Competency information


Gain informed consent from a volunteer adult subject to:

  • Perform LogMAR visual acuity
  • Perform Ishihara colour vision assessment
  • take and store an ocular image
  • visual field or a confrontational field.


  • The importance of explaining the procedure for each investigation to the patient and gaining informed consent.
  • The relevant procedures and requirements for patient conformance.
  • Principles, guidance and law with respect to informed consent.
  • Relevant protocols for procedure and their correct interpretation.

 Principles of visual acuity

  • The principles of and relationship between visual acuity measurement and refractive error and how to estimate refractive error from unaided visual acuity.
  • The range of tests for visual acuity, appropriate for age, ability, vision levels and occupation (e.g. driving standards), including distance and near LogMAR (e.g. EDTRS), Snellen, E-test, Sheridan-Gardiner, Cardiff Cards, preferential looking techniques, crowded and single letter presentations.
  • How to measure visual acuity in patients with language or communication difficulties, illiteracy and patients with low vision. Different strategies and tests for measuring visual acuity in children of different ages, and the difficulties and limitations of these tests.

Principles of equivalent refractive for working distances of different tests

  • When and how to use lenses to correct for the test distance of different tests, e.g. colour vision and visual fields, focusing retinal images in high myopia or hypermetropia.
  • How to identify a spectacle optical prescription by inspection.
  • Reasons for altering test distance.
  • Background lighting needed to perform different tests.
  • Importance of image focus and confounders.
  • The principles and use of pinhole to correct reduced visual acuity due to uncorrected refractive error and its limitations.
  • The non-refractive causes of reduced visual acuity and how they affect the measurement of visual acuity.
  • Requirements for accurate and legible recording of information.

Relevant learning outcomes

# Outcome
# 1 Outcome Measure visual acuity using a LogMAR chart for adult subjects.
# 2 Outcome Perform an Ishihara colour vision assessment on an adult subject.
# 3 Outcome Perform an automated static perimetry or confrontation visual field on an adult subject.
# 4 Outcome Label the main peaks of a normal electroretinogram (ERG).