Rigid contact lens fitting relationships in keratoconus

Timothy B. Edrington, Loretta B. Szczotka, Joseph T. Barr, Joel F. Achtenberg, Dennis S. Burger, Andrea M. Janoff, Harald E. Olafsson, Melissa W. Chun, John W. Boyle, Mae O. Gordon, Karla Zadnik

Research output: Contribution to journalArticlepeer-review

27 Scopus citations


Purpose. Although the influence of flat-fitting contact lenses on corneal scarring in keratoconus is frequently debated, the current standard of care with regard to the apical fitting relationship in keratoconus remains undocumented. Methods. Patients were examined at baseline in the Collaborative Longitudinal Evaluation of Keratoconus (CLEK) Study (N = 1209). Patients wearing a rigid contact lens in one or both eyes (N = 808) had their habitual rigid contact lenses analyzed, and the fluorescein patterns and base curves were compared to the first definite apical clearance lens (FDACL). The FDACL is the flattest lens in the CLEK Study trial lens set that exhibits an apical clearance fluorescein pattern. For patients wearing a rigid contact lens in both eyes, one eye was selected randomly for analysis. Results. Twelve percent of the rigid contact lens-wearing eyes were wearing lenses fitted with apical clearance based upon the clinician's fluorescein pattern interpretation. The remainder (88%) was wearing lenses fitted with apical touch. For mild (steep keratometric reading <45 D) keratoconus corneas, the mean estimate of the base curve to cornea-fitting relationship was 1.18 D fiat (SD ± 1.84 D); moderate (steep keratometric reading: 45 to 52 D) corneas were fitted on average 2.38 D flat (SD ± 2.56 D); and severe (steep keratometric reading > 52 D) corneas were fitted an average of 4.01 D flat (SD ± 4.11 D). Conclusions. Despite the potential risk for corneal scarring inposed by flat-fitting rigid contact lenses, most CLEK Study patients wear flat-fitting lenses. Overall, rigid lenses were fitted an average of 2.86 D (SD±3.31 D) flatter than the FDACL.

Original languageEnglish
Pages (from-to)692-699
Number of pages8
JournalOptometry and Vision Science
Issue number10
StatePublished - 1999


  • CLEK Study
  • Contact lenses
  • Keratoconus
  • Keratometry


Dive into the research topics of 'Rigid contact lens fitting relationships in keratoconus'. Together they form a unique fingerprint.

Cite this