Ординатура / Офтальмология / Английские материалы / Comprehensive Ophthalmology_Khurana_2007

Presntation of a short case

Students are required to evaluate a short case under following headings:

1.Name, age, sex, occupation and address of the patient.

2.Chief complaints with only one or two relevant questions of history.

3.Ocular examination

4.Diagnosis and differential diagnosis if any

5.List of important diagnostic tests

6.Line of management

List of short cases. During clinical posting in the outdoor (OPD), students should see and evaluate the common short cases. These include a case of— chalazion, stye, trichiasis, entropion, ectropion, ptosis, blepharitis, symblepharon, pterygium, pinguecula, phlyctenular conjunctivitis, spring catarrh, trachoma, Bitot’s spots, xerosis, red eye, corneal ulcer, corneal opacity, arcus senilis, bandshaped keratopathy, anterior staphyloma, proptosis, phthisis bulbi, senile cataract (immature, mature, hypermature, nuclear), congenital cataract, traumatic cataract, aphakia, pseudophakia, iridocyclitis, absolute glaucoma, fixed dilated pupil, miosed pupil, amaurotic cat’s eye reflex etc.

Description of clinical cases and viva questions

Description of common clinical cases and related viva questions and other miscelaneous viva questions are described chapterwise.

DISEASES OF THE CONJUNCTIVA

A CASE OF PTERYGIUM

CASE DISCRIPTION

Age and sex. More common in males than females (2:1) and usually occurs past-middle age. Presenting symptoms. Patients usually present with:

A cosmetically unacceptable dirty white growth on the cornea. Usually there are no other symptoms in early stages.

Patient may experience slight irritation or foreign body sensation.

Diminution of vision may occur due to astigmatism produced by traction on the cornea. Gross diminution of vision occurs when it encroaches upon the pupillary area.

Occasionally diplopia may occur due to limitation of ocular movements.

Usually there is history of prolonged exposure to

sunny, hot, dusty atmosphere.

Signs on examination. A wing-shaped fold of conjunctiva encroaching upon the cornea in the area of palpebral aperture is seen (Fig.4.28), more commonly on the nasal than the temporal side.

A fully-developed pterygium consists of three parts: head (optical part present on the cornea), neck (limbal part) and body (scleral part extending between limbus and the canthus).

Pterygium may be progressive or regressive.

–Progressive pterygium is thick, fleshy and vascular with a few infiltrates in the cornea in front of the head (called cap of pterygium).

–Regressive pterygium is thin, atrophic, attenuated with very little vascularity. There is no cap.

Ultimately it becomes membranous (pterygium siccus) but never disappears.

Differential diagnosis Pterygium must be differentiated from pseudopterygium.

RELATED QUESTIONS

What is a pterygium ?

Pterygium is degenerative condition of the subconjunctival tissue which proliferates as vascularized granulation tissue and is characterized by formation of a triangular fold of conjunctiva encroaching on the cornea.

What is a pseudopterygium; how does it differ from the pterygium?

Pseudopterygium is a fold of bulbar conjunctiva attached to the cornea. It is formed due to adhesions of chemosed bulbar conjunctiva to the marginal corneal ulcer. It usually occurs following chemical burns of the eye.

Differences between the pterygium and pseudopterygium are as depicted in Table 22.1.

What complications can occur in an untreated case of pterygium ?

Cystic degeneration

Neoplastic change (rarely) to: epithelioma, fibrosarcoma or malignant melanoma.

Table 22.1: Differences between ptergium and pseudopterygium

How can we prevent the recurrence after surgical excision of the pterygium?

Recurrence of the pterygium after surgical excision is the main problem (30-50%). It can be reduced by any of the following measures:

Peroperative use of mitomycin-C

Postoperative use of antimitotic drops such as mitomycin-C or thiotepa

Surgical excision with bare sclera

Surgical excision with mucous membrane grafts.

Old methods not used now included:

–Transposition of pterygium to the lower fornix (MxReynold’s operation) and

–Postoperative beta-irradiation

What is a pinguecula ?

Pinguecula is a degenerative condition of the conjunctiva characterized by formation of a yellowish white triangular patch near the limbus.

What are the causes of conjunctival xerosis ?

Depending upon the aetiology, conjunctival xerosis can be divided into two groups:

I.Parenchymatous xerosis: It occurs due to cicatricial disorganization of the conjunctiva as seen in the following conditions:

Trachoma

Membranous conjunctivitis

Stevens-Johnson syndrome

Pemphigus

Pemphigoid

Conjunctival burns (thermal, chemical or radiational)

Prolonged exposure of conjunctiva as in lagophthalmos.

II.Epithelial xerosis: It occurs due to hypovitaminosisA.

What is pannus ?

Pannus is infiltration of the cornea associated with vascularization. In progressive pannus, the infiltration is seen ahead of the parallel blood vessels, while in regressive pannus it stops short and the blood vessels extend beyond the corneal haze.

DISEASES OF THE CORNEA

AND SCLERA

A CASE OF CORNEAL ULCER

CASE DESCRIPTION

Age and sex. May occur at any age in both the sexes. Comparatively males are more commonly affected due to higher chances of injury to the eyes and exposure to infection because of outdoor activity.

Presenting symptoms. A case of corneal ulcer presents with pain, photophobia, lacrimation, discharge, redness, swelling of eyelids and defective vision.

Predisposing factors. A meticulous history taking may reveal presence of any of the following predisposing factors:

Injury to the eye by vegetative matter, nail, foreign body, etc.

Chronic dacryocystitis.

Acute or chronic conjunctivitis

Chronic foreign body sensation in the eye as in trichiasis and concretions.

Contact lens wear

Use of topical steroids

Diatetes mellitus.

General physical and systemic examination should be performed with specific aim to rule out presence of vitamin A deficiency, malnutrition, diabetes mellitus, source of infection in the body including nasal cavity, paranasal sinuses and teeth and gums.

Signs on ocular examination may include (Fig.5.5 & 5.6):

Visual acuity is diminished

Lids show oedema, blepharospasm, lashes may be matted and trichiasis may be present sometimes.

Lacrimal sac. Regurgitation test is positive when there is associated chronic dacryocystitis.

Conjunctiva reveals conjunctival as well as circumcorneal congestion and chemosis. Concretions may be seen on tarsal conjunctiva due to old trachoma.

Cornea on meticulous examination may reveal:

–Loss of normal corneal transparency

–Corneal ulcer (better seen after staining with 2% fluorescein dye) should be described with reference to its site, size, shape, depth, margins and floor. Typical features of the bacterial, fungal or viral ulcer may be seen.

–Window reflex and Placido’s disc reflex are distorted.

–Corneal sensations may be diminished or absent.

–Superficial peripheral corneal vascularization may be seen.

–A descematocele may sometimes be seen in a deep ulcer.

Anterior chamber may or may not show pus (hypopyon). It is a feature of bacterial as well as fungal corneal ulcers.

Iris may be slightly muddy in colour.

Pupil small due to associated toxin-induced iritis.

Intraocular pressure is usually normal. IOP may be raised if hypopyon or associated uveitis is present.

(Note: To record IOP, Schiotz tonometer is never used in corneal ulcer. Always non-contact tonometer is used)

Differential diagnosis. Efforts should be made to describe the type of corneal ulcer whether bacterial, fungal, viral, degenerative or nutritional.

RELATED QUESTIONS

Define keratitis

Keratitis refers to inflammation of the cornea. It is characterized by corneal oedema, cellular infiltration and conjunctival reaction, Keratitis may be either ulcerative or non-ulcerative.

Define corneal ulcer

Corneal ulcer may be defined as discontinuation in the normal epithelial surface of the cornea associated with necrosis of the surrounding corneal tissue. Pathologically, it is characterized by oedema and cellular infiltration.

Classify keratitis

Keratitis can be classified in two ways: topographically and aetiologically.

Topograhical (morphological) classification

(A) Ulcerative keratitis (corneal ulcer): It can be further classified variously as follows:

1.Depending on location:

(a)Central corneal ulcer

(b)Peripheral corneal ulcer

2.Depending on purulence:

(a)Purulent corneal ulcer or suppurative corneal ulcer (mostly bacterial and fungal corneal ulcers are purulent).

(b)Non-purulent corneal ulcer (most of the viral, chlamydial, allergic and other non-infective 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:

(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)Superficial punctate keratitis

(b)Diffuse superficial keratitis

2.Deep keratitis

(a)Non-suppurative

(1)Interstitial keratitis

(2)Disciform keratitis

(3)Keratitis profunda

(4)Sclerosing keratitis

(b)Suppurative deep keratitis

(1)Central corneal abscess

(2)Posterior corneal abscess

Aetiological 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

4.Keratitis associated with diseases of the skin and mucous membranes.

5.Keratitis associated with systemic collagen vascular disorders.

6.Traumatic keratitis which may be due to mechanical trauma, chemical burns, radiational burns or thermal burns.

7.Idiopathic keratitis, e.g.,

(a)Mooren’s ulcer

(b)Superior limbic keratoconjunctivitis

(c)Superficial punctate keratitis of Thygeson.

Name the common bacteria responsible for corneal ulceration?

Common bacteria associated with corneal ulceration are: Staphylococcus aureus, Pseudomonas pyocyanea, Streptococcus pneumoniae, E.coli, Proteus, Klebsiella, Neisseria gonorrhoeae, Neisseria meningitidis and Corynebacterium diphtheriae.

What is the prerequisite for most of the infecting agents to produce corneal ulceration?

Damage to the corneal epithelium is a prerequisite for most of the infecting organisms to produce corneal ulceration. Damage to corneal epithelium may occur in following forms:

Corneal abrasion due to small foreign body, misdirected cilia, trivial trauma, etc.

Necrosis of epithelium as in keratomalacia.

Epithelial damage due to trophic changes as in neuroparalytic keratitis.

Desquamation of epithelial cells as a result of corneal oedema, corneal xerosis and exposure keratitis.

Name the bacteria which can invade the intact corneal epithelium and produce ulceration.

Neisseria gonorrhoeae

Neisseria meningitidis

Corynebacterium diphtheriae

Name the layers of cornea.

1.Epithelium

2.Bowman’s membrane

3.Corneal stroma

4.Descemet’s membrane

5.Endothelium

What are the pathological stages of corneal ulceration?

1.Stage of progressive infiltration

2.Stage of active ulceration

3.Stage of regression

4.Stage of cicatrization

What are the characteristic features of bacterial corneal ulcer ?

A clinical diagnosis of bacterial corneal ulcer is made in patients with a greyish white central or marginal ulcer associated with marked pain, photophobia, blepharospasm, lacrimation, circumcorneal congestion, purulent/mucopurulent discharge, presence or absence of hypopyon with or without vascularization.

What do you mean by hypopyon corneal ulcer?

A purulent corneal ulcer associated with collection of pus in the anterior chamber is called hypopyon corneal ulcer.

Name the common organisms responsible for hypopyon corneal ulceration.

1.Most fungal ulcers are associated with hypopyon.

2.Common bacteria producing hypopyon ulcer are

Pneumococcus, Pseudomonas, Gonococcus and Staphylococcus.

What is ulcus serpens ?

The characteristic hypopyon ulcer caused by pneumococcus is called ulcus serpens.

Name the complications of corneal ulcer

1.Toxic iridocyclitis

2.Secondary glaucoma

3.Descemetocele

4.Corneal perforation, which may be complicated by:

Iris prolapse

Subluxation or dislocation of the lens

Anterior capsular cataract

Purulent iridocyclitis often leading to endophthalmitis or even panophthalmitis

Intraocular haemorrhage in the form of a vitreous haemorrhage or expulsive choroidal haemorrhage.

5.After healing of corneal ulcer following complications: may be left as sequelae:

Keractasia

Corneal opacity which may be nebular, macular, leucomatous or adherent leucoma

Anterior staphyloma which usually follows a sloughing corneal ulceration

What is a descemetocele ?

When a corneal ulcer extends up to Descemet’s membrane, it herniates (bulges out) as a transparent vesicle called the descemetocele or keratocele.

What are the signs of an impending corneal perforation?

Descemetocele formation associated with excessive corneal oedema are the signs of an impending corneal perforation.

What are the clinical features of perforation of corneal ulcer ?

Following perforation of a corneal ulcer, immediately pain is decreased and patient feels some hot fluid (aqueous) coming out of the eyes. Anterior chamber becomes shallow and iris prolapse may occur.

How will you manage a case of corneal ulcer ?

Management of a case of corneal ulcer is as follows:

Clinical evaluation

1.Meticulous history should be taken and a thorough ocular examination including slit-lamp biomicroscopy should be carried out to reach at a clinical diagnosis for the type of corneal ulcer.

2.Regurgitation test and syringing of lacrimal sac should be carried out to rule out associated dacryocystitis.

3.General physical and systemic examination should be carried out to elucidate the associated malnutrition, diabetes mellitus and any other chronic debilitating disease.

Laboratory investigations

1.Routine laboratory investigations such as haemoglobin, TLC, DLC, ESR, blood sugar and complete urine examination should be carried out in each case.

2.Microbiological investigations: Material is obtained by scraping the base and margins of the corneal ulcer (under topical anaesthesia) and is used for following investigations:

Gram and Giemsa-stained smears for possible identification of infecting organisms.

10 per cent KOH wet preparation is made for identification of fungal hyphae

Culture on blood agar medium for aerobic organisms

Culture on Sabouraud’s dextrose agar medium for fungi.

Treatment of uncomplicated corneal ulcer

I.Specific treatment for the cause: Bacterial corneal ulcer is treated by topical and systemic antibiotics.

1.It is preferable to start concentrated amikacin (40-100 mg/ml) eyedrops along with fortified cephazolin (33 mg/ml) eyedrops every one hourly for first five days and then reduced to 2 hourly, 3 hourly, 4 hourly and 6 hourly.

2.Antibiotic eye ointment should be applied at night

3.Subconjunctival injection of gentamicin 40 mg and cephazolin 125 mg once a day for 5 days

should be given in sloughing corneal ulcer

II.Non-specific treatment includes:

1.Cycloplegic drugs, e.g., 1 per cent atropine, 0.5 per cent homatropine or cyclopentolate

2.Systemic analgesics and anti-inflammatory drugs to relieve the pain and oedema

3.Vitamins (A, B-complex and C) help in early healing of the ulcer

III.Physical and general measures:

1.Hot fomentation gives comfort, reduces pain and causes vasodilatation

2.Rest and good diet are useful for smooth convalescence

What do you mean by a non-healing corneal ulcer? Enumerate its common causes.

When a corneal ulcer does not start healing despite the best therapy for about 7 to 10 days it is labelled as a non-healing corneal ulcer. Common causes of

non-healing corneal ulcers are as follows:

Local causes

Associated raised intraocular pressure

Multiple large concretions

Misdirected cilia

An impacted foreign body

Dacryocystitis

Wrong diagnosis, e.g., fungal ulcer being treated as a bacterial ulcer

Lagophthalmos

Excessive vascularization of the ulcer area

Systemic causes

Diabetes mellitus

Severe anaemia

Malnutrition

Chronic debilitating diseases

Immunocompromised patients

Patients on systemic steroids

How will you treat a case of non-healing corneal ulcer?

1.Removal of any known cause of non-healing: A thorough search should be made to find out any already missed cause of non-healing and when found it should be removed.

2.Mechanical debridement of the ulcer to remove necrosed material may hasten the healing.

3.Chemical cauterization with pure carbolic acid or 10 to 20 per cent trichloroacetic acid may be considered in indolent cases.

4.Peritomy, i.e., severing of perilimbal conjunctival vessels may be useful in the presence of excessive corneal vascularization.

What extra measures will you take for the treatment of impending perforation ?

1.Patient should be advised to avoid strain during sneezing, coughing, passing stool, etc.

2.Pressure bandage should be applied to give some external support.

3.Lowering of intraocular pressure by simultaneous use of acetazolamide 250 mg qId orally, 0.5 per cent timolol eyedrops twice a day and intravenous mannitol (20%) drip stat. Even paracentesis with slow evacuation of the aqueous from the anterior chamber may be done, if required.

4.Tissue adhesive glue such as cyanoacrylate is helpful in preventing perforation.

5.Conjunctival flap may be used to cover and support the weak tissue.

6.Bandage soft contact lenses are also useful.

7.Therapeutic keratoplasty, when available, is considered the best mode of treatment.

How will you treat a case of perforated corneal ulcer?

The best treatment is an immediate therapeutic keratoplasty. However, short of it, depending upon the size and location of the perforation measures like use of a tissue glue (cyanoacrylate), bandage soft contact lens or conjunctival flap may be used over and above the conservative management with pressure bandage.

What is a marginal catarrhal ulcer ?

Marginal catarrhal ulcer is a superficial ulcer situated near the limbus, usually seen in association with chronic staphylococcal blepharo-conjunctivitis. It is thought to be caused by hypersensitivity reaction to staphylococcal toxins.

Name the common fungi associated with mycotic corneal ulceration.

The fungi most commonly responsible for mycotic corneal ulceration are: Aspergillus, Candida and Fusarium.

What are the predisposing factors for a mycotic corneal ulcer ?

1.Injury by vegetative material.

2.Immunosuppressed patients are prone to secondary fungal ulcers.

3.Excessive use of topical antibiotics and steroids predispose the cornea for fungal infections.

What are the characteristic features of a fungal corneal ulcer?

1.A typical fungal corneal ulcer is dry looking, greyish white with elevated rolled-out margins and delicate feathery finger-like extensions into the surrounding stroma under the intact epithelium.

2.A sterile immune ring (yellow line of demarcation) may be present where fungal antigen and host antibodies meet.

3.Multiple, small satellite lesions may be present around the ulcer.

4.Usually a massive and thick hypopyon is present even if the ulcer is very small.

5.A history of trauma (especially by vegetative material) and clinical signs out of proportion to the symptoms, i.e., less marked photophobia and lacrimation with intense ciliary and conjunctival congestion support a fungal origin.

How will you confirm the diagnosis of a fungal corneal ulcer ?

Confirmation is made by laboratory investigations, which include examination of a wet KOH, Gram’s and Giemsa-stained films for fungal hyphae and culture on Sabouraud’s dextrose agar medium.

Name the ocular antifungal drugs.

1.Polyene antifungals, e.g.,

1.Nystatin 3.5 per cent eye ointment

2.Amphotericin-B (0.75 to 3% eyedrops)

3.Natamycin 5 per cent suspension

II.Imidazole antifungal drugs, e.g., ketoconazole, fluconazole miconazole, clotrimazole and

econazole

III. Pyrimidine, e.g., flucytosine

IV. Silver compounds, e.g., silver sulphadiazine eyedrops

Enumerate the ocular lesions of herpes simplex.

Ocular involvement by herpes simplex virus (HSV) occurs in two forms:

I.Primary herpes – It is characterized by:

1.Vesicular lesions involving the skin of lids

2.Acute follicular conjunctivitis

3.Fine or coarse epithelial punctate keratitis

II.Recurrent herpes – Its lesions are as follows:

1.Punctate epithelial keratitis

2.Dendritic ulcer

3.Geographical or amoeboid ulcer

4.Disciform keratitis

Describe the characteristic features of recurrent herpetic keratitis.

Dendritic ulcer is a typical epithelial lesion of the recurrent herpetic keratitis. The ulcer is of an irregular zigzag linear branching shape (Fig.5.9). The branches are generally knobbed at the ends. Floor of the ulcer stains with fluorescein and the virus laden cells at the margin take up rose bengal stain. There is an associated marked diminution of the corneal sensations.

Sometimes, the branches of the dendritic ulcer enlarge and coalesce to form a large epithelial ulcer typically known as geographical or amoeboid ulcer.

What are the features of herpes simplex virus (HSV)?

Herpes simplex virus is an epitheliotropic, DNA virus. It is of two types: HSV type-1 which typically causes infection above the waist (herpes labialis) and HSV type-II which causes infection below the waist (herpes genitalis).

Name the predisposing/precipitating stress stimuli which trigger an attack of herpetic keratitis.

Fever, especially malaria

General ill health

Exposure to ultraviolet rays

Mild trauma

Use of topical and systemic steroids

Immunosuppression

What is disciform keratitis ?

Disciform keratitis is stromal keratitis which occurs due to delayed hypersensitivity reaction to the HSV antigen. It is characterized by a focal disc-shaped patch of stromal oedema without necrosis. Associated diminished corneal sensations and fine keratic precipitates differentiate it from other causes of stromal oedema.

Name the antiviral drugs.

Idoxuridine (IDU), trifluorothymidine (TFT), adenine arabinoside (vidarabine) and acyclovir.

Which antiviral drug is effective for stromal viral keratitis?

Acyclovir

Enumerate the causes of decreased corneal sensations.

Viral keratitis, neuroparalytic keratitis, diabetic neuropathy and leprosy.

What is herpes zoster ophthalmicus?

Herpes zoster ophthalmicus is an acute infection of the gasserian ganglion of the fifth cranial nerve by varicella zoster virus. In it, frontal nerve is more frequently affected than the lacrimal and nasociliary nerve. About 50 per cent cases of herpes zoster ophthalmicus develop ocular complications.

Ocular involvement in herpes zoster ophthalmicus is associated with involvement of which nerve ?

Nasociliary nerve.

What are the characteristic features of herpes zoster?

1.Fever and malaise occur at the onset

2.The vesicular eruptions are preceded by severe neuralgic pain along the course of the involved nerves

3.The lesions are strictly limited to one side of the midline of head (pathognomonic feature)

Enumerate the ocular lesions of herpes zoster ophthalmicus.

Conjunctivitis, keratitis, episcleritis, scleritis, iridocyclitis and secondary glaucoma.

What is Mooren’s ulcer ?

Mooren’s ulcer (chronic serpiginous or rodent ulcer) is a peripheral degenerative ulcerative keratitis of unknown aetiology. It is characterized by a shallow furrow-shaped ulcer having whitish overhanging margin at the advancing edge (Fig.5.13).

What are the features of neuroparalytic keratitis?

1.No pain, no lacrimation and complete loss of corneal sensations

2.Marked ciliary congestion

3.Corneal sheen is dull

4.Corneal ulcer is usually superficial and involves the interpalpebral area

What are the causes of exposure keratitis ?

1.Extreme proptosis

2.Bell’s palsy

3.Symblepharon

4.Patients in deep coma

What is superficial punctate keratitis; name a few of its causes ?

Superficial punctate keratitis (SPK) refers to occurrence of multiple, spotty lesions in superficial layer of cornea. Its common causes are:

1.Viral infections, e.g., adenovirus infection, epidemic keratoconjunctivitis, herpes zoster keratitis, herpes simplex keratitis, and pharyngoconjunctival fever

2.Chlamydial infections, e.g., trachoma

3.Toxic, e.g., in association with blepharoconjunctivitis

4.Trophic lesions, e.g., exposure keratitis and neuroparalytic keratitis

5.Allergic lesions, e.g., vernal keratitis

6.Keratoconjunctivitis sicca

7.Specific type of idiopathic SPK, e.g., Thygeson’s SPK and superior limbic keratoconjunctivitis

8.Photophthalmitis

What is photophthalmia ?

Photophthalmia refers to occurrence of multiple epithelial erosions due to exposure to ultraviolet rays having a wavelength of 290-311 mµ. It occurs in the following conditions:

1.Exposure to naked arc light as in industrial welding and cinema operators

2.Exposure to bright light of a short circuit

3.Snow blindness due to reflected ultraviolet rays from the snow surface

What is filamentary keratitis/keratopathy? Name its few important causes.

Filamentary keratitis is a type of superficial punctate keratitis associated with formation of corneal epithelial filaments. Its common causes are:

1.Keratoconjunctivitis sicca (KCS)

2.Recurrent corneal erosion syndrome

3.Herpes simplex keratitis

4.Thygeson’s superficial punctate keratitis

5.Prolonged patching of the eye particularly following ocular surgery like cataract

6.Trachoma

What is interstitial keratitis? What are its common causes ?

Interstitial keratitis is inflammation of the corneal stroma without primary involvement of the epithelium or endothelium. Its common causes are: congenital syphilis, tuberculosis, acquired syphilis, Cogan’s syndrome (interstitial keratitis with acute tinnitus, vertigo and deafness).

What are corneal dystrophies ?

Corneal dystrophies are inherited disorders characterized by development of corneal haze in otherwise normal eyes that are free of inflammation or vascularization. These are classified as follows:

1.Anterior dystrophies which primarily affect epithelium and Bowman’s membrane, e.g., recurrent corneal erosion syndrome.

2.Stromal dystrophies: These include: granular dystrophy, macular dystrophy and lattice dystrophy

3.Posterior dystrophies which primarily affect the corneal endothelium and Descemet’s membrane, e.g., cornea guttata, Fuchs’ dystrophy

4.Ectatic dystrophies e.g., keratoconus, keratoglobus.

What is Fuchs’ dystrophy ?

Also called as epithelial endothelial dystrophy, affects females more than the males between 5th and 7th decade of life. It is a slowly progressive bilateral condition. Its clinical features can be divided into following four stages:

Stage of cornea guttata

Oedematous stage or stage of endothelial decompensation

Stage of bullous keratopathy

Stage of scarring

Define keratoconus and describe its treatment.

Keratoconus is a non-inflammatory ectatic condition of the cornea. It is usually bilateral and manifests at puberty with gradual loss of vision.

The high myopic irregular astigmatic refractive error seen in keratoconus may be treated by hard contact lens in early stages. Ultimately penetrating keratoplasty is required.

A CASE OF CORNEAL OPACITY

CASE SUMMARY

Presenting symptoms. A patient with corneal opacity usually presents with a whitish scar, causing defective vision as well as cosmetic blemish.

History may reveal a history of trauma to the eye or symptoms suggestive of healed corneal ulceration. Examination reveals an opacity on the cornea (Fig.5.20) which may be nebular, macular or leucomatous. The location, size, shape and density of the opacity must be described.

RELATED QUESTIONS

What is a corneal opacity ?

The term corneal opacity is used for the loss of corneal transparency due to scarring.

What are common causes of corneal opacity?

1.Congenital opacities

2.Healed corneal wounds

3.Healed corneal ulcers

What are the types of corneal opacity?

1.Nebular corneal opacity. It is a faint opacity which results due to scars involving up to a few superficial lamellae of corneal stroma.

2.Macular opacity. It is a dense opacity produced by scars involving up to about half the thickness of the stroma.

3.Leucomatous corneal opacity (leucomasimplex). It is a very dense,white opacity, which results due to scarring of more than half thickness of corneal stroma.

4.Adherent leucoma. It results when healing occurs after perforation of cornea with incarceration of the iris.

Name the secondary changes which can occur in a long standing case of corneal opacity.

1.Hyaline degeneration

2.Calcareous degeneration

3.Pigmentation

4.Atheromatous ulceration

How will you treat a case with corneal opacity?

1.Optical iridectomy. It may be performed in cases with central macular or leucomatous corneal opacities; provided vision improves with pupillary dilatation.

2.Keratoplasty. It provides good visual results in uncomplicated cases with corneal opacities; where optical iridectomy is not of much use.

3.Tattooing of scar. It used to be performed for cosmetic purposes. It is suitable only for firm scars in a quite eye without useful vision. Presently it is sparingly used.

How do you perform tattooing ?

First of all, the epithelium covering the opacity is removed under topical anaesthesia. Then a piece of blotting paper of the same size and shape soaked in 4 per cent gold chloride (for brown eyes) or 2 per cent platinum chloride (for dark colour) is applied over it. After 2 to 3 minutes the piece of blotting paper is removed and a few drops of freshly-prepared hydrazine hydrate (2%) solution are poured over it. Lastly, eye is irrigated with normal saline and patched after instilling antibotic and atropine eye ointment. Epithelium grows over the pigmented area.

What are the causes of corneal vascularization?

Normal cornea is avascular. In pathological states, superficial or deep corneal vascularization may occur (Fig.5.22).

1.Superficial corneal vascularization. In it, vessels are arranged in an arborizing pattern, present below the epithelium and their continuity can be traced with the conjunctival vessels. Its common causes are:

Trachoma

Phlyctenular keratoconjunctivitis

Superficial corneal ulcers

Rosacea keratitis

2.Deep corneal vascularization. In it, the vessels are generally derived from the anterior ciliary arteries and lie in the corneal stroma. These vessels are usually straight, not anastomosing and their continuity cannot be traced beyond the limbus. Its common causes are:

Interstitial keratitis

Disciform keratitis

Deep corneal ulcers

Chemical burns

Sclerosing keratitis

Corneal graft vascularization

What is keratoplasty ?

Keratoplasty is an operation in which the patient’s diseased cornea is replaced by the donor’s healthy clear cornea. It is of two types:

1.Lamellar keratoplasty (partial thickness)

2.Penetrating keratoplasty (full thickness)

Name the indications for keratoplasty.

Lamellar keratoplasty

Indolent corneal ulcer, superficial corneal opacity and lattice dystrophy.

Penetrating keratoplasty

1.Optical, i.e., to improve vision in patient with corneal opacity, bullous keratopathy, corneal dystrophies and advanced keratoconus

2.Therapeutic, i.e., to replace inflamed cornea not responding to treatment (indolent deep ulcer)

3.Tectonic grafts, i.e., to restore the integrity of eyeball in corneal perforation and marked corneal thinning

4.Cosmetic, i.e., to improve appearance of the eye in deep leucomas with no vision in the eye.

What is the optimum time for the removal of donor eyes from the body of a deceased ?

The donor eyes should be removed as early as possible (within 6 hours of death) and should be stored under sterile conditions.

What are the methods of corneal preservation?

1.Short-term storage (up to 48 hours): The whole globe is preserved at 4°C in a moist chamber.

2.Intermediate storage (up to 2 weeks): The donor corneal button is prepared and stored in McCareyKaufman (MK) medium and various chondroitin sulphate-enriched media such as optisol.

3.Long-term storage (up to 35 days): It is done by organ culture method or cryopreservation.

Enumerate the complications of keratoplasty operation.

I.Early complications are: flat anterior chamber, iris prolapse, infection, secondary glaucoma, epithelial defects, primary graft failure

II.Late complications are: graft rejection, recurrence of disease, marked astigmatism and cystoid macular oedema.

From which sources cornea derives its nutrition?

Perilimbal capillaries

Aqueous humour

Oxygen from atmosphere

What is the nerve supply of cornea ?

Cornea is supplied by the nasociliary branch of the ophthalmic division of the trigeminal nerve.

What is a corneal facet?

A corneal facet is a transparent depressed scar. On slit-lamp examination light beam appears to dip in the area of a facet.

What is kerotomalacia ?

Keratomalacia refers to corneal necrosis due to vitamin A deficiency. In this condition, there is no inflammatory reaction.

What is arcus senilis?

Arcus senilis is a degenerative condition of the cornea characterized by an annular lipid infiltration concentric to limbus. The ring of opacity is about 1-mm wide and is separated from the limbus by a clear zone (lucid interval of Vogt).