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Maria Walker, Laura P Pardon, Rachel L Redfern, Nimesh Bhikhu Patel; Assessing the Changes in Optic Nerve Head Morphology during Acute Scleral Lens Wear. Invest. Ophthalmol. Vis. Sci. 2019;60(9):6337.
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© ARVO (1962-2015); The Authors (2016-present)
It has been hypothesized that the scleral lens (SL) may impact intraocular pressure (IOP) by compressing episcleral veins and reducing aqueous drainage. Because the optic nerve head morphology is sensitive to changes in IOP, measures of the neuroretinal rim (NRR) as quantified using optical coherence tomography (OCT) can be used to indirectly assess pressure fluctuations. The purpose of this study was to evaluate changes in the minimum rim width (MRW), a measure of the NRR, during SL wear.
Twelve normal SL neophytes were recruited, and one eye was randomly selected to wear a SL (test eye) while the fellow eye served as a control. IOP measurements (iCare and Diaton) and 24-line radial OCT scans centered on the optic nerve head were acquired prior to SL application, at two and six hours post-SL application, and after SL removal at the end of six hours. Statistical analysis was done using the paired t-test.
The mean change in MRW in test eyes was -8.58±7.03mm (range -21 to +3), and was -4.42±6.23mm (range -16 to +6) in control eyes, negative values indicating MRW thinning. There was a trend of more MRW thinning in the test eyes, although a significant difference was not observed (p=0.06). The MRW difference between test and control eye was calculated for each subject, and the mean difference between eyes was -4.17±6.79mm (range -22 to +5) with negative values indicating that the test eye showed greater MRW thinning. Using iCare, mean IOP changed by +0.1±1.7mmHg (range -4.0 to +2.3) in the control eyes, and +1.5±2.3mmHg (range -1.6 to +4.0) in the test eyes during the 6 hour testing period. Mean IOP change with Diaton was -0.2±3.5mmHg (range -8.3 to +4.5) in the control eyes, and -0.2±3.1mmHg (range -3.8 to +5.0) in the test eyes. While greater variability was seen in the test eyes, there were no significant differences found with either instrument in IOP change between test and control eyes (iCare: p=0.07; Diaton: p=0.98).
This pilot study shows a trend of greater MRW thinning in the test eyes than the control eyes, although not statistically significant. IOP measurements were variable and do not appear to provide reliable measurements during active SL wear. These studies suggest that SL wear may increase IOP in certain individuals and is an important consideration for SL patients at risk or with a diagnosis of glaucoma.
This abstract was presented at the 2019 ARVO Annual Meeting, held in Vancouver, Canada, April 28 - May 2, 2019.
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