Scleral Versus Corneal RGP Contact Lenses in Irregular Cornea Disorders

Summary

The most common causes for irregular cornea (IC) in hospital contact lens practice are Keratoconus (KC) and related cornea thinning disorders. These conditions cause mild to marked impairment of vision and cannot be effectively corrected by spectacles and soft contact lenses. The gold standard in the management of KC is Corneal Rigid Gas Permeable contact lenses (corneal lenses), which correct approximately 90% of the corneal irregularity.

Compared with a normal cornea, the cornea in KC is irregular and this results in a compromise to the fit of rigid corneal lenses. Specifically, they bear on the cornea and this, together with the vulnerability of the cornea in KC, are implicated in corneal scarring, and disease progression as well as a significantly reduced vision related quality of life (QoL) in KC compared with corneal lens wearers who have no KC.

In cases where the compromise fit of corneal lenses proves problematic, large diameter Scleral RGP contact lenses (scleral lenses) may be used as a problem solver. Unlike the smaller corneal lenses which bear on the cornea, the scleral lenses completely bridge over the cornea and bear on the sclera.

The aim of this research is to investigate the performance of scleral lenses in KC participants who habitually wear corneal lenses.

The research question: is there a measurable difference in the visual performance and visual quality of life in participants with Irregular cornea disorders like keratoconus and other related conditions, who habitually wear corneal lenses in comparison with scleral lenses.

Conditions

• Irregular; Contour of Cornea
• Keratoconus
• Pellucid Marginal Corneal Degeneration
• Injury of Cornea
• Irregular Astigmatism

Interventions

DEVICE

Scleral rigid gas permeable contact lenses (SRGPcl) (Zenlens™)

Custom manufactured scleral rigid gas permeable contact lenses. These lenses are designed to fit the eye with high level of precision. The aim is to bridge the cornea and fit in alignment with the sclera, thus avoiding any detrimental effects associated with the corneal rigid gas permeable lenses.

DEVICE

Corneal Rigid gas Permeable contact lenses (CRGPcl) (Rose K2)

The Rose K2 lens is a widely used corneal gas permeable lens designed for keratoconus and other irregular cornea disorders

Sponsors & Collaborators

• London South Bank University

  lead OTHER

Principal Investigators

• Alexander Levit, FCOptom · London South Bank Unversity

• Martin Benwell, PhD · London South Bank University

• Bruce Evans, PhD · Institute of Optometry

Study Design

Allocation

RANDOMIZED

Purpose

TREATMENT

Masking

SINGLE

Model

CROSSOVER

Eligibility

Min Age

18 Years

Max Age

69 Years

Sex

ALL

Healthy Volunteers

Yes

Timeline & Regulatory

Start

2015-10-25

Primary Completion

2019-01-29

Completion

2019-01-29

Countries

• United Kingdom

Study Locations