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A Hess chart is a diagnostic test used to map eye muscle movement and coordination. It records how each eye moves in different gaze directions. The test creates a visual chart that shows muscle underaction or overaction. It is commonly used for strabismus and nerve-related eye movement problems. Results help guide diagnosis and treatment planning.
read more about hess chart ...The test separates input from each eye using colored filters or glasses. The patient aligns targets on a screen while one eye is tested at a time. Eye movements are plotted across multiple gaze positions. The final chart reflects how well the eyes move and work together. Differences between eyes highlight muscle or nerve issues.
The chart can show clear patterns when muscle balance is off. Clinicians often review these features together:
Each finding is compared between the two eyes for accuracy.
This test is often ordered when double vision is present. It is also useful after eye muscle surgery to track recovery. Sudden eye movement changes may prompt testing. Some clinics use it during long-term monitoring. The decision depends on symptoms and exam findings.
A Hess chart is a mapping test that records how each eye performs across different directions of gaze. By separating what each eye sees (often using filters), the test plots alignment responses to targets and produces a chart pattern that can point to underaction in a weak muscle and related overaction elsewhere. Clinicians use the map to identify patterns that fit nerve palsies, restrictive conditions, or post-surgical changes. Comparing charts over time can also show whether the problem is improving, stable, or shifting.
No, the test is noninvasive and painless. You only look at targets and respond visually. Mild eye fatigue can happen if testing is prolonged.
Testing usually takes several minutes per eye. Time varies based on cooperation and exam goals. Breaks can be given if needed.
Older children can complete the test if attention allows. Younger children may need alternative methods. The clinician decides what fits best.
No, cover testing checks alignment in a simpler way. A Hess chart provides a detailed map of eye movement. Both tests are often used together.
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Strabismus. NCBI Bookshelf. https://www.ncbi.nlm.nih.gov/books/NBK560782/. Date Accessed March 23, 2026.
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The Lees screen test. PubMed. https://pubmed.ncbi.nlm.nih.gov/21149147/. Date Accessed March 23, 2026.
A scoring method for Hess charts. PubMed. https://pubmed.ncbi.nlm.nih.gov/1289147/. Date Accessed March 23, 2026.