Optimising Visual Acuity Measurement in Macular Degeneration

Study Overview
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Brief Summary
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Age-related macular degeneration (AMD) is the leading cause of visual impairment in the UK. The condition is characterised by damage to the region of the retina (macula) responsible for detailed central vision, this leading to problems with tasks such as reading and face-recognition. The ability to accurately measure vision is central to the detection and management of AMD. The most common test (visual acuity) typically requires patients to identify black letters of varying size on a white background, with the smallest letter read representing the limit of vision. Conventional tests are however known to be variable, making it difficult to determine if a true change in vision has occurred. Previous work has found the Moorfields Acuity Chart, which contains specially constructed letters composed of a black core and white border, to be more sensitive to early AMD compared to standard charts. Despite this advantage, it is unclear if there is an associated increase in measurement variability with the Moorfields Acuity Chart and if this changes with the severity of disease. In this study, the relationship between vision test sensitivity and measurement variability will be quantified with both conventional visual acuity tests and the new Moorfields Acuity Chart to identify the optimal vision test to detect and monitor AMD in the clinic.

Official Title
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Quantifying the Disease Signal to Measurement Noise Ratio With the Moorfields Acuity Chart in Age-related Macular Disease

Conditions
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Age Related Macular Degeneration

Intervention / Treatment
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* Device: Visual acuity and contrast sensitivity measurement


Participation Criteria
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Eligibility Criteria
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Group 2 - Healthy control participants: Inclusion criteria will include: Absence of ocular disease in either eye Male or female, aged 18 years or older The absence of significant media opacities Ability to understand nature/purpose of the study and to provide informed consent Ability to follow instructions and complete the study Ability to speak English Exclusion criteria will include: Any systemic disease likely to affect visual performance Presence of any ocular disease Hearing impairment sufficient to interfere with hearing instructions Poor understanding of English language and/or alphabet Any condition which, in the investigator's opinion, would conflict or otherwise prevent the subject from complying with the required procedures, schedule, or other study conduct.

Ages Eligible for Study
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Minimum Age: 20 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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Accepts Healthy Volunteers

Study Plan
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How is the study designed?
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Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Control<br>150 healthy control participants | Device: Visual acuity and contrast sensitivity measurement<br>* Those subjects who meet the inclusion criteria will undergo the study tests. These measurements will be performed on one eye only. Visual acuity will be quantified using two forms of the MAC chart (MAC 1 and 2) and two forms of a conventional letter design chart (C1 and 2). Contrast sensitivity will be measured using the two forms of the Pelli-Robson chart (CS1 and CS2). The order with which the test charts will be presented, in addition to the charts used (i.e. MAC 1 or 2, C1 or 2, and CS1 or 2), will be selected at random. Finally, a measurement of eye length will be collected using an IOL Master (Carl-Zeiss Meditec, USA).<br>|
| AMD Cohort high-contrast VA group i<br>Better than 0.4 logMAR | Device: Visual acuity and contrast sensitivity measurement<br>* Those subjects who meet the inclusion criteria will undergo the study tests. These measurements will be performed on one eye only. Visual acuity will be quantified using two forms of the MAC chart (MAC 1 and 2) and two forms of a conventional letter design chart (C1 and 2). Contrast sensitivity will be measured using the two forms of the Pelli-Robson chart (CS1 and CS2). The order with which the test charts will be presented, in addition to the charts used (i.e. MAC 1 or 2, C1 or 2, and CS1 or 2), will be selected at random. Finally, a measurement of eye length will be collected using an IOL Master (Carl-Zeiss Meditec, USA).<br>|
| AMD Cohort high-contrast VA group ii<br>0.4-0.6 logMAR | Device: Visual acuity and contrast sensitivity measurement<br>* Those subjects who meet the inclusion criteria will undergo the study tests. These measurements will be performed on one eye only. Visual acuity will be quantified using two forms of the MAC chart (MAC 1 and 2) and two forms of a conventional letter design chart (C1 and 2). Contrast sensitivity will be measured using the two forms of the Pelli-Robson chart (CS1 and CS2). The order with which the test charts will be presented, in addition to the charts used (i.e. MAC 1 or 2, C1 or 2, and CS1 or 2), will be selected at random. Finally, a measurement of eye length will be collected using an IOL Master (Carl-Zeiss Meditec, USA).<br>|
| AMD Cohort high-contrast VA group iii<br>0.6-0.8 logMAR | Device: Visual acuity and contrast sensitivity measurement<br>* Those subjects who meet the inclusion criteria will undergo the study tests. These measurements will be performed on one eye only. Visual acuity will be quantified using two forms of the MAC chart (MAC 1 and 2) and two forms of a conventional letter design chart (C1 and 2). Contrast sensitivity will be measured using the two forms of the Pelli-Robson chart (CS1 and CS2). The order with which the test charts will be presented, in addition to the charts used (i.e. MAC 1 or 2, C1 or 2, and CS1 or 2), will be selected at random. Finally, a measurement of eye length will be collected using an IOL Master (Carl-Zeiss Meditec, USA).<br>|
| AMD Cohort high-contrast VA group iv<br>0.8-1.0 logMAR | Device: Visual acuity and contrast sensitivity measurement<br>* Those subjects who meet the inclusion criteria will undergo the study tests. These measurements will be performed on one eye only. Visual acuity will be quantified using two forms of the MAC chart (MAC 1 and 2) and two forms of a conventional letter design chart (C1 and 2). Contrast sensitivity will be measured using the two forms of the Pelli-Robson chart (CS1 and CS2). The order with which the test charts will be presented, in addition to the charts used (i.e. MAC 1 or 2, C1 or 2, and CS1 or 2), will be selected at random. Finally, a measurement of eye length will be collected using an IOL Master (Carl-Zeiss Meditec, USA).<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Ratio of disease signal (test sensitivity) to measurement noise (variability) in AMD with conventional and Moorfields Acuity Charts | The disease signal to measurement noise ratio (SNR) is defined as the ratio of AMD test sensitivity to the degree of measurement variability for each chart investigated in this study. | 2 years | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Test-retest variability for the Moorfields Acuity Chart and conventional logMAR visual acuity tests | Measurement variability (difference in two measures captured using the same vision test on the same day) will be quantified for each vision test used in this study. This analysis will also be undertaken for participants with a range of AMD related vision loss. | 2 years |