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Scleral Versus Corneal RGP Contact Lenses in Irregular Cornea Disorders

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ClinicalTrials.gov Identifier: NCT02444923
Recruitment Status : Completed
First Posted : May 15, 2015
Last Update Posted : August 19, 2019
Sponsor:
Information provided by (Responsible Party):
London South Bank University

Brief 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.


Condition or disease Intervention/treatment Phase
Irregular; Contour of Cornea Keratoconus Pellucid Marginal Corneal Degeneration Injury of Cornea Irregular Astigmatism Device: Scleral rigid gas permeable contact lenses (SRGPcl) (Zenlens™) Device: Corneal Rigid gas Permeable contact lenses (CRGPcl) (Rose K2) Not Applicable

  Show Detailed Description

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Study Type : Interventional  (Clinical Trial)
Actual Enrollment : 30 participants
Allocation: Randomized
Intervention Model: Crossover Assignment
Intervention Model Description: Randomised control trial with a 2x2 crossover
Masking: Single (Investigator)
Masking Description: The practitioner who measures the visual outcomes is naive to the type of lens the participant is wearing
Primary Purpose: Treatment
Official Title: A Randomised Controlled Research to Asses the Clinical Performance and Effect on Vision Related Quality of Life of Rigid Gas Permeable Scleral Versus Corneal Contact Lenses for Keratoconus and Other Irregular Cornea Disorders
Actual Study Start Date : October 25, 2015
Actual Primary Completion Date : January 29, 2019
Actual Study Completion Date : January 29, 2019


Arm Intervention/treatment
Experimental: Scleral rigid gas permeable contact lenses
The experimental intervention is the Scleral Rigid Gas Permeable contact lens (SRGPcl), Zenlens™. These lenses are designed to bridge the cornea and fit in alignment with the sclera, thus avoiding any detrimental effects associated with corneal contact.
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.
Other Names:
  • Scleral lenses
  • Zenlens
  • Custom Scleral Contact Lenses
  • RGP Scleral 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
Other Name: Rose K2 corneal gas permeable contact lenses

Placebo Comparator: Corneal rigid gas permeable contact lenses
The control intervention is the RoseK2™ Corneal Rigid Gas Permeable contact lens (CRGPcl). Corneal lenses are considered the gold standard in the management of the visual disability due to keratoconus and other related irregular cornea disorders.
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.
Other Names:
  • Scleral lenses
  • Zenlens
  • Custom Scleral Contact Lenses
  • RGP Scleral 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
Other Name: Rose K2 corneal gas permeable contact lenses




Primary Outcome Measures :
  1. Monocular Best Corrected Visual Acuity (BCVA) [ Time Frame: Baseline and after a minimum of 6 weeks of wear of each contact lens type, report at study completion ]
    High contrast BCVA will be measured by the specially constructed crowded, Logarithmic Minimum Angle of Resolution (LogMAR), Early Treatment Diabetic Retinopathy Survey (ETDRS) letter charts. An average score of 3 different, randomly presented charts will be taken as the final acuity score. It will be performed utilising the CSV1000E, under the established recommended standardised testing conditions utilised in a multitude of research protocols.


Secondary Outcome Measures :
  1. Contrast Sensitivity Function [ Time Frame: Measure at recruitment (Baseline), subsequent measurement after 6 weeks of wear, of lens 1 and 6 weeks of wear of lens 2. Study completion after 6-12 months. ]
    The Contrast Sensitivity Function (CSF) will be assessed at each of the four spatial frequencies 3, 6, 12 and 18 Cycles Per Degree (CPD) averaging the results from 2 different charts with sinusoidal grating patterns. This will be performed utilising the CSV1000E, under the established recommended standardised testing conditions utilised in a multitude of research protocols.

  2. The National Eye Institute-Visual Function Questionnaire (NEI-VFQ) [ Time Frame: Measure at recruitment (Baseline), subsequent measurement after 6 weeks of wear, of lens 1 and 6 weeks of wear of lens 2. Study completion after 6-12 months. ]
    The National Eye Institute-Visual Function Questionnaire (NEI-VFQ) (Mangione 2000) is a vision-related quality of life instrument designed to assess patients' perception of visual function and quality of life. The measurements include general health, general vision, ocular pain, near and distance activities, driving, colour vision, and peripheral vision. There are four components of psychological well being, these are; social function, mental health, role difficulties, and dependency function. It has been used to characterize the quality of life for patients with uveitis, diabetic retinopathy, glaucoma, and age-related macular degeneration (Mangione, Lee et al. 2001)

  3. The Levit Subjective Comfort and Vision Scales [ Time Frame: Measure at recruitment (Baseline), subsequent measurement after 6 weeks of wear, of lens 1 and 6 weeks of wear of lens 2. Study completion after 6-12 months. ]
    The Levit Subjective Comfort Scale (LSCS) and The Levit Subjective Vision Scale (LSVS) are Likert like scales which grade the participants' perception of their comfort and vision in contact lenses, on a scale from 1( worse) to 10 (best).

  4. The final lens choice [ Time Frame: At study completion after 6-12 months ]
    Each participant chose one of the two experimental lenses they wished to keep for future habitual use



Information from the National Library of Medicine

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Ages Eligible for Study:   18 Years to 69 Years   (Adult, Older Adult)
Sexes Eligible for Study:   All
Accepts Healthy Volunteers:   Yes
Criteria

Inclusion Criteria:

  • Diagnosis of keratoconus or related corneal irregularity
  • Age 18 years to 69 years.

Exclusion Criteria:

  • Good visual quality with soft contact lenses and or spectacles

Information from the National Library of Medicine

To learn more about this study, you or your doctor may contact the study research staff using the contact information provided by the sponsor.

Please refer to this study by its ClinicalTrials.gov identifier (NCT number): NCT02444923


Locations
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United Kingdom
Central Middlesex Hospital
London, United Kingdom, NW10 7NS
Sponsors and Collaborators
London South Bank University
Investigators
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Principal Investigator: Alexander Levit, FCOptom London South Bank Unversity
Study Director: Martin Benwell, PhD London South Bank University
Study Chair: Bruce Evans, PhD Institute of Optometry

Additional Information:
Publications of Results:
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Responsible Party: London South Bank University
ClinicalTrials.gov Identifier: NCT02444923     History of Changes
Other Study ID Numbers: Levita
First Posted: May 15, 2015    Key Record Dates
Last Update Posted: August 19, 2019
Last Verified: August 2019
Individual Participant Data (IPD) Sharing Statement:
Plan to Share IPD: No
Keywords provided by London South Bank University:
Corneal rigid gas permeable contact lenses
Scleral rigid gas permeable contact lenses
Custom Scleral contact lenses
Keratoconus
Irregular cornea
Pellucid marginal degeneration
Post keratoplasty irregular cornea
Post refractive surgery irregular cornea
Traumatic irregular cornea
Additional relevant MeSH terms:
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Keratoconus
Astigmatism
Corneal Diseases
Eye Diseases
Refractive Errors