Optometry Resources

Evidence-based medicine (EBM) or evidence-based practice (EBP) is the process of making informed decisions that take into account internal evidence that you have gathered about your patient, the best external evidence, your clinical expertise, and the patient’s perspectives. 

EBP Process:

1. Assess your patient
2. Ask an answerable, well-built clinical question
3. Find the evidence in the healthcare literature
4. Appraise the evidence for its validity and acceptability
5. Apply the evidence to patient care
6. Evaluate the whole process

The library can help you with steps 2-4: Ask, Find, and Appraise. 

Keep a Research Log

When searching, keep a log of your research. This will keep you organized and save you time. It will help you remember what search terms you've used and get ideas for how to change them to bring more relevant search results.

Also, get the full citation for each source that you find and the permanent link to the source immediately. This will save you time so you don't have to spend time creating a citation or looking for a source later. 

Taking notes about your impressions regarding each source's credibility and relevance will hep you remember the source when you look at it later. This will also save you time.

Keep a research log that includes:

• Clinical or research question
• Databases searched
• Search terms/filters used
• Full citations for each source 
• Permanent links to sources
• Notes about credibility and relevance of source, what info it provides to help you answer your clinical question

PICO is an acronym to help you break down your clinical question in order to identify clearly what evidence you need to find. You can use this to create keywords for your searches.

• Patient, Population, Problem: What are the most important characteristics of this patient? What subset of the patient population are you researching? What specific condition or disease are you addressing?  
• Intervention, Prognostic Factor, Exposure: Which intervention, prognostic factor, or exposure are you considering?
• Comparison: What is the main alternative to compare with the intervention?
• Outcome: What do you hope to accomplish, measure, improve or affect?

Example:

• Patient, Population, Problem: Retired teacher with presbyopia who reports mild eye burning feeling after reading for long periods of time. She has high IOP measure and some visual field loss. 
• Intervention, Prognostic Factor, Exposure: Topical medications
• Comparison: Trabeculoplasty
• Outcome: Reduce risk for vision loss

PICOTT questions: See the Ask a PICOTT Question section to learn how to add the TT to your PICO question.

Background vs. Foreground Questions

Background Questions

• Ask for general information about a condition, disease, or treatment
• Ask who, what, when, why, and how about a disorder

Best answered by: 

• Medical textbooks, point of care tools, narrative reviews

Examples: 

• What is a cataract? 
• What are floaters and flashes? 

Foreground Questions

• Ask for specific information about a disorder or treatment for clinical decision making
• Usually relate to a specific patient or particular population
• Tend to be more specific and complex and makes comparisons

Best answered by: 

• Studies from medical databases like PubMed

Example: 

• Questions that include the four PICO components: patient, intervention, comparison, outcome

Question Type and Preferred Evidence-Base/Study Type

*Harm data may be included in the results of a RCT as adverse effects of a treatment. However depending on the intervention, it may be unethical to deliberately expose patients to harm. 

Sackett, D.L., Straus, S.E., Richardson, W.S., Rosenberg, W., & Haynes, R.B. (2000). Evidence-based medicine: How to practice & teach EBM (2nd ed.). Churchill Livingstone.

Study Types

From BMJ: A Glossary of EBM Terms

• Meta-Analysis: A statistical technique that summarizes the results of several studies in a single weighted estimate, in which more weight is given to results of studies with more events and sometimes to studies of higher quality.
• Systematic Review: A review in which specified and appropriate methods have been used to identify, appraise, and summarize studies addressing a defined question. It can, but need not, involve meta-analysis).
• Randomized Controlled Trial (RCT): A trial in which participants are randomly assigned to two or more groups: at least one (the experimental group) receiving an intervention that is being tested and another (the comparison or control group) receiving an alternative treatment or placebo. This design allows an assessment of the relative effects of interventions.
• Diagnostic Studies: A study that evaluates a test for diagnosing a disease. (Learn more from BJM at Diagnostic test studies: Assessment and Critical Appraisal.)
• Cohort Studies: A non-experimental study design that follows a group of people (a cohort), and then looks at how events differ among people within the group. A study that examines a cohort, which differs in respect to exposure to some suspected risk factor (e.g., smoking), is useful for trying to ascertain whether exposure is likely to cause specified events (e.g., lung cancer). Prospective cohort studies (which track participants forward in time) are more reliable than retrospective cohort studies.
• Case Control Studies: A study design that examines a group of people who have experienced an event (usually an adverse event) and a group of people who have not experienced the same event, and looks at how exposure to suspect (usually noxious) agents differed between the two groups. This type of study design is most useful for trying to ascertain the cause of rare events, such as rare cancers.
  Case-control studies can only generate odds ratios (OR) and not a relative risk (RR). Case-control studies provide weaker evidence than cohort studies but are more reliable than case series.
• Nonrandomized Trials (Controlled Clinical Trial [CCT)]: A trial in which participants are assigned to two or more different treatment groups. The term is often used to refer to controlled trials in which treatment is assigned by a method other than random allocation. When the method of allocation is by random selection, the study is referred to as a randomized controlled trial (RCT). Non-randomized controlled trials are more likely to suffer from bias than RCTs.
• Cross Sectional Studies: A study design that involves surveying a population about exposure, or condition, or both, at one point in time. It can be used for assessing the prevalence of a condition in the population. Cross-sectional studies should never be used for assessing the causality of a treatment.
• Case Series: Analysis of a series of people with the disease (there is no comparison group in case series). Case series provide weaker evidence than case-control studies.

Primary vs. Secondary Sources

Cantrell, S., & Von Isenburg, M. (2021). EBP and the medical librarian. Duke University. 

Evidence Pyramid

Cantrell, S., & Von Isenburg, M. (2021). EBP and the medical librarian. Duke University. 

PICOTT Question

Add TT to your PICO question:

• Patient, Population, Problem: What are the most important characteristics of this patient? What subset of the patient population are you researching? What specific condition or disease are you addressing?  
• Intervention, Prognostic Factor, Exposure: Which intervention, prognostic factor, or exposure are you considering?
• Comparison: What is the main alternative to compare with the intervention?
• Outcome: What do you hope to accomplish, measure, improve or affect?
• Type of Question: What type of question are you asking? (E.g., Therapy, prognosis, harm/etiology, diagnosis, prevention)
• Type of Study: What study types are preferred as evidence for your type of question. (E.g., Therapy question: systematic review or randomized controlled trial)

Example:

• Patient, Population, Problem: Retired teacher with presbyopia who reports mild eye burning feeling after reading for long periods of time. She has high IOP measure and some visual field loss. 
• Intervention, Prognostic Factor, Exposure: Topical medications
• Comparison: Trabeculoplasty
• Outcome: Reduce risk for vision loss
• Type of Question: Therapy
• Type of Study: meta-analysis, systematic review, randomized controlled trial

Background Resources

Optometry Handbooks

Search the Library Search Box by the title of the book to find these.

• Clinical Manual of Contact Lenses 
• Duane’s Ophthalmology
• Massachusetts Eye and Ear Infirmary
• Wills’ Eye Manual

Point-of-Care Resources

Drug Information

Foreground Resources

EBM Resources

Practice Guidelines are not intended to be construed or to serve as a standard of medical care. Standards of medical care are determined on the basis of all clinical data available.

Databases

These are primarily where you'll find your studies (e.g., randomized-controlled trials). 

Quality of Evidence Grades

American Optometric Association: Key to Quality of Evidence and Strength of Clinical Recommendation Grading

Once you have found evidence that provides information to help you answer your clinical question, you want to appraise the evidence to determine it's strength and quality. This should help you determine whether and how to apply the evidence when making your clinical decision and care plan for your patient.

Quality of Evidence Levels

Visit the Library How Tos guide, Cite Your Sources page for links to citation guides.

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