Fungal Keratitis Dr Soujanya K MBBS MS Ophthal

Fungal Keratitis Dr. Soujanya K MBBS, MS (Ophthal), DNB, FPRS Assistant Professor YMCH

Etiology • i. Filamentous fungi : – Aspergillus (most common), Fusarium, Alternaria, Cephalosporium, Curvularia and Penicillium. • ii. Yeasts: Candida and Cryptococcus.

Modes of infection

Modes of infection • i. Injury by vegetative material • ii. Injury by animal • iii. Patients who are immunosuppressed systemically or locally

Clinical features • Symptoms : – are similar to the central bacterial corneal ulcer – less marked than the equal-sized bacterial ulcer – overall course is slow and torpid.

Symptoms Fungal Bacterial

Signs • Dry in appearance. • Feathery borders • An immune ring (Wesseley) : deposition of immune complexes and inflammatory cells around the ulcer. • Satellite lesions. • Hypopyon : thick and immobile, and is due to direct invasion into the anterior chamber of fungal hyphae enmeshed in thick exudates. • There is marked ciliary and conjunctival congestion,

Bacteral Keratitis • Symptoms are more ( Pain, lid edema) • Round or oval ulcer in central part of cornea • Satelite lesions : Absent • Immune ring: Absent • Hypopyon : Sterile, mobile Fungal Keratitis • Symptoms are less • Dry appearing, feathery margin • May be present • Contains fungal hyphae, thick

Laboratory investigations • Wet KOH, • Calcofluor white, • Gram's and Giemsa- stained films for fungal hyphae and • Culture on Sabouraud's agar medium.

Treatment • 1. Topical antifungal eye drops should be used for a long period (6 to 8 weeks): – Natamycin (5%) eye drops – Fluconazole (0. 2%) eye drops – Nystatin (3. 5%) eye ointment.

• 2. Systemic antifungal drugs may be required for severe cases of fungal keratitis. • Tablet fluconazole or ketoconazole may be given for 2 -3 weeks.

Viral keratitis

• Herpes simplex • Herpes zoster

Herpes simplex

HSV 1 HSV 2

Clinical reactivation • A variety of stressors such as – fever, – hormonal change, – ultraviolet radiation, – trauma

Herpes simplex – ocular manifestations • Blepharitis, • Conjunctivitis, • Keratitis • Iridocyclitis

Primary infection • No previous viral exposure, • Childhood • Subclinical or mild prodromal symptoms. • Blepharitis and follicular conjunctivitis : mild and selflimited. • Treatment: topical aciclovir ointment for the eye and/or cream for skin lesions.

• Superficial Punctate keratitis— – numerous minute whitish plaques , arranged in rows or groups. – Desquamate erosions heal rapidly leaving no opacity – Cornea: relatively insensitive.

• The corneal involvement can be – Epithelial (dendritic or geographic keratitis), – Stromal (necrotizing and non-necrotizing stromal keratitis) and – Endothelial

Dendritic ulcers

Swollen opaque epithelial cells arranged in Coarse Stellate punctate pattern Central desquamation a linear-branching (dendritic) ulcer with terminal buds

Swollen opaque epithelial cells arranged in Coarse Stellate punctate pattern Central desquamation A linear-branching (dendritic) ulcer with terminal buds

• Floor of the ulcer stains with fluorescein and the virus-laden cells at the margin take up rose bengal.

fluorescein rose bengal

Corneal sensations – markedly reduced

Geographical ulcer

Branches of dendritic ulcer enlarge Steroid use Coalesce to form a large epithelial ulcer ( 'geographical' or 'amoeboid' configuration. )

Geographical ulcer

Specific treatment • 1. Antiviral drugs are the first choice presently. – Aciclovir – Ganciclovir – Triflurothymidine – Vidarabine

• 2. Mechanical debridement : helps by removing the virus-laden cells.

Disciform keratitis

Pathogenesis HSV

Hypersensitivity reaction

Low grade stromal inflammation and damage to the underlying endothelium Corneal oedema Disciform keratitis

Signs

• Ring of stromal infilterate (Wessley immune ring): junction between viral Ag and host Ab. • Corneal sensations are diminished. • Intraocular pressure (IOP) may be raised despite only mild anterior uveitis. • In severe cases, anterior uveitis may be marked

> Focal disc-shaped patch of stromal oedema without necrosis, > Folds in Descemet's membrane,

Central epithelial and stromal oedema keratic precipitates Disciform Keratitis Wessely ring precipitates

Treatment • Steroid eye drops with an antiviral cover. • Tapered over a period of several weeks. • When disciform keratitis + infected epithelial ulcer antiviral drugs should (5 -7 days) steroids

Iritis: Treated with a combination of : topical steroids+ topical antiviral drugs +cycloplegics.

In Summary Epithelial keratitis due to active viral replication Treated with antivirals Stromal keratitis due to immune mechanism Treated with steroids

Herpes zoster

• Herpes zoster is caused by the same virus that causes chickenpox (varicella zoster virus).

After an infection with chickenpox in childhood or youth the virus lies dormant Reactivation- particularly in elderly people with depressed cellular immunity, causing the clinical picture of zoster.

Herpes Zoster Ophthalmicus

• Gasserian ganglion from where the virus travels down one or more of the branches of the ophthalmic division of the trigeminal nerve, so that its area of distribution is marked out by rows of vesicles or the scars left by them.

• Fever and malaise at the onset • Severe neuralgic pain along the course of the nerves. • Eruptions • Characteristic distribution of the lesions especially the strict limitation to one side of the midline of the head. • The vesicles often suppurate, bleed and cause small, permanent, pitted scars.

• 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).

Ocular lesions • Conjunctivitis • Zoster keratitis – Fine or coarse punctate epithelial keratitis. – Microdendritic epithelial ulcers – Nummular – Disciform keratitis occurs – Neuroparalytic ulceration – Exposure keratitis – Mucous plaque keratitis ��

Microdendritic epithelial ulcers • Usually peripheral and stellate rather than exactly dendritic in shape. • Have tapered ends which lack bulbs.

Nummular keratitis: multiple tiny granular deposits surrounded by a halo of stromal haze.

• Episcleritis and scleritis • Iridocyclitis: hypopyon and hyphaema (acute haemorrhagic uveitis). • Acute retinal necrosis • Anterior segment necrosis and phthisis bulbi. • Secondary glaucoma

Neurological Complications. • 1. Motor nerve palsies especially third, fourth, sixth and seventh. • 2. Optic neuritis • 3. Encephalitis

Treatment • Systemic therapy for herpes zoster: • Oral antiviral drugs. – Acyclovir in a dose of 800 mg 5 times a day for 10 days, or – Valaciclovir in a dose of 500 mg TDS • Analgesics. • Systemic steroids: neurological complications such as third nerve palsy and optic neuritis. • Cimetidine: to reduce pain and pruritis • Amitriptyline: to relieve the accompanying depression in acute phase

• Local therapy for ocular lesions • For zoster keratitis, iridocyctitis and scleritis • i. Topical steroid eye drops. • ii. Cycloplegics such as cyclopentolate eyedrops or atropine eye ointment • iii. Topical acyclovir