a young man was referred with a chief complaint of blurred vision and pain of the left eye 1 month after herpetic encephalitis in the left frontotemporal lobe . the patient had multiple foci of retinitis in the retinal periphery associated with vitritis , blot retinal hemorrhage and retinal arteriolitis . the impression of acute retinal necrosis was confirmed by polymerase chain reaction of aqueous humor by detecting herpes simplex virus type 2 ; therefore , the patient received intravenous acyclovir . herpetic encephalitis may be a risk factor for acute retinal necrosis . the virus may reach the eye by the trans - axonal route . acute retinal necrosis ( arn ) is one of the clinical presentations of herpes simplex virus ( hsv ) . this disease may present several years after a primary infection , or it may occur following systemic herpetic infection such as herpetic dermatitis . the prevalence of the disease is equal in both sexes and it occurs in the 5th-7th decade of life . american uveitis society criteria for the diagnosis of arn syndrome are : one or more foci of retinal necrosis with discrete borders located in the peripheral retina , rapid progression in the absence of antiviral therapy , circumferential spread , occlusive vasculopathy with arteriolar involvement , prominent vitritis , and anterior chamber inflammation . optic neuropathy , scleritis , and pain are supportive but not required . in most patients , the diagnosis is made clinically . polymerase chain reaction ( pcr ) analysis of the aqueous humor can detect the cause of arn specifically . pcr is very helpful in the detection of the varicella zoster , hsv type 1 and 2 . patients with arn due to hsv-1 and varicella zoster virus tend to be older , whereas those with arn due to hsv-2 tend to be younger [ 3 , 4 ] . in this article , we report one case of unilateral arn 1 month after the herpetic encephalitis . the patient is a 25-year - old man who was admitted with a chief complaint of decreased vision and pain in left eye for the previous 4 days . the patient also complained of perception of floating objects in the visual field of the left eye . the patient had no past medical history indicating an immunocompromised state ; he had been admitted to the neurology ward due to herpetic encephalitis 1 month previous to the occurrence of visual symptoms . herpetic encephalitis diagnosis was made by brain mri ( fig . 1 ) and pcr analysis of the cerebrospinal fluid . he did not report any underlying disease or drug consumption except oral acyclovir 800 mg every 8 h. at physical examination , the right eye was normal . in the left eye , visual acuity was 0.1 , papillary reflex was normal and marcus gunn sign was negative . slit lamp examination of the left eye revealed conjunctival hyperemia and ciliary injection , diffuse fine keratic precipitates in the corneal endothelium , 3 + cellular reaction in the anterior chamber , 3 + cellular reaction in the vitreous without snowball or snowbank opacities , or vitreous hemorrhage . in fundoscopic examination , multiple foci of retinitis and retinal necrosis 2 ) associated with arteriolar involvement ( arteriolitis ) , blot retinal hemorrhage and optic disc hyperemia . pcr analysis of aqueous humor revealed hsv-2 , so the patient was admitted with the diagnosis of arn and received intravenous acyclovir for 10 days ( 10 mg / kg / day ) . after 48 h of antiviral therapy , a systemic corticosteroid ( prednisolone 1 mg / kg / day ) was introduced and subsequently tapered over several weeks to treat active inflammation . the patient also received aspirin to treat an associated hypercoagulable state . with this treatment , no new lesion developed and opacity of the media decreased ; so prophylactic barrier laser photocoagulation in the areas of healthy retina at the posterior borders of the necrotic lesion prevented retinal detachment . intravitreal antiviral agents such as ganciclovir and foscarnet were not used in this patient because the disease was controlled by intravenous acyclovir . after discharge from hospital , oral acyclovir 400 mg every 5 h was started . during follow - up , the inflammation decreased and the patient had no vitreous traction or retinal detachment or other eye involvement . the brain and retinal involvement were on one side ; after 1 month of left frontotemporal lobe involvement of the brain , the retina was involved on the left side . some of the studies report arn several years after neonatal and infantile herpetic encephalitis [ 5 , 6 ] ; therefore , herpetic encephalitis may be a risk factor for arn development . other articles report that the virus accesses the retina from the brain by the trans - axonal route ; consequently , this virus can cause recurrent episodes of arn [ 8 , 9 ] . these reports may necessitate a prophylaxis with antiviral agents after herpetic encephalitis to prevent arn . in a study by pavsio et al . , the role of long - term prophylaxis with acyclovir in children who had herpetic encephalitis is an important issue . prophylaxis could be considered after hsv encephalitis to prevent arn or after arn to prevent second eye involvement . acyclovir used as prophylaxis for recurrent genital hsv infection in adults for 5 or more years has been associated with minimal toxicity and the selection of resistant strains has not been demonstrated , but there is little experience with the duration of prophylaxis that would have been necessary to prevent arn in our patient . with this report we reemphasize the correlation between these two diseases . on the other hand , arn may be an indication of possible central nervous system involvement and neuroimaging may be necessary in all cases of arn to rule out herpetic encephalitis .
purposeto report a case of unilateral acute retinal necrosis after herpetic encephalitiscase reporta young man was referred with a chief complaint of blurred vision and pain of the left eye 1 month after herpetic encephalitis in the left frontotemporal lobe . 
 the patient had multiple foci of retinitis in the retinal periphery associated with vitritis , blot retinal hemorrhage and retinal arteriolitis . 
 the impression of acute retinal necrosis was confirmed by polymerase chain reaction of aqueous humor by detecting herpes simplex virus type 2 ; therefore , the patient received intravenous acyclovir.conclusionherpetic encephalitis may be a risk factor for acute retinal necrosis . 
 the virus may reach the eye by the trans - axonal route . 
 prophylaxis with acyclovir may be necessary after herpetic encephalitis to prevent acute retinal necrosis .