The<unk>  <unk> , is an objective measurement and the gold standard in measuring strabismus, i.e. ocular misalignment, or a deviation of the eye. It is used by ophthalmologists and orthoptists in order to measure the vertical and horizontal deviation and includes both manifest and latent components. Manifest is defined by the eye deviating constantly or intermittently, whereas latent is where the deviation is normally controlled but becomes present when the eyes are dissociated. A<unk>  reveals the total deviation and cannot distinguish between latent and manifest strabismus as you are using an alternate<unk>  test. A number of different instruments are required when performing a<unk> . * Horizontal and vertical<unk>  bars (or loose<unk> s). * An occluder * Near accommodative target. For example, near fixation stick * Distance target. For example, most commonly a Snellen chart is utilised, however the LogMAR chart is preferred as it has letters of equal legibility, same numbers of letters on each row and uniform spacing between letters and rows This compared to the Snellen Chart which has ‘poor reproducibility and reliability’ In order to perform a<unk> , you must first perform a<unk>  test as this gives an estimation of the size of the strabismus, thus an approximate starting point on the<unk>  bar. You can also get an indication of presence and type of strabismus by observing the patients’ eye and observing corneal reflections, also known as Hirschbergs. It also shows whether the patient has a manifest or latent deviation. If a manifest deviation is present, it reveals which eye has the deviation or if it is alternating between both eyes.
Prism cover test
Holtzman inkblot technique
Farnsworth–Munsell 100 hue test
Lamellar body count
Worth 4 dot test
Stenger test
Four prism dioptre reflex test
Vernier acuity