BACKGROUND: Along with traditional RGP lenses there are several proprietary designs for corneal irregularity due to keratoconus, keratoplasty and refractive surgery. Despite providing excellent vision and oxygen transmissibility, patients may be unable to tolerate rigid lenses or achieve their desired wearing schedules even when the lenses are fitting well. In these cases, hybrid designs, speciality soft lenses or piggy-back systems may be considered.

CASE REPORT: A 50 year old keratoconic patient presented for contact lens aftercare. She had a history of rigid lens intolerance and unacceptable visual acuity with spectacles and standard soft lens designs. She had been successfully fitted with SoftPerm (CIBA Vision) lenses five years previously and reported that these lenses provided good vision but reduced comfort over the long (18 hours per day) wearing schedule required. Slit lamp examination revealed limbal and bulbar injection, corneal staining and corneal vascularisation in both eyes. Various speciality lenses were trialled without success. In view of the bulbar injection and corneal vascularisation, a piggy-back system using a high Dk silicone hydrogel lens (Focus Night & Day, CIBA Vision) and a hyper Dk rigid lens (Z alpha, Menicon) was trialled on a daily wear basis. RESULTS. This novel contact lens system provided a significant improvement in visual acuity, comfort and lens wear time. There was a marked reduction in corneal vascularisation and ocular hyperaemia.

CONCLUSIONS: This hyper Dk piggy-back system satisfied the ocular and visual requirements of this patient where other non-surgical options for visual correction had failed. The hyper oxygen transmissible lens materials available make these dual-lens systems a viable option for the compromised cornea.