The therapeutic and optical application of a rigid gas permeable semi-limbal diameter contact lens☆

Abstract 

Purpose

To evaluate the therapeutic and optical application of a semi-limbal diameter (S-LIM) rigid gas permeable (RGP) contact lens.

Method

A retrospective non-comparative case series of 14 consecutive patients (22 eyes) who were referred to one senior optometrist for the fitting of S-LIM contact lenses at Moorfields Eye Hospital. The cases comprised of 11 patients (17 eyes) with keratoconus, 1 patient (2 eyes) post-surgical ectasia from previous LASIK, 1 (1 eye) post-graft patient, and 1 patient (2 eyes) who required corneal protection secondary to lagophthalmos. These patients had failed previously with other lens designs because of lens intolerance, unstable vision, chronic 3 and 9 o’clock corneal staining, and inadequate corneal protection for the patient with lagophthalmos. A conventional method of using diagnostic lenses with fluorescein assessment was adopted in fitting the S-LIM lenses.

Results

The median duration of problems encountered with previous lenses was 4 years (range 0.5–10 years). The median visual acuity with the S-LIM lens was 6/9 (range 6/5–6/24). A median of 1 diagnostic lens (range 1–3 lenses) was required to achieve a satisfactory fit. At the last recorded follow-up, 10 patients (14 eyes) had no clinically observable problem and were wearing their lenses with a median wearing time of 8h per day (range 1–18h). The median duration of follow up was 6 months (range 2–18 months). One patient (1 eye) abandoned lens wear because of satisfactory unaided vision.

Conclusion

The use of a semi-limbal diameter lens can be an effective modality in patients with intolerance to other lens designs. However, lens modification from the standard design and the use of ocula lubricants are often required to optimise lens fit and to enhance tolerance.

Keywords: Semi-limbal diameter contact lens, Irregular astigmatism, Therapeutic contact lens, Keratoconus