New technologies to assess lens-mediated effects of the cornea.
Contact lenses can affect the cornea in a variety of ways. Corneal structure can be altered so that its thickness changes to involve the epithelium and the stroma. As a result, the curvature may be affected, but whether it is the front or the back surface that is affected depends on the type of lens used. If thickness increases sufficiently, corneal transparency may decrease. Contact lenses can also affect cellular structure of all layers of the cornea through mechanical trauma, hypoxia, or toxicity from solutions that are used in association with lenses. More serious complications, such as inflammation and infection, can arise. All these changes can be detected by clinicians using slitlamp biomicroscopes and keratometers if the changes are significant enough. Since the development of computers, optical instruments have become more sophisticated and have enabled the detection of subtle changes but have also facilitated more precise measurement of these conditions along with the ability to capture images of the alterations or defects. This article describes some of the newer techniques and, specifically, the application of optical coherence tomography, confocal microscopy, and esthesiometry.
Fonn
Desmond
D
Center for Contact Lens Research, School of Optometry, University of Waterloo, Waterloo, Ontario, Canada.
Simpson
Trefford
T
Woods
Jill
J
Woods
Craig
C
D003261:Contact Lenses / Q000009:adverse effects*; D003315:Cornea / Q000473:pathology; D003316:Corneal Diseases / Q000175:diagnosis* / Q000209:etiology* / Q000503:physiopathology; D003941:Diagnostic Techniques, Ophthalmological / Q000295:instrumentation; D006801:Humans; D018613:Microscopy, Confocal; D012677:Sensation; D013194:Staining and Labeling; D041623:Tomography, Optical Coherence