Reply

We thank Tello et al for raising important considerations regarding the roles of genetic and environmental factors in keratoconus. We agree that eye rubbing, sleep position, and family history are important factors to consider in every evaluation of patients with keratoconus. In fact, our recently published article surveyed parents of pediatric patients with keratoconus specifically inquiring about patient eye rubbing.¹ In addition, another recent study by our group was the first to demonstrate a decrease in eye rubbing after corneal collagen cross-linking.² Although we were unable to specifically include these factors in this particular study, we considered both atopy and obstructive sleep apnea. These are associated with eye rubbing and floppy eyelids, which can cause the mechanical trauma hypothesized to underly the pathogenesis of keratoconus.^3–5

Our study does not claim socioeconomic factors lead to more severe keratoconus, but rather that these factors are correlated with more severe disease. We believe they should be considered risk factors irrespective of the underlying pathogenic mechanism. To continue the lung cancer analogy, we might find that low socioeconomic status is associated with a higher risk of advanced disease. On further review, it might be determined that this is mediated by, for example, a higher prevalence of smoking in low socioeconomic populations or delayed diagnosis due to disparities in access to care. However, the presence of the association remains important as it suggests a risk difference between groups that warrants further exploration and understanding. In keratoconus, the association might be mediated, for example, by a higher prevalence of eye rubbing in socioeconomically marginalized populations due to greater exposure to air pollution. Alternatively, limited health literacy may render patients or parents unaware of the association between eye rubbing and keratoconus. In our recently published article, we demonstrated lower keratoconus literacy among socioeconomically marginalized parents and a tendency toward more severe keratoconus disease in their children.¹

As we note in our article, our retrospective study is limited in that we did not prospectively collect relevant variables. Although we reviewed patient charts for documentation of eye rubbing and family history, in most cases, these were not reported. This could be, as Tello et al suggest, due to provider attitudes or neglect of the importance of these risk factors, or simply failure of the record to fully reflect the discussions in the clinician’s office. We wholeheartedly agree that all ophthalmologists must solicit and document a detailed family history and health behaviors.