Corneal Thickness Changes With Scleral Contact Lenses

April 8, 2020 updated by: Luigina Sorbara, University of Waterloo

Changes in Corneal Thickness in Keratoconic Eyes With Variation in Scleral Contact Lens Central Clearance

The purpose of this study is to investigate changes in the corneal thickness of scleral contact lens wearers in a keratoconic (KC) population and compare to age-matched controls. The hypothesis is that scleral contact lens wear is associated with low levels of corneal hypoxia including measurable changes in corneal thickness. Corneal thickness will be altered post scleral lens wear compared to pre-lens wear and the amount of alteration will correlate to the fitting characteristics in the central zone of the scleral lenses. We propose to take a sample of keratoconic and control participants, fit them in scleral lenses, and to measure topographic corneal thickness after 8-10 hours of scleral lens wear after three weeks of wear, to compare two instruments in the measurement of corneal thickness, and to compare the effects of varying central corneal clearance of the scleral lens on corneal thickness.

Study Overview

Status

Status

Indicates the current recruitment status or the expanded access status.
Unknown

Conditions

Conditions

The disease, disorder, syndrome, illness, or injury that is being studied. On ClinicalTrials.gov, conditions may also include other health-related issues, such as lifespan, quality of life, and health risks.

Intervention / Treatment

Intervention / Treatment

A process or action that is the focus of a clinical study. Interventions include drugs, medical devices, procedures, vaccines, and other products that are either investigational or already available. Interventions can also include noninvasive approaches, such as education or modifying diet and exercise.

Detailed Description

The purpose of this study is to investigate changes in the corneal thickness of scleral contact lens wearers in a keratoconic (KC) population and compare to age-matched controls. The hypothesis is that scleral contact lens wear is associated with low levels of corneal hypoxia including measurable changes in corneal thickness.

This will be a prospective, dispensing study design. The study will involve up to 20 keratoconic participants and up to 20 age matched controls. Participants will attend 1 screening/fitting visit wearing their habitual contact lenses where the two test lens designs (350 and 450microns) will be fitted. There will then be a delivery visit for each design (randomly selected) and a single follow up visit after 8-10 hours of scleral lens wear, three weeks later. A washout period of a minimum of 48 hours will be applied between the cross-over of each lens design. Lenses to be worn in this study will be made of Boston XO material and are approved by Health Canada. The lenses will have a diameter of 14.8-17.0mm with a high and low sagittal depth in the corneal zone. As to which of the two lenses is being assessed, both the investigator and the participant will be masked as the assistant will provide the lenses in an unlabeled case. Masking the investigator will prevent bias when measuring corneal thickness and analyzing the data. The objectives of this study are to take a sample of keratoconic and control participants, fit them in scleral lenses, and to measure topographic corneal thickness after 8-10 hours of scleral lens wear after three weeks of wear, to compare two instruments in the measurement of corneal thickness, and to compare the effects of varying central corneal clearance of the scleral lens on corneal thickness. Secondary objectives include comparing ocular physiological outcomes between the two test lens designs. Corneal thickness will be altered post scleral lens wear compared to pre-lens wear and the amount of alteration will correlate to the fitting characteristics in the central zone of the scleral lenses.

Study Type

Study Type

Describes the nature of a clinical study. Study types include interventional studies (also called clinical trials), observational studies (including patient registries), and expanded access.
Interventional

Enrollment (Anticipated)

Enrollment

The number of participants in a clinical study. The "anticipated" enrollment is the target number of participants that the researchers need for the study.
40

Phase

Phase

The stage of a clinical trial studying a drug or biological product, based on definitions developed by the U.S. Food and Drug Administration (FDA). The phase is based on the study's objective, the number of participants, and other characteristics. There are five phases: Early Phase 1 (formerly listed as Phase 0), Phase 1, Phase 2, Phase 3, and Phase 4. Not Applicable is used to describe trials without FDA-defined phases, including trials of devices or behavioral interventions.
  • Not Applicable

Contacts and Locations

This section provides the contact details for those conducting the study, and information on where this study is being conducted.

Study Contact

Study Contact

The name and contact information for the person who can answer enrollment questions for a clinical study. Each location where the study is being conducted may also have a specific contact, who may be better able to answer those questions.

Study Locations

  • Canada
    • Ontario
      • Waterloo, Ontario, Canada, N2L3G1
        • Recruiting
        • University of Waterloo School of Optometry and Vision Science
        • Contact:
        • Contact:

Participation Criteria

Researchers look for people who fit a certain description, called eligibility criteria. Some examples of these criteria are a person's general health condition or prior treatments.

Eligibility Criteria

Eligibility Criteria

The key requirements that people who want to participate in a clinical study must meet or the characteristics they must have. Eligibility criteria consist of both inclusion criteria (which are required for a person to participate in the study) and exclusion criteria (which prevent a person from participating). Types of eligibility criteria include whether a study accepts healthy volunteers, has age or age group requirements, or is limited by sex.

Ages Eligible for Study

18 years and older (Adult, Older Adult)

Accepts Healthy Volunteers

No

Genders Eligible for Study

All

Description

Inclusion Criteria (Test Group):

  • Had been diagnosed with keratoconus in at least one eye.
  • Is at least 18 years of age and has full legal capacity to volunteer.
  • Has read and understood the information consent letter.
  • Is willing and able to follow instructions and maintain the appointment schedule.

Inclusion Criteria (Control Group)

  • Had been NOT diagnosed with keratoconus in at least one eye.
  • Is at least 18 years of age and has full legal capacity to volunteer.
  • Has read and understood the information consent letter.
  • Is willing and able to follow instructions and maintain the appointment schedule.

Exclusion Criteria (Test Group):

  • Is using any topical medications that will affect ocular health.
  • Has any ocular pathology or severe insufficiency of lacrimal secretion (severe dry eyes) that would affect the wearing of contact lenses.
  • Has persistent, clinically significant corneal or conjunctival staining using sodium fluorescein dye.
  • Has any clinically significant lid or conjunctival abnormalities and active neovascularization.
  • Is aphakic.
  • Has undergone penetrating keratoplasty.
  • Is participating in any other type of eye related clinical or research study.
  • Has any known allergies or sensitivity to the diagnostic pharmaceuticals or products, such as fluorescein, used in this study.

Exclusion Criteria (Control Group):

  • Is using any topical medications that will affect ocular health.
  • Has any ocular pathology or severe insufficiency of lacrimal secretion (severe dry eyes) that would affect the wearing of contact lenses.
  • Has persistent, clinically significant corneal or conjunctival staining using sodium fluorescein dye.
  • Has any clinically significant lid or conjunctival abnormalities and active neovascularization.
  • Is aphakic.
  • Has undergone any corneal surgery.
  • Is participating in any other type of eye related clinical or research study.
  • Has any known allergies or sensitivity to the diagnostic pharmaceuticals or products, such as fluorescein, used in this study.

Study Plan

This section provides details of the study plan, including how the study is designed and what the study is measuring.

How is the study designed?

Design Details

  • Primary Purpose: Treatment
  • Allocation: Randomized
  • Interventional Model: Parallel Assignment
  • Masking: Double

Arms and Interventions

Participant Group / Arm

Participant Group / Arm

A group or subgroup of participants in a clinical trial that receives a specific intervention/treatment, or no intervention, according to the trial's protocol.
Intervention / Treatment

Intervention / Treatment

A process or action that is the focus of a clinical study. Interventions include drugs, medical devices, procedures, vaccines, and other products that are either investigational or already available. Interventions can also include noninvasive approaches, such as education or modifying diet and exercise.
Experimental: Keratoconics wearing ZenLens with high central clearance
Scleral contact lenses designed to provide approximately 450 microns of central clearance.
Device: ZenLens™
The ZenLens™ semi-scleral lenses are manufactured by Alden Optic Laboratories Inc., Lancaster, NY. They will be made in Boston XO material.
Experimental: Keratoconics wearing ZenLens with low central clearance
Scleral contact lenses designed to provide approximately 350 microns of central clearance.
Device: ZenLens™
The ZenLens™ semi-scleral lenses are manufactured by Alden Optic Laboratories Inc., Lancaster, NY. They will be made in Boston XO material.
Active Comparator: Healthy controls wearing ZenLens with high central clearance
Scleral contact lenses designed to provide approximately 450 microns of central clearance.
Device: Zen™ RC
The Zen™ RC semi-scleral lenses are manufactured by Alden Optic Laboratories Inc., Lancaster, NY. They will be made in Boston XO material.
Active Comparator: Healthy controls wearing ZenLens with low central clearance
Scleral contact lenses designed to provide approximately 350 microns of central clearance.
Device: Zen™ RC
The Zen™ RC semi-scleral lenses are manufactured by Alden Optic Laboratories Inc., Lancaster, NY. They will be made in Boston XO material.

What is the study measuring?

Primary Outcome Measures

Primary Outcome Measures

In a clinical study's protocol, the planned outcome measure that is the most important for evaluating the effect of an intervention/treatment. Most clinical studies have one primary outcome measure, but some have more than one.
Outcome Measure
Measure Description
Time Frame
Corneal Thickness
Time Frame: 6 weeks
Corneal thickness after 8-10 hours of scleral contact lens wear will be measured with the Spectralis OCT and Oculus Pentacam
6 weeks

Secondary Outcome Measures

Secondary Outcome Measures

In a clinical study's protocol, a planned outcome measure that is not as important as the primary outcome measure for evaluating the effect of an intervention but is still of interest. Most clinical studies have more than one secondary outcome measure.
Outcome Measure
Measure Description
Time Frame
Visual acuity
Time Frame: 6 weeks
Both high and low contrast visual acuity will be measured before and after 8-10 hours of scleral contact lens wear
6 weeks
Conjunctival redness
Time Frame: 6 weeks
Conjunctival redness will be measured with the Keratograph before and after 8-10 hours of scleral lens wear
6 weeks
Corneal and conjunctival staining
Time Frame: 6 weeks
Corneal and conjunctival staining will be assessed with the Keratograph and biomicroscope before and after 8-10 hours of scleral lens wear
6 weeks
Tear biochemistry: proteases and cytokines
Time Frame: 6 weeks
The level of proteases (MMP-1, MMP-9) and cytokines (IL-1, IL-6, IL-8, TNFα) in each of the tear samples collected from the lenses will be measured using the Meso Scale Discovery System (MSD-ECL) before and after 8-10 hours of scleral lens wear.
6 weeks
Tear biochemistry: cell count
Time Frame: 6 weeks
Polymorphonuclear leukocyte (PMN) cells in each of the tear samples collected from the lenses will be analyzed and counted using the BD FACS Calibur™ Flow Cytometer and Bright-Line Hemacytometer before and after 8-10 hours of scleral lens wear.
6 weeks

Collaborators and Investigators

This is where you will find people and organizations involved with this study.

Sponsor

Sponsor

The organization or person who initiates the study and who has authority and control over the study.
University of Waterloo

Collaborators

Collaborators

An organization other than the sponsor that provides support for a clinical study. This support may include activities related to funding, design, implementation, data analysis, or reporting.
Bausch & Lomb Incorporated

Investigators

Investigators

A researcher involved in a clinical study. Related terms include site principal investigator, site sub-investigator, study chair, study director, and study principal investigator.
  • Principal Investigator: Luigina Sorbara, OD MSc, University of Waterloo

Publications and helpful links

The person responsible for entering information about the study voluntarily provides these publications. These may be about anything related to the study.

General Publications

Study record dates

These dates track the progress of study record and summary results submissions to ClinicalTrials.gov. Study records and reported results are reviewed by the National Library of Medicine (NLM) to make sure they meet specific quality control standards before being posted on the public website.

Study Major Dates

Study Start (Actual)

Study Start

The actual date on which the first participant was enrolled in a clinical study. The "anticipated" study start date is the date that the researchers think will be the study start date.
June 22, 2017

Primary Completion (Anticipated)

Primary Completion

The date on which the last participant in a clinical study was examined or received an intervention to collect final data for the primary outcome measure. Whether the clinical study ended according to the protocol or was terminated does not affect this date. For clinical studies with more than one primary outcome measure with different completion dates, this term refers to the date on which data collection is completed for all the primary outcome measures. The "anticipated" primary completion date is the date that the researchers think will be the primary completion date for the study.
December 1, 2020

Study Completion (Anticipated)

Study Completion

The date on which the last participant in a clinical study was examined or received an intervention/treatment to collect final data for the primary outcome measures, secondary outcome measures, and adverse events (that is, the last participant's last visit). The "anticipated" study completion date is the date that the researchers think will be the study completion date.
December 1, 2020

Study Registration Dates

First Submitted

First Submitted

The date on which the study sponsor or investigator first submitted a study record to ClinicalTrials.gov. There is typically a delay of a few days between the first submitted date and the record's availability on ClinicalTrials.gov (the first posted date).
June 15, 2017

First Submitted That Met QC Criteria

First Submitted That Met QC Criteria

The date on which the study sponsor or investigator first submits a study record that is consistent with National Library of Medicine (NLM) quality control (QC) review criteria. The sponsor or investigator may need to revise and submit a study record one or more times before NLM's QC review criteria are met. It is the responsibility of the sponsor or investigator to ensure that the study record is consistent with the NLM QC review criteria.
August 14, 2017

First Posted (Actual)

First Posted

The date on which the study record was first available on ClinicalTrials.gov after National Library of Medicine (NLM) quality control (QC) review has concluded. There is typically a delay of a few days between the date the study sponsor or investigator submitted the study record and the first posted date.
August 15, 2017

Study Record Updates

Last Update Posted (Actual)

Last Update Posted

The most recent date on which changes to a study record were made available on ClinicalTrials.gov. There may be a delay between when the changes were submitted to ClinicalTrials.gov by the study's sponsor or investigator (the last update submitted date) and the last update posted date.
April 10, 2020

Last Update Submitted That Met QC Criteria

Last Update Submitted That Met QC Criteria

The most recent date on which the study sponsor or investigator submitted changes to a study record that are consistent with National Library of Medicine (NLM) quality control (QC) review criteria. It is the responsibility of the sponsor or investigator to ensure that the study record is consistent with the NLM QC review criteria.
April 8, 2020

Last Verified

Last Verified

The most recent date on which the study sponsor or investigator confirmed the information about a clinical study on ClinicalTrials.gov as accurate and current. If a study with a recruitment status of recruiting; not yet recruiting; or active, not recruiting has not been confirmed within the past 2 years, the study's recruitment status is shown as unknown.
April 1, 2020

More Information

Terms related to this study

Additional Relevant MeSH Terms

Other Study ID Numbers

Other Study ID Numbers

Identifiers or ID numbers other than the NCT number that are assigned to a clinical study by the study's sponsor, funders, or others. These numbers may include unique identifiers from other trial registries and National Institutes of Health grant numbers.
  • 22186

Plan for Individual participant data (IPD)

Plan to Share Individual Participant Data (IPD)?

No

Drug and device information, study documents

Studies a U.S. FDA-regulated drug product

No

Studies a U.S. FDA-regulated device product

No

This information was retrieved directly from the website clinicaltrials.gov without any changes. If you have any requests to change, remove or update your study details, please contact register@clinicaltrials.gov. As soon as a change is implemented on clinicaltrials.gov, this will be updated automatically on our website as well.

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