Characteristics and functional outcomes of 130 patients with keratoconus attending a specialist contact lens clinic.

Abstract

To evaluate the demographic profile, management and functional outcomes of patients with keratoconus attending the contact lens clinic of a tertiary ophthalmic referral centre over a one year period. A retrospective cohort analysis was conducted by reviewing the computerised hospital records of 130 patients attending The Western Eye Hospital contact lens department over the period 1st Jan 1999 to 31st Dec 1999. Data on age, gender, referral pattern, visual acuity, contact lens fitting, degree of visual success, and some information on penetrating keratoplasty were obtained. 16.4% of all patients attending the Contact Lens clinic had keratoconus. The mean age at referral was 28.6 years and the mean age of keratoconus during the study period was 34.9 years. There was a predominance of male patients. Optometrists formed 72.2% of the referrals, and had prescribed some form of refractive correction in 70% of patients (two-thirds contact lenses) prior to hospital assessment. Of the 130 patients seen in the department during the study period, the post-referral management included bilateral contact lens fitting for 102 patients (78.5%), monocular contact lens fitting for 24 patients (18.5%) and no intervention in four patients (3%). The types of contact lenses used included PMMA lenses (2.7%), rigid gas permeable lenses (96.1%) of the spherical, elliptical and special cone lens designs, Keratosoft or Softperm lenses (0.8%) and scleral lenses (0.4%). Eleven eyes of eight patients had received penetrating keratoplasty (PK) prior to hospital assessment, of whom seven eyes needed post-surgical contact lens fitting. The main reasons for PK were contact lens intolerance (83%), frequent contact lens displacement (8.5%) and unsatisfactory visual acuity despite good contact lens fit (8.5%). Sixty-five per cent of patients were able to wear their contact lenses for more than 12 hours a day. With contact lens wear, 87% of patients had a visual acuity of 6/9 or better and 59% of eyes had improved visual acuity of 0.6 logMAR or more. Optometrists were the main source of referral for keratoconus patients to the Hospital Eye Service (HES). The mean age at referral was 28.6 years, with a predominance of male patients. Blurred vision formed the main presenting visual symptom on initial hospital assessment; subsequently, more than two-thirds of patients required bilateral contact lenses. Rigid gas permeable contact lenses remain the mainstay treatment for advanced keratoconus, with various designs enabling a large proportion of patients to attain improved visual acuity.