Abstract
Purpose: :
Solution toxicity associated with contact lens use manifesting as generalized, low grade, punctate epithelial staining is common and widely reported to be asymptomatic with no substantial clinical sequelae. The purpose of this paper is to determine if there is a relationship between solution toxicity, corneal inflammatory adverse events and ocular comfort in soft contact lens (SCL) daily wear (DW).
Methods: :
Records of 596 SCL DW subjects (2,329 study visits) were retrospectively analyzed. Subjects wore one of a range of commercially available lens types bilaterally with monthly disposal and overnight disinfection using one of several marketed solutions for a minimum of two weeks and maximum of three months. Solution toxicity was defined as diffuse punctate staining in at least four out of five areas of the cornea. Corneal infiltrative events were diagnosed according to classifications previously defined (Sweeney et al, 2003). First events of any corneal infiltrative condition per eye were compared between toxic stainers and non–affected controls. Subjective comfort ratings (1=poor to 10=excellent) were regularly (up to five times) obtained.
Results: :
Subjects exhibiting solution toxicity were four times more likely to experience a corneal infiltrative event than non–affected controls (odds ratio 4.02, p=0.003, 95% CI 1.73–9.32). There were two cases of Infiltrative Keratitis (IK) and eight cases of Asymptomatic Infiltrates (AI) out of a total of 133 eyes in the toxic staining group, compared to 13 cases of IK and 11 cases of AI out of a total of 1,059 eyes in the non affected control group. When visits where solution toxicity was noted were excluded, toxic stainers nevertheless reported lower insertion (7.9 ± 2.0 vs 8.4 ± 1.6, p = 0.015) and end of day (6.7 ± 2.1 vs 7.2 ± 2.1, p = 0.043) comfort than non–affected controls.
Conclusions: :
The types of infiltrative events experienced by subjects who exhibit solution toxicity and non–affected controls are similar, however, subjects who experience solution toxicity are more likely to experience a corneal infiltrative event and to report slightly lower subjective comfort. Alternative solution/lens type combinations should be investigated to reduce the general level of staining
Keywords: contact lens • drug toxicity/drug effects • clinical (human) or epidemiologic studies: risk factor assessment