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Welcome message by the President of the Nigerian Optometric Association for the NOA 2019 conference

noang.org/ In this video, we look at the main advantages and disadvantages of RCT and the common methods of randomisation. We then illustrate these topics through the UK Glaucoma Treatment Study RCT which was carried out to clarify the relationship between intraocular pressure and glaucoma.

noang.org/ When developing an RCT you must create a detailed and comprehensive protocol which is approved by an appropriate ethics board or committee. This protocol should include the following information: The rationale for the RCT included a detailed literature review Definition of the hypothesis (research question) Proposed methods to be used: the study objectives, sample size calculations, ...

noang.org/ Glaucoma was defined by this group as an optic neuropathy, characterised by specific structural findings in the optic disc and particular functional deficits in automated visual field testing. They recommended that intraocular pressure should be regarded as a continuous variable in risk factor or clinical studies.

noang.org/ Errors in expression tend to occur when the terms "more" or "less" are used. Because it is a ratio and expresses how many times more probable the outcome is in the exposed group, the simplest solution is to use the words "times the risk" or "times as high as" in your interpretation.

noang.org/ A major challenge for all cohort studies is the feasibility of long-term follow-up in terms of cost and resources. It can be very time-consuming to regularly trace all cohort subjects. A loss to follow-up is also a major source of bias. Cohort participants may die, migrate, change jobs and even refuse to participate in the study. Loss can also be due to outcome e.g people who develop...

noang.org/ In a cohort study, it is essential to select study participants who are representative of the population from which they are drawn, apart from their exposure status. The choice of study population depends on the hypothesis under investigation and has to be balanced with practical constraints.

noang.org/ Currently, about 347 million people are affected by diabetes. Ophthalmic complications of diabetes include diabetic retinopathy (DR)

noang.org/ In case-control studies, the odds estimate the strength of the association between exposure and outcome

noang.org/ Poorly designed studies can result in non-comparability between cases and controls. Selection of controls that are unrepresentative of the population from which cases are selected can lead to an incorrect estimation of the exposure rate. Selection bias can be controlled during the design phase.

noang.org/ In all case-control studies, as in all epidemiological studies, we must begin with a clearly defined question or hypothesis. We also need to establish a clear case definition at the very outset of the study. This lets us implement a case selection process using standardised diagnostic criteria. Selecting good controls in a case-control study can be problematic. We have to do it in a ...

noang.org/ The condition we now call age-related macular degeneration (AMD) was first described in 1874, as a "symmetrical central choroido-retinal disease occurring in senile persons.” AMD is a major cause of ocular morbidity among people over the age of 65 in high-income countries.

noang.org/ In this video, we discuss how to recognise when a variable may be a confounder and what can happen when confounding is present. As you watch consider some of the consequences if researchers fail to identify a confounder?

noang.org/ In eye care, rapid assessment methods had emerged by the mid-1990s for cataract, onchocerciasis, and trachoma. More recently, the Rapid Assessment of Avoidable Blindness (RAAB) has been developed to find the main causes of avoidable blindness and visual impairment. The global action plan for universal eye health prioritises the use of rapid assessment methods to establish local preva...

1.4 Cross sectional study for cataract

1.3 The epidemiology of cataract

1.1 Welcome to the course and lesson 1

3.10 Conclusion and next steps

3 8 What is confounding

3.6 What is bias

3 5 Other study designs

3 4 Linking research questions and methods Part 2

3 3 Cross sectional studies

3 2 Linking research questions and methods Part 1

2 4 The effect of exposure on incidence

2 3 How to calculate incidence

2 2 What is incidence in epidemiology

1 9 The Global Action Plan and VISION 2020

1 8 Epidemiology of visual impairment