9 Visual Acuities

Visual acuities are not recitals – the patient doesn’t have to read every letter in the chart to determine their acuity

Once you establish an initial line that the patient can read, isolate one line of the chart and have the patient read the next smallest line.  After they read two letters on a line, move down a line (or two, depending on your judgment of how easy it was for them to read that line) and repeat until you determine their visual acuity.

I call this the “L” technique – moving quickly down the chart, investing more “horizontal” time on a line when the patient slows down (and you approach their visual acuity).

Always make the patient guess – and blink – during visual acuities, and make sure the phoropter is not fogged/dirty

Patients will often tell you that they can’t read a line after reading most or all of a prior line.  If this is the case, make them guess.  Isolate the desired line and ask the patient to, “Guess the first two letters of this line.”  If they read the first two letters, have them continue.

Patients with suspected dry eyes may have inconsistent visual acuities.  Reminding these patients (the elderly, previously diagnosed dry eye patients, etc.) to blink while performing visual acuities, subjective refraction, etc. will often improve your final results.

During the summer, the phoropter may “fog” as patient sweat condenses on the colder lenses.  Additionally, patient eye make-up may sometimes “fog” the lenses.  If your results are inconsistent/variable, check to make sure this is not an issue, and clean.

Binocular visual acuities

You know that they’ll be better than monocular visual acuities, so consider not taking them.  A notable exception – mono-vision patients should always have binocular distance and near visual acuities taken.

Pinhole visual acuities

If you intend to perform refraction during an examination, consider not performing pinhole if initial visual acuities are reduced.  Your refraction in over 90% of all cases will result in visual acuities of 20/20, making pinhole unnecessary.  However, if your subjective refraction does not yield 20/20 visual acuities within the normal amount of time it takes to perform a refraction, obtain pinhole acuities.

Pinhole is also great for brief visits (such as red eyes) where the patient does not enter as 20/20; however, the rule still applies – every patient needs to be 20/20 in each eye, or have an explanation as to why they are not (see below).

Perotti’s “20/20 or die!” rule

This is simple:  every patient has to leave your examination with 20/20 visual acuities (either distance or near, corrected or uncorrected, or pinhole) in each eye, or have an explanation as to why they don’t.