Practice Based Research

Reliable Assessment of Visual Function

Accurate and reliable assessment of the patient’s visual function is a critical factor for both diagnosing visual problems and evaluating the outcome of a treatment.1 Ideally, tests used for such assessment should satisfy rigorous requirements, including high specificity and sensitivity, as well as good test–retest reliability. But from a clinical point of view, they also need to be quick and easy to administer.

Research is still greatly needed to collect reference data in order to determine the clinical value of many vision tests and procedures commonly used in vision clinics. For example, further research is still required to establish appropriate age-specific limits of normal visual acuity for adults2,3 and children;4 to ascertain what is the minimum change in VA that can be considered significant, or to define cut-off VA values for normal and abnormal results for screening purposes (especially in children).3

Furthermore, validation studies for every new and current clinical test are necessary to determine their specificity, sensitivity, likeehood ratios, etc., and hence to know their usefulness in clinical practice.

Practice Based Research

In Practice-Research and Evidence-Based Medicine

Practitioners tend to lack the knowledge needed to design a research study or analyze the data collected (as they usually have limited understanding of biostatistics required for clinical research5,6), however, clinicians are essential to implement studies designed by other research experts.

The clinical experience and expertise of eye-care practitioners places them in a privileged position to carry out clinical validation studies of tests and procedures commonly used in daily clinical work. Practice-based Research – on real patients and in real settings – is most useful for validating clinical procedures, as is bound to produce more realistic data than experiments conducted under special lab conditions. Furthermore, the joint contribution from different clinical sources to provide data that will be analyzed globally, adds generalizability to the conclusions reached in those studies.

Previous practice-based research studies have succeeded in investigating the validation of specific clinical vision tests.7,8,9 At the present time, practice-based research is being encouraged amongst community optometrists as a foundation for evidence-based optometry.10,11 To that end, professional bodies like the British College of Optometrists have established programs such as iPRO (Innovation in Practice-based Research for Optometrists), involving community optometrists.

The Optonet Project – Validation on Clinical Vision Tests & CET/CPD 

Continuing education and training (CET) and Continuing Professional Development (CPD) by all healthcare professionals is essential to update their knowledge. This is well recognized by the Optometric profession, as CET in optometry is nowadays compulsory in most developed countries. The Optonet Project invites eyecare professionals to participate in community practice-based research, as a part of a CET/CPD program.

Practice-based research through the Optonet Project is ideal to test the usefulness of commonly used clinical vision tests and procedures. By conducting collaborative studies we aim to determine the following characteristics of clinical vision tests:

Trueness (or Validity) – Does the test measure what it is supposed to measure?

Precision (Repeatability & Reproducibility) – Are the results of the test repeatable?

Diagnostic Accuracy – Does the test provide diagnostically useful information?

Normative Data and Age-related changes – What is a normal result according to the patient’s age?

Agreement between tests – Do all the tests which are designed to measure a specific function provide similar results?

This hands-on research approach carried out by the practitioners working in their own practices and on their own untrained patients (in a “real world” scenario), allows collection of a significant amount of data. But to the practitioners it offers insight into the principles and procedures of research, a most useful skill to understand, criticize and interpret research literature, which should be the base of clinical decisions in eye care.12,13

The Optonet CET program is designed to provide practitioners with important scientific knowledge and skills,14,15 in order to promote evidence-based decisions in clinical optometry and vision sciences.13

We expect that data obtained through the Optonet project will help develop the next generation of vision tests, based on their real-world performance determined by participating clinicians. Ultimately, this collective effort will afford more efficient and sensitive diagnosis and monitoring of visual function in daily clinical practice.

Finally, the Optonet Project provides a forum to meet and share clinical information with other community eye-care practitioners, by undertaking collaborative primary research.


Are you interested in evidence based best practice?

Do you want to learn the basis of conducting a research study?

Do you want to improve your knowledge on medical statistics

Would you like to gain and develop new skills in research to apply to everyday practice?

Do you wish to move your own practice forward?


1. Chung, S. T. L., Burns, S. A., Levi, D. M. & McGraw, P. V. Testing vision: from laboratory psychophysical tests to clinical evaluation. Vision Res. 90, 1 (2013).
2. Elliott, D. B., Yang, K. C. & Whitaker, D. Visual acuity changes throughout adulthood in normal, healthy eyes: seeing beyond 6/6. Optom. Vis. Sci. Off. Publ. Am. Acad. Optom. 72, 186–191 (1995).
3. Ohlsson, J. & Villarreal, G. Normal visual acuity in 17–18 year olds. Acta Ophthalmol. Scand. 83, 487–491 (2005).
4. Mcoptom, K. J. S. Testing Visual Acuity of Young Children : An Evidence-based Guide for Optometrists. 11, 161–168 (2010).
5. Novack, L., Jotkowitz, A., Knyazer, B. & Novack, V. Evidence-based medicine: assessment of knowledge of basic epidemiological and research methods among medical doctors. Postgrad. Med. J. 82, 817–822 (2006).
6. Windish, D. M., Huot, S. J. & Green, M. L. Medicine residents’ understanding of the biostatistics and results in the medical literature. JAMA 298, 1010–1022 (2007).
7. Adler, P. M., Cregg, M., Viollier, A.-J. & Margaret Woodhouse, J. Influence of target type and RAF rule on the measurement of near point of convergence. Ophthalmic Physiol. Opt. J. Br. Coll. Ophthalmic Opt. Optom. 27, 22–30 (2007).
8. Tang, S. T. W. & Evans, B. J. W. The Near Mallett Unit Foveal Suppression Test: a cross-sectional study to establish test norms and relationship with other optometric tests. Ophthalmic Physiol. Opt. J. Br. Coll. Ophthalmic Opt. Optom. 27, 31–43 (2007).
9. Karania, R. & Evans, B. J. W. The Mallett Fixation Disparity Test: influence of test instructions and relationship with symptoms. Ophthalmic Physiol. Opt. J. Br. Coll. Ophthalmic Opt. Optom. 26, 507–522 (2006).
10. Elliott, D. B. Evidence-based optometry and in-practice research. Ophthalmic Physiol. Opt. J. Br. Coll. Ophthalmic Opt. Optom. 32, 81–82 (2012).
11. Evans, B. In-practice (in-office) optometric research. Ophthalmic Physiol. Opt. J. Br. Coll. Ophthalmic Opt. Optom. 32, 83–88 (2012).
12. Elliott, D. B. Lies, damned lies and………. Ophthalmic Physiol. Opt. J. Br. Coll. Ophthalmic Opt. Optom. 34, 499–501 (2014).
13. Suttle, C. M., Jalbert, I. & Alnahedh, T. Examining the evidence base used by optometrists in Australia and New Zealand. Clin. Exp. Optom. J. Aust. Optom. Assoc. 95, 28–36 (2012).
14. Rao, G. & Kanter, S. L. Physician numeracy as the basis for an evidence-based medicine curriculum. Acad. Med. J. Assoc. Am. Med. Coll. 85, 1794–1799 (2010).
15. Windish, D. M., Huot, S. J. & Green, M. L. Medicine residents’ understanding of the biostatistics and results in the medical literature. JAMA 298, 1010–1022 (2007).