THE EYE EXAMINATION
OPTIC NERVE FUNCTION
- First, the size and shape of each pupil should be recorded. An irregularly shaped pupil (corectopia), especially a teardrop- shaped pupil, should raise concern about an anterior penetrating injury to the eye. The point of the teardrop may point toward a laceration hidden beneath conjunctival swelling (chemosis), where the iris has become incarcerated and sealed the wound.
- The second part of the pupil examination is an assessment of the reactivity to bright light. Each pupil should be viewed independently. A grading system understood by all non- ophthalmologists is trace, sluggish, and brisk. Then, one should swing the light from one eye to the other and back to determine whether there is a relative afferent pupillary defect. An easy way to test this is to watch just one pupil, for example, the left. One should shine the light in the left eye and watch the degree of constriction. While still watching the left pupil, one should move the light into the right eye. The left pupil should minimally dilate in the time it takes to move the light from the left eye to the right, but should then constrict to the same degree as when the light was shined directly into the left eye. If the left pupil does not constrict as well when the light is shined in the right, then there is a problem somewhere along the right visual pathway (retina, optic nerve, optic chiasm, or optic tract). Very nice explanation of anisocoria and abnormal light reflexes by Dr Jeff Mann here.
- The third part of the pupil examination is assessment of miosis during near synkinesis, often erroneously referred to as pupillary accommodation. This test, in fact, is of little value when evaluating eye trauma, especially if the remainder of the pupil examination is normal, and more properly belongs as part of a complex neurologic evaluation.
VISUAL FIELD DETERMINATION
- The first, central visual field, evaluates overall central retinal (or macular) function. There are several formal testing mechanisms, such as the Amsler grid. A simplified test is to stand roughly 2 feet from the patient, cover one of the patient's eyes, ask the patient to focus on your nose, and while doing so, the patient should be able to see all the features of your face, including your ears, without any dark or blurry spots. Repeat this test for the patient's second eye.
- Secondly, to assess peripheral visual field, position yourself 2 to 3 feet in front of the patient with both of you covering mirror eyes (if the patient covers the left eye, you should cover your right eye). Then, with your contralateral hand equidistant between your two heads, bring a wiggling finger in from the far periphery. Have the patient say when the moving finger is first visible. You and the patient should see the finger at approximately the same time. This assumes that you don't have any peripheral vision problems.
- The third part of visual field analysis, double simultaneous confrontation, more properly belongs as part of a complex neurologic evaluation.
INTEROCULAR PRESSURE MEASUREMENT
MOTILITYThe first part of a motility examination determines whether both eyes work together while the patient is looking straight ahead in primary gaze position.
- If there is sufficient vision to see a finger or pencil held at 3 feet, and the vision is roughly equal in both eyes. It is enough to simply ask a cooperative patient whether or not he or she sees one image. The finger should be held first vertically and then horizontally to check for diplopia in both primary meridians. If diplopia is present, then record the approximate test distance and type of diplopia (e.g., vertical, horizontal, torsional, or a combined).
- Most significant movement disorders are identified by simply testing up, down, left, and right gaze. Clearly record which movement are normal or abnormal in the medical record. For example, if only four positions of movement are tested, a plus sign should be noted, as opposed to an H, if six positions are examined. For the uninitiated, simply writing the left eye has trouble in up-gaze is probably adequate.
- When evaluating orbital trauma, a carefully performed and documented ocular motility assessment is critical. Whereas globally restricted movement may indicate diffuse orbital swelling needing delay before surgery, movement more limited in one meridian (e.g., up-gaze and down-gaze) is worrisome for an inferior rectus entrapment that may require urgent orbital exploration and fracture repair to avoid muscle ischemia and permanent dysfunction.
- Children younger than 12 years, and certainly those younger than 6 years, are at risk for developing amblyopia if they have prolonged dysmotility and do not use their eyes together.
TRUE OPHTHALMIC EMERGENCIES
- copious irrigation with any pH-neutral solution such as water, half-normal saline, or even lactated Ringer's solution. In the presence of severe chemical burns, 10 to 20 liters of irrigant may be appropriate. One way to determine when enough irrigation has been performed is to check for a pH of 7 in the inferior ocular fornix, wait 10 minutes, and check again. In the absence of narrow-range pH paper, a urine dipstick (trimmed if necessary) may offer some indication.
- Placing a topical anesthetic in the eye first will greatly facilitate the process.
- Irrigating contact lenses should be used with caution, as they can trap injurious chemical particles.
- Remember, a bone-white appearance to the conjunctiva may be a bad prognostic sign, indicating severe ocular surface ischemia.
ORBITAL COMPARTMENT SYNDROME
POSTTRAUMATIC OPTIC NEUROPATHY
The Eye Examination in Facial Trauma for the Plastic Surgeon; Plastic & Reconstructive Surgery. Craniofacial Trauma. 120(7) Supplement 2:49S-56S, December 2007; Soparkar, Charles N. S. M.D., Ph.D.; Patrinely, James R. M.D.
Head, Face, and Neck Trauma: Comprehensive Management By Michael G. Stewart; Google Book
Assessment and Management of Ocular Trauma by Sudeep Pramanik, M.B.A., M.D.; University of Iowa Health Care
Ocular Trauma Management for the Primary Care Provider by Joseph M. Rappon, O.D., M.S., F.A.A.O.