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Novel mini-scleral lens performs well on irregular corneas
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A new mini-scleral lens with bitangential, nonrotational periphery provides stable and comfortable lens fitting in eyes with irregular corneas, according to a study.
Designed in collaboration with a lens manufacturer in The Netherlands (NKL Contactlenzen), this new lens consists of a large front optical zone of 10 mm, a spherical back optical zone of 11 mm and a midperipheral and landing zone of 2.5 mm.
Two different angles in two perpendicular meridians create a bitangential periphery, where the steeper meridian has a larger tangential angle, and the flatter meridian has a narrower tangential angle. The difference between the two angles is 6 degrees, allowing rotational stabilization and correction of residual astigmatism with a toric front curve.
A total of 133 patients were fitted with this lens in the left eye. The majority had keratoconus (45%), followed by irregular astigmatism (22%) due to a variety of corneal disorders. The remaining eyes had corneal surface disease or high refractive error or had undergone keratoplasty.
The majority of patients rated lens comfort between 4 and 5 on a 5-point scale. The median daily wearing was 14 hours, 7 days a week, with most patients wearing the lens continuously for 12 hours. More than half of the patients achieved visual acuity of 20/20 or better. The lens was well positioned, with a median central corneal clearance of 0.26 mm.
“Here, we show that a mini-scleral lens can be fitted successfully in patients with an anterior scleral elevation, including pingueculas, nodules or elevations caused by surgery or trauma, conditions that can make it difficult to fit a large scleral lens,” the authors wrote.
Among patients in this study, there were also several with a glaucoma valve and one with multiple scleral irregularities due to a fireworks-related injury. In these difficult cases, the lens was successfully fitted. – by Michela Cimberle
Disclosures: Otten reported no relevant financial disclosures. Please see the study for the other authors’ financial disclosures.
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