Diplopia and headaches after a cycling concussion

The findings fit symptomatic convergence insufficiency with accommodative insufficiency after mild traumatic brain injury. The near exophoria is large, the near point of convergence is remote at 18 cm, and near base-out ranges are reduced. Symptoms are worse at near and later in the day, which is typical. The accommodative amplitude of 6.5 D is low for a 34-year-old and may explain the fatigue and blurred near vision.

Alternatives and contributors:

• Decompensating exophoria: possible, but the post-traumatic onset and reduced convergence make a new post-trauma vergence disorder more likely.
• Accommodative insufficiency alone: does not fully explain the diplopia and remote NPC.
• Vestibular or ocular motor dysfunction after concussion: common and may coexist; ask about dizziness, motion sensitivity and headache with head movement.
• Refractive error: his refraction is negligible, but a small hyperopic correction or near add can relieve accommodative demand and should be considered.
• Neurological cause: pupils, motility and fundoscopy are normal and there are no acute red flags, but a new or worsening neurological picture would need referral. The key is that this is not simply 'eye strain' and it is not answered by reassurance alone.

Management should combine active rehabilitation with symptom control so he can keep working.

• Explain the diagnosis: the eyes are not teaming efficiently at near and the focusing system tires quickly after his injury. This is common and treatable, but it may take weeks to months.
• Vision therapy: office-based vergence and accommodative therapy with home exercises is first-line. It should be goal-directed, with measurable outcomes such as NPC, near phoria, base-out ranges and symptom scores.
• Temporary optical support: if he needs immediate relief for teaching and screens, consider a small temporary base-in prism for near or a low near addition after checking that it improves symptoms and does not worsen vergence. Explain that this is a bridge, not a cure. His concern about appearance is valid; temporary stick-on prisms or a separate pair of work glasses may be acceptable.
• Workplace advice: shorter screen blocks, frequent breaks, larger font and avoiding prolonged near work at the end of the day.
• Review: reassess in 4-6 weeks. If there is no meaningful improvement, refer for neuro-optometric or ophthalmological assessment.
• ACC and rehabilitation: in New Zealand, his concussion is an ACC-sensitive injury. With his consent, write to his GP and ACC concussion service about the visual findings and functional impact. Coordinate with physiotherapy or occupational therapy if vestibular symptoms are present. Do not promise that ACC will fund a particular treatment; document the clinical rationale and let ACC determine cover.

I would refer urgently if there were any new neurological signs or progression:

• papilloedema, unexplained visual field loss or a new afferent pupillary defect;
• acquired anisocoria, ptosis or limited eye movement;
• diplopia at distance or in primary gaze that is new and constant;
• worsening headache, vomiting, drowsiness, confusion or focal weakness;
• ataxia, new imbalance or other brainstem signs;
• sudden visual loss or a history of significant head injury with ongoing symptoms.

In this case, normal pupils, full motility and normal fundoscopy are reassuring, but they do not exclude a post-traumatic process. I would document the baseline and give clear safety-net advice: if any of these occur, he should seek urgent medical care rather than wait for optical review. The presence of a normal examination also helps me explain why vision therapy is appropriate rather than investigations.