After your child suffers a concussion, don’t be misled by the part of the emergency room examination that includes the eyes. That examination is generally limited to an assessment of extraocular movements and the pupils (equal and reactive to light). A normal eye examination in the emergency room following a head injury cannot rule out a traumatic brain injury.
The eye examination that is performed in the emergency room or at a physician’s office following a head injury is part of a basic neurological exam that includes examination of the cranial nerves. This is an examination that assesses whether there is a neurological lesion in the visual pathways served by the cranial nerves. This examination, however, does not examine the integrity of gray matter and subcortical white matter tracts that can be disrupted as a result of primary or secondary injury following any head injury. Following a traumatic brain injury, a patient experience a number of visual disturbances that are listed below. Hopefully, an adult will perceive visual changes, unless the severity of the injury is too great. However, it is much less likely that a child will recognize a visual disturbance that can interfere with a number of functions previously in tact, including reading and doing school work.
One cannot automatically depend upon the ability of the usual eye care professional to detect the types of visual abnormalities that can follow a traumatic brain injury or a concussion. Anatomically, the second cranial nerve is the optic nerve and testing for the integrity of the second cranial nerve includes:
- Testing visual acuity (near & far);
- Testing gross visual fields (often using the finger confrontation test); and
- Ophthalmoscopic exam.
The testing of vision focuses on central vision and peripheral vision.
The third, fourth and sixth cranial nerves regulate the pupils and lateral and vertical gaze. The acronym PERLA often appears in the record. It represents that “pupils equal and responsive to light and accommodation,” but examiners rarely perform this entire part of the exam, and the results are never particularly meaningful standing alone.
Following a traumatic brain injury or concussion, a patient can have a normal ocular examination while at the same time experiencing several visual disturbances or problems related to visual dysfunction including:
- Diplopia (double vision);
- Vertigo (dizziness);
- Eye fatigue;
- Focusing difficulty;
- Movement of print when reading;
- Tracking difficulty;
- Reduced field of vision;
- Sensitivity to light;
- Reduced color and contrast sensitivity;
- Reduced reading speed;
- Altered depth perception;
- Spatial disorientation;
- Midline shift (inability to track the midline point);
- Impairment of posture and balance;
- Delayed reaction time; and
- Deficits in visual memory.
The primary difference between the basic examination of the function of the eyes in the emergency department and the examination by a neuro-optometrist or neuro-ophthalmologist or other similar professional is that the examination by specialists involves a sensory motor evaluation combined with a refractive examination (the type of examination that determines if a person requires corrective lenses). Then the examiner integrates the findings from the two assessments to determine if the brain is properly communicating with the eyes. The sensory motor portion of the evaluation looks to see how the patient organizes visual skills for actions such as tracking, quick eye movements (saccadic fixations), convergence and how patients focus their eyes. It’s a more dynamic and functional assessment of the functioning of the visual process through the eyes.
Many of these problems can be caused by head trauma that results in disruption of the visual pathways in the brain. This is known as disruption of the ambient visual process or spatial visual process.
Among the deficits and diagnoses that are common following traumatic brain injury are:
- Convergence disorder – the ability of the patient to maintain eye alignment as a target is brought closer to the eyes.
- Visual mid-line shift syndrome – resulting in shift of body mass in relation to the plain of a surface causing alteration in posture and balance.
- Aniseikonia – Condition where the eyes perceive the size of something to be different.
- Deficit in saccadic eye movements.
- Accommodative insufficiency – an imbalance in the refractive state causing myopia (nearsightedness), far-sightedness, astigmatism (unequal nature of far-sightedness or near-sightedness) in the eye as well as an inability to sustain focus or a tendency to over focus one or both eyes. Improvement can be created with the use of appropriate lenses and prism.
- Deficiencies of smooth pursuit movements. This is an ocular motor dysfunction causing an inability to track a moving object that may be due to an ocular motor paresis and/or visual processing dysfunction. This causes a spatial imbalance in visual process and lack of ability to coordinate position sense of the eyes with fixation.
In the context of traumatic brain injury, the resulting collective visual disturbance is sometimes referred to as “Post-Trauma Vision Syndrome.”
It is extremely unlikely that any person who has sustained a traumatic brain injury or even a sports concussion will be properly assessed for any signs or symptoms of Post-Trauma Vision Syndrome without an appropriate evaluation by a vision specialist with experience in neuro-ophthalmology, neuro-optometry, rehabilitative optometry, or a behavioral developmental optometrist. A lawyer experienced with traumatic brain injuries and specifically trying brain injury cases should be able to make a proper referral.
By Stewart Casper. Posted March 22, 2016