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Cherie B Nau, Muriel Schornack, Jeff Pyle, Jay W McLaren, Arthur J Sit; Intraocular Pressure after 2 Hours of Small-diameter Scleral Lens Wear. Invest. Ophthalmol. Vis. Sci. 2014;55(13):4668.
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Small-diameter scleral lenses completely cover the cornea and are supported by the sclera just posterior to the limbus. Within two hours after placement, these lenses settle posteriorly, and this shift, in combination with a relatively concentrated area of contact, could compress episcleral vessels, which drain the aqueous humor. If wear of these lenses increases pressure in the episcleral veins, this could contribute to increased intraocular pressure (IOP), although the effect of scleral lens wear on IOP is unknown. In this study we examined the effect of two hours of small-diameter scleral lens wear on IOP.
Twenty-six subjects (29 ± 6 years, mean ± SD; range 22-44 years) with no history of eye disease, eye surgery, or previous scleral lens wear were fitted with a 15-mm Jupiter scleral lens (Visionary Optics, Front Royal, VA) on one eye selected randomly. IOP was measured in both eyes by pneumatonometry (Model 30 Classic, Reichert Inc., Buffalo, NY); the mean of three consecutive measurements was accepted as the IOP. The scleral lens was then placed on the selected eye and was worn for 2 hours. IOP was then re-measured in the control eye, the lens was removed, and IOP was re-measured immediately in the eye that wore the lens. IOP after removal of the scleral lens was compared to IOP before placing the lens and to IOP in the fellow eye by using paired t-tests.
Before placing the lens the IOP was not different in the eye that wore the lens (13.7 ± 1.9 mmHg, mean ± SD) compared with the control eye (13.8 ± 2.2 mmHg, p=0.87). Immediately after removing the scleral lens, the IOP was also not different in the eye that wore the lens (13.8 ± 3.2 mmHg) compared with the control eye (13.4± 2.3, p=0.47) or in the same eye before lens wear (p=0.85). This study had an 80% chance of finding a difference as small as 1.5 mmHg between IOP immediately after lens removal and IOP before lens placement or in the control eye, if such a difference existed (α=0.05, β=0.8).
Wear of a 15-mm scleral lens for two hours does not raise IOP in normal subjects. Whether or not IOP is increased by small scleral lenses in glaucoma patients needs to be investigated.
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