Shah and Dutta: Approach to a neuro‑ophthalmology case 4. Atypical optic neuritis may present with bilateral involvement. The differential of neuromyelitis optica (NMO) or Devic’s disease should be considered 5. MRI imaging of the brain, spine, and orbit can be a useful adjunct to diagnose demyelinating disorders such as MS and NMO 6. For suspected cases of RBN, pattern VEP can provide supplementary evidence for demyelination. Nonarteritic anterior ischemic optic neuropathy Nonarteritic anterior ischemic optic neuropathy (NAION) is usually seen in the elderly age group. The patient can present with nonspecific complaints or may have a characteristic scotoma in the inferior field, with difficulty in walking and climbing stairs. The history of systemic diseases such as hypertension, obstructive sleep apnea syndrome, dyslipidemia, diabetes mellitus, and nocturnal hypotension should be elicited with particular note of the timing of drugs administered, and control of the disease. Any history of past treatment for visual loss should also be noted. The salient examination features not to be missed in these cases are enlisted below: 1. Visual acuity may be preserved even in advanced cases. Confrontational fields show a constriction of the inferior field 2. Fundus examination may show disc edema, disc hemorrhages, or disc pallor. Focal or diffuse lesions in the superior fundus which may mimic inferior field defects should be ruled out 3. Examination of the fellow eye is essential. The presence of a small disc, with a shallow cup and a cup:disc ratio of 0.1–0.2:1, suggests a disc at a high disc NAION 4. Advanced cases may show disc pallor with attenuation of disc vessels 5. Automated perimetry shows a typical inferior altitudinal defect 6. Intraocular pressure should always be checked to rule out overlying glaucomatous disc damage. Palsy of oculomotor, trochlear, or abducent (III, IV, or VI) nerves The patients of paralytic strabismus classically present with sudden-onset diplopia with a deviation of the involved eye. A meticulous history of any associated focal neurological deficits should be noted, to narrow down upon neurological syndromes associated with cranial nerve palsies. The history of predisposing systemic conditions should also be noted. Afew important examination findings to be specifically looked for are: 1. Visual acuity is often well-preserved. Diminution of visual functions can point toward a concurrent involvement of the optic nerve 2. Pupil examination may show anisocoria in cases of oculomotor nerve or sympathetic plexus lesions. Detailed pupil examination can help distinguish these lesions. A pupil may be spared in microangiopathy-associated oculomotor nerve injuries, characteristically seen in diabetic patients. However, cases of head trauma with extradural hematoma can have oculomotor nerve compression with dilatation of the ipsilateral pupil, called as Hutchinson pupil 3. Ptosis is present in lesions of the superior division of the oculomotor nerve, complete oculomotor nerve, and oculomotor nuclei. Head tilt (trochlear nerve palsy) or face turn (abducent nerve palsy) can be present 4. The globe position on the Hirschberg test gives a fair idea about the lesion. Extraocular movements can be limited. Forced duction tests and force generation tests should be invariably done to rule out paralytic, paretic, and restrictive lesions 5. Diplopia can be crossed or uncrossed, depending on the nerve involvement. The patients of complete oculomotor nerve palsy may not complain of trouble-some diplopia due to associated complete ptosis. Diplopia charting can help monitor the progression of the disease, and the response to treatment 6. Nystagmus can be present in the contralateral eye in early cases 7. Concurrent involvement of oculomotor and trochlear nerves can be ascertained by looking for intorsion of the globe during the attempted depression, using conjunctival vessels or iris patterns as landmarks 8. The involvement of trigeminal, facial, or auditory nerves should be checked. A proper neurological examination can elicit associated deficits, and help narrow down the lesion. Conclusion Neuro-ophthalmology patients can present as an open Pandora’s box. The complaints and clinical signs should be assessed in a systemic manner and relevance of each finding should be established. Clinical diagnosis is possible in most cases, without the need for additional imaging. Neuroimaging may be essential in certain cases for diagnosis, planning of further treatment, and prognostication. A holistic and multidisciplinary approach to the patient aids in the early diagnosis of neuro-ophthalmology patients. Financial support and sponsorship Nil. Conflicts of interest There are no conflicts of interest. 372 Delhi Journal of Ophthalmology ¦ Volume 33 ¦ Issue 4 ¦ October-December 2023
Edited by Dr. Kirti Singh, Printed and published by Wolters Kluwer India Pvt. Ltd. on behalf of Delhi Ophthalmology Society, A-23, First Floor, Green Park Main, New Delhi – 110016, Delhi, India, and published at A-202, 2nd Floor, The Qube, C.T.S. No.1498A/2 Village Marol, Andheri (East), Mumbai - 400 059, India