Learn from the Masters: Clinical Highlights in Neuro-ophthalmology

Dr. DurgaPriyadarshini S
Published Online: April 1st, 2021 | Read Time: 46 minutes, 36 seconds

Neuro-ophthalmology is a unique subspecialty of ophthalmology and neurology where there is a complex interaction of neurologic and systemic disorders in the visual system. Neuro-ophthalmic conditions are not only about vision-threatening but sometimes life-threatening too! It needs the most comprehensive examination from ophthalmic, neurologic, and medical viewpoint. The trick lies with a systematic approach starting from history taking to specific examination techniques and localization of the condition. We have put together a few fundamental questions on clinical highlights in neuro-ophthalmology, and they were addressed to the experts who have been phenomenal in the field. Let’s learn from their vivid explanation and expand our neuro-ophthalmology skills.

Dr. Ambika Selvakumar is a senior consultant and the head of the Neuro-ophthalmology services, Sankara Nethralaya, Chennai, India. She has done MBBS from prestigious Stanley medical college, Chennai. Postgraduation in ophthalmology and fellowship in Neuro-ophthalmology from Medical research foundation Chennai. She has done observership in Neuro-ophthalmology under legends like Dr. Andrew Lee atthe University of Iowa, Dr. James Goodwin at the University of Illinois, Dr. Averatna Noronha at the University of Chicago and Dr. Joel Glaser at the Bascom palmer eye institution, Miami U.S. and now is into the field of neuro-ophthalmology with a work experience of 20 years. She authored the “Atlas of Neuro-ophthalmology”, which was the first Indian Atlas in this specialty, was published in 2002 and the “Atlas in Neuroimaging” in 2015. She has written many chapters in ophthalmology and neurology textbooks and has many publications in reputed journals in neuro-ophthalmology, ophthalmology, and neurology. She is a recipient of many awards in national ophthalmology and neurology conferences. She has been an invited speaker in many international and national ophthalmology, neurology and neurosurgery conferences. She is an executive board member of the Indian Neuro-ophthalmology society and reviewer on board of Indian journal of ophthalmology.

Dr.Dan Mileais a Neuro-ophthalmologist and a senior consultant who holds an MD and a PhD in Neuroscience from the University of Pierre et Marie Curie, Paris, France. He was a neuro-ophthalmology consultant at the PitieSalpetriere University Hospital in Paris, then a Professor of Neuro-Ophthalmology in Copenhagen, Denmark, before being the Chairman and Professor of Ophthalmology at the Angers University Hospital, France. In Singapore since 2012, he is a Senior Clinician in the Department of Neuro-ophthalmology at SNEC. He has published over 150 articles in peer-reviewed journals and he is a Principal Investigator for several studies in Clinical Neuro-ophthalmology and Visual Neuroscience. Professor Milea is also a member of the faculty staff at Duke-NUS Graduate Medical School. Being passionate about research related to neuro-ophthalmology, he is the leader of a clinical research group in Visual Neuroscience at the Singapore Eye Research Institute. He is involved in the Neuro-ophthalmology teaching programs and mentoring of residents, trainees, and research staff.

Dr.Rohit Saxena is a senior consultant of the Neuro-ophthalmology and Strabismology department at Dr. Rajendra Prasad Centre for Ophthalmic Sciences, All India Institute of Medical Sciences (AIIMS), New Delhi. He is a principal investigator in 8 funded projects and has 260 publications on his list, out of which 160 are indexed. He had been the editor of 2 books and authored 50 chapters in various national and international books on squint and neuro-ophthalmology. He has been the invited speaker at numerous National Conferences and CME meets and regularly conducts the Instruction course at AIOS in Squint and Neuro-ophthalmology. He has been invited as faculty and attended >22 international conferences including conducting Instructional Courses and has been conferred with many awards in national and international conferences. He is the reviewer for 12 International indexed journals and a Member Editorial Advisory Board of 3 International indexed journals.

eOphtha:Why did you choose the field of neuro-ophthalmology? How do you feel the journey is through the years?

Dr. Ambika Selvakumar: Well, it’s an interesting question asked by many of my well-wishers!! Neuro-ophthalmology was surprisingly attractive to me even in those days when it was hardly considered as an ophthalmic specialty in India, 20 years back. Since this specialty deals with ophthalmic diseases that can have their roots in other specialties like neurology / ENT/ rheumatology/oncology..it can be life-threatening at times and not only vision-threatening. Since all cases are unique in their presentation it may not be possible to follow a stipulated algorithm. These varied and atypical presentations are always filled with surprises, which makes it exhilarating to be a neuro-ophthalmologist. I have no regrets in choosing this as my specialty, as the professional satisfaction I got in these two decades was phenomenal. I am happy to see off late this specialty is gaining its perch in ophthalmology and neurology in our country.

Dr. Dan Milea: From my youngest age, I was fascinated, just as many kids of my generation, by the human brain: there was nothing more interesting in the whole world, obviously! Later, as an adolescent, my eclectic readings made me discover Charcot and his world-famous Neurology lessons at the Pitié-Salpêtrière hospital in Paris. My interest in cognition and brain could only grow after I joined this same medical school where some of the biggest masters in Neurology used to teach their art: I could see and touch patients’ notes written by Babinski, Parinaud, Pierre, Castaigne, any many others who have made history. At the same time, the eyes and vision were just as fascinating. A wonderful, dedicated, and accomplished practicing neuro-ophthalmologist at the same hospital, did the rest. I wanted to emulate her wonderful clinical activity, adding also a research dimension into it.

Dr. Rohit Saxena: Neuro-ophthalmology is an academically oriented specialty that offers something new every day with atypical and challenging cases. It stimulates your brain and makes you think. It offers the satisfaction of not only saving vision but also saving lives. This specialty is the connecting link between ophthalmology and various other fields of medicine, especially neurology. The exciting thing about this specialty is that I think “it’s time has come,” especially in India. Sometime back, it was a poorly understood and rarely discussed field but now there is serious interest with significant research and teaching. A lot of patients that were missed earlier are now being diagnosed and managed.

Pearl: Neuro-ophthalmology is a fascinating sub-specialty in ophthalmology and neurology with lots of clinical challenges and evolving research in treatment strategy. So practicing such a scintillating specialty is always intriguing but can give an accomplished feeling by saving not only vision but life!

eOphtha: We know that history taking is very important when it comes to neuro-ophthalmology.Your tips and tricks on history taking to recognize neuro-ophthalmic emergencies.

Dr. Ambika Selvakumar: The key to successful neuro-ophthalmic practice is only a proper history taking. Many think that Neuro-ophthalmologist always needs expensive MRI /CT like investigations but its nothing better than listening to patients. If history taking is adequate, at times even before the fundus evaluation we can guess what we are going to look in the ophthalmoscope. Many complaints like headache, fever, jaw pain, snoring chronic drug intake, trauma, poor sphincter control, paresthesias, previous malignancies, surgeries, etc, patients may not attribute to be associated with their present ocular symptoms. So it becomes mandatory for us to shoot leading questions to get the relevant history before proceeding to investigate any neuro-ophthalmic condition. And the same complaints can have different causes in different age groups - like acute vision loss at young age can be due to demyelination but in the elderly, it could be ischemic.

Details regarding the onset of the disease, painful /painless, progressive nonprogressive, spontaneous recovery all can help us to plan the management. Let me explain with a few instances. If a young lady presents with sudden vision loss -the monocular or binocular first thing to ask for, was it painful, any viral prodrome, physical exhaustion, to rule out any demyelinating etiology. If a patient presents with sudden painful diplopia, headache and ptosis it is important to rule out an infective/ inflammatory etiology particularly involving the orbital apex. If the patient is a diabetic, detailed history of his DM control, any ENT procedures are vital to rule out fungal infections. A chronic progressive painless vision loss could be due to an intracranial space-occupying lesion along the visual pathway. A sudden bilateral profound vision loss in young male always need to be probed for alcohol intoxication. Any patient presenting with transient vision loss episodes has to ask for any cardiac or neurological disease symptoms like associated syncope, palpitations, seizures, etc..So the more we talk to patients we will be able to diagnose the condition earlier.

Dr. Dan Milea: There is something unfair about history taking in clinics in relationship with the person who does it, I am sure you are familiar with this. It’s the typical story of a young resident or fellow who spends unsuccessfully, a lot of time trying to identify, via history taking, the source of a clinical problem (let’s say, an acute Horner’s syndrome). Unsuccessful and frustrated, the young doctor gives up and hands the case to the senior consultant, to whom the patient confesses immediately: “I was on a very fast roller-coaster yesterday, just before I felt sudden neck pain and noticed a droopy eyelid on the same side”. Missing such an obvious carotid dissection may seem unfair and frustrating for a young doctor, but after being in that same position for many years, I am convinced now that he had played a critical role in the whole process, making the patient realize (although possibly not verbalize), a relevant event. Therefore, my tip on history taking: if despite asking, again and again, you fail to find something relevant, ask someone else to ask. The patient, better prepared, might deliver a new perspective on his medical history!

Dr. Rohit Saxena:Any patient visiting an ophthalmologist does not think it is important to inform about systemic symptoms and diseases. For neuro-ophthalmology, this information is essential for workup and diagnosis. This is particularly true for issues that are associated with stigma eg smoking, alcohol, tuberculosis, and Covid-19 at present. You must keep a high index of suspicion and direct questioning must be done if there is any doubt.

All positive symptoms and signs must be probed in detail. When they began, course, severity, associations, relieved by etc. by asking direct questions. Sometimes a shorter duration of a symptom is reported as it may not be incapacitating initially but will affect the approach and the differential diagnosis.

Any sudden onset neuro-ophthalmic feature should raise concern. Acute vision loss (unilateral/bilateral) or diplopia, fever, headache, neurological complaints, anisocoria, acute painful or painless homonymous hemianopia, severe pain in head/neck, and painful ophthalmoplegia is usually an emergency. Transient vision loss can be an indicator of a transient ischemic attack (TIA). A pupil-involving third cranial nerve palsy with pain may be due to aneurysm and warrants urgent neuro-imaging. Horner syndrome may indicate underlying malignancy or carotid artery aneurysm. Severe headache with neck stiffness and sudden diminution of vision may be due to meningitis or pituitary apoplexy. Another important history is the intake of neurotoxic substances like methanol or drugs. Scalp tenderness and persistent jaw pain are indicators of giant cell arteritis.

Therefore spending time on history, in the beginning, will save a lot of time and money by avoiding unnecessary investigations and tests.

Pearl: History taking is the key to a neuro-ophthalmic evaluation. It is mandatory to ask patients the relevant leading questions of present illness, past history, associated medical conditions including social history, and if it fails we may be misleading. So talking and listening to our patients is the crux that can make a difference!

eOphtha: Pupil evaluation is fundamental in the neuro-ophthalmic examination. What do you look for in a pupil examination? How to reduce errors while doing pupil examination?

Dr. Ambika Selvakumar:Pupil can be referred to as a peephole to the brain and our body. A proper pupillary examination is mandatory in Neuro-ophthalmic examination as it is the hallmark of optic nerve dysfunction. But one should remember that pupils can be normal in any retrochiasmal lesion and yet have a visual deficit. Anisocoria -unequal pupils can be noted in 20 % normal population also [physiological anisocoria]

  1. Requirements for a proper pupil examination include a dark room with ambient light to visualize the pupils, a distant target, a bright and narrow beam of light.
  2. It is always important to check each pupil separately with patient fixing at a distant target and without accommodating and ensure the light falls only in that eye which is being checked. So it is tricky to confirm which pupil is affected the bigger or the smaller one. Both direct and consensual reflexes have to be checked.
  3. Before we examine the pupils it is important to elicit a detailed history of any eye drops to use, trauma/surgery, drug intake, any uveitis history, etc.
  4. When we check pupils we assess the size, shape, [brisk or sluggish ]reaction to light and relative afferent pupillary defect. Pupils should be checked in both dark and light conditions. Anisocoria worse in dark can be due to Horner’s syndrome and anisocoria worse in light could be due to structural damage to pupil or Adies pupil
  5. Both light and near reflexes have to be checked to look for any light near dissociation.
  6. RAPD- Relative afferent pupillary defect can be appreciated if there is a monocular optic pathway defect and in case of a bilateral defect then both pupils will be sluggishly reacting to light and however if involvement is asymmetrical then still RAPD can be appreciated. Classical “swinging flashlight” is a very useful clinical test to check for RAPD, if performed properly.
  7. Pupil examination can help us to identify a malingerer and remember RAPD can be noted in severe retinal diseases, dense amblyopia, and not only optic nerve diseases.

Dr.Dan Milea:The classical simple, fundamental clinical rules for examining pupils are most often sufficient in regular clinics. Following them avoids me to be obliged to perform formal pupillometry recordings, which may be, rarely, the only way to investigate subtle pupillary dysfunctions.

Dr. Rohit Saxena:Pupillary evaluation is an important aspect of neuro-ophthalmic examination that helps you to assess the intactness of the visual pathway. It is the best clinical test to check for optic nerve involvement.

Do the examination in a dark room with just enough ambient illumination to see the pupils. The light you put to test the reactions must be bright and focussed and not fall on the other eye. For near reflex, give an accommodative target to see. Several points that one must observe are:

  • Pupil size and shape- should be assessed in both light and dark conditions with the patient fixating at distance. Do check for anisocoria
  • Light reaction- direct and consensual; uniformity, speed, and sustaining of constriction; Do check for the presence of RAPD- points towards asymmetric optic nerve involvement.
  • Near reflex
  • Near lightdissociation is tested in a room with a light that is adequate for the patient to fixate an accommodative target. It can be seen in conditions like dorsal midbrain lesion, Argyll Robertson pupil, Adie’s pupil, Aberrant regeneration of III nerve.

Pearls: Ensure prerequisites of pupil examination (dark room, distant target, and bright narrow beam of light ) are adequate. Follow the fundamental clinical rules of pupil examination which includes size, shape, and reaction to light for all neuro-ophthalmic cases.

eOphtha: Your tips to differentiate true vs. pseudo disc edema.

Dr. Ambika Selvakumar: We have to remember that “Not all disc edema is papilledema.” Optic disc edema can be due to various causes and it is important to differentiate the true edema from pseudoedema to avoid unnecessary investigations. Let me revise the basics of how true or pseudo edema appears.

True disc edema can be either optic neuropathy if it is associated with vision loss or papilledema if the vision is intact [ usually vision is preserved in early stages of papilledema ] True disc edema appears hyperemic with peripapillary elevation, obscuration of vessels, hemorrhages, obliteration of cup disc ratio and engorged vessels. Patients with true disc edema are mostly symptomatic with headache/vision loss / transient vision loss. But a comfortable patient can walk in for routine eye evaluation and still be picked with true disc edema caused by an ICSOL [ intracranial space-occupying lesion].

Pseudo edema appears lumpy bumpy, preserved cup, with or without hyperemia, vessels unscathed. On fluorescein angiography, true edema does leak but pseudo does not leak. B-scan Ultrasound can pick an optic nerve head drusen causing pseudo edema if it is calcified, but noncalcified drusen can be missed. At times it may be difficult to differentiate early true disc edema, from pseudo edema. In these cases, it is better to keep them in close follow up, especially even when there is no vision loss or headache or field loss. It is ideal to document the appearance of the disc by serial photos for future follow up. Optical coherence tomography [OCT] will be able to record the structural changes -RNFL thickness and reproduce on follow up to compare if there is a doubt in the early stages of true edema. But OCT role in later stages of true disc edema is debatable, due to evolving atrophy and ganglion cell loss. Any patient presenting with bilateral true disc edema and headache, blood pressure has to be recorded first before planning any other investigations.

Each case of disc edema has to be analyzed carefully, correlate with history, and then plan the investigations accordingly. So it is mandatory to find out the disc edema is due to optic neuropathy or papilledema apart from differentiating true or pseudo.

Dr.Dan Milea:Distinguishing the two conditions is particularly challenging in young children, who may have buried optic disc drusen, often difficult to discriminate from true papilledema.

Among various, more or less organized clinical strategies, detecting spontaneous vein pulsations at the optic disc level is always reassuring!

Dr. Rohit Saxena: Always examine the disc stereoscopically using a slit lamp and a +90 D or similar lenses. Filling up of the cup is a feature of true edema. Clinically, the presence of peripapillary hemorrhage and watermarks goes in favor of true edema.

- See for associated symptoms. Headache, TIAs, diplopia which may be transient, etc may be seen in papilloedema with raised intracranial pressure. Some form of visual function deficit like visual acuity, color vision, contrast sensitivity, and visual fields is usually present in true edema although there can be exceptions. However it important to remember that they may incidentally be coexisting with pseudo disc edema.

-OCT is a very useful and non-invasive test to differentiate the two. Rarely you may need to do an FFA to check for optic nerve head leak which is confirmatory of true edema.

- Finally, if the doubt remains in very early disc edema, I will follow up in a week to see for change when a repeat optic nerve head examination/fundus photograph and an OCT can be compared with the previous test.

Pearls: Analyse the disc edema carefully, with special attention to the appearance - associated mechanical and vascular changes. Correlate with history and associated clinical findings then plan the relevant investigations. It is mandatory to differentiate optic neuropathy and papilledema, not only true vs pseudo disc edema.

eOphtha: Many feel optic atrophy is the end of the road! Enlighten us about this myth. What are the strategies that you follow to evaluate a case of optic atrophy?

Dr. Ambika Selvakumar:Optic disc pallor is a sign of optic nerve dysfunction. It can be divided based on its etiology/appearance/pathology etc… It can be diffuse /temporal /sectoral pallor . Not all optic atrophy is non-treatable. Patients presenting with optic atrophy can also regain normal vision if they present earlier. Appearance of disc pallor can provide some clue to its etiology

  1. Temporal pallor can be seen in hereditary optic neuropathy, toxic, nutritional neuropathies, post neuritic.
  2. Diffuse pallor -post ischemia , compressive ,post neuritic.
  3. Sectoral pallor - the hallmark of ischemic optic neuropathy.
  4. Bowtie pallor - chiasmal syndrome.
  5. Primary optic atrophy - occurs without disc edema.
  6. Secondary optic atrophy - follows revolving disc edema.
  7. Optic neuritis, toxic, nutritional, compressive optic neuropathies are treatable to a certain extent when we pin the etiology earlier. Most of them do regain normal vision and field defects do resolve .we have seen many patients with ethambutol toxicity who recovered back near-normal vision, provided they present to us early.
  8. But optic atrophy due to papilledema, methanol poisoning, ischemic optic neuropathy do not yield good outcomes post-treatment.
  9. Be it disc edema or pale disc any optic nerve disorder requires a stepwise optic nerve function assessment including -vision, color vision, pupillary examination, contrast sensitivity, and visual fields. There is a vital role for visual field assessment as it helps us to identify the etiology like central defects - post neuritis, hereditary, centrocecal -toxic, nutritional altitudinal- ischemic optic neuropathy or neuritis, temporal hemianopia -chiasmal lesions, homonymous hemianopia -contralateral intracranial visual pathway lesions.
  10. Blood investigations play an important role when we suspect atypical optic neuropathy as the cause for disc pallor, as many times fellow eye of the pale disc may be in the subacute stage when patients present to us. Commonly done blood workup are Hemogram, CRP, lipid profile, RA, ANA, ANCA, VDRL, Sarcoid workup, Mantoux NMO /MOG Ab testing, B12/folate, etc.

Dr.Dan Milea:Unexplained optic atrophy requires very careful evaluation, since it may just signal that someone else has missed its true cause for at least 6 weeks! Thus, if otherwise unexplained, the work-up of optic atrophy prompts appropriate brain/orbit imaging, to rule out compression of the visual pathways. I have been very surprised, over the years, to find that we can identify, by appropriate testing, quite high numbers of patients who are harboring mutations causing genetically determined optic neuropathies (Leber’s hereditary optic neuropathy, Autosomal Dominant Optic atrophy, etc). The clinical manifestations of these optic neuropathies do not always follow the classical presentations that we read in books. I still test these patients, with surprising results, even when I am convinced that they are primarily affected by nutritional, drug-induced or toxic causes.

Dr. Rohit Saxena: The extent of disc pallor may not correlate with the severity of the visual functional deficit. Relatively good vision is possible in marked disc pallor and mild temporal pallor can have a severe visual loss. A disc pallor is a symptom like a fever. It is a manifestation of damage/ loss of ganglion cell axons and needs to be evaluated for the cause which will require treatment. Removing the cause may help to bring about some visual recovery as in cases of toxic/ nutritional neuropathies. Identification and removal of ICSOLs can be life-saving. Therefore optic atrophy may often be the start of a process of identifying etiology which can bring very gratifying results.

In a case of optic atrophy, evaluation should follow a plan or possible differential diagnosis. A detailed history and clinical exam is necessary to try to get possible clues to the cause. Some of the key points can be:

  • History- age of the patient, onset and progression of the disease, laterality, associated neurological features, family history
  • Ophthalmological work-up
    • Visual function parameters- visual acuity, color vision, contrast sensitivity
    • Anterior and posterior segment evaluation- fundus should be evaluated to assess the disc status, vascular architecture, presence of other features like exudates, hemorrhages. Based on this we can identify whether it is optic atrophy associated with disc edema (secondary) or without disc edema (primary). Never miss the peripheral fundus examination.
    • Perimetry is done to evaluate the visual field
    • Neuroimaging is warranted especially in bilateral optic atrophy cases with progressive vision loss. Direct the imaging based on the likely site of the lesion.
    • OCT ONH for assessment of peripapillary RNFL
    • Electrophysiological tests help to evaluate the intactness of the visual pathway in cases with severe vision loss
    • Blood Investigations may be indicated in post-optic neuritis optic atrophy: NMO antibodies, MOG; auto-immune profile; infectious screen
    • CSF analysis in cases of TBM, suspected malignancy, CSF opening pressure in IIH
    • Genetic analysis- LHON

Pearls: Optic atrophy is not a diagnosis but a sign of optic nerve dysfunction. Identify the type of optic atrophy and go back to history taking and clinical correlation to plan further investigations. Hitting the spot can recover and save one's vision and sometimes life. So optic atrophy is not always the end......at times.

eOphtha: Your quick tests in the office to differentiate a supranuclear and infranuclear eye movement disorders

Dr. Ambika Selvakumar: Supranuclear movement disorders are mostly bilateral, unlike infranuclear lesions which are mostly unilateral [exceptions do occur]. A simple Doll’s eye movement differentiates both supra vs infra nuclear disorders. Supranuclear movement disorders are mostly associated with other signs like saccade and pursuit abnormalities, gaze palsies, tonic gaze deviation, and nystagmus. Infranuclear disorders are cranial nerve palsies that occur below the level of cranial nerve nuclei and they manifest as specific cranial nerve palsies affecting extraocular movements.

Dr.Dan Milea:Nothing fancy: just testing vestibulo-ocular reflexes in patients with bilateral conjugate eye movements, as well as convergence.

Dr.Rohit Saxena:Supranuclear disorders result from lesions above the level of the motor nerve nuclei. Eye movement abnormalities of supranuclear origin are characterized by bilateral and symmetrical gaze palsies, tonic gaze deviation, saccadic and smooth pursuit disorders, vergence abnormalities, nystagmus, and ocular oscillations. Infranuclear or nuclear disorders produce ocular motor palsies depending on the site of cranial nerve involvement. The presence of reflex eye movements like the ‘Doll’s eye maneuver’ can help differentiate supranuclear from infranuclear involvement.

Pearl: Performing ‘Dolls eye maneuver’, conjugate and vergence eye movements along with checking for gaze palsies and nystagmus will differentiate supranuclear and infranuclear nerve palsies.

eOphtha: In cranial nerve palsy, when do you decide a patient will not require a neuroimaging or vice versa?

Dr.Ambika Selvakumar: Not all cranial nerve palsies require Neuroimaging Brain. Acute mononeuropathy in an elderly with vascular risk factors may not warrant imaging brain, but if there are associated neurological signs and symptoms, systemic illness better to image. There is no role of CT brain in cranial nerve palsy, MRI Brain, and orbit with contrast is the neuroimaging of choice. Always ask for MRI BRAIN AND ORBIT with contrast and adequate sections. It’s better to guide the radiologist, what to look for, and trace the cranial nerve course -[or else - you are going to end up with a report -normal imaging -correlate clinically!!!!

Do image -

  • Acute painful cranial nerve palsy with or without vision loss with H/O Headache, tinnitus, transient vision loss, ENT procedures, fever
  • History of TB/Sarcoid/malignancies/ ICSOL
  • An elderly patient with jaw and scalp pain, fever
  • Any cranial nerve palsy in younger age group <45 YRS
  • Multiple cranial nerve palsies
  • Recurrent cranial nerve palsies
  • Acquired Nystagmus
  • Partial 3rd nerve palsy with or without pupil involvement
  • pupil involving 3rd N palsy
  • Previous demyelination episodes [optic neuritis ]

Dr.Dan Milea:It’s rarer and rarer that I actively reject neuroimaging in these circumstances. Maybe, except fourth and sixth nerve palsies in patients with known, multiple, vascular risk factors. In fact, very often, many patients have these investigations done before they come to see me!

Dr. Rohit Saxena:In a case of acute cranial nerve palsy, one should ideally image every case. However possible sites of the lesion must always be localized so that appropriate modality of investigation and attention is given by the radiologist. Incorrect investigation or not imaging the potential site of the lesion can lul us in a false sense of security.

In cases of mono-neuropathy which are likely to be due to an ischemic cause ie older patient with associated systemic diseases, one may defer imaging. However, the patient must be kept on close followup so that any increase in symptoms or non-resolution after an adequate period must result in the decision to image.

It is a must in the following scenarios:

  • Acute cranial nerve palsy in young (<40 years)
  • Multiple cranial nerve involvement/polyneuropathy
  • Associated neurological signs
  • Pupillary involving third nerve palsy / Partial third nerve palsy with pupil sparing
  • Previous history of carcinoma
  • Worsening/ Non-resolving palsies

Pearl: Any patient with isolated cranial nerve palsy,if neuroimaging deferred, it is better to keep them in the periodic follow-up. Neuroimaging of choice is ONLY - MRI Brain and orbit with contrast. Prompt guidance to the radiologist regarding the site of interest of imaging will be effective for early diagnosis.

eOphtha: What is your take on electrophysiological tests?

Dr. Ambika Selvakumar: Electrophysiologic tests are always an adjunct to clinical evaluation. VEP and ERG are widely used in Neuro-ophthalmic practice.It makes sense to ask for both tests, particularly in conditions like unexplained vision loss. Visual evoked potential -VEP has a vital role in the evaluation of demyelinating diseases, unexplained vision loss, malingerers, cortical blindness, visual screening in children, h/o trauma, etc. Electroretinogram ERG -Pattern / Full-field - ERG can help us to differentiate associated retinopathy in conditions like drug toxicity, autoimmune /inflammatory/ischemic retinopathies / paraneoplastic syndromes. Pattern ERG has a role in demyelinating diseases along with VEP. Mf ERG has a role in confirming the macular health while screening for causes of central visual field loss. Although these electrophysiological tests help us in our clinical practice they do have their limitations and it's not advisable to treat a patient based on these reports only.

Dr.Dan Milea:Ocular electrophysiology is, unfortunately, becoming a forgotten art, probably because fewer and fewer labs can provide accurate, interpretable results. On the opposite, the structural examination of the eyes has become so preponderant in these days, leaving, paradoxically, their functional evaluation for behind.

Dr. Rohit Saxena: ERG is useful in retinal diseases that simulate neuro-ophthalmic conditions, in cases with vision loss in the absence of evident ophthalmoscopic findings and in toxic or nutritional optic neuropathies. Multifocal ERG highlights localized pathologies and so is helpful in differentiating a maculopathy from neuropathy.

VEP (flash or pattern) is useful in several neuro-ophthalmological conditions especially in children, suspected malingerers, and cortical blindness. P100 wave latency is prolonged in demyelinating disorders like multiple sclerosis.

Electrophysiological tests are very useful in appropriate setting but they must be ordered if a disorder is suspected based on detailed history and examination. Indiscriminate tests only compound confusion and do not provide answers.

Pearl: Electrophysiological tests are only adjunct to clinical evaluation, they can help to a certain extent differentiating optic neuropathy from retinopathy. It's not advisable to treat patients based on electrophysiological reports alone. VEP, ERG, or PERG and MFERG all have their specific roles in the armamentarium of neuro-ophthalmologists but choosing the right one at the right time is mandatory as they can mislead at times.

eOphtha: We know that Neuro-ophthalmology is a field that requires a multidisciplinary approach. When do you decide a neuro-ophthalmic condition can be managed by an ophthalmologist and when a neurologist has to be involved?

Dr. Ambika Selvakumar:Neuro-ophthalmology is a challenging specialty, which always deals with diseases that do not respect only a particular specialty of the medical field. So we have to follow a holistic, multidisciplinary approach in managing these patients. It will be apt to have a reliable network of specialists in radiology, neurology, neurosurgery, physician, ENT, immunology, etc ., in evaluating and managing neuro-ophthalmic diseases. Although these patients present to ophthalmic centers with ocular symptoms they may require neurosurgery for a brain tumor, immune suppression for demyelinating diseases, antiedema measures for raised CSF pressure, etc. As these responses for treatment have to be re-evaluated by a neuro-ophthalmologist eg: we decide when to plan a CSF diversion procedure if papilledema [IIH]does not respond to medical treatment. It is mandatory to review these patients and follow them periodically to monitor their clinical progress. So I feel each case is atypical and unique and requires a customized approach of inter specialty management in neuro-ophthalmology and it cannot be cordoned off to ophthalmology only!!

So let me end with a note that Neuro-ophthalmology is a scintillating adventurous journey that can be quite rewarding in patient management if done properly. No other ophthalmic specialty, you can enjoy watching a patient who came with NO light perception improving to 6/6!!!.. in front of your eyes...

Dr.Dan Milea:Collaborating with other specialties is one of the biggest joys in Neuro-Ophthalmology, it is such a privilege to interact and be educated by other specialists! As an ophthalmologist, I am trying to exchange as much as I can with Neurologists for most of my neuro-ophthalmic patients. This is particularly true in patients with visual pathways involvement, myasthenia, ocular motor palsies, headache, and many many others.

Dr. Rohit Saxena: Management of neuro-ophthalmic disorders very frequently necessitates a multidisciplinary approach and whenever there is a doubt, it always helps to get a different perspective, whether it is of a neurologist, radiologist or a physician.

Diseases that involve the CNS (IIH, intracranial space-occupying lesions, meningitis, encephalitis) or multisystem diseases like multiple sclerosis, sarcoidosis require referral to and management by various disciplines. In patients that need surgical intervention like refractory IIH not responding to medical therapy or intracranial space-occupying lesion, a neurosurgical referral is a must.

Isolated cranial nerve palsies, clinically isolated syndrome (optic neuritis), optic nerve disorders like LHON, NAION, CRAO, toxic neuropathy, etc can usually be managed by an ophthalmologist. However, here too the associated systemic disease management must be done along with the treating physician.

Pearl: Neuro-ophthalmology deals with complex neurological and systemic diseases, yet patients can present with ocular symptoms. So it always requires multidisciplinary interaction and a holistic management approach. It has to be dealt with carefully, as it also awaits many medico-legal pitfalls.

Dr. DurgaPriyadarshini S
Consultant , Department of Neuroophthalmology, Sankara Nethralaya, Chennai.
Dr.DurgaPriyadarshini.S is a young neuro ophthalmologist from Chennai . She had her under graduation degree from KAPV Government medical college at Trichy and pursued post graduation diploma in ophthalmology and completed a neuroophthalmology fellowship from one of the premier eye institution in India - Medical Research Foundation, SankaraNethralaya ,Chennai. She is a recipient of gold medal during post graduation and has cleared the exams conducted by ICO. She is at present a consultant in department of neuro ophthalmology at her alma mater .She had presented many scitentific papers and posters in national conferences and has actively been a part of the organising team of neuro ophthalmology and cataract conferences conducted by the parent institution. She constantly pursues to widen her knowledge in her sub speciality .
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