Visual Acuity Project
This is the overview page for the efforts to improve Intraocular Pressure Archetype(s).
Quick links: previous trunk version of VA Archetype, current branch draft.
Clinical brainstorming zone: The comment section below this page (Login required).
Short on time but want to make sure we don’t forget about a certain quirk of Visual Acuity testing or documentation? Please write a comment about it below, even if it is just something that is relevant in special clinical circumstances. If you think of ten seperate things, add ten comments, references are appreciated.
Modelling discussions:
These have mostly taken place in the Discourse Forum thread so far, which was OK but not very easy to follow. We will evaluate how and when remaining issues get added as subtasks in the VA Archetypes Jira page
Comments
We need to draw a proper line between low-vision VA testing and light projection testing.
Light projection (LP) testing is a quick, rough test of retinal and optic nerve function. It only takes a pen torch, see this video:
https://www.youtube.com/watch?v=4Gy-v79ud-M
Based on how VA is defined, testing light projection, which means testing whether the patient can identify the direction of a light source is NOT a VA test. It is usually done when the VA is “Light perception”, and because most EMRs do not explicitely model this test its result (LP accurate / LP inaccurate) usually makes it into some free text VA field.
It is neither specific nor sensitive, but regardless it is the sort of test that may be done in any sort of healthcare setting and if it is done it’s result needs to be recorded.
While I initially considered just modelling it in the VA Archetype I don’t think that is ideal.
So here it is modelled as it’s own archetype: https://ckm.openehr.org/ckm/archetypes/1013.1.8236/mindmap
There is regional variation of expressions to indicate that single letters were missed on Charts that are intended to scored by the full line, such as “p” for partial, or a count of letters that were missed in that line.
I’m not aware that this is part of any standard testing protocoll, and perhaps it is debatable whether that is actually part of the VA measurement or more of a comment.
Especially on charts like Snellen charts that have different numbers of letter per line, the merits of noting the “number of missed letters”, are controversial, but in some countries including the USA it is a common practice to record two missed letters on the 20/20 line this as 20/20 -2
In some circumstances a VA test may be performed using corrective lenses PLUS a pinhole occluder at the same time!
(We are already accounting for that in the current draft, this comment is just to illustrate the sort of clinical peculiarity that’s worth keeping in mind, and thus worth posting in this comment section, please do so if you have more)