Can a Concussion Affect your Vision?
Mild, moderate and severe concussions cause closed head injuries (aka traumatic brain injuries) (TBI). A concussion of any severity may cause visual dysfunction. These visual symptoms may be dramatic and obvious –think blindness and double vision or much more subtle like difficulty focusing at near objects-print or computer screens.
I have been caring for patients with visual problems after concussion and head injuries for over 30 years and have also experienced visual problems myself after a head injury. Hence I developed a keen interest in how to carefully examine these patients to ensure that no pathology is overlooked. I subsequently developed a routine for neuro-ophthalmic examination that separates the wheat from the chaff and ensures that no cause of visual dysfunction is overlooked. In the following series of articles I will examine the causes of visual dysfunction after head injury and concussion.
Vision Symptoms from a Concussion
Accommodative-convergence insufficiency is the most common visual squeal of concussion. It is also commonly overlooked or ignored. These patients complain of decreased vision especially at near. This is the same visual loss that occurs in everyone as they age; but is most dramatic in young people with otherwise healthy eyes. As we age we lose our ability to focus at near because of changes in the lenses in our eyes. After a concussion we lose this ability because the portion of the brainstem that controls focusing of the lens is injured by the trauma. These injuries are almost NEVER evident on MRI scans; but are very real and disturbing to the patient.
Personal Concussion story
When I was in my early forties I was skiing with my family in Montana and my 12 -year -old daughter was getting ahead of me. I wasn’t going to let this happen so I pointed my skis down the hill to catch up and pass her. My skis crossed and I went head over heals into a pile of fresh snow and hit my head pretty hard. After I stopped “seeing stars” and could move all my body parts we skied down the hill for lunch. I opened the newspaper and could not read it. Even as a Neuro-ophthalmologist this scared me to death until I remembered my anatomy and physiology and realized that my accommodative convergence center in the mid-brain had been injured causing premature presbyopia. I bought a pair of drug store reading glasses and my symptoms abated. Welcome to premature middle age.
I see 2 or 3 new patients a week who have suffered concussions or whiplash type injuries and complain that they never had to wear glasses prior to their accident and now everything is blurry. A good refraction reveals normal corrected vision but a complicated refractive error that the patients were able to focus thru before their injury (latent refractive error) and can no longer do so after their injury to their accommodative center in their brainstems. These patients are lucky and their symptoms resolve with a pair of glasses for distance and near.
It took my own injury for me to realize this and to understand why the patient’s need for glasses is related to their accident and head injury. I still have to fight with some of the insurance companies over this issue but win most of the battles now.
When you shift your focus from distance to near three things have to happen: your eyes have to cross (converge), your lens has to focus (accommodate) and your pupils need to constrict to increase your depth of focus (miosis) (think f stop of a camera lens). This is known as the near reflex. It’s a reflex, you cannot control it, and it controls you.
After a concussion and head injury one or all of these mechanisms may become dysfunctional. We have discussed accommodation and visual loss. Now lets look at loss of convergence.
This may occur with or without loss of accommodation. These patients complain of difficult reading or working at the computer.
After a short time their vision begins to blur, they get a headache and eventually see double if they continue trying to work at near. They have injured their convergence area of the brain stem. The degree of disability depends on the patient’s occupation. The more your work is a near (reading, writing, computers) the more difficulty you will have with convergence insufficiency. Once the diagnosis is made treatment with near point exercises and/or prisms may be very beneficial. This is becoming more of a problem now that most everyone has some computer work in his or her daily schedule.
Total loss of the near reflex is a rarity but may be seen after severe concussion or brain surgery. These patients cannot converge (cross) their eyes; focus and their pupils are both dilated.
These are straightforward, easy to understand visual problems occurring after concussion and head injury. They are very treatable if they are diagnosed in a timely fashion.
In the next article I will discuss more serious injuries to the visual system after a concussion.
If you have noticed visual changes after a concussion (no matter the cause of the concussion) call 941-921-5335 in Sarasota area or 586-582-7860 to schedule an appointment.