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Optometry Digital Literacy Toolkit

A toolkit to assist Optometry students with developing personal digital literacy capacity

The Hierarchy of Evidence

Now that you understand a bit more about different ways to frame your information needs (i.e. your questions), it’s time to consider where you look to find that information.

Using the best available evidence is an important part of evidence-based practice, and knowing where to find it will save you time. To help you understand where to look we use the principles illustrated by the Hierarchy of Evidence.

The Hierarchy ranks different sources of evidence, ranging from single studies to systems. Click on the different sections of the Hierarchy to learn more:

Image and text based on Alper, BS, & Brian Haynes, R 2016, 'EBHC pyramid 5.0 for accessing preappraised evidence and guidance', Evidence Based Medicine, vol. 21, no. 4, p. 123.

Using the Hierarchy of Evidence

Ideally, evidence from sources higher up in the levels of the hierarchy would guide our decision, as evidence at this level has been built on the sum of the evidence below. However, appropriate use of the hierarchy depends on the situation it is being applied to.

Resources in the Hierarchy

Now let’s look at where you find these types of evidence.

Click on the hierarchy again to see names of resources available from the Library which contain each level of evidence. Note that some resources contain evidence from more than one level of the hierarchy.

Image based on Alper, BS, & Brian Haynes, R 2016, 'EBHC pyramid 5.0 for accessing preappraised evidence and guidance', Evidence Based Medicine, vol. 21, no. 4, p. 123.

Activity: Search and Reflect

Let's look at three specific sources of evidence and learn a bit more about what they offer.

1. Optometry Australia guidelines

Visit the Optometry Australia site and look at their guidelines. What do you find? What's NOT there?
What are your alternatives? What are the implications for your practice or study?

2. Cochrane Eyes and Vision

Visit the website of the Cochrane Eyes and Vision Group and have a look at a few of the reviews they've published (it might be easiest to view by subtopic). What do the methods sections in these documents tell you about the evidence you're looking at?

3. PubMed

PubMed is a well-known source of biomedical literature. Visit PubMed and search for 'glaucoma'. What do you find? What type of evidence appears in the search results? What does it tell you about PubMed vs. what is available from Cochrane?

Searching for Evidence

So now you know where you can search, but what about how to search?

Well, remember PICO from earlier? You can use your PICO work as the basis for a search in the databases as well.

Some parts of PICO won’t need to be translated to the search as they'll be implied by other search terms, or would unnecessarily narrow the boundaries of the search if included.

Your earlier PICO looked like this:

In this case we need only search on the I and the C, as the P is too broad and the O is implied by the terms in I and C.

Therefore, PICO helps both frame the question accurately and initiates the process of searching for evidence using databases.

Using the Databases

How do we use the various databases available to us in our search for healthcare evidence?

While each one is slightly different, principles of searching in the databases are generally the same: entering your search term in the search box will return some search results which can then be reviewed.

However, in order to get more precise results, conduct more complex searching and be a more efficient searcher, there are techniques you should get used to applying:

From our original PICO search you may only have one usable search term: 'conjunctivitis'! If we take into account the techniques above, we could have a search that is much more specific and looks more like this:

Further Help

The Optometry Digital Literacy Toolkit was developed by Deakin University Library.
Please get in touch if you have any questions or feedback.