Influence of Scleral Lens on Intraocular Pressure

Purpose Since Scleral Lenses (SL) rest entirely on the sclera and may affect underlying anatomical structures that may influence aqueous humor flow, it is important to determine the effect of SL wear on intra-ocular pressure (IOP).   Methods Nine subjects with normal corneas were recruited for an Institutional Review Board-approved study. Best fit SL from a 15.8 mm diameter 0.4mm thick diagnostic-lens set was fitted on a randomly selected eye, with a silicone-hydrogel soft lens (soft lens) on the other eye. Three IOP measurements were taken with rebound iCare tonometer prior to lens application (baseline data measured at about 9:30AM), and immediately after lens removal (final data measured at about 5:30PM). Baseline and final lens vault was determined with anterior segment Zeiss optical coherence tomography (OCT). Mean baseline and final IOP for each eye was analyzed with a Student-t-test, 2-way repeated ANOVA, and the Bland-Altman plot.   RESULTS IOP was elevated with SL wear for all subjects. Soft lens eyes showed a slight elevation for some but decreased in others. Mean IOP change was 5.81 ± 1.62 mm Hg for SL and -0.62 ± 0.88 mm Hg for soft lens eyes. When mean IOP in SL eyes was compared to soft lens eyes, unpaired t-test showed a significant difference (p <0.05) between the means. Bland-Altman bias was 6.43 (SD of bias 3.139). Repeated ANOVA also showed a significant difference between baseline and final IOP.   CONCLUSIONS The results indicate that SL wear can elevate IOP. Eye care practitioners (ECP) must consider this possible outcome in treating patients wearing SL. Additional studies are needed to determine the clinical implications of SL wear on IOP.