What Do We Really Know About GP Lens Discomfort?
BY NANCY CHAN, OD, & JOHN MARK JACKSON, OD, MS, FAAO
Contact lens discomfort (CLD) may be the leading cause of dissatisfaction and contact lens dropout globally, but there has been no general agreement on what it is and how to manage it. The Tear Film & Ocular Surface Society (TFOS) conducted an exhaustive literature review, recently published in Investigative Ophthalmology & Visual Science, to better understand CLD (Nichols et al, 2013).
1 What is CLD? “CLD is a condition characterized by episodic or persistent adverse ocular sensations related to lens wear, either with or without visual disturbance, resulting from reduced compatibility between [contact lenses (CL)] and the ocular environment, which can lead to decreased wearing time and discontinuation of CL wear” (Nichols J, Jones et al, 2013; Nichols J, Willcox et al, 2013; Nichols K et al, 2013). When describing CLD, the terms “CL dry eye” should not be used unless the patient has a pre-existing dry eye condition (Nichols J, Willcox et al, 2013).
2 Long-Term GP Lens Comfort Studies found no difference in long-term comfort between adapted corneal GP lens wearers and soft lens wearers who wore lenses on a continuous basis. At the end of one 12-month study, survey data of lens comfort suggested that GP wearers might ultimately be more comfortable compared to soft lens wearers (Nichols J, Willcox et al, 2013). Although it takes longer to adapt to GPs, practitioners who hesitate to fit them should feel better about their long-term comfort.
3 Specific GP Issues It is evident that GP comfort is affected by the lens edge configuration, lens thickness, and diameter. Edge clearance contributes to tear exchange and lid attachment of GPs (Nichols J, Willcox et al, 2013; Jones et al, 2013). However, CLD increases with greater edge clearance because of increased interaction between the lens edge and eyelid during blinking (Nichols J, Willcox et al, 2013; Jones et al, 2013). CLD also increases with a thinner GP lens; while paradoxical, studies attributed this to thinner lenses having increased on-eye flexure. A larger-diameter GP may decrease the incidence of CLD by reducing lens movement and lid interaction (Nichols J, Willcox et al, 2013; Jones et al, 2013).
4 What We Still Don’t Know Other factors are likely to be associated with CLD, but more research needs to be done. Factors such as surface friction, wettability, deposits, plasma treatments, edge chips and defects, etc., are logical choices for ongoing evaluation (Nichols J, Wilcox et al, 2013; Nichols K et al, 2013; Papas et al, 2013).
5 Non-Lens Factors Non-CL-related factors—such as age, gender, systemic/ocular disease, and medications—may play a part in CLD (Nichols J, Willcox et al, 2013; Nichols K et al, 2013; Dumbleton et al, 2013; Papas et al, 2013). Care solutions and compliance can also contribute to CLD (Nichols J, Willcox et al, 2013; Nichols K et al, 2013; Papas et al, 2013). It is interesting to note that many methods used to treat dry eye—such as artificial tears, punctual occlusion, and oral omega-3 fatty acids—also may be helpful in treating CLD.
A Path for Future Research
The TFOS workshop has enhanced our understanding of what we do and do not know about CLD. Future research will reveal more secrets to happier, healthier contact lens wear. CLS
For references, please visit www.clspectrum.com/references.asp and click on document #221.
Dr. Chan is the current cornea and contact lens resident at Southern College of Optometry. Dr. Jackson is an associate professor at Southern College of Optometry, where he works in the Advanced Contact Lens Service, teaches courses in contact lenses, and performs clinical research. You can reach him at email@example.com.