IT IS CERTAINLY reflexive to think that patients who have keratoconus would achieve their best outcomes with GP lenses. However, soft contact lenses can be a successful alternative for patients who have mild keratoconus (Eiden and DeNaeyer, 2012). The challenge for these cases is often achieving a stabilized fit that corrects for high amounts of astigmatism.

CASE REPORT

A 28-year-old patient who had no previous history of contact lens wear and had been diagnosed with mild keratoconus presented for specialty lens fitting because he was unhappy with his glasses-corrected vision. His manifest refraction was OD +1.00 –4.00 x 073 20/25 and OS +4.75 –4.00 x 083 20/20.

After discussion, he was fit into specialty keratoconus lathe-cut soft lenses (methafilcon A); diameter of 15mm and base curve of 8.9mm in both eyes; center thickness (CT) OD 0.24mm/OS 0.3mm, and OD +1.50 –4.00 x 073 20/25 and OS +5.00 –4.25 x 083 20/20. Although his measured visual acuity was the same as his manifest refraction, the patient reported that he was so happy with the results that, “The first day I left with the lenses I started crying.” He wore the lenses daily using a nightly hydrogen peroxide care system and replacing the lenses every three months.

Seven years later, the patient was doing well, but his soft lens design was discontinued. Seeking an alternative design, the patient was agreeable to trying a specialty made-to-order (MTO) soft contact lens design that could be replaced monthly rather than quarterly.

Although the high toricity was available with the MTO lenses, he ultimately was unsuccessful with them because they were both unstable and provided poor vision. The MTO lenses did not have adjustable base curve, diameter, or center thickness options, so he was refit into an alternate lathe-cut specialty lens design that replicated the exact parameters of his original custom lenses, and now successfully wears them.

DISCUSSION

Some patients who have mild keratoconus have success with standard molded soft lenses that can be replaced daily or monthly using MTO soft designs to accommodate high cylinder correction. Specialty lathe-cut lens designs offer the additional advantage of larger diameters, which improves fit and stability because of increased sagittal depth.

Additionally, these specialty designs often have increased center thicknesses to attempt to mask some surface corneal irregularity, minimizing higher-order aberrations. For this patient’s left eye, aberrometry over the 0.3mm contact lens measured reduced vertical coma (Figures 1 and 2). Additional wavefront correction can be added to the front surface to correct for residual aberrations, but was not necessary for this patient because he is subjectively happy with the vision that his specialty lathe-cut lenses provide. CLS

REFERENCES

1. Eiden SB, DeNaeyer, GW. Keratoconus Fitting with Specialty Soft Lenses. Contact Lens Spectrum. 2012 Jan;27:34-37.
2. Marsack JD, Parker KE, Niu Y, Pesudovs K, Applegate RA. On-eye performance of custom wavefront-guided soft contact lenses in a habitual soft lens-wearing keratoconic patient. J Refract Surg. 2007 Nov;23(9):960-4.