Researchers have yet to settle the debate on whether scleral lenses increase the wearer’s IOP. A few years ago, investigators found eight hours of scleral lens wear was associated with a rise in IOP of more than 5.00mm Hg.1 Still others found just 4.5 hours of lens wear led to a jump of more than 4.00mm Hg.2 However, a more recent study using OCT as an indirect assessment of IOP found no statistically significant difference in global minimum rim width in scleral lens wearers.3
Now, new data is adding to the evidence, this time with a newer optic nerve measure: Bruch’s membrane opening minimum rim width (BMO-MRW). Researchers in Canada found scleral lens wearers experienced a decreased BMO-MRW by −8µm after six hours of lens wear, possibly due to increased IOP, they wrote in their paper.
The study included 20 healthy subjects who participated in serial ocular measurements to establish normative diurnal curves over a six-hour time-frame. The researchers collected IOP, corneal rigidity and central corneal thickness (CCT) measures and BMO-MRW using OCT. The following day, the patients wore 16mm scleral lenses on one eye and underwent the same series of testing.
The team found the average variation in BMO-MRW without lens wear was −4.65μm but was 8µm lower the next day during lens wear. The average diurnal variation in BMO-MRW also dropped to −3.35μm. The change in BMO-MRW was not associated with corneal rigidity, or CCT refractive error, the researchers noted.
“Scleral lens wear induces a statistically significant decrease in BMO-MRW that could potentially be attributed to a change in IOP,” the researchers wrote. Still, more research is needed to validate the findings and explore the significance of BMO-MRW changes at the optic nerve head.
1. Aitsebaomo AP, Wong-Powell J, Miller W, Amir F. Effect of scleral lens wear on intraocular pressure. ARVO 2018. Abstract 1765.
2. Michaud L, Samaha D, Giasson CJ. Intra-ocular pressure variation associated with the wear of scleral lenses of different diameters. Cont Lens Ant Eye. 2019;42(1):104-10.
3. Walker M, Pardon LP, Redfern R, Patel N. IOP and optic nerve head morphology during scleral lens wear. Optom Vis Sci. 2020;97(9):661-68.
4. Samaha D, Michaud L. Bruch membrane opening minimum rim width changes during scleral lens wear. Eye Contact Lens. October 9, 2020. [Epub ahead of print].