Infectious optic neuropathy (ION), how to recognise it and manage it

Abstract

Optic neuropathy can be of infectious or non-infectious/idiopathic aetiology. Many infectious organisms can cause optic neuropathy that can be of varied presentation including papillitis, retrobulbar optic neuritis, neuroretinitis, and optic perineuritis. Detailed history, ocular, systemic/neurologic examination along with appropriate laboratory evaluation can help clinicians to identify the infectious agent causing optic neuropathy. In spite of recent advanced techniques in serological testing and molecular diagnostics like polymerase chain reaction (PCR), the identification of these pathogens is still a diagnostic challenge. It is ideal to have an infectious disease (ID) consultant in the management team, as most of these infections are multisystem involving diseases. Most infectious agents can be effectively treated with specific antibiotics, with or without corticosteroid therapy, but visual recovery is highly variable and depends entirely on early diagnosis of the causative agent. This review article will provide an overview of common pathogens involved in ION and will describe their management paradigms.

Fig. 1

Classification of ION based on systemic, ocular, and neurological features.

Fig. 2. A case of optic disc granuloma that responded well to anti-tuberculous therapy.

CASE 1: A 58-year old female presented with rapid painless vision drop in left eye of 2 months duration. BCVA was 6/6 in right eye and 6/24 in left eye. Left eye had dyschromatopsia and sluggish reacting pupil. She had a prior exposure to TB 32 years back. Anterior segment was unremarkable. Fundus was normal in right eye, while left eye had vitreous cells, gross disc oedema, and peripapillary/subhyaloid haemorrhage. Visual fields showed peripheral constriction in left eye. MRI brain and orbit showed thickening of left chorioretinal layers and normal optic nerve. HRCT chest was normal, however, Mantoux and Quantiferon TB gold tests were positive. She was treated with intravenous methyl prednisolone 1 gm × 3 days followed by oral steroids 1 mg/kg/day. ID specialist consultation was obtained and in view of latent TB, concurrent ATT use was not advised. She continued oral steroids and by 3 months follow-up, left eye vision improved to 6/7.5, however, disc oedema persisted and there was no improvement in visual fields. Subsequently, she received anti-tuberculous therapy for 1 year with maintenance low dose oral steroid 10 mg, visual acuity improved to 6/6 in left eye. Disc oedema resolved and visual field improved. A Gross disc oedema with haemorrhages on presentation. B Persistent disc oedema on 3 months follow-up while she was on oral steroids only. Resolution of disc oedema after ATT. C On 6 months follow-up. D On 1 year of follow-up.

Fig. 3. Pizza pie fundus in Cytomegalovirus infection.

CASE 2: A 34-year-old male presented with left eye diminution of vision of 1.5 months duration. He was positive for HIV with a CD4 count of 280 cells/mm³ and on anti-retroviral therapy with oral steroids started elsewhere. Visual acuity was 6/6 in right eye and CFCF in left eye. Left eye showed anterior chamber and vitreous cells with extensive active retinitis (pizza pie appearance). AC tap was done and was positive for CMV in PCR assay. Patient was treated with intravitreal ganciclovir and oral valgancyclovir 450 mg BD and by 6 months follow-up, visual acuity was 2/60 in left eye with left eye disc pallor and healed lesions. A Fundus photo of left eye taken elsewhere showed active retinitis inferior to disc and right eye was normal fundus. B Left eye fundus showed extensive retinal necrosis with haemorrhages (pizza pie appearance). C CMV-PCR targeting MTR 2 gene positive. D Fundus photo showing disc pallor with healed retinal lesions post-treatment.

Fig. 4. Toxoplasma neuroretinitis with choroiditis.

CASE 3: A 43-year-old male presented with right eye diminution of vision of 2 months duration. Visual acuity was CFCF in right eye and 6/6 in left eye. Anterior segment was unremarkable. Right eye fundus showed vitreous cells, disc oedema, and hard exudates in the posterior pole. Right eye had an active choroiditis lesion adjacent to an old scar in the inferior peripheral retina. Left eye fundus was normal. IgG anti-toxoplasma antibodies were positive while IgM antibodies were negative. Patient was diagnosed as toxoplasma choroiditis with neuroretinitis and treated with tablet Bactrim DS BD and tablet clindamycin 300 mg QID for 6 weeks along with oral steroids. On 3 months follow-up, right eye vision improved to 6/18 with disc pallor and healed toxoplasma lesions. A Right eye fundus photo showed disc oedema with macular fan. B Active choroiditis lesion adjacent to an old scar. C Fundus photo montage showing both disc and retinal findings. D Fundus photo showing disc pallor and healed lesions in the retinal periphery post-treatment.

Fig. 5. Optic neuropathy associated with mucormycosis.

CASE 4: A 44-year-old male came with complaints of both eyelid swelling, right-sided weakness and diminution of vision in both eyes since 2 months. He had COVID-19 infection few months back and was hospitalised. He also had uncontrolled glycemic levels. MRI brain and orbit showed near complete opacification of right ethmoid, sphenoid, bilateral frontal, and maxillary sinus. The intra-sinus soft tissue displayed isointense signal in T1WI, mixed signal in T2WI and there was extension of soft tissue lesion into the orbital apex. Acute watershed infarct in left MCA–PCA territory was also noted. Endoscopic sinus debridement done elsewhere showed mucormycosis for which he was treated with intravenous amphotericin B followed by oral antifungals. On examination, he had no perception of light in both eyes, the right eye had total ophthalmoplegia with complete ptosis and pale disc, left eye had auto eviscerated globe. He underwent left eye exenteration and right orbital debulking with FESS and was advised to continue oral antifungals under the care of infectious disease specialist. A, B External photo showing fixed globe in right eye and auto eviscerated globe in left eye. C, D MRI brain and orbit – left globe is not visualised, enlarged left extraocular muscles, bilateral perimuscular and retrobulbar fat stranding, necrotic soft tissue in the left superomedial orbit. E Sub-acute left parietal infarct.