A Checklist for Diagnosing Acute-Onset Diplopia in Adults
Introduction
Acute-onset diplopia, or double vision, can pose a significant challenge in clinical optometry which necessitates accurate investigation and diagnosis. By nature, acute-onset diplopia presenting in adults can be indicative of a range of underlying conditions; a small majority of which will require urgent neuro-radiological intervention (O’Colmain et al. 2014).
This blog aims to share some best practices that optometrists can implement for diagnosing acute-onset diplopia. This non-exhaustive checklist will underline the importance of comprehensive investigation, and appropriate referral to orthoptics and ophthalmology for further evaluation.
Understanding Acute-Onset Diplopia
Diplopia can be categorised into monocular and binocular types. Understanding this distinction is crucial for diagnosing ocular motility and binocular vision disorders.
Acute-onset diplopia can result from various aetiologies, including but not limited to vascular, neurological, and decompensating strabismus. Distinguishing acute-onset diplopia from sinister and benign pathologies is important for protecting our patients from harm (O’Colmain et al. 2014).
Patient Assessment
A thorough case history is foundational to all patients presenting with a disturbance of binocular vision. Questioning should be focused around the nature of diplopia and whether the symptoms are an isolated phenomena, or accompanied with co-existing signs and symptoms. Ocular features might include ptosis, proptosis, pupil involvement, pain, or vision loss. Neurological signs to be wary of include nystagmus, dizziness, headaches, nausea, and gait issues.
A comprehensive visual examination that assesses visual acuity, ocular alignment, and ocular motility. Particular attention should be paid to red flags in the history and clinical findings that necessitate urgent referral (Merrill et al. 2018).
1. Case History
☐ Enquire about the specific onset, duration, direction, distances, time and progression of diplopia. It is important to note associated signs, symptoms or precipitating factors. In practice you might ask the patient, ‘when is the double-vision worse?’.
☐ Enquire about general health, medications, recent head trauma, illness, and concurrent risk-factors. Microvascular risk factors are a common cause of isolated neurogenic palsies in adults over the age of 50 years, but does not preclude sinister pathologies in a proportion of patients (Tamhankar et al. 2013). Microvascular events are significantly associated with increasing age (Choi et al. 2019).
☐ Enquire about family history and previous ocular history. Enquiring whether the diplopia has occurred previously is particularly relevant for decompensating strabismus, amblyopia, and other pre-existing conditions.
2. Visual Acuity
☐ Measure visual acuity to identify any concurrent vision loss that may aid differential diagnosis.
☐ Assessment of colour vision and contrast sensitivity may be considered.
3. Cover Test, Ocular Motility and Convergence
☐ Perform a cover test to evaluate ocular alignment and identify strabismus. This should be performed at near (1/3m) and distance in the primary position as a minimum standard. Testing in other positions of gaze can be advantageous for detecting incomitant strabismus.
☐ Perform ocular motility using a pen-torch at (0.5m) whilst observing corneal reflections. It is helpful to ask the patient to report single or double vision. The full range of eye movements should be examined and the clinician should note limitations and under-actions of eye movement, pain or nystagmus.
☐ Note the quality of smooth pursuits.
☐ Assess convergence.
4. Pupillary Reflexes
☐ Assess pupillary responses to light and near stimuli, noting any anomalies that could suggest optic nerve involvement or an afferent pupillary defect.
☐ Beware of the rule of the pupil. A pupil-sparing third nerve palsy does not rule out sinister pathology, such as intracranial aneurysm (Patel and Burdon, 2022).
5. Coexisting Signs / Symptoms
☐ Check for coexisting signs and symptoms. These might include ptosis, proptosis, palpebral fissure sizes, nystagmus, variability, pain or discomfort, periorbital changes etc.
6. Management
☐ Counsel the patient on the assessment findings and next steps. This is often a worrying time for patients.
☐ Make the patient comfortable with occlusion or Fresnel prism in the first instance. Prismatic correction should only be incorporated after 6 months of ocular stability.
☐ Provide advice on driving standards according to DVLA guidance and maintaining personal safety.
7. Referral
☐ Immediate referral to an orthoptist and ophthalmologist is often warranted to investigate the cause of acute-onset diplopia and initiate treatment. This is especially important when there is new evidence of ocular misalignment or abnormal motility findings.
☐ Red flags might include acute-onset diplopia with headache, other systemic symptoms, or signs indicative of a neurological involvement.
Differential Diagnosis
Key conditions to consider in the differential diagnosis include:
- Cranial nerve palsies: Note particularly the involvement of the third, fourth, or sixth cranial nerves.
- Autoimmune conditions: Such as, myasthenia gravis or thyroid orbitopathy.
- Orbital pathologies: Such as, trauma or tumours.
- Vascular disorders: Including transient ischaemic attacks or stroke.
- Decompensating strabismus: Can often be determined from the case history.
Conclusion
Acute-onset diplopia is a clinical challenge that requires a systematic approach to investigation, diagnosis and management. This is by no means an exhaustive checklist and clinicians should use their judgement when presented with such cases. It is clear that a thorough assessment and appropriate referral contributes to better patient outcomes. Understanding local referral pathways and maintaining open lines of communication with orthoptists and ophthalmologists are key to managing this diverse condition.
References
-Choi KD, Choi SY, Kim JS, Choi JH, Yang TH, Oh SY, Kim SH, Lee HS, Lee SH, Jeong SH, Kim HJ, Choi JY. (2019) ‘Acquired Ocular Motor Nerve Palsy in Neurology Clinics: A Prospective Multicenter Study’, J Clin Neurol, 15(2), pp. 221-227. doi: 10.3988/jcn.2019.15.2.221. PMID: 30938109; PMCID: PMC6444141.
-Merrill, KS., Lee, MS. and McClelland, CM. (2018) ‘Red Flags in the Assessment of Adult Ophthalmoplegia’, Journal of binocular vision and ocular motility, 68(1), pp. 20–23. doi: 10.1080/2576117X.2017.1420134.
-O’Colmain, U., Gilmour, C. and MacEwen, CJ. (2014) ‘Acute–onset diplopia’, Acta ophthalmologica (Oxford, England), 92(4), pp. 382–386. doi: 10.1111/aos.12062.
-Patel, R.D. and Burdon, M.A. (2022) ‘Isolated third cranial nerve palsies—modern management principles’, Eye (London), 36(1), pp. 232–233. doi:10.1038/s41433-020-01349-1.
-Tamhankar, MA. et al. (2013) ‘Isolated third, fourth, and sixth cranial nerve palsies from presumed microvascular versus other causes: A prospective study’, Ophthalmology (Rochester, Minn.), 120(11), pp. 2264–2269. doi: 10.1016/j.ophtha.2013.04.009.
