Original article
Baseline Factors Predictive of Incident Penetrating Keratoplasty in Keratoconus

https://doi.org/10.1016/j.ajo.2006.07.026Get rights and content

Purpose

To identify baseline demographic and clinical factors associated with undergoing penetrating keratoplasty (PK) in a prospective cohort of 1,065 keratoconus patients followed for eight years in the Collaborative Longitudinal Evaluation of Keratoconus (CLEK) Study.

Design

Multicenter, prospective, observational cohort study.

Methods

We report the rate of PK over eight years and baseline factors predictive of PK in 1,065 patients who, at the time of study enrollment, had not undergone PK in either eye.

Results

Eighty-two percent of patients completed the eight-year close-out visit. Twelve percent (126 of 1,065) had PK in one (9.3%) or both eyes (2.5%). Baseline factors associated with increased likelihood of PK included younger age, steeper keratometric values, worse visual acuity, corneal scarring, poorer contact lens comfort, and poorer vision-related quality of life. The percent of eyes undergoing PK was 15% for patients 40 years old and younger, 28% for eyes with a steep keratometric value greater than 52 diopters, 33% for visual acuity less than 20/40, and 24% for eyes with corneal scarring.

Conclusions

The CLEK Study confirmed previous reports of the increased likelihood of PK associated with corneal scarring, steeper keratometry values, poorer visual acuity, and poorer contact lens comfort. The CLEK Study is among the first to report an increased risk of PK associated with younger age, worse vision-related quality of life, and flatter contact lens fits. Knowledge of these factors is beneficial to clinicians in patient education and may be useful in disease management.

Section snippets

Methods

The CLEK Study protocol was approved by each clinic’s institutional review board, and the clinics obtained informed consent from each patient. The protocol has been described in detail elsewhere.18 Eligibility criteria included age 12 years or older, an irregular corneal surface in either eye, and the presence of biomicroscopic findings in at least one eye (Vogt striae, Fleischer ring, or corneal scarring characteristic of keratoconus). Exclusion criteria were bilateral corneal transplants or

Results

At baseline, 118 of the initially enrolled 1,209 patients had already undergone corneal surgery (116 penetrating keratoplasties and two epikeratoplasties) and were excluded from the analysis. Also excluded were 26 patients who dropped out of the study before completing any follow-up visits. Thus the analysis sample for this report consisted of 1,065 patients who had not undergone penetrating keratoplasty or epikeratoplasty and had completed at least one follow-up visit. Of these 1,065 patients,

Discussion

The CLEK Study is the first prospective cohort study to report the rate of PK in a large and geographically dispersed sample of patients diagnosed with keratoconus. Over eight years of follow-up, 12% of the 1,065 patients who entered the study without PK in either eye underwent PK in one or both eyes (9.3% in one eye; 2.5% in both eyes). The 82% completion rate of the close-out visit protects against biased loss to follow-up and biased ascertainment of PK. The rate of PK was similar at CLEK

Mae O. Gordon, PhD, Professor, Department of Ophthalmology and Visual Sciences and Division of Biostatistics at Washington University School of Medicine, is Director of Coordinating Centers for the Collaborative Longitudinal Evaluation of Keratoconus Study and the Ocular Hypertension Treatment Study. Dr Gordon research interests include design and implementation of clinical trials, development of outcome measures, and adherence to treatment regiments.

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    Mae O. Gordon, PhD, Professor, Department of Ophthalmology and Visual Sciences and Division of Biostatistics at Washington University School of Medicine, is Director of Coordinating Centers for the Collaborative Longitudinal Evaluation of Keratoconus Study and the Ocular Hypertension Treatment Study. Dr Gordon research interests include design and implementation of clinical trials, development of outcome measures, and adherence to treatment regiments.

    See accompanying Editorial on page 1044.

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