Ocular Trauma Score: Components and Prognosis

The ocular trauma score (OTS) is a simple tool that estimates the likely visual outcome of a serious eye injury from findings that are available at the first examination.

It helps clinicians to counsel patients and families, to compare series, and to consider the effort of treatment.

Researchers developed it from a large registry of injuries, and it remains in wide use.

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Why the Ocular Trauma Score Is Useful

After a severe eye injury, patients and relatives ask a question that is hard to answer: how much vision will return?

Experience shapes clinical judgment, but it varies from one clinician to another.

A scoring system that links initial findings to later outcomes gives a consistent starting point.

Also, Kuhn and colleagues proposed the OTS from data of the United States Eye Injury Registry and the Hungarian Eye Injury Registry (see the references).

Ocular Trauma Score: Terminology First

Consistent language is the basis of any trauma score, and the Birmingham Eye Trauma Terminology provides it.

• Closed globe injury: the eye wall is not full thickness open, as in contusion or lamellar laceration
• Open globe injury: a full-thickness wound of the cornea or sclera (see ruptured globe)
• Rupture: a wound caused by blunt force, with the eye bursting at its weakest point
• Laceration: a wound caused by a sharp object, which may also be penetrating, with one entry wound, or perforating, with entry and exit wounds
• Intraocular foreign body: a retained fragment (see intraocular foreign body)

The Components

Clinicians build the score from the following findings.

• Initial visual acuity: the main determinant, due to no light perception to 20/40 or better
• Globe rupture: adds negative points
• Endophthalmitis: adds negative points
• Perforating injury: adds negative points
• Retinal detachment: adds negative points
• Relative afferent pupillary defect: adds negative points

The initial acuity gives a number of raw points, with higher points for better acuity, and then clinicians subtract points for each of the other findings present.

Calculating the Score

• No light perception gives the lowest base value, and light perception or hand movements, counting fingers to a low acuity, and better acuity give successively higher values
• The base value is reduced by a fixed amount for each of the five negative factors
• Clinicians convert the raw sum into one of five categories, due to 1, with the worst prognosis, to 5, with the best

Clinicians then link categories to the probability of reaching each of six acuity levels at six months, from no light perception to 20/40 or better.

In category 1, most eyes end with no light perception, and in category 5, nearly all eyes retain 20/40 or better.

Online calculators and tables make the calculation simple, so also take the exact figures from the original publication.

How to Use It

• Calculate the score at the first examination, when the findings are clear, and before treatment
• Use it to inform counselling, with the understanding that it is a probability and not a certainty
• Compare outcomes within and between centers
• Use it in research to stratify patients

Patients and families appreciate a clear explanation of the factors that affect the outcome.

Limitations of Ocular Trauma Score

• Researchers developed it in a population with different injuries and treatments, and it may not match every setting
• The score does not include the location of the wound, the type of foreign material, or the extent of damage to the retina and optic nerve
• The score is based on findings at presentation, and later events, such as proliferative vitreoretinopathy, are not included
• Do not use it to decide whether to repair an eye, since the first aim is to restore the integrity of the globe
• Some studies suggest that its accuracy varies across populations

Even category 1 eyes may be worth repairing, because anatomic preservation has value, and some eyes do better than predicted.

Practical Pointers

Record the findings that make up the score in the first note, including the acuity and the pupil response.

Revisit the prognosis after surgery and when the results of examination under anesthesia are known.

Offer support, counselling, and rehabilitation services early, and refer to low-vision care when appropriate.

Using the Score in a Real Case

A young man arrives with a rupture after a blunt blow, light perception vision, an afferent pupillary defect, and a retinal detachment seen on ultrasound.

The initial acuity gives a low base value, and the rupture, the pupillary defect, and the retinal detachment each subtract points, so the total falls into a low category.

The surgeon can tell the patient honestly that the chance of recovering good vision is low, that the repair is still worthwhile to preserve the eye, and that further surgery may be needed.

This conversation is more useful than vague reassurance, and it prepares the family for the course.

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References

1. Kuhn F, Maisiak R, Mann L, Mester V, Morris R, Witherspoon CD. The Ocular Trauma Score (OTS). Ophthalmol Clin North Am. 2002;15:163-165.
2. Kuhn F, Morris R, Witherspoon CD, Mester V. The Birmingham Eye Trauma Terminology system (BETT). J Fr Ophtalmol. 2004;27:206-210.
3. Kuhn F, Morris R, Witherspoon CD. Birmingham Eye Trauma Terminology (BETT): terminology and classification of mechanical eye injuries. Ophthalmol Clin North Am. 2002;15:139-143.
4. American Academy of Ophthalmology. Basic and Clinical Science Course, Section 8: External Disease and Cornea. AAO; current edition.