a 50-year - old lady was referred for retinal evaluation to rule out aids - related retinal or ocular disorders . optic nerves appeared normal . a visual field examination using 30 - 2 program on oculus center field perimeter was performed to rule out lesions along the visual pathway , as clinical examination could not explain the visual loss or the symptoms . it showed good reliability in both eyes and a left homonymous hemianopia [ figs . 1 and 2 ] . magnetic resonance imaging ( mri ) of brain was done to determine the cause of homonymous hemianopia , such as infarct / bleed or space - occupying lesion . mri scan showed irregular white matter hyperintensity in the right occipital lobe and a hyperintense lesion in the left frontoparietal region in the subcortical and periventricular white matter [ fig . 3 ] . it also showed irregular white matter hyperintensity and a large area of increased t2-weighted and decreased t1-weighted signal in the left frontal lobe posteriorly involving the subcortical white matter and extending into the centrum semiovale and corona radiata , without enhancement or mass effect . mri showing lesions in right parieto - occipital lobe and elsewhere she was referred to a neurologist for evaluation . a cerebrospinal fluid ( csf ) tap was advised for polymerase chain reaction ( pcr ) evaluation for jc virus . pml is a progressive fatal demyelinating disorder associated with oligodendroglial infection by the human papovavirus jc . occasional cases are described in pregnancy , and some cases may have no identifiable evidence of immunosuppression . the causative agent , the jc virus , invades oligodendroglial cells , causing multiple foci of demyelination . after the primary infection , jc virus remains latent in kidneys and lymphoid organs . up to 64% of healthy adults have shedding of jc virus in urine in the absence of any clinical symptoms , suggesting that asymptomatic active jc virus infection is common in immunocompetent persons . the presenting symptoms in a case of pml are focal deficits like mental deterioration , speech disturbance , ataxia , paralysis , hemiparesis , facial weakness , memory failure , and also ophthalmic symptoms like nystagmus , homonymous hemianopia and diplopia with cranial nerve palsy in one eye and cortical blindness in the other eye . previously reported cases are different from the one we are presenting here , as our patient had come with nonspecific visual complaints and no other neurological symptoms . however , pml should also be suspected in the differential diagnosis of apparently healthy patients with focal deficits , like our patient who had no other symptoms except some visual disturbances in both eyes which she could not categorize . the purpose of presenting this case was to highlight the fact that we , as ophthalmologists , may be the first to see patients with pml and we should have a high degree of suspicion in an appropriate clinical setting . this would help us to carry out necessary tests such as visual field examination and , if necessary , an mri scan to arrive at a diagnosis of pml which is a potentially life - threatening disease but may be helped by highly active anti - retroviral therapy ( haart ) . pml should be kept in mind along with other ocular manifestations , such as cmv retinitis , which are commoner . diagnosis of pml may be difficult . because a large percentage of the population is seropositive for jc virus , csf identification of jc virus by pcr is useful and studies suggest a sensitivity of 95% and specificity of 9099% . the mri findings are characteristic in pml , with a high t2 signal and a low t1 signal which does not enhance with gadolinium and has no mass effect . pml is uniformly fatal , and the survival rate is only a few months following the diagnosis . there are recent reports of improved survival following aggressive haart in hiv , and specific jc antiviral treatment with interferon  or cidofovir favor early diagnosis . hence , we should consider pml in all patients who present with progressive neurological deficits ( such as visual field defects ) which are usually , but not always multifocal . if jc virus is absent in the csf , brain biopsy should be considered .