Effect of Time on Scleral Lens Settling and Change in Corneal Clearance

TitleEffect of Time on Scleral Lens Settling and Change in Corneal Clearance
Publication TypeJournal Article
Year of Publication2017
AuthorsOtchere, H., L. Jones, and L. Sorbara
JournalOptometry and Vision Science
Keywordsadult, Central point, Clearance loss, contact lens, Contact lenses, Cornea, Corneal Topography, Effect of time, eye refraction, female, follow up, Follow-Up Studies, Horizontal meridians, human, Humans, keratoconus, keratometry, Location, male, middle aged, Ocular, Optical Coherence Tomographer, pathology, pathophysiology, Peripheral points, physiology, procedures, Prospective Studies, prospective study, Refraction, sclera, time factor, Time Factors, Time points, Ultra longs, Visual acuity, young adult

{SIGNIFICANCE With the increase in the use of scleral contact lenses among practitioners, questions regarding lens settling are gradually gaining attention. This is because current studies support the notion that scleral lenses settle back over time. More research is needed to understand the exact cause and the factors that underpin such phenomenon. PURPOSE The present study aims to assess the effect of time on topographic corneal clearance of three scleral contact lenses of varying sagittal depths. METHODS Three scleral contact lenses were fitted to 20 subjects with previous diagnosis of keratoconus (n = 18) or pellucid marginal degeneration (n = 2). The fit was based on corneal sagittal height measured with the Visante optical coherence tomographer (OCT) at 15 mm along the horizontal meridian. To select an appropriate lens from the diagnostic lens set, values of 325 μm (lens 1), 375 μm (lens 2), and 425 μm (lens 3) were randomly added in sequence to the corneal sagittal height. Subjects wore each lens for 1 hour. Corneal clearance was measured at 10-minute intervals for 1 hour using a custom ultra-long OCT. To assess change in clearance, central point and two mid-peripheral points (+3 mm and -3 mm) along an 8-mm chord were measured by taking differences at each time point up to 1 hour. Measurements were repeated for the two other lenses. RESULTS Mean central corneal clearance loss for all three lenses was 33.83 ± 48.40 μm. This was 26 ± 27 μm (13 ± 14 μm, +3 mm; 34 ± 37 μm, -3 mm), lens 1; 35 ± 59 μm (38 ± 61 μm, +3 mm; 52 ± 69 μm, -3 mm), lens 2; and 41 ± 54 μm (33 ± 26 μm, +3 mm; 52 ± 48 μm, -3 mm), lens 3, respectively. There was no significant difference (P = 0.06) at central and other locations for lens 1 (location and over time). There were significant differences for both lenses 2 and 3 (P <.001