How do you test the vision of someone with TBI who cannot communicate — talk or respond otherwise to questions? The patient holds magazines close to his eyes and he squints his left eye at more distant objects, but that’s all I can ascertain.
The eye care clinicians I work with quite often face this dilemma and the key is establishing a form of communication. Usually, we think of communication as verbal; simply carrying on a conversation. But when a TBI makes verbal communication impossible we need to be creative. Can the individual understand what is being said to him? Does he have some motor control that can be used to indicate simple responses such as “yes” or “no”? If the individual can understand, then simple communication can be done using eye blinks; one blink for “yes” or two for “no.” Alternatively, or in addition, if the individual can move his fingers, he can respond to visual acuity tests which use numbers instead of letters. This process can be as simple as the clinician pointing to a number and asking the person to tell them to name the number by raising the appropriate number of fingers. This process is repeated until the size of the number is too small for the person to see.
Quite often visual acuity remains good for people with a TBI. Visual field loss tends to be a more common deficit. One method of getting an approximation of visual field is to use a handheld arc perimeter. The clinician holds the perimeter in front of the patient and asks him to indicate when he can see a target or not see a target. The person can do this by holding up a finger when he sees the target and lowering it when he doesn’t. Another technique is to keep his eyes open when he sees the target and close them for a few seconds when he doesn’t. The clinician can then get an approximation of the person’s visual field although this technique isn’t as accurate as automated perimetry and it may be time consuming. Still, the information is useful.
Of course, the visual consequences of TBI include many things other than, or in addition to, visual acuity and visual field deficits. Binocular vision may be affected (the person may see blurred objects or have double vision), may not be able to track moving targets, or have other problems. Visual perception may also be affected and this may mean the person cannot name objects, recognize faces, or have other consequences.
In summary, it is usually possible to establish some form of communication that allows a better understanding of the person’s visual status. This is easier with somewhat simple tests of visual acuity and visual field and, simple communication may not be sufficient for assessing more complex deficits. Still, it provides a starting point and with persistence and creativity more effective communication may become possible. And hopefully, the individual’s ability to communicate will improve with time and therapy.