Contact Lens Spectrum
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C O N T A C T L E N S S P E C T R U M S P E C I A L E D I T I O N 2 0 1 6 c l s p e c t r u m . c o m 20 VISUAL PERFORMANCE O ver the past few years, there has been increased focus on and significant advances in our understanding of the ocular environment, includ- ing the complex interaction with contact lenses. There have also been important developments in novel contact lens materials and designs. Considering these advances, we continue to research the relationship between the ocular environment and the patient's experience of contact lens wear. This article summarizes current knowledge of the ocular surface and the surface environment, focusing on how contact lenses and the ocular environment in- teract. It examines the dynamics of contact lens-related symptoms throughout the day and the attitudes that lens wearers associate with various symptoms. It also offers insight and suggestions for successfully managing these patients. THE TEARS AND CONTACT LENSES Otto Wichterle, the brilliant chemist and father of contact lens material science, conceived of a hydrogel material considered impossible at that time: a com- bination of hydrophobic plastics and water. His goal was to create materials that would mimic and serve as replacements for human tissues. It is difficult to imag- ine that Wichterle fully understood the benefits his in- vention would have for mankind and the complexity of how his invention interacts with a tear layer whose intricacies were not well understood. A contemporary view of the tears and the ocular surface is based on the role of the tear layer in human function. Tears lubricate, protect, and provide nutri- ents to the cornea. In addition, the interface between the tears and the external environment plays an im- portant role in maintaining a smooth optical surface on the cornea where the majority of refraction occurs. With thousands of blinks each day, a stable, intact tear film is as critical for function today as it was for survival during our evolution. Because the tears exist on a verti- cal convex surface, significant "engineering" must be applied to keep them in place and sufficiently stable to allow clear, crisp vision. Spreading and maintaining the tear film on a contact lens complicates matters. F i n d ou t w h at y ou r p at i e n t s a r e n ' t t e l l i ng y ou A R T H U R B. E P S T E I N, O D, B E T H W I L S O N, & W I L L I A M T. R E I N D E L, O D, M S HOW VISUAL PERFORMANCE INFLUENCES PATIENTS' PERCEPTIONS OF CONTACT LENS WEAR IS THIS YOUR PATIENT? U sing data from this evaluation, a profile emerges of a contact lens wearer who may be experiencing blurry vision at least once a week but who may not be talking about it. This is someone who is likely to: • wear contact lenses every day • apply lenses immediately after waking • wear lenses for up to 15 hours per day. Compared with a national sample of contact lens wearers, this person is also likely to: • spend more time per day working on a computer (5.8 hours vs. 5.3 hours) • experience other visual symptoms, specifically tired eyes, dry eyes, glare, sensitive eyes, and itchy eyes • notice lens issues, such as lenses that are dry to touch, cloudy, collecting dirt, opaque, or appear dehydrated.