The incidence of microbial keratitis post-DSAEK can vary from 1.3% (3) to 6.6% (4). In the past decade, lamellar keratoplasty has such DALK, DSAEK and DMEK replaced, Penetrating keratoplasty as the preferred procedure for selective replacement of corneal pathology. (5)
The herpes simplex virus inhabits the human neuronal ganglia. The age-group-specific prevalence of HSV neuronal latency increases from 18.2% in 0–20 years to 100% in persons older than 60 years. (6) Therefore, a patient post-keratoplasty can be at risk of ocular HSV even without a prior history.
The incidence of newly acquired herpetic keratitis after penetrating keratoplasty was reported to be 1.2 per 1000 person-years. (7)
Reactivation of the virus can occur due to various stimuli like fever, UV light, stress, menstruation, hormonal changes, and trauma. (9) Any local trauma and surgical interventions cause neuronal disruption and increase the shedding of the virus (8, 10) The routine post-operative course of steroids can also lead to the reactivation of the virus and can worsen the infection in the absence of anti-viral cover. (7)
Corneal inflammation due to HSV can involve the epithelium, stroma, and endothelium.
Epithelial keratitis can present as coarse punctate swollen epithelial cells which coalesce to form dendrites. These ulcers can progressively increase in size to take an ameboid or geographic shape. (11)
Stromal keratitis (SK) presents as stromal oedema with infiltration, the necrotizing form appears similar fashion with accompanying necrosis and ulceration. SK can also present as disciform stromal oedema with underlying keratic precipitates. (11)
The endothelial form presents as stromal oedema, keratic precipitates and anterior chamber inflammation. The virus is also implicated in causing impairment of corneal sensory innervation, leading to neurotrophic ulceration of the cornea. (11) (12)
Our patient presented to us with epithelial dendrites- 15 days post-DSAEK, which later increased in size to form a large geographic ulceration, after a few days he developed anterior stromal infiltration, a diagnosis of HSV necrotizing stromal keratitis was made. Even though the infiltrate reduced in size with antiviral medications, heaped-up margin of epithelial defect was noted, here a diagnosis of neurotrophic ulceration was made.
There are very few case reports of HSV keratitis after endothelial keratoplasty in literature and according to our knowledge, there are no previous case reports of HSV NSK after DSAEK.
Parsher et al reported a case of Herpetic Keratitis After DSAEK for a Failed Graft, one week after DSAEK the patient presented with two dendritic epithelial defects, the patient had resolution of corneal lesions after treatment with oral acyclovir and topical trifluridine. (13)
Zarei‑Ghanavati reported a case of HSV endothelitis after Descemet’s membrane endothelial keratoplasty (DMEK), The patient underwent a combined DMEK triple for corneal endothelial decompensation and dense cataract. Graft detachment was noted on days 3 and 5 post-operatively. After 1 week, Keratic precipitates were noted. Polymerase chain reaction (PCR) analysis for the aqueous sample showed positivity for HSV. The corneal oedema resolved with spontaneous attachment of the recipient corneal graft after initiation of oral antiviral and topical steroids. (14)
Hwang et al reported a case of HSV keratitis after DMEK. The patient underwent DMEK for Pseudophakic bullous keratopathy, two months after DMEK The patient presented with defective vision .On slit-lamp examination, a narrow dendrite was noted. He was started on oral valacyclovir for suspected HSV epithelial keratitis. HSV type 1 was also identified on PCR. After three weeks of antiviral medications, the corneal lesion resolved. (15)
HSV keratitis can develop following keratoplasty even in the absence of a previous history of infection, this could be attributable to the high seropositivity rate within the population despite being asymptomatic. Additionally, local trauma and surgical intervention can cause neuronal disruption and increase viral shedding and topical corticosteroids can cause local immunosuppression. (10) (16) (17)
HSV keratitis should be considered as a differential diagnosis for patients with non-resolving epithelial defects post keratoplasty. In the late postoperative period, it can also be misdiagnosed as endothelial graft rejection, having a high degree of suspicion and early medication management can lead to complete resolution of the infection.
The outcomes can vary from a complete resolution of infection with scarring with medication management, graft failure or the need for therapeutic keratoplasty when medical management fails. (4)
LEARNING POINTS AND TAKE-HOME MESSAGE:
HSV keratitis can develop following keratoplasty even in the absence of a previous history of infection.
HSV keratitis should be considered as a differential diagnosis for patients with non-resolving epithelial defects post keratoplasty.
With early medical management, there can be a complete resolution of infection with scarring.