title: Impact of Contact Lens Material, Design, and Fitting on Discomfort.
abstract: OBJECTIVE
  To review the effect of contact lens (CL) material, design, and fitting characteristics on CL discomfort.
  
  
  METHODS
  A PubMed search identified publications describing subjective comfort and CL material, fitting, and design parameters. The review included clinical signs associated with discomfort that may be a consequence of these parameters.
  
  
  RESULTS
  Reduced lens movement or more CL tightness were associated with improved comfort. Increased lens-induced paralimbal conjunctival staining and indentation, considered as quasi-indicators of CL fitting or edge design, were also associated with better comfort. No recent studies have evaluated varying CL design parameters and subjective comfort. Silicone hydrogel CLs are no different in comfort compared with hydrogel CLs. Lower equilibrium water content is associated with improved comfort in hydrogel CL wear. Coefficient of friction shows promise as a material factor potentially associated with comfort. Lid wiper epitheliopathy and lid-parallel conjunctival folds have been linked with comfort in established wearers.
  
  
  CONCLUSIONS
  Recent studies have confirmed the association between more mobile CLs and more discomfort, whereas closer conformity of the CL to the bulbar conjunctiva improved subjective comfort. There is no evidence to support the perceived comfort difference between silicone hydrogel and hydrogel CL. There has been limited progress in understanding the impact of varying specific CL design parameters. Although specific clinical signs may be predictive of discomfort, their role in the natural history of discomfort remains unclear. A better understanding of the relationship between coefficient of friction and comfort and strategies to improve lubricity may hold promise for limiting CL discomfort.
authors.affiliation: School of Optometry and Vision Science, University of New South Wales, Sydney, Australia.
authors.forename: Fiona
authors.initials: F
authors.lastname: Stapleton
authors.forename: Jacqueline
authors.initials: J
authors.lastname: Tan
mesh_terms: D003263:Contact Lenses, Hydrophilic / Q000009:adverse effects; D003316:Corneal Diseases / Q000209:etiology*; D015352:Dry Eye Syndromes / Q000209:etiology*; D005141:Eyelid Diseases / Q000209:etiology*; D006801:Humans; D020100:Hydrogels / Q000737:chemistry*; D011474:Prosthesis Design; D017755:Prosthesis Fitting
chemical_list: D020100:Hydrogels