Approach to acute visual loss

11 : 2 Satish Khadilkar, Pramod Dhonde, Mumbai Introduction Acute visual loss is common in clinical practice. The symptom is very disturbing to patients and requires rapid clinical analysis and therapy, as it can be associated with significant morbidity. Etiologies of acute range from to the occipital cortex, resulting in a plethora of presentations. For example in a case of retinal disease patient may feel as if a curtain is rising or dropping and in cases of occipital lesions, patients may give history of bumping into the objects without realization. Also, patients tend to mistake for visual loss, which needs careful analysis. Acute visual loss could either be monocular or binocular. Monocular loss is often related to local eye pathologies as , , or neurological diseases like (ON) and anterior ischemic (AION). Binocular diseases are usually associated with lesions affecting structures such as optic chiasma, lateral geniculate body, occipital radiations and occipital cortex. Pain is an important association of visual loss. Painful visual impairment is seen in ON, Tolosa Hunt Syndrome, orbital apex syndrome, pituitary apoplexy and glaucoma. On the other hand, diseases of the optic tracts, radiations, occipital cortex and AION tend to be painless. The natural history of the visual impairment is helpful in the differential diagnosis. Transient visual deficit is seen in vascular diseases, demyelinations, raised intracranial tension and hyper coagulable states. Lasting deficits are seen with, strokes, tumors and AION. Following cases will illustrate various clinical situations of acute visual impairment, encountered by clinicians. Case 1 32 yrs old female presented with right sided acute onset painful visual loss which progressed within 2-3 hours. Pain was worse with eye movements. On examination, the visual acuity was 6/60 with cecocentral on field testing, right sided relative afferent papillary defect (RAPD) on swinging flash light test, affected colour vision and normal fundus. Investigations revealed P100 latency of 145 ms on visual evoked potential (VEP), MRI Brain with orbital cuts with fat saturation revealed right enhancement with normal MRI spine. CSF study showed normal glucose with mild raised proteins with pleocytosis. Patient was started on methylprednisolone (MP) for 5 days with mild recovery over 3 weeks. Discussion The diagnosis is of right optic neuritis. Demyelinating optic neuritis is the most common non glaucomatous optic neuropathy in young people. The incidence of ON is around 5.1 per 100,000 and a prevalence of 115 per 100,000.1 Females are more commonly affected than males in approximately 3:1 ratio. Symptoms usually start with acute onset vision loss with progression over hours to days. Pain is often associated with eye movements, but can be continuous. Pain is a consistent feature, seen in almost 92% of cases which usually distinguishes ON from other optic neuropathies. Painful visual loss can also be seen with orbital apex syndrome, but associated extraocular muscle involvement differentiates this from ON. Dyschromatopsia is common, and patients often report that colors,

554 Approach to Acute Visual Loss

Table 1 : Differentiating features between macular and optic Table 2: Differences between papilloedema and papillitis nerve lesions Papilloedema Papillitis Characteristics Macular lesions Optic nerve lesions Visual acuity Preserved Reduced Reduced visual acuity Yes Yes Enlargement of blind spot; Central scotoma Metamorphosis Yes No loss of peripheral vision Photostress test (bright Slow recovery Rapid and significant re- Colour testing Normal Loss of red vision light for 10 seconds) covery Pupillary reflex Not affected RAPD Central scotoma Yes Yes Eye movements No pain on movements Pain on movement Reduced colour vision Moderate Often severe Laterality Bilateral Unilateral Pain No Yes Fundus Absent of venous pulsation Venous pulsations present RAPD No (Yes if severe) Yes normal and may show pallor later in the illness. Papilloedema and papillitis can be differentiated as follows [Table 2] The diagnosis of ON is mainly clinical and some ancillary tests are required for further evaluation and prognostication. VEP, CSF study and MRI brain with fat saturation images with contrast with orbital cuts are the initial investigations required. Sometimes papilloedema is difficult to differentiate from papillitis. In such cases differences as shown in Table 2 helps. Optic neuritis is commonly the first demyelinating event in Multiple sclerosis (MS). MRI of the brain can help confirm the diagnosis of optic neuritis and helps to stratify the risk of progression to MS. Those with a normal MRI finding at the time of optic neuritis diagnosis have a 15% risk of progression to MS at 5 years, 22% at 10 years, and 25% at 15 years; those with an abnormal brain MRI finding have a 42% risk of progression to MS at 5 years, 56% at 10 years, and 72% at 15 years.3-5 Additionally aquaporin 4 antibody testing can be considered for diagnosis of neuromyelitis optica (NMO) as these can present with ON. Also MRI spine in MS reveals usually short segment involvement while in NMO it shows long segment involvement. Treatment options include Fig. 1: Swinging flash light test. In this example, the left optic nerve is not functioning properly, and there is a paradoxic dilation methylprednisolone for the acute event and interferons in case of the left as the light is directed into it (left relative afferent of MS and plasmapheresis in case of NMO. 2 pupillary defect). Case 2 particularly red, appear less intense in the affected eye. Visual A 74 year old male presented with fever, malaise, weight loss, acuity may range from 6/6 to complete blindness. Visual field progressive headache since 8 weeks, diminution of vision testing varies from enlargement of blind spot to cecocentral and inability to open mouth since 5 days. On examination scotoma to complete blindness. RAPD ipsilateral to visual patient had stable vitals with necrotic patches over scalp, lip loss, seen with optic neuropathy or severe retinal disease (in and tongue. Visual acuity revealed only hand movement in which case retina looks abnormal on fundus examination) is both eyes. Fundus showed left eye anterior ischaemic optic the most important clue to differentiate from other diseases. neuropathy. There was bilateral scalp tenderness with non ON closely mimics maculopathy and can be differentiated as pulsatile tender temporal arteries (Fig 1). follows (Table 1). Investigations showed thrombocytosis (8.32 lakhs/cmm), ESR RAPD is tested by the swinging flashlight test. This simple was 108 mm and C-reactive protein was increased. Temporal and useful clinical test depicted in Figure 1. artery biopsy confirmed . Discussion A close clinical differential diagnosis of optic neuritis is Optic nerve ischemia occurs most frequently at the optic nerve papilloedema. When the disc head is inflamed, the changes head, where structural crowding of nerve fibers and reduction can look close to rise of intracranial pressure. On the other of the vascular supply may combine to impair perfusion to hand, in cases of retrobulbar neuritis the optic head is often a critical degree and produce edema. The most

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Fig 2: Showing thickened temporal artery with scalp necrosis and AION.

Table 2: Comparison between arteritic and nonarteritic females 2 to 6 times more commonly than males. Clinical AION.7 criteria most strongly suggestive of giant cell arteritis include Feature Arteritic AION Nonarteritic AION AION, jaw claudication, C-reactive protein above 2.45 mg/ Age (mean yrs) 70 60 dl, neck pain, and an erythrocyte sedimentation rate of 47 Sex ratio F>M M=F mm/hour or more, in that order. C-reactive protein tend to be Associated symptoms Headache, scalp tender- Pain occasionally noted a little more sensitive (100%) than erythrocyte sedimentation ness, jaw claudication rate (92%) for detection of giant cell arteritis; erythrocyte Visual acuity Upto 76% < Upto 61% > 20/200 sedimentation rate combined with C-reactive protein give the 9 20/200(6/60) (6/60) best specificity (97%). American college of rheumatology Disc Pale > hyperemic oede- Hyperemic > pale (1990) suggested three or more of the following five criteria ma oedema to have a specificity of 93.5% and sensitivity of 91.2%. Cup normal Cup small 1. Age of onset greater than 50 years Mean ESR (mm/hr) 70 20-40 Natural history Improvement rare Improvement in upto 2. Onset of new headaches Fellow eye in upto 95% 43% Fellow eye in < 30% 3. Temporal artery abnormalities (tenderness or reduced pulsation) Treatment Corticosteroids None proved 4. Elevated erythrocyte sedimentation rate (>50 mm/h us- common such syndrome is AION.6 ing the Westergren method) AION has been divided into arteritic (associated with Giant 5. Positive temporal artery biopsy. cell arteritis) and nonarteritic. Table 2 points out the differences in the arteritic and non arteritic types. Corticosteroids started at the earliest, form the mainstay of treatment. One may choose not to wait for the biopsy when AION presents with rapid onset of painless, unilateral visual visual compromise is seen, as it can lead to permanent visual loss manifested by decreased visual acuity, visual field, or loss and neurological complications like strokes. Therapy is both. The level of visual acuity impairment varies widely, from to be continued for at least 1-2 years depending on the clinical minimal loss to no light perception, and the visual field loss condition. Scalp necrosis seen in the present case is a rare may conform to any pattern of deficit related to the optic disc. phenomenon in GCA. An altitudinal field defect is most common, but generalized depression, broad arcuate , and cecocentral defects In 90–95% of cases, AION is unrelated to temporal arteritis. are also uncommonly seen. A relative afferent pupillary defect The nonarteritic form (NAION) of the disease occurs in a invariably is present with monocular optic neuropathy. The relatively younger age group (mean age of 60 years) and usually optic disc is edematous at onset, and edema occasionally is associated with less severe visual loss. Frequently, visual precedes visual loss by weeks to months.8 impairment is reported upon awakening, possibly related to nocturnal systemic hypotension.10 NAION is associated with Giant cell arteritis presents in later decades of life, affecting

556 Approach to Acute Visual Loss

Fig 3: Right occipital infarct

Fig 4: Bilateral occipital subcortical white matter changes suggestive of PRES. carotid occlusive disease, CNS small vessel disease, diabetes Case 3 and hypertension. Diabetic papillopathy characterized by 48 yrs old male, working in a color factory, returned home and optic disc edema (unilateral in approximately 60%), only mild rang the doorbell. When his wife opened the door, he did not optic nerve dysfunction and type 1 diabetes is of particular recognize her, apologized and started climbing down. Wife importance in ischaemic optic neuropathies. NAION has called him and he immediately recognized her by voice. On no proven therapy. Leber’s hereditary optic neuropathy examination his visual acuity was normal, but he was not (LHON) can also present acutely with vision loss like AION. able to identify famous personalities. He was not able to mix LHON progress over a period of time and associated cardiac and match colors too, which was his job of many years. Final abnormalities can be seen with this condition. Fundus in acute diagnosis of acute onset prosopagnosia with color agnosia conditions is normal, but presence of telangiectasias favors made. Patient was found to be hypertensive. MRI study LHON. Diagnosis of LHON is achieved by genetic analysis. confirmed a right parieto occipital infarct (Fig. 3).

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Table 3: Cerebral visual loss pressure was 180/110 mm of Hg with normal fundus and Mechanism Etiologies of vision loss papillary examination. On confrontation she was having left Vascular Vertebrobasilar ischemia (PCA territory) homonymous hemianopia and MRI Brain was suggestive Cerebral anoxia of bilateral posterior subcortical white matter changes with Cerebral venous thrombosis (superior sagittal si- normal angio sequences (Fig 4). Final diagnosis of Anton’s nus) syndrome was made as patient was denying blindness as Hypertensive encephalopathy (posterior revers- ible encephalopathy syndrome) well as confabulating things, due to posterior reversible Eclampsia encephalopathy syndrome (PRES). Patient recovered over Head trauma Occipital lobe injury 2-3 weeks with complete resolution of MRI changes. Occipital mass Tumor Discussion Abscess Vascular (aneurysm, arteriovenous malformation) PRES is a clinico radiological entity, more prevalent in Hemorrhage women and presents with headache, visual disturbances Demyelinating disease Multiple sclerosis (eg, blurry vision, , visual neglect, cortical Infection Occipital abscess blindness), seizures, altered mental status and occasionally Meningitis hemiparesis.12 It is usually seen in the setting of moderate Progressive multifocal leucoencephalopathy to severe hypertension. Preeclampsia, immunosuppressants (PML) Creuzfeldt-Jacob disease (Tacrolimus, Cyclosporine A), autoimmune diseases (eg, SSPE lupus), sepsis and shock are some of the precursors of 12-14 Toxic Cyclosporine PRES. Complete recovery of the MRI changes as well as Tacrolimus clinical disability over 2-3 weeks, is common. Compromise Methanol of autoregulatory mechanisms of cerebral blood flow is the Metabolic Hypoglycemia most accepted theory for PRES.14 Porphyria Hepatic encephalopathy Cortical blindness usually occurs with bilateral PCA occlusions. Migraine Migranous visual aura Basilar artery thrombosis and vertebral artery dissection tend Seizure Occipital lobe seizures [and its causes] to result in such visual loss. Table 3 enumerates etiologies for cerebral visual loss with underlying mechanisms. The Discussion management of such cases depends on the underlying etiologies. In this case, patient’s inability for face recognition suggested prosopagnosia. Prosopagnosia is defined as an inability Lastly, non organic visual loss, not too uncommon, to recognize faces in the absence of loss of visual acuity needs a special mention.15 There are various clinical and and general intellectual functions. It usually results from ophthalmological tests to differentiate it from organic causes. bilateral occipitotemporal infarcts and sometimes right sided For example, the patient is instructed to look straight ahead involvement only. Some studies have suggested for object at the mirror and the mirror is rotated from side to side. Eye recognition, left occipitotemporal lobe is activated while for movements indicate that the patient can see his or her own face recognition, right occipitotemporal lobe is activated.11 In image in the mirror. Another test is a person who is truly blind such cases, prognosis is good with significant recovery over can touch the tips of the fingers properly and a person with 3-4 months. Cerebral disturbances of vision can be caused nonorganic visual loss is often unable to touch the fingers by affection of visual association areas or subcortical white properly. Also positive optokinetic indicates matter. Alzheimer’s disease, posterior cortical atrophy and vision of at least 20/400 vision in tested eye.16 Stereopsis, Creuzfeldt-Jacob disease (Heidenhain variant) can cause tangent screen testing and visual evoked potential can aid visual agnosias of insidious evolution. in diagnosing nonorganicity. Vision funnels in organic and tunnels in nonorganic vision loss. Case 4 A 30 years old pregnant female with history of preeclampsia Concluding remarks on day 3 after uneventful delivery, presented with new onset As seen from the above discussion, acute vision loss can headaches and difficulty in vision. She denied blindness be a result of lesions involving anterior or posterior visual and made up visual sequences [confabulations]. She was pathways. History and clinical examination are the most feeling persistence of images after removing her gaze important aspects to help reach the localization. Relevant from objects (palinopsia). She was seeing flashes of lights hematological tests, followed by neuroimaging help further (photopsias) and saw relatives in front of her, in their absence differential diagnosis. As visual loss results in decline of (formed visual hallucinations). On examination her blood quality of life, early recognition and therapy is of paramount

558 Approach to Acute Visual Loss importance in the total outlook of recovery. 4. Optic Neuritis Study Group. High- and low-risk profiles for the development of multiple sclerosis within 10 years after optic neu- Examination should start with pin hole testing; if it improves ritis: experience of the optic neuritis treatment trial. Arch Ophthal- vision then is most likely. Visual acuity mol 2003; 121:944–9. testing, confrontation visual testing, pupillary reactions, 5. Optic Neuritis Study Group. Multiple sclerosis risk after optic ophthalmoscopy, external examination of the eye with a neuritis: final optic neuritis treatment trial follow-up.Arch Neurol torchlight and tonometry to measure the intraocular pressure 2008; 65:727–32. should be performed in all cases. The following flow diagram 6. Arnold A.C.: Ischemic optic neuropathies. Ophthalmol Clin North gives the approach towards the visual loss. Am 2001; 14:83-98.

rd Approach to acute 7. Yanoff and Duker Ophthalmology 3 edition.970. vision loss 8. Hayreh S.S.: Anterior ischemic optic neuropathy. V. Optic disk edema an early sign. Arch Ophthalmol 1981; 99:1030-1040. Anterior (involves Posterior (spares 9. Hayreh SS. Giant cell arteritis: validity and reliability of various in many pupils in most of the diagnostic criteria. Am J Ophthalmol 1997;123:285-96. cases) cases)

9 10. Hayreh SS, Zimmerman BM, Podhajsky PA, Alward WLM. Noc- turnal arterial hypotension and its role in optic nerve head and

Painful Painless Painful Painless ocular ischemic disorders. Am J Ophthalmol 1994;117:603–24.

Hemianopia and 11. Nakamura K, Kawashima R, Sato N et al.Functional delineation Optic Neuritis AION P9it uitary apoplexy cortical blindness due of human occiptotemporal areas related to face and scene proces-

Orbital apex syndrome Toxic to various etiologies sing. A PET study Brain 2000;123:1903-1912. (Rare, If given in Table 3. Pituitary apoplexy LHON postfixed 12. Hinchey J, Chaves C, Appignani B et al.A reversible posterior leu- chiasmal Methanol poisoning coencephalopathy syndrome. N Engl J Med 1996;334:494e500. affection)

13. Aranas RM, Prabhakaran S, Lee VH. Posterior reversible ence-

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