eye was subsequently fitted with a new keratoconus soft lens design from Innovations In Sight in Front Royal, VA. This lens incorporates two primary curves on the posterior lens surface. A central curve accommodates the steep central or paracentral apical radius, and a flatter mid-peripheral curve aligns the more normal peripheral cornea (Figure 2).

The actual lenses dispensed were OD 8.6mm, ­2.50D, 14.5mm and OS 7.4mm (central radius)/8.6mm (peripheral radius), ­6.00D, 14.5mm. At the one-week follow-up visit, the patient's visual acuities were OD 20/20, OS 20/50. An over-refraction in the left eye revealed +0.50­1.50 x 146, 20/30. The sphere and cylinder powers were incorporated into a new left lens, with a final visual acuity of 20/30 and a wearing time of 16 hours in both eyes (Figure 3).


Figure 3. The custom toric keratoconus design. (OD left, OS right)

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.