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Research Update #46

Welcome to our monthly Research Update, available exclusively to IACLE and BCLA members to support your teaching and practice.

October 2020
SPECIAL ISSUE: Advances in Scleral Lenses

While scleral contact lenses are not a new idea, they are currently reviving contact lens practice as there is a lot of energy in this field and new applications are emerging frequently.

Nevertheless, there remain some clinical anatomical and physiological challenges to scleral contact lens success, and that is the focus of this feature issue of Optometry and Vision Science: ‘to shine a light on the open questions, bring new evidence to the field, and stimulate others to help take up the challenge of advancing scleral contact lenses,’ says the Editor.

This issue addresses some important themes related to scleral lens wear such as the effects on intraocular pressure, oxygenation and corneal health, safety and efficacy, vision quality, and patient satisfaction.

Here are some excerpts from the issue.

The IACLE Education Team

JOURNALS

Journal reviewed in this issue:

Optometry and Vision Science 97:9

IOP

Scleral lens wear and optic nerve head morphology

To assess changes in optic nerve head morphology as an indirect assessment of intraocular pressure (IOP) and evaluate other IOP assessment methods during scleral lens (SL) wear, Walker et al applied SL to randomly selected eyes of 26 adults. Global minimum rim width and IOP were measured at baseline, 2h and 6h after SL application, and again after lens removal. The results suggest that SLs have a minimal effect on IOP homeostasis during lens wear and an insignificant impact on the optic nerve head morphology in healthy adult eyes.

Optom Vis Sci 2020;97:9 661-668. DOI:10.1097/OPX.0000000000001567. Read the full text 

Scleral tonometry changes during scleral lens wear 

To compare scleral IOP and anterior chamber angle (ACA) before, during, and after 4h of scleral lens wear in healthy neophyte scleral lens wearers from a black African population, Obinwanne et al fitted scleral lenses to 20 randomly selected eyes of 20 subjects. Scleral IOP was measured and ACA was assessed before scleral lens wear; at 10mins, 2h, and 4h during wear; and 10mins after scleral lens removal. Results suggest that 4h of non-fenestrated scleral lens wear did not have a significant impact on IOP or ACA.

Optom Vis Sci 2020;97:9 720-725. DOI:10.1097/OPX.0000000000001568. Read the abstract

PHYSIOLOGY

Scleral lens oxygen permeability and corneal physiology

Dhallu et al conducted this randomized, masked, crossover clinical study to identify the minimum oxygen permeability of a scleral lens needed to maintain healthy anterior eye physiology. Fifteen masked young adults were bilaterally fitted with five different scleral lenses (Dk 65, 100, 125, 163, and 180+) and one soft silicone hydrogel lens. A masked observed performed relevant investigations before and after 8 hours of wear. In conclusion, a Dk ≥125 is advised for safe scleral lens daily wear.

Optom Vis Sci 2020;97:9 669-675. DOI:10.1097/OPX.0000000000001557. Read the abstract

Corneal health and scleral lens wear

This prospective, double-masked, randomized, bilateral study by Tse et al evaluated the effects of 3 months of scleral lens wear on corneal epithelial barrier function, dendritic cell density, and nerve fiber morphology. Fluorosilicone acrylate scleral lenses were worn bilaterally by 27 neophytes without overnight wear. Corneal measurements and imaging were performed at baseline and after 1 and 3 months of wear. No subclinical changes to healthy corneas of young subjects were observed during 3 months of scleral lens wear.

Optom Vis Sci 2020;97:9 676-682. DOI:10.1097/OPX.0000000000001566. Read the abstract

PERFORMANCE

Safety and efficacy of scleral lenses for keratoconus

To evaluate the safety and efficacy of contemporary scleral contact lenses in the visual rehabilitation of the keratoconic population, Fuller & Wang retrospectively analysed records of 157 eyes of 86 subjects. Only eyes fit successfully with scleral lenses for ≥1 year were included. Physiological adverse events occurred in 9.6% of eyes. Overall, the lenses significantly improved best-corrected distance visual acuity over spectacles. The study showed excellent safety and efficacy of scleral contact lenses in subjects with keratoconus.

Optom Vis Sci 2020;97:9 741-748. DOI:10.1097/OPX.0000000000001578. Read the full text

Vision quality with scleral lenses

Macedo-de-Araújo et al reported 12 months of follow-up of 69 patients: 99 eyes with irregular cornea (IC) and 27 with regular cornea (RC) to evaluate optical quality outcomes with scleral lenses. Relevant clinical tests and investigations were performed with habitual correction, best spectacle correction, and scleral lenses at baseline and follow-up visits (1, 3, 6, and 12 months). The authors concluded that scleral lenses promote better subjective and objective visual quality, mainly in patients with IC. 

Optom Vis Sci 2020;97:9 775-789. DOI:10.1097/OPX.0000000000001570. Read the abstract

Patient satisfaction and care burden in keratoconus

To compare patient satisfaction and care burden with corneal gas permeable (GP) and scleral lenses for managing keratoconus, Shorter et al administered an electronic survey on lens complications, access to care, lens handling time, annual out-of-pocket treatment costs, vision, comfort, and ease of use satisfaction. A total of 422 responses were received, including from 75 bilateral GP and 76 bilateral scleral lens wearers. Scleral lens wearers with keratoconus reported greater satisfaction with vision and comfort than GP wearers, although patients in both groups reported cloudy vision and lens discomfort.

Optom Vis Sci 2020;97:9 790-96. DOI:10.1097/OPX.0000000000001565. Read the abstract

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© International Association of Contact Lens Educators 2020

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