The cat as a model to predict on eye adherence of contact lenses in the human

Purpose. To determine if the cat model can be used to predict on eye adherence of contact lenses in the human. Methods. A range of different materials in the form of contact lenses were assessed on eye after at least one hour of wear. Up to 10 human and 5 cat subjects were involved and similar lens designs were used in each case. Adherence was defined as any lens which displayed 100% lightness with the push up test. Beyond this, the strength of adherence as indicated by resistance to lateral digital pressure was graded on a 0-4 scale. A zero grade indicated a easily displaced lens while grade four denoted an absence of movement with even strong digital force. Results. The cat demonstrated a sensitivity of 74% and a specificity of 72% in predicting human contact lens binding. The association between the grade of adherence assessments made in cats and humans was highly significant (r = 0.69, p < 0.0001). Conclusions. This study suggests that the cat may provide a useful model for predicting the adherence of contact lenses in human eyes.