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Optometry and Vision Science Research Guide: Asking and answering clinical questions

Research resources and information for vision science.
  Evidence-based research and practiceAsking and answering clinical questions

Tools and guides

Clinical scenarios

The 49 Clinical Questions series: Experts and practitioners ask a series of structured questions based on clinical scenarios. 

Answering clinical questions with evidence


Clinical questions can fall into two categories; (1) background questions, and (2) foreground questions. To examine how these questions can arise, let's consider the following patient encounter:

Clinical Scenario  
Smiling child wearing glasses and an eyepatch

A 4-year-old patient with amblyopia is in your office with his Dad. 

Treatment plan: corrective lenses and schedule a follow-up at which point you may prescribe an eyepatch. 

You now have some additional questions that you would like answered by the evidence, prior to the follow-up appointment. These clinical questions are background and foreground questions. 

Background questions help us improve our understanding of a topic. These types of questions ask for general knowledge about a condition or a thing. 


  1. Does amblyopia present different in pediatric patients?
  2. After successful treatment, can amblyopia reoccur? What is the likelihood of this happening? 

Foreground questions "ask for specific knowledge to inform clinical decisions or actions."2

These questions are usually more complex as they contain several concepts such as a specific population, intervention, comparison and outcome. The organization of these concepts in a clinical questions, is referred to as PICO. For example:

P Population Pediatric patient presenting with amblyopia
I Intervention Eye-patch
C Comparison Glasses
O Outcome Improvement of condition

Example of a PICO-structured foreground question:

Is an eyepatch recommended for the treatment of a child with amblyopia who is already being treated with glasses?


Formulating complex PICO questions takes practice. If you need help, please contact the Optometry and Vision Science Librarian

What information are we looking for?

The 4s's: Studies (unfiltered information), and Syntheses, Synopses, and Summaries (filtered information)
Filtered Information

Filtered information, in this context, is pre-appraised evidence. 

To get filtered or “secondary” information, evidence from our primary literature is synthesized and evaluated. Those processes of evaluation, synthesizing data, and synopses take time and a lot work. 

Filtered literature will often provide a more definitive answer than individual research reports.

Sources containing filtered information
Based on analysis of synopses Summaries and systems: Point-of-care tools
 Based on analysis of syntheses Synopses: Clinical practice guidelines, evidence-based textbooks.
Based on analysis of original research studies Syntheses: systematic reviews, meta-analyses, and literature and scoping reviews.


Unfiltered Information

Unfiltered information includes original research studies that have not yet been synthesized or aggregated. As such, they can be more difficult to read, interpret, and apply to practice. 

Unfiltered does NOT mean that the research has not been peer-reviewed. This term refers to  study design, not quality. 

Studies, original research
  Randomized Controlled Trials (RCTs):
  Cohort studies: Prospective and retrospective cohort studies.
  Case-controlled studies: case reports and case series
  Laboratory studies: in-vitro trials