A 45-year-old patient with a recent history of a concussion from a motor vehicle collision presents to your office with complaints of dizziness and visual discomfort when reading. The patient has been using their progressive lenses, which you prescribed a year ago for their presbyopia, but the patient reports that they get blurry vision after 10 to 15 minutes of reading, and then they have to stop before nausea and headaches set in. They come to you asking for help. The glasses worked just fine the day before their concussion, and now they don’t work at all. Their distance visual acuity is 20/20 in each eye at distance and 20/40 in the right eye and 20/30 in the left eye at near. What do you do?
Most clinicians’ first step will be to refract them. It has been a year since their last exam, and it is possible that their prescription has changed due to age, but don’t be surprised if their distance refraction is stable. After all, think about their complaint — their progressives worked just fine a few weeks ago, and then they just stopped working, all of a sudden, after a mild traumatic brain injury (mTBI).
Will brain injury alter refractive error? While there is some research showing increased rates of myopia after blast-related mTBI,1 there have been no studies of true refractive shifts after non-blast-related mTBI. More commonly, patients with posttraumatic blurry vision suffer from posttraumatic pseudomyopia or accommodative spasm, accommodative insufficiency, and/or dry eye. Sometimes, but rarely, in mTBI, there is indirect traumatic optic neuropathy — the latter of which will not present with intermittent, but rather constant, blurry vision. Accommodative dysfunction is actually the most common oculomotor dysfunction postconcussion, even more common than convergence insufficiency.2 When a patient older than 40 presents with near blur complaints, the majority of clinicians’ first reaction is to increase the near add, assuming their complaint is from their presbyopia. However, prescriber beware: increasing the near add and keeping a patient with posttraumatic oculomotor dysfunction in a progressive can make their complaints of headaches, dizziness, nausea, and blur worse.
Accommodative Dysfunction in Presbyopia vs mTBI
When normally aging adults reach presbyopia, they lose the ability to accommodate due to the ever-increasing hardening of the crystalline lens. While some theorize that the ciliary muscle also loses strength with age, ciliary muscle function is overall preserved in older humans.3 Because both lenses age for the same amount of time, patients with presbyopia require symmetric near add changes every 1 to 2 years.
When a patient acquires accommodative dysfunction after TBI, it is due to damage to the extensive neural network behind the accommodative pathway, which includes the cortical and subcortical regions in the occipital, parietal, and cerebellar regions, as well as the superior colliculus, Edinger-Westphal nucleus, and cranial nerve III.4 This relationship means that the accommodative dysfunction in patients post-TBI is due to abnormal innervation of the ciliary muscle, which can lead to accommodative insufficiency beyond the patient’s presbyopic norms and/or accommodative spasm, regardless of the patient’s age. Because pathophysiologic damage can alter one side of the brain more than the other, it is also not uncommon for a patient to have asymmetric accommodative function post-TBI, and patients may even present with an accommodative spasm in one eye and accommodative insufficiency in the other eye.5
To diagnose posttraumatic accommodative insufficiency in presbyopes, measure the patient’s monocular near point of accommodation through their distance refraction. I recommend using the pushup technique in free space (because the near rod is centered and not centered over each eye) and repeating it 3 to 5 times. Patients with presbyopia will have an age-related, consistent, asymptomatic blur break at their age-related minimum near point of accommodation, based on Hofstetter’s formula. Patients with posttraumatic accommodative insufficiency will be symptomatic with testing — experiencing dizziness, nausea, headaches, etc. — and they will have variable measurements with repetition that are either far stronger or far weaker than expected for their age norm.
Treating Posttraumatic Accommodative Dysfunction: Why Progressives Are Likely Contraindicated, Multifocal Contacts, and Monovision Too
The best way to treat post-TBI accommodative dysfunction is with vision therapy, even in adults. This process can be undertaken at home with simple monocular pushups and near/far training, or in the office. Glasses will be helpful in the interim, but I recommend prescribing single-vision modalities for a number of reasons. First and foremost, the majority of patients with visual dysfunction post-TBI often also have posttraumatic vestibular, cervical, and cognitive dysfunction, making them hypersensitive to visual motion and visual distortion. The inherent peripheral distortion in the progressive lenses can exacerbate dizziness with eye and head movements in postconcussion patients, causing them to experience imbalance and nausea. Furthermore, with the graduated lens change as the patient looks up and down, the progressive lens causes the brain and eyes to continuously change focal points and coordinate accommodative and vergence movements, which may be altered postconcussion, making it difficult to stabilize the patient’s vision and find the “sweet spot.” Additionally, the cognitive effort required to adapt to progressive lenses can be particularly taxing for individuals with brain injuries, and the increased cognitive load can exacerbate their symptoms of fatigue, headaches, and difficulty concentrating, ultimately hindering the patient’s recovery and overall quality of life.
Finally, the most problematic part of progressives and lined bifocals is that they require that the patient look in down gaze to read. Due to the cervical-oculomotor reflex, when patients look >30° to 45° off of primary gaze, their cervical muscles start to engage to turn the head. In patients with whiplash, this chronic engagement of cervical muscles can exacerbate headaches with reading, and the constant adaptation of the patient tilting their head up and down to find the constantly elusive sweet spot can also exacerbate cervicogenic headaches in whiplash patients.
What about multifocal or monovision contact lenses? While less distorted and symptom provoking than progressives, these modalities can still cause increased dizziness, nausea, and headaches in patients recovering from concussion/TBI. Especially if a patient has lost their oculomotor (accommodative/vergence) coordination, monovision can be a huge barrier to recovery, as the brain cannot relearn how to coordinate the eyes if they are not focused on the same plane.
A final consideration to think about is that many patients post-TBI have dry eye — for a number of reasons, including lack of sleep, stress, neuroinflammation, or damage to the lacrimal glands. Contact lenses may just be uncomfortable due to posttraumatic dry eye, and a contact lens vacation may be the best thing for your patients.
Prognosis and Future Return to Progressives, Multifocals, and Monovision
The good news I always tell my patients is that this switch to single-vision distance, intermediate, and near is not forever. It’s just for now. Once the patient is in single-vision modalities, it is easier to rehabilitate their oculomotor system, and patients recover faster in their physical, occupational, and cognitive therapies. When their vestibular-oculomotor dysfunction has resolved and if their whiplash/cervicogenic headaches are well managed, patients can go back to the progressives/multifocal/monovision contacts that they love.
References
1. Fortenbaugh FC, Gustafson JA, Fonda JR, Fortier CB, Milberg WP, McGlinchey RE. Blast mild traumatic brain injury is associated with increased myopia and chronic convergence insufficiency. Vision Res. 2021;186:1-12.
2. Merezhinskaya N, Mallia RK, Park D, Bryden DW, Mathur K, Barker FM 2nd. Visual deficits and dysfunctions associated with traumatic brain injury: a systematic review and meta-analysis. Optom Vis Sci. 2019;96(8):542-555.
3. Tabernero J, Chirre E, Hervella L, Prieto P, Artal P. The accommodative ciliary muscle function is preserved in older humans. Sci Rep. 2016;6:25551.
4. Green W, Ciuffreda KJ, Thiagarajan P, Szymanowicz D, Ludlam DP, Kapoor N. Accommodation in mild traumatic brain injury. J Rehabil Res Dev. 2010;47(3):183-199.
5. Theis J, Starzynski S, Mohan S, Yaramothu C. Presence of accommodative dysfunction postconcussion in an adult population [abstract]. J Head Trauma Rehabil. 2022;37(6):e535.
Disclosures: Dr. Theis has no relevant disclosures for this article.
