Contact information
Type
Scientific
Primary contact
Prof Bruce Evans
ORCID ID
Contact details
Institute of Optometry
56-62 Newington Causeway
London
SE1 6DS
United Kingdom
+44 (0)20 7407 4183
bruce.evans@virgin.net
Additional identifiers
EudraCT number
ClinicalTrials.gov number
Protocol/serial number
M0003101241
Study information
Scientific title
Acronym
Study hypothesis
Amblyopia has a prevalence of 1-4% and is the leading cause of monocular visual loss in the age group 20-70 years (Simons, 1996) . Since AD 900 (Thabit Ibn Qurrah, 900), amblyopia has been treated by occluding the eye with better acuity. Although the lack of randomised controlled trials (RCTs) has been criticised (Moseley et al., 1995), this form of treatment is widely accepted clinically as long as the patient is treated within the so-called 'sensitive period' or 'critical period' of relatively high neural plasticity (Nelson, 1989).
Evans et al. (1999) carried out a clinical audit of Mallett's IPS treatment for amblyopia. The mean improvement was two lines of the Snellen chart and 100% of this improvement had occurred after 5 treatment sessions.
The purpose of the current study is to compare the Mallett IPS treatment with a placebo, using a randomised double-masked protocol.
Ethics approval
Added 28 July 2008:
Received from City University and Institute of Optometry .
Study design
Double-masked randomised controlled trial
Primary study design
Interventional
Secondary study design
Randomised controlled trial
Trial setting
Not specified
Trial type
Not Specified
Patient information sheet
Full verbal and written information is provided to each participant and is available on request.
Condition
Eye Diseases: Amblyopia
Intervention
Patients meeting strict diagnostic criteria for amblyopia are randomly allocated to an experimental and a control group. The control treatment (modified CAM) was developed to give subjects the same degree of time, attention, and use of 'high-tech' equipment as the IPS treatment, but to have no features which are likely to generate a treatment effect. A two-interval 26 alternative forced choice method is used to measure LogMAR acuities on three consecutive weekly occasions before treatment. Subjects are then treated for 6 weeks and, a week after the final treatment, acuities are again measured but by a researcher who does not know which treatment the subjects have received.
Intervention type
Other
Phase
Not Specified
Drug names
Primary outcome measures
A table of findings will be drawn up describing the characteristics of the participants in the experimental group (e.g., age of onset, type of amblyopia, age at treatment) and participants will be ranked in this table in terms of their improvement in VA following treatment (based on their own z-score of improvement). The data will be inspected to see if there are any trends whereby particular types or sub-groups of amblyopia improve with IPS.
Secondary outcome measures
Not provided at time of registration
Overall trial start date
01/11/2001
Overall trial end date
31/12/2010
Reason abandoned
Eligibility
Participant inclusion criteria
Subjects will be aged 10-65 years. Visual acuity between 6/9 and 6/36 in the amblyopic eye and 6/6 or better in the good eye and where the amblyopia is the result of strabismus or anisometropia. Participants will meet the following selection criteria:
1. No personal history of epilepsy.
2. Willing to attend the Institute of Optometry for the three pre-treatment assessments, six treatment sessions, the post treatment assessment, and the follow-up assessment.
3. Unilateral amblyopia with visual acuity better than 6/36 but worse than 6/9 in the amblyopic eye and 6/6 or better in the non-amblyopic eye.
4. Amblyogenic factor: amblyopic eye is either strabismic or has at least 1D more hypermetropia or 2D more astigmatism than the non-amblyopic eye.
5. No ophthalmoscopically detectable anomalies of fundus or defects of the visual pathway. This will be taken to mean no clinically significant departure from a normal ophthalmoscopic appearance and 30 degrees visual fields (static perimetry) within normal limits.
6. Patients must be at least 10 years old and have signed the informed consent form, or have this signed by a parent or guardian if under 16 years old.
7. No history of strabismus or other cause of reduced visual acuity (e.g., cataract) in first two years of life.
8. Subjects must have had a recent (within the last 1 year) eye examination and must be wearing the appropriate refractive correction. The cost of this appointment and of any refractive correction will have to be met by the participant. Anisometropic participants will be encouraged to wear contact lenses as this has been shown to be the best option to minimise aniseikonia (Winn et al., 1988). Participants must be adapted to any refractive correction, having worn the correction for at least four months (Stewart et al., 2004).
Participant type
Patient
Age group
Adult
Gender
Not Specified
Target number of participants
Sample size calculations indicate that the study will be continued until 32 participants have finished in each group.
Participant exclusion criteria
1. Personal history of epilepsy.
2. Unilateral amblyopia with visual acuity worse than 6/36 or better than 6/9 in the amblyopic eye and 6/9 or worse in the non-amblyopic eye.
3. Amblyogenic factor: cases where amblyopic eye has less than 1D more hypermetropia or less than 2D more astigmatism than the non-amblyopic eye.
4. Ophthalmoscopically detectable anomalies of fundus or defects of the visual pathway.
5. Patients under 10 years old
6. History of strabismus or other cause of reduced visual acuity (eg cataract) in first two years of life
Recruitment start date
01/11/2001
Recruitment end date
31/12/2010
Locations
Countries of recruitment
United Kingdom
Trial participating centre
Institute of Optometry
London
SE1 6DS
United Kingdom
Sponsor information
Organisation
Department of Health
Sponsor details
Richmond House
79 Whitehall
London
SW1A 2NL
United Kingdom
+44 20 7307 2622
dhmail@doh.gsi.org.uk
Sponsor type
Government
Website
Funders
Funder type
Government
Funder name
City Eye Clinic (EYENET) (UK) NHS R&D Support Funding
Alternative name(s)
Funding Body Type
Funding Body Subtype
Location
Results and Publications
Publication and dissemination plan
Not provided at time of registration
Intention to publish date
Participant level data
Not provided at time of registration
Results - basic reporting
Publication summary
1. 2011 results in http://www.ncbi.nlm.nih.gov/pubmed/21158885
Publication citations
-
Results
Evans BJ, Yu CS, Massa E, Mathews JE, Randomised controlled trial of intermittent photic stimulation for treating amblyopia in older children and adults., Ophthalmic Physiol Opt, 2011, 31, 1, 56-68, doi: 10.1111/j.1475-1313.2010.00801.x.