Clinical evaluation of flat peripheral curve design with aspherical-curve and multi-curve hard contact lenses for keratoconus

Abstract

Aspherical- and multi-curve rigid gas-permeable hard contact lenses (HCLs) have a flattened curve in the peripheral zone and are mostly used for patients with keratoconus who cannot wear glasses, soft contact lenses, or spherical HCLs. In this retrospective study, a total of 95 eyes of 77 patients who used aspherical- or multi-curve HCLs (mean age: 40.0 ± 11.0 years) were evaluated. This study examined the types of aspherical- and multi-curve HCLs, best-corrected visual acuity (BCVA) values before and after wearing HCLs, the association with the Amsler-Krumeich classification, duration of wear, corneal/conjunctival disorder, and the frequency of changing HCLs. There were 78 eyes that used aspherical-curve HCLs and 17 that used multi-curve HCLs. BCVA significantly improved from 0.42 logMAR to 0.06 logMAR after wearing either form of HCL. The Amsler-Krumeich classification showed that aspherical-curve HCLs were commonly used for patients with stage 2 keratoconus, and multi-curve HCLs were commonly used for stage 4 patients. The BCVA values were worse when the disease stage was more severe (stages 3 and 4) regardless of HCL type. The mean base curve of the lenses was steeper in multi-curve HCLs than in aspherical-curve HCLs. The more severe the disease stage, the steeper the base curve in both aspherical- and multi-curve HCLs. The duration of wear significantly improved from 2.1 h to 10.2 h, and corneal/conjunctival disorder similarly improved. The mean frequency of changing HCL types was 1.1 times. This study suggests that a flat peripheral curve design with aspherical- and multi-curve HCLs is useful for patients with keratoconus.

The Lifetime Expenditure in People with Keratoconus in Saudi Arabia

“…Keratoconus is an ectatic disorder characterised by progressive thinning, scarring, and anteriorly protrusion of the cornea, which results in irregular astigmatism, opacity, and impaired vision [1][2][3]. While its causation remains unknown, it was initially thought to affect 1 in every 2000 people [2,3]. With the advancements in diagnostic technologies, however, the incidence rates are now known to be more acute [2].…”

“…While its causation remains unknown, it was initially thought to affect 1 in every 2000 people [2,3]. With the advancements in diagnostic technologies, however, the incidence rates are now known to be more acute [2]. In a study of mandatory health insurance records of 4.4 million patients aged 10-40 in the Netherlands, for example, Godefrooij et al [4] estimated the prevalence of keratoconus at 1 in 375 (95% Confidence Interval (CI)).…”

“…In patients with keratoconus, the corneal apex often occurs in the lower region and is severely protruded. This results in an uneven corneal shape [2].…”

“…As the disorder is progressive, the corneal shape and extent of astigmatism are usually mild at the onset, which is why early-stage keratoconus is correctable with either soft contact lenses or glasses. While rigid gas-permeable hard contact lenses are contra-indicated, spherical hard contact lenses may be used as they have an even structure with an evenly reducing curvature radius towards the periphery [2]. The characteristically uneven corneal shape renders the use of hard contact lenses impractical as the disease advances, but aspherical and multi-curve hard contact lenses may still be used [1,2].…”

“…While rigid gas-permeable hard contact lenses are contra-indicated, spherical hard contact lenses may be used as they have an even structure with an evenly reducing curvature radius towards the periphery [2]. The characteristically uneven corneal shape renders the use of hard contact lenses impractical as the disease advances, but aspherical and multi-curve hard contact lenses may still be used [1,2].…”