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The cornea
continuation
4- Viral keratitis:
b- Herpes Zoster ophthalmicus (HZO):
It is a disease caused by Varicella Zoster virus (VZV), which is
morphologically identical to HSV but different antigenically and clinically.
Chickenpox (Varicella) and Zoster are different conditions caused by the same
virus, Zoster mainly affects elderly patients. Primary disease occurs during
childhood is usually chickenpox,virus remains dormant in sensory root ganglia.
Later, it reactivates and migrates back down sensory nerves to the skin and eye
ad causes the characteristic lesions. Therefore, herpes zoster in a young person
make us think that patient is immune compromised.
- Approximately, 15% of all cases of herpes zoster affect the ophthalmic
division of the trigeminal nerve (HZO).
* If we have crust lesion at the tip of the nose "Hutchinson sign", it indicates
ocular involvement?. because the distribution of the ophthalmic division of the
trigeminal nerve.
Clinically, HZO can be divided into:
i- Acute phase: acute symptoms, which may totally resolve after a while.
ii- Chronic phase: which may persist for years.
iii- Relapsing phase: where the acute or chronic lesions reappear years later.
Now we will discuss them separately:
i- Acute phase:
Systemic features:
Influenza-like illness: Fever, malaise, headache and depression.
Herpetic neuralgia: Varies from a superficial itching or burning sensation
to severe deep boring or lancing pain.
Skin rash: Progress rapidly from papules →vesicles →pustules → crust
and scar formation.
Ocular Features:
Keratitis(dendritic lesion smaller & finer than HS dendritis without terminal
bulbs, conjunctivitis, episcleritis, scleritis and anterior uveitis.
Neurological Complication:
Cranial nerve palsies: 3
rd
, 4
th
or 6
th
cranial nerve palsy.
Optic neuritis.
Encephalitis.
Contralateral hemiplegia.
Treatment:
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Systemic: Valaciclovir 1g t.i.d for 7 days
Or Famciclovir 250mg t.i.d for 7 days.
Topical: a- Skin: Steroid + Antibiotics skin cream, e.g. Hydrocortisone
1% with Fusidic acid 2%.
b- Eye: Herpetic ulcer →Aciclovir ointment.
Autoimmune → Topical steroid. Sometimes, both of
them are used.
* Unlike herpes simplex keratitis, here we can use steroids from the beginning
of the treatment accompanying other medications.
ii- Chronic phase:
Ocular features:
Keratitis, neurotrophic keratitis (denervation of the cornea that causes
recurrent epithelial erosions or ulcers, which may not respond to treatment or
heal) which may lead to severe ulceration, secondary bacterial infection and
even perforation.
Other ocular complications:
Ptosis: as a result of scarring which may also produce trichiasis or
madarosis.
Mucus secreting conjunctivitis.
Scleritis.
Post-herpetic neuralgia: may lead to depression and even suicidal
attempts.
Treatment: Accordingly.
iii- Relapsing phase:
It may appear even 10 years after acute or chronic disease. They may be
precipitated by the sudden withdrawal or reaction of topical steroids.
Ocular features:
Keratitis, episcleritis, scleritis, iritis & glaucoma .
Keratoconus
It is a progressive disorder in which the cornea assumes an irregular conical
shape. The onset is at around puberty with slow progression thereafter and
become stationary at any time (age).
* the cornea has two surfaces; anterior and posterior, & the thickness of the
cornea at the center is 0.5mm and about 1mm at the periphery. In keratoconus,
there is progressive and irregular changes in the cornea making it more convex
and make it have a more conical shape, also there is severe thinning of the cornea
that the cornea may reach 1/3 its original thickness (about 0.16mm). These
deformities will affect the visual acuity (as the cornea is the most important
focusing power) leading to myopia and irregular astigmatism.
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Presentation:
1- Unilateral impairment of vision due to progressive myopia and regular
astigmatism, which subsequently becomes irregular.
2- Frequent changes in spectacle prescription or decrease tolerance to contact
lens (due changes in the shape of cornea).
3- The fellow eye usually has normal vision with negligible astigmatism at
presentation because of the asymmetrical nature of the condition.
Signs of keratoconus:
The hallmarks are: 1- Central or paracentral stromal thinning.
2- Apical protrusion.
3- Irregular astigmatism.
1- Direct ophthalmoscope from a distance of one foot shows an oil droplet
reflex.
2- Retinoscpoy (used for diagnosis of refraction errors) shows an irregular
reflex.
3- Slit-lamp shows very fine, vertical, deep stromal striae "Vogt's lines" due to
protrusion of cornea.
4- Later, there is progressive corneal thinning as little as one third of normal
thickness, associated with poor visual acuity (irregular myopic astigmatism).
5- Bulging of the lower lid in down gaze "Munson sign".
6- Acute hydrops: It is an acute influx of aqueous into the cornea as a result of
a rupture in Descemet's membrane →sudden decrease in visual acuity associated
with discomfort and watering (lacrimation).
The break usually heals within 6-10 weeks and the corneal oedema clears.
Management:
Eye rubbing should be avoided
1- Spectacles: In early cases to correct regular and mild irregular astigmatism.
2- Rigid contact lenses: For higher degree of astigmatism, they only reshape
the cornea, there refractive power is zero.
3- Corneal collagen cross-linking CXL.
4- Intracorneal ring segment implantation
5- Keratoplasty: In advanced progressive disease, especially with significant
corneal scarring.
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Keratoplasty (Corneal transplantation, Grafting)
It is an operation in which abnormal corneal host tissue is replaces by healthy
donor cornea, it is either Full-thickness (Penetrating keratoplasty) or Partial
thickness (Lamellar keratoplasty).
Penetrating keratoplasty:
Indications:
1- Optical keratoplasty: To improve visual acuity indicated in e.g.
keratoconus, dystrophies, degenerations, scarring of cornea and pseudophakic
bullous keratopathy (oedema due damage of the endothelium after implantation
of a prosthetic lens).
* The most common indication in western countries is pseudophakic bullous
keratopathy.
2- Tectonic keratoplasty: To restore corneal integrity, indicated in stromal
thinning and descemetoceles (A descemetocele is an outward displacement of
Descemet's membrane in an area where the overlying corneal stroma has been
destroyed by inflammation).
3- Therapeutic keratoplasty: Removal of infected corneal tissue in eye
unresponsive to antimicrobial therapy.
4- Cosmetic keratoplasty: Rare indication, to improve the appearance of the
eye.
Sclera
The scleral stroma is composed of collagen bundles of varying size and
shape that are not uniformly orientated as in the cornea, and so are not
transparent. The inner layer of the sclera (lamina fusca) blends with the
uveal tract. Anteriorly the episclera consists of a connective tissue layer
between the superficial scleral stroma and Tenon capsule..
Scleritis & episcleritis
Episcleritis
Episcleritis is a common, usually idiopathic and benign, recurrent and
frequently bilateral condition. Females may be affected more commonly
than males.
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a- Simple episcleritis
Common, benign, self-limiting but frequently recurrent, typically
affects young adults & Seldom associated with a systemic disorder
Treatment
Topical steroid
If unresponsive systemic ibuprofen 200 mg tid
b- Noduler episcleritis
Localized nodule which can be moved over sclera, may take longer
to resolve, less common than simple episcleritis.
Treatment - similar to simple episcleritis
Scleritis
A- Anterior scleritis
1 • Non-necrotizing
a • Diffuse
Relatively benign - does not progress to necrosis , widespread scleral
and episcleral injection.
Treatment : Oral NSAIDs, if unresponsive Oral steroids..
b • Nodular
More serious than diffuse scleritis & on cursory examination resembles
Nodular episcleritis, Scleral nodule cannot be moved over underlying
tissue.
Treatment - similar to diffuse non-necrotizing scleritis
2 • Necrotizing
a. with inflammation
• Vaso-occlusive : like RA.
• Granulomatous: like polyarteritis nodosa
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• Surgically induced (can also be infective)
Painful and most severe type of scleritis.
Treatment :
Oral steroids, if unresponsive must start with Immunosuppressive agents
(cyclophosphamide, azathioprine, cyclosporine), & lastly we can use
Combined intravenous steroids and cyclophosphamide
b• necrotizing without inflammation called it ( Scleromalacia perforans)
Associated with rheumatoid arthritis, Asymptomatic and untreatable
Characterized by Progressive scleral thinning with exposure of underlying
uvea.
B- Posterior scleritis
About 30% of patients have systemic disease & represent about 20% of all
cases of scleritis
Diagnosed by imaging technique like B scan.
Treatment : similar to necrotizing scleritis with inflammation.