Rating Vision Loss: Whole Person Impairment

The Architecture of the Visual System Rating

The AMA Guides rate the visual system on two measured functions:

• Visual acuity — the sharpness of central vision, measured as best-corrected visual acuity (BCVA), meaning acuity with the examinee's optimal glasses or contact lens correction in place. Uncorrected vision does not drive the rating; an eye correctable to 20/20 with glasses is not impaired for rating purposes merely because it is blurry without them.
• Visual field — the extent of peripheral vision. This is the point at which the rating framework and everyday clinical testing diverge: the Guides score field loss along specified meridians across the full peripheral field, which standard automated threshold testing (24-2 or 30-2) does not capture, because it samples only the central 24 to 30 degrees. Goldmann kinetic perimetry, or an equivalent full-field protocol, is required for rating purposes. A file containing only automated central fields is frequently insufficient to rate visual field impairment, and counsel should expect an evaluator to say so rather than approximate. Field loss is scored by the extent and location of the deficit, since not all field loss is functionally equal.

Each function is scored for each eye, and the scores are combined into a functional vision assessment that weights the two eyes the way people actually use them: the better-functioning eye dominates the calculation, reflecting the reality that a person with one normal eye and one badly injured eye retains substantial — though not complete — visual function. This weighting has a consequence attorneys should anticipate: total loss of one eye with a normal fellow eye yields a materially lower whole person impairment than intuition might suggest, because the rating measures binocular function, not tragedy.

From Functional Vision Score to WPI

The acuity and field scores merge into a functional vision score, which is then converted to an impairment of the visual system and finally to whole person impairment through the chapter's conversion structure. The Guides also permit limited, documented adjustment for visual dysfunction not captured by acuity and fields — such as disabling glare, diplopia (double vision), or contrast loss — when objectively supported. That adjustment is where evaluator judgment enters, and where a report must be explicit about the evidence: an adjustment justified by documented irregular corneal astigmatism after injury is defensible; one resting solely on unverifiable complaint is not.

Where Vision Ratings Go Wrong

Recurring errors in rated eye claims include:

1. Rating uncorrected acuity, or accepting a stale refraction — both inflate impairment in eyes whose vision is largely correctable.
2. Rating before permanent and stationary status, capturing a healing cornea or an unoperated traumatic cataract; timing is addressed on the P&S page.
3. Accepting unreliable fields. Automated perimetry reports its own reliability indices, and non-physiologic patterns — field loss respecting no anatomic boundary, dramatic variability between sessions — require investigation, not transcription.
4. Ignoring structure-function correlation. Claimed profound acuity loss with a normal OCT (optical coherence tomography, objective retinal imaging), normal pupils, and normal electrophysiology is anatomically unexplained; a rating built on it is built on sand.
5. Double-counting the same deficit through both a field score and a subjective adjustment.

Objectivity and Its Limits

Acuity and field testing both require examinee participation, so neither is fully objective; the rating method presumes honest effort. The evaluator's safeguard is convergence: reproducible measurements, cross-checks that do not depend on responses (pupillary testing, OCT, electrophysiology where warranted), and consistency between the measured deficit and observed function. Where effort or consistency is doubtful, the honest report documents the discrepancies and may conclude that a reliable rating cannot yet be assigned — itself a legitimate medical-legal finding. Interpretation of the underlying tests is discussed in the attorney resources on visual acuity and visual fields.

Relation to Apportionment and Disability

The WPI number is the beginning of the legal analysis, not the end. The rating feeds the disability calculation, and the evaluator must still apportion the impairment between industrial and non-industrial causation under Labor Code §§4663–4664 — the subject of the apportionment page. How rating percentages translate into benefits is a legal question for counsel.

What to Provide the Evaluator

Actual test printouts, not summaries: serial acuity measurements with refractions, complete automated perimetry printouts including reliability indices, OCT imaging, and operative reports. When challenging an existing rating, identify the specific measurement or step in the calculation in dispute — a challenge aimed at a demonstrably flawed input is far stronger than a general disagreement with the result. Dr. Shomer performs these ratings in QME and AME evaluations and reviews disputed ratings through record-based consultation.

Frequently Asked Questions