False positives and fixation monitoring in Esterman tests

A false positive occurs when the patient responds when no stimulus was presented. In a driving-field context, false positives can make a field look better than it is because missed points may be under-represented.

Austroads sets a clear reliability boundary for Esterman licensing use: the false-positive score must be no more than 20 percent. If the score is higher, the field should not be treated as reliable evidence for a favourable driving opinion.

The important teaching point is that a wide, clean-looking field with excessive false positives is not a wide, clean field. It is an unreliable test.

Austroads states that fixation monitoring must be performed and recorded on the test. The Optometry NSW/ACT guide explains the practical point plainly: fixation is monitored by observing the patient during the test.

Without fixation monitoring, a patient may scan toward stimuli, especially if they understand that the test affects driving. That can convert a peripheral-field test into a search task and make the result less meaningful.

If fixation monitoring is absent, unclear, or not recorded, the report should not sound as confident as a standard reliable Esterman. DRIVE Fields should either request the missing information or route to manual review depending on the pathway.

When the field is unreliable, the most useful next step is usually a repeat test with better instruction, careful fixation observation, and clear printout settings. This is especially true when the field is close to a threshold or will affect a commercial licence.

Patients may perform poorly because they misunderstood the task, were tired, had poor positioning, used inappropriate correction, or were anxious about losing a licence. A repeat test can turn uncertainty into useful evidence.

Do not average a bad field and a good field without thinking. If the unreliable result reflects poor testing conditions, repeat under better conditions and document why the repeat is preferred.

Roving Esterman is a specific pathway in Austroads for binocular Esterman visual fields conducted without fixation monitoring. It requires two consecutive tests, limited false positives, and numeric point-by-point output.

That pathway is sometimes misunderstood as permission to ignore fixation. It is not. It is a different evidentiary pathway and should be labelled as such.

If the authority requests roving Esterman, the clinician should provide the requested format and avoid substituting a standard unreliable test.

A useful report states whether fixation monitoring was performed and recorded, lists the false-positive score, and says whether reliability supports interpretation. It should not hide reliability in a screenshot or leave it for the reader to infer.

For example: "Fixation monitoring was recorded and false positives were 6 percent, supporting interpretation of the marked point pattern." Or: "False positives were 28 percent; the result is not reliable enough for a favourable licensing opinion and repeat testing is recommended."

That kind of wording protects the patient, the clinician, and the licensing process because it makes uncertainty explicit.

There are cases where the printed reliability metrics look acceptable but the clinician still doubts the field: inconsistent patient behaviour, obvious artefact, mismatch with disease pattern, or unusual misses. In those cases, the clinician should still slow down.

Austroads gives thresholds, but clinical judgement decides whether the whole result is coherent. DRIVE Fields can highlight formal reliability issues; it cannot replace the person watching the patient and reading the original printout.

The best teaching habit is to ask: would I be comfortable explaining this reliability to the licensing authority if the patient had a crash tomorrow? If not, repeat or review.