Understanding Visual Acuity Records in Litigation

How Snellen Notation Works

Visual acuity is usually recorded in Snellen notation: 20/20, 20/40, 20/200. The first number is the testing distance in feet; the second is the distance at which a person with normal vision could read the same letters. A person with 20/40 vision must stand at 20 feet to read what a normally sighted person reads at 40 feet — the vision is worse than normal, not "twice as good." Larger second numbers mean worse acuity. When letters cannot be read at all, charts record counting fingers (CF), hand motion (HM), light perception (LP), or no light perception (NLP), in descending order of function.

Uncorrected Versus Best-Corrected: The Distinction That Decides Cases

An acuity of 20/200 measured without glasses in a patient who needs glasses tells you almost nothing about eye health — it may reflect nothing more than uncorrected refractive error, fully fixable with a prescription. Charts distinguish these measurements with abbreviations: "sc" (without correction), "cc" (with correction), and notations of the refraction used. BCVA is the acuity after a careful refraction finds the best possible correction. Impairment ratings, driving standards, and legal blindness definitions all turn on corrected acuity, because society expects people to wear their glasses. A record showing "VA 20/200" without more is ambiguous, and building a damages theory on it without confirming whether it was corrected is a recurring and avoidable error.

Pinhole Testing: The Quick Screen

When time does not permit a full refraction, clinicians use a pinhole occluder — a shield with small holes that admits only central rays of light, largely neutralizing refractive error. If acuity improves through the pinhole, the deficit is mostly optical (glasses-correctable). If it does not improve, the cause lies in the eye or visual pathway itself — cornea, lens, retina, or optic nerve. A chart entry like "20/80 PH 20/25" says the eye is probably healthy and simply needs correction; "20/80 PH NI" (no improvement) points to disease or injury. This single notation often carries more medical-legal significance than the headline acuity number.

Distance and Near Acuity

Standard acuity testing is at distance. Near acuity, tested with a reading card, can differ — particularly after age forty, when presbyopia (age-related loss of focusing ability) affects near vision in everyone, and after cataract surgery, when a monofocal intraocular lens provides sharp focus at only one distance. A claimant with excellent distance acuity and difficulty reading may be describing an expected optical consequence rather than an injury; conversely, certain conditions degrade near function first. Which measurement matters depends on the claim being made.

From Acuity to Impairment Ratings

Formal impairment ratings convert measured acuity into standardized percentages. Under the AMA Guides to the Evaluation of Permanent Impairment, 5th Edition — the edition California workers' compensation uses — visual impairment is computed from best-corrected acuity in each eye together with visual field data, then expressed as whole person impairment. The arithmetic is mechanical, but the inputs require judgment: the rating is only as valid as the acuity measurement behind it, which is why effort, refraction quality, and test consistency matter. Ratings and their apportionment are discussed further under whole person impairment for vision and permanent and stationary evaluations.

Common Misreadings by Non-Specialists

• Treating an uncorrected acuity as if it were best-corrected — the most frequent error, in both directions.
• Assuming acuity measured during an acute episode (corneal abrasion, inflammation) reflects permanent function.
• Overlooking pinhole notations that show the deficit was refractive.
• Comparing acuities across records without noticing that one was distance and one was near, or that testing conditions differed.
• Equating 20/200 in one eye with legal blindness — statutory definitions generally refer to the better eye, best-corrected.

What Attorneys Should Provide

Send every record containing an acuity measurement — including optometry and ER records — plus refraction data and the imaging that bears on structure, so measured function can be checked against anatomy. Where acuity is central to damages, the sequence of measurements over time matters more than any single reading.

Frequently Asked Questions