Corneal Thickness Changes With Scleral Contact Lenses
- Conditions
- KeratoconusHealthy Controls
- Interventions
- Device: ZenLens™Device: Zen™ RC
- Registration Number
- NCT03249233
- Lead Sponsor
- University of Waterloo
- Brief Summary
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.
- 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.
Recruitment & Eligibility
- Status
- UNKNOWN
- Sex
- All
- Target Recruitment
- 40
Not provided
Not provided
Study & Design
- Study Type
- INTERVENTIONAL
- Study Design
- PARALLEL
- Arm && Interventions
Group Intervention Description Keratoconics wearing ZenLens with low central clearance ZenLens™ Scleral contact lenses designed to provide approximately 350 microns of central clearance. Healthy controls wearing ZenLens with low central clearance Zen™ RC Scleral contact lenses designed to provide approximately 350 microns of central clearance. Healthy controls wearing ZenLens with high central clearance Zen™ RC Scleral contact lenses designed to provide approximately 450 microns of central clearance. Keratoconics wearing ZenLens with high central clearance ZenLens™ Scleral contact lenses designed to provide approximately 450 microns of central clearance.
- Primary Outcome Measures
Name Time Method Corneal Thickness 6 weeks Corneal thickness after 8-10 hours of scleral contact lens wear will be measured with the Spectralis OCT and Oculus Pentacam
- Secondary Outcome Measures
Name Time Method Conjunctival redness 6 weeks Conjunctival redness will be measured with the Keratograph before and after 8-10 hours of scleral lens wear
Tear biochemistry: cell count 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.
Tear biochemistry: proteases and cytokines 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.
Visual acuity 6 weeks Both high and low contrast visual acuity will be measured before and after 8-10 hours of scleral contact lens wear
Corneal and conjunctival staining 6 weeks Corneal and conjunctival staining will be assessed with the Keratograph and biomicroscope before and after 8-10 hours of scleral lens wear
Trial Locations
- Locations (1)
University of Waterloo School of Optometry and Vision Science
🇨🇦Waterloo, Ontario, Canada