Herpes Zoster Ophthalmicus Medical Terminology

Medical terminology course explain about Herpes zoster ophthalmicus is an acute infection of Gasserian ganglion of the fifth cranial nerve by the varicella-zoster virus (VZV).
It constitutes approximately 10 percent of all cases of herpes zoster.

Etiology

Varicella zoster virus. It is a DNA virus and produces acidophilic intranuclear inclusion bodies. It is neurotropic in nature.

Comprehensive OPHTHALMOLOGY

Mode of infection. The infection is contracted in childhood, which manifests as chickenpox and the child develops immunity. The virus then remains dormant in the sensory ganglion of trigeminal nerve.
It is thought that, usually in elderly people (can occur at any age) with depressed cellular immunity, the virus reactivates, replicates and travels down along one or more of the branches of the ophthalmic division of the fifth nerve.

Clinical features

In herpes zoster ophthalmicus, frontal nerve is more frequently affected than the lacrimal and nasociliary nerves.
About 50 percent cases of herpes zoster ophthalmicus get ocular complications.
The Hutchinson's rule, which implies that ocular involvement is frequent if the side or tip of nose presents vesicles (cutaneous involvement of nasociliary nerve), is useful but not infallible.
Lesions of herpes zoster are strictly limited to one side of the midline of head.
Clinical phases of H. zoster ophthalmicus are :
1. Acute, which may totally resolve.
2. Chronic, which may persist for years.
3. Relapsing, where the acute or chronic lesions reappear sometimes years later.

Inflammations Of The Cornea Medical Terminology

Medical terminology online course explain about Inflammation of the cornea (keratitis) is characterised by corneal oedema, cellular infiltration and ciliary congestion.

Classification

It is difficult to classify and assign a group to each and every case of keratitis; as overlapping or concurrent findings tend to obscure the picture.
However, the following simplified topographical and etiological classifications provide a workable knowledge.

Topographical (morphological) classification:
(A) Ulcerative keratitis (corneal ulcer) Corneal ulcer can be further classified variously.
1. Depending on location:
(a) Central corneal ulcer
(b) Peripheral corneal ulcer
2. Depending on purulence:
(a) Purulent corneal ulcer or suppurative corneal
ulcer (most bacterial and fungal corneal ulcers
are suppurative).
(b) Non-purulent corneal ulcers (most of viral, chlamydial and allergic corneal ulcers are non-suppurative).
3. Depending upon association of hypopyon:
(a) Simple corneal ulcer (without hypopyon).
(b) Hypopyon corneal ulcer.
4. Depending upon depth of ulcer:
(a) Superficial corneal ulcer
(b) Deep corneal ulcer
(c) Corneal ulcer with impending perforation
(d) Perforated corneal ulcer.
5. Depending upon slough formation:
(a) Non-sloughing corneal ulcer
(b) Sloughing corneal ulcer
(B) Non-ulcerative keratitis.

1. Superficial keratitis:
(a) Diffuse superficial keratitis
(b) Superficial punctate keratitis (SPK)
2. Deep keratitis:
(a) Non-suppurative
(i) Interstitial keratitis
(ii) Disciform keratitis
(iii) Keratitis profunda
(iv) Sclerosing keratitis
(b) Suppurative deep keratitis
(i) Central corneal abscess
(ii) Posterior corneal abscess.

Etiological classification:
1. Infective keratitis:
(a) Bacterial
(b) Viral
(c) Fungal
(d) Chlamydial
(e) Protozoal
(f) Spirochaetal
2. Allergic keratitis
(a) Phlyctenular keratitis
(b) Vernal keratitis
(c) Atopic keratitis
3. Trophic keratitis
(a) Exposure keratitis
(b) Neuroparalytic keratitis
(c) Keratomalacia
(d) Atheromatous ulcer
4. Keratitis associated with diseases of skin and mucous membrane.
5. Keratitis associated with systemic collagen vascular disorders.
6. Traumatic keratitis, which may be due to mechanical trauma, chemical trauma, thermal burns, radiations.
7. Idiopathic keratitis e.g:
(a) Mooren's corneal ulcer
(b) Superior limbic keratoconjunctivitis
(c) Superficial punctate keratitis of Thygeson.