Contact Lens Spectrum Supplements

Special Edition 2017

Contact Lens Spectrum

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Page 42 of 75

c l s p e c t r u m . c o m 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 7 41 prescribed to protect and lubricate the ocular surface. In a recent study, researchers found that symptomatic soft contact lens wearers have poorer tear film kinetics than asymptomatic lens wearers. 15 This is an area of re- search that needs to be explored in scleral lens wearers. Patients who are intolerant of corneal GP lenses are ideal candidates for scleral lenses. The transition to scleral lenses is easy, and patients will benefit from crisp, clear vision and improved lens comfort — without the risk of lenses dislodging spontaneously. SCLERAL LENSES FOR HEALTHY EYES Several studies on the use of scleral lenses for healthy eyes have been reported in the literature. In a study of normal corneas, scleral lenses of 14.8 mm and 15.8 mm diameters were fit on 35 patients ranging in age from 19 to 37 years. 16 These patients had high visual demands at distance, intermediate, and near, and they were ac- customed to excellent visual acuity. Seventy-seven per- cent of patients successfully wore scleral lenses up to 16 hours per day and achieved logMAR visual acuity of 0.2 (Snellen 20/32) or better. The majority of patients were satisfied with scleral lenses; however, handling was the primary reason for any dissatisfaction. Visser and colleagues assessed the performance of scleral lenses for a wide range of clinical indications. 17 This cross-sectional study evaluated 281 current contact lens patients fitted with lenses based on a lens selection algorithm. The authors determined that contact lenses significantly improved corrected distance visual acuity compared to spectacles. In addition, satisfactory wearing times improved. The vision correction modality for both the scleral lens group and the soft lens group was gener- ally effective, and each group had high subjective scores with similar results. Overall satisfaction was high in the Scleral lenses can resolve the two primary reasons why soft contact lens wearers drop out of lens wear: poor comfort and inadequate vision, particularly in patients with astigmatism and presbyopia. 9 Because of their ex- cellent stability and gas permeable optics, scleral lenses provide superb vision, and if needed, front toric optics can correct residual astigmatism. For patients who ex- perience glare and halos with contact lens wear, scleral lenses offer a solution by virtue of their larger optical zone diameter (OZD). Typically, the OZD of soft con- tact lenses is 6 mm to 7 mm, which may be reduced to 4 mm to 5 mm in toric designs. 11 Scleral lenses offer an OZD of 8 mm to 9 mm, which can be customized and made even larger if needed. Thus, scleral lenses reduce halos and glare and improve vision, even in difficult conditions, such as driving at night. In a study that evaluated frequent or constant dryness and discomfort in patients currently wearing soft contact lenses, 23% reported dryness, 13% reported discomfort, and 27% reported at least 2 hours of uncomfortable lens wear. 12 Corresponding ocular signs included limbal hy- peremia (6%), bulbar hyperemia (10%), and corneal staining 12%. 12 To address comfort issues, scleral lenses are applied with preservative-free fluid that constantly bathes the ocular surface. A 2012 study of patients with dry eye whose symptoms could not be controlled by conven- tional treatments found that mini-scleral lenses effec- tively decreased lens discomfort and dry eye symptoms, decreased the frequency of artificial tear use, and im- proved visual acuity. 13 Thus, scleral lenses can benefit wearers who experience lens-induced dryness. Diurnal variation in symptoms associated with ocular discomfort in contact lens wearers and non-contact lens wearers has also been evaluated. 14 Researchers used the Ocular Surface Disease Index (OSDI) questionnaire to assess overall symptoms to evaluate diurnal changes in comfort, grittiness, stinging, irritation, and vision. Contact lens wearers and symptomatic non-contact lens wearers exhibited a significantly greater diurnal de- crease in comfort and subjective vision. 14 The contact lens wearers reported significantly more dryness, gritti- ness, and irritation than the non-contact lens wearers. 14 Interestingly, the diurnal decrease in dryness symptoms was most marked in young contact lens wearers. In clinical practice, investigating how contact lenses feel and if patients experience fluctuating vision at the beginning, middle, and end of the day may help prevent contact lens dropout. The OSDI questionnaire is a use- ful tool for practitioners to use to evaluate symptoms in- cluding vision changes. 14 It can be administered prior to any contact lens fitting and at subsequent visits to deter- mine if changes are needed. If symptoms suggest contact lens discomfort or vision changes, scleral lenses can be SCLERAL LENSES Figure 1. Scleral lens evaluation with sodium fluorescein using a slit beam with white light.

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