In Herpes Zoster Keratitis all occurs except:
Correct Answer: Sclerokeratitis
Description: Ans is 'c' i.e. sclerokeratitisHerpes zoster (HZ) keratitis: Herpes zoster is the clinical manifestation of VZV infection and occurs only in individuals who have had primary VZV infection (varicella) by either wild-type or vaccine-type VZV. DNA studies confirm that HZ is a reappearance of the same specific childhood virus. Varicella-zoster virus, like other herpes viruses, has developed complex control of virus- host interactions to ensure continued survival in the human population. It lies largely dormant in the ganglion but may move down the neurons and satellite cells along sensory axons to the skin. Once there, the virus may spread from cell to cell and form lesions that eventually penetrate the epidermis; a viremia accompanies this reaction. Histopathologic studies of ganglia undergoing this process reveal inflammation, necrosis, and disruption of the morphology of neuronal and non neuronal cells; this process may extend into the anterior horn cells, producing myelitis and deficits of motor function. Periodic episodes of subclinical reactivation of VZV from the ganglia occur throughout an individual's lifetime, serving as immune boosters that increase the cell-mediated immune response to VZV. Herpes zoster presents as an acute, painful, vesicular eruption distributed along a single dermatome and is associated with a prodrome of fever, malaise, headache, and pain in the dermatome. Although the zoster rash is a characteristic feature of HZ, "zoster sine herpestes" is diagnosed in patients who have acute unilateral neuropathic pain or unilateral features of HZ with all attendant complications, including HZ ophthalmicus (HZO), in the absence of a recognizable skin involvement.Herpes zoster ophthalmicus (HZO) is defined as HZ involvement of the ophthalmic division of the fifth cranial nerve. The ophthalmic division further divides into the nasociliary, frontal, and lacrimal branches, of which the frontal nerve is most commonly involved with HZO. The nasociliary nerve innervates the anterior and posterior ethmoidal sinuses, skin of both eyelids and the tip of the nose, conjunctiva, sclera, cornea, iris, and choroid. Hutchinson's sign is defined as skin lesions at the tip, side, or root of the nose and is a strong predictor of ocular inflammation and corneal denervation in HZO, especially if both branches of the nasociliary nerve are involved. Herpes zoster ophthalmicus accounts for approximately 10% to 20% of cases of HZ, and therefore, every individual has about a 1% risk of developing HZO during his or her lifetime. HZ eruptions may include fever, malaise, headache, and pain in the eye. Ocular involvement occurs overall in about 50% of patients with HZO (before the antiviral era), but it is not always correlated with age, sex, or severity of the skin rash. The pathophysiology of the diffuse and severe ocular complications of HZO includes components of virus infection, inflammatory and immune reactions, vascular and neural inflammation, and tissue scarring. As a consequence of these neuro pathogenic and vasculopathy processes, the benefit of antiviral agents is limited in patients with HZO. The disease may manifest with acute, chronic, or relapsing components, depending on the mechanisms involved.There is a long list of potential complications associated with HZO, beginning with the skin and anterior segment of the eye but potentially involving the optic nerve, retina, and CNS. It is not clear why some individuals have no or minimal complications and others develop a range of complications; it may be related to virulence of the infection, the host immune response, or both.Multiple corneal lesions may be found in HZO. Pseudo dendrites are early and transient epithelial lesions which mimic as dendritic lesions of Herpes simplex but are not true dendritic lesions. Kerato uveitis/endotheliitis presents with localized stromal edema, keratic precipitates, and cell and flare, and may represent direct viral infection of the endothelium or an immune reaction. A nummular anterior stromal keratitis can develop, which usually resolves but may become chronic. A disciform stromal keratitis may represent a VZV infection of the endothelium or may be related to a zoster immune reaction.The surface of the globe may demonstrate an episcleritis or deeper involvement with scleritis in the early stages of the disease that may become persistent or appear in a delayed fashion. The scleritis may progress toward the limbus, manifesting as a limbal vasculitis and sclerokeratitis with a later patchy scleral atrophy.In this question answer will be sclerokeratitis, on two accounts: first, sclerokeratitis is seldom a presenting feature or primary lesion in HZO. It usually results, as mentioned above, owing to spread of scleritis toward the limbus or cornea. Second, in all published reports of HZO, sclerokeratitis is the least common type of ocular involvement in HZO.
Category:
Ophthalmology
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