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Cherie Nau, Muriel Schornack; Decreased Clearance between Scleral Contact Lens and Cornea after 2 Hours of Lens Wear. Invest. Ophthalmol. Vis. Sci. 2013;54(15):5469.
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© ARVO (1962-2015); The Authors (2016-present)
Scleral lenses have become increasingly popular in the management of ocular surface disease because of their unique ability to maintain a post-lens fluid reservoir. However, the lens may "settle" during wear, reducing the depth of the reservoir, and the extent of settling has not been assessed. In this study we examined the change in spacing between the lens and cornea during the first two hours of small-diameter scleral contact lens wear.
Four participants, two men and two women age 23-42 years (29 ± 9 years, mean ± SD) with healthy eyes (no history of eye disease or surgery and no previous scleral lens wear), were fitted on one eye with a 15-mm diameter Jupiter scleral lens (Visonary Optics, Front Royal, VA). Lenses were selected from a diagnostic fitting set to provide 200-300 μm clearance between the lens and central cornea. Within 5 minutes after placement, slit images of the lens and cornea were recorded twice by Scheimpflug photography (Pentacam, Oculus, Inc.). The clearance between the back surface of the lens and the anterior surface of the cornea was measured in the vertical Scheimpflug image by using the caliper tool in the Pentacam analysis software. Clearance was the average of depth within 450 μm above and below the center of the cornea in two images. Scheimpflug photography was repeated after two hours of continuous lens wear, and the central clearance was measured in the same manner. The central corneal clearance at 2 hours was compared to the initial clearance by using a paired t-test.
Scleral lens clearance after initial placement of the lens was 165 ± 62 μm (range: 82-289 μm). After two hours of lens wear, clearance was reduced to 80 ± 23 μm (range: 59-141 μm; p = 0.03).
Within two hours after placing a 15-mm scleral lens, the central clearance between the posterior lens surface and the cornea decreases by as much as 50 percent. When fitting scleral lenses, sufficient time must be allowed for the lens to reach a stable position before assessing the depth of the post-lens fluid reservoir. If a lens fit is assessed prematurely, the subsequent lens settling could greatly reduce reservoir volume and increase contact with the cornea, and this would limit the value of using these lenses in patients with severe ocular surface disease.
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