Exploring the Psychophysics of Keratoconus Using the Moorfields Acuity Chart

Not Applicable

Completed

• Conditions: Keratoconic Subjects
• Interventions: Device: Moorfields Acuity Chart

• Registration Number: NCT02429609
• Lead Sponsor: Moorfields Eye Hospital NHS Foundation Trust

Brief Summary

The measurement of visual acuity is made using black letters of varying size superimposed on a uniform white background. The objective is to determine the smallest letter, or optotype, that can be correctly identified. One limitation of current tests is the variability of measurements, this making it difficult for clinicians to determine if changes in visual acuity are related to ocular disease. This variability has been attributed to the design of current optotypes, in particular their differing legibilities. Our group has recently demonstrated that a new type of letter chart (Moorfields Acuity Chart), containing letters with a black core and a white border presented on a grey background, reduces the variability of visual acuity measurements. In this study the investigators wish to determine if changes in vision owing to keratoconus, a disease that causes the cornea to adopt an irregular shape, may be detected more easily using the Moorfields Acuity Chart compared with conventional letter charts.

Detailed Description

Not available

Study Timeline

• Study First Submitted: 2015-04-09
• Study Start: 2015-04-15
• Study First Submitted QC: 2015-04-24
• Study First Posted: 2015-04-29
• Primary Completion: 2016-04-30
• Study Completion: 2016-04-30
• Status Verified: 2022-04
• Last Update Submitted: 2022-04-04
• Last Update Posted: 2022-04-12

Recruitment & Eligibility

• Status: COMPLETED
• Sex: All
• Target Recruitment: 80

Inclusion Criteria

Not provided

Exclusion Criteria

Not provided

Study & Design

• Study Type: INTERVENTIONAL
• Study Design: SINGLE_GROUP

Arm && Interventions

Group	Intervention	Description
Keratoconic subjects	Moorfields Acuity Chart	1. Short clinical interview (Questions pertaining to ocular and systemic health, medications, family history and date of birth). (approx. 2 minutes) 2. Visual acuity measurement using EDTRS chart at 4 m (approx. 4 minutes) 3. Refraction: retinoscopy and subjective, at 4m (approx. 10 minutes) 4. Anterior eye examination (approx. 4 minutes) 5. Fundus examination using binocular indirect ophthalmoscopy or a standard ophthalmoscope - to screen for eye disease that is likely to affect visual ability in this study. (approx. 5 minutes) 6. Corneal topography measurement with an Oculus Pentacam (Oculus Gmbh., Germany). (approx. 5 minutes) Two measurements of visual acuity will be made: 1. Standard ETDRS logMAR acuity measurement (5 minutes) 2. Vanishing Optotype logMAR acuity measurement (5 minutes)
Healthy subjects	Moorfields Acuity Chart	1. Short clinical interview (Questions pertaining to ocular and systemic health, medications, family history and date of birth). (approx. 2 minutes) 2. Visual acuity measurement using EDTRS chart at 4 m (approx. 4 minutes) 3. Refraction: retinoscopy and subjective, at 4m (approx. 10 minutes) 4. Anterior eye examination (approx. 4 minutes) 5. Fundus examination using binocular indirect ophthalmoscopy or a standard ophthalmoscope - to screen for eye disease that is likely to affect visual ability in this study. (approx. 5 minutes) 6. Corneal topography measurement with an Oculus Pentacam (Oculus Gmbh., Germany). (approx. 5 minutes) Two measurements of visual acuity will be made: 1. Standard ETDRS logMAR acuity measurement (5 minutes) 2. Vanishing Optotype logMAR acuity measurement (5 minutes)

Primary Outcome Measures

Name	Time	Method
The relative difference in visual acuity measurement between subjects with and without keratoconus when examined with different types of visual acuity chart.	9 months

Secondary Outcome Measures

Name	Time	Method
The relationship (if any) between optical imperfections (high order aberrations) and measurements of visual acuity when measured using different test chart designs.	9 months