1. Cornea and external disease
   • Corneal ulcer
   • Anatomy of cornea
   • Trachoma classification
   • Keratoconus
   • HSV keratitis and herpes zoster ophthalmicus
2. Glaucoma and anterior chamber angle
   • Angle anatomy and acute angle-closure glaucoma
   • Antiglaucoma drugs
   • Phacolytic glaucoma
3. Lens and cataract
   • Aphakia: definition, causes, management
   • Types of cataract surgery
4. Eyelids
   • Anatomy of the eyelid with diagram points
   • Congenital lid anomalies
5. Orbit
   • Thyroid ophthalmopathy

1. Cornea and external disease
   • Corneal ulcer
   • Anatomy of cornea
   • Trachoma classification
   • Keratoconus
   • HSV keratitis and herpes zoster ophthalmicus
2. Glaucoma and anterior chamber angle
   • Angle anatomy and acute angle-closure glaucoma
   • Antiglaucoma drugs
   • Phacolytic glaucoma
3. Lens and cataract
   • Aphakia: definition, causes, management
   • Types of cataract surgery
4. Eyelids
   • Anatomy of the eyelid with diagram points
   • Congenital lid anomalies
5. Orbit
   • Thyroid ophthalmopathy

1. Cornea and external disease
2. Glaucoma and anterior chamber angle
3. Lens and cataract
4. Eyelids
5. Thyroid ophthalmopathy

Corneal Ulcer - 10 Marks

Definition

Etiology

1. Infective causes

• Bacterial: Staphylococcus aureus, Streptococcus pneumoniae, Pseudomonas aeruginosa.
  • Pseudomonas is particularly associated with contact-lens wear and can rapidly perforate the cornea.
• Fungal: Fusarium, Aspergillus, Candida.
  • Common after trauma with vegetative matter, especially in agricultural workers.
• Viral: Herpes simplex virus, varicella-zoster virus.
• Protozoal: Acanthamoeba, especially in contact-lens users exposed to contaminated water.

2. Predisposing factors

• Corneal trauma, particularly vegetative trauma
• Contact-lens use, poor lens hygiene, overnight lens wear
• Foreign body or corneal abrasion
• Chronic dacryocystitis
• Blepharitis, trichiasis, entropion, lagophthalmos
• Dry eye, exposure keratopathy, neurotrophic cornea
• Topical corticosteroid misuse
• Diabetes mellitus, malnutrition, immunosuppression
• Previous corneal disease or surgery

Clinical Features

Symptoms

• Severe ocular pain
• Redness
• Watering or purulent discharge
• Foreign-body sensation
• Photophobia and blepharospasm
• Blurred vision or decreased visual acuity
• Headache may occur in severe cases

Signs

• Circumcorneal congestion or ciliary injection
• Corneal epithelial defect which stains with fluorescein
• White or gray stromal infiltrate beneath the epithelial defect
• Corneal edema and haze
• Mucopurulent discharge in bacterial ulcers
• Anterior uveitis with cells and flare
• Hypopyon may be present
• Reduced corneal sensation in herpetic disease
• Raised intraocular pressure may occur secondarily

Characteristic Features of Important Types

Investigations

1. Visual acuity assessment and documentation.
2. Slit-lamp examination
   • Measure site, size and depth of ulcer.
   • Note infiltrate, epithelial defect, hypopyon, thinning, and anterior chamber reaction.
3. Fluorescein staining to outline epithelial defect.
4. Corneal scraping, preferably before starting antibiotics:
   • Gram stain
   • KOH wet mount for fungus
   • Giemsa stain where indicated
   • Culture and sensitivity on appropriate media
5. Culture contact lens, lens case, or solution in contact lens-related disease.
6. Check corneal sensation if HSV is suspected.
7. B-scan ultrasonography if the posterior segment cannot be viewed and endophthalmitis is suspected.

Management

A. Immediate measures

• Treat as an ocular emergency.
• Stop contact lenses immediately.
• Do not patch the eye.
• Do not instill topical corticosteroids initially.
• Take corneal scrapings and cultures when indicated, but do not delay therapy in severe ulcers.
• Admit if ulcer is large, central, rapidly progressive, associated with hypopyon, impending perforation, poor compliance, or monocular status.

B. Specific medical treatment

1. Bacterial corneal ulcer

• Start intensive topical broad-spectrum antibiotic therapy.
• Options include:
  • Fourth-generation fluoroquinolone monotherapy, such as moxifloxacin or gatifloxacin, in appropriate cases.
  • Fortified topical antibiotics in severe ulcers, for example a cephalosporin for Gram-positive organisms plus an aminoglycoside for Gram-negative organisms.
• Initially administer drops frequently, often hourly in severe cases, then modify according to clinical response and culture sensitivity.
• Pseudomonas requires urgent aggressive treatment.

2. Fungal corneal ulcer

• Topical natamycin 5% is commonly used for filamentous fungi.
• Topical amphotericin B may be used for yeast infections such as Candida.
• Add systemic antifungal therapy in deep, large, or refractory infection when indicated.
• Treatment is prolonged and guided by clinical response.

3. Herpes simplex epithelial keratitis

• Topical or oral antiviral therapy, such as acyclovir, according to the clinical type and severity.
• Avoid topical steroids in active epithelial dendritic ulcer, as they may worsen viral replication.

4. Acanthamoeba keratitis

• Requires prolonged antiamoebic therapy, commonly biguanides with or without diamidines, under specialist supervision.

C. Supportive treatment

• Cycloplegic, such as homatropine or atropine:
  • Relieves pain due to ciliary spasm
  • Prevents posterior synechiae
• Oral analgesics
• Control raised intraocular pressure if present, avoiding miotics and prostaglandin analogues in active inflammation.
• Treat associated blepharitis, dry eye, dacryocystitis, lid malposition, or systemic illness.

D. Surgical treatment

• Cyanoacrylate tissue adhesive with bandage contact lens for small perforation
• Amniotic membrane graft in selected nonhealing epithelial defects
• Therapeutic penetrating keratoplasty for uncontrolled infection, descemetocele, or perforation
• Optical keratoplasty later for dense corneal opacity after infection has resolved

Complications

• Corneal scar and opacity
• Irregular astigmatism
• Adherent leukoma
• Descemetocele
• Corneal perforation
• Iris prolapse
• Anterior synechiae
• Secondary glaucoma
• Endophthalmitis or panophthalmitis
• Permanent loss of vision or loss of eye

Simple Diagram to Draw in Examination

1. Epithelial defect
2. Stromal infiltrate
3. Surrounding corneal edema
4. Ciliary congestion
5. Hypopyon in anterior chamber

10-mark answers

1. Corneal ulcer
   • Definition, etiology, clinical features, investigations, treatment, complications, diagram.
2. Anatomy of anterior chamber angle and acute angle-closure glaucoma
   • Angle structures in order, mechanism, risk factors, symptoms, signs, emergency treatment, definitive treatment, diagram.

5-mark answers

1. Anatomy of cornea
   • Dimensions, layers, nutrition, nerve supply, functions, diagram.
2. Classification of trachoma
   • WHO simplified grading: TF, TI, TS, TT, CO.
3. Antiglaucoma drugs
   • Classification by mechanism, examples, major adverse effects and uses.
4. Aphakia
   • Definition, causes, clinical features, optical correction and management.
5. Phacolytic glaucoma
   • Definition, pathogenesis, clinical features and management.
6. Keratoconus
   • Definition, features, signs, investigations and treatment.
7. HSV keratitis and herpes zoster ophthalmicus
   • Etiology, clinical types/features, treatment and complications.
8. Thyroid ophthalmopathy
   • Etiology, clinical features, investigations, management.
9. Cataract surgeries and types
   • ICCE, ECCE, SICS, phacoemulsification, femtosecond laser-assisted surgery, and IOL implantation.
10. Eyelid anatomy, diagram, and congenital anomalies

• Layers, lid margin, glands, blood/nerve supply, plus coloboma, epicanthus, congenital ptosis, epiblepharon, and blepharophimosis.

1. 10-mark: anterior chamber angle anatomy and acute angle-closure glaucoma
2. All 5-mark cornea/external disease answers
3. All 5-mark glaucoma answers
4. All 5-mark lens/cataract answers
5. All 5-mark eyelid and orbit answers

1. Cornea and infections
   • Anatomy of cornea
   • Trachoma classification
   • Keratoconus
   • HSV keratitis and herpes zoster ophthalmicus
2. Glaucoma
   • Antiglaucoma drugs
   • Phacolytic glaucoma
3. Lens and cataract
   • Aphakia
   • Cataract surgeries and types
4. Eyelids and orbit
   • Anatomy of lid with congenital anomalies
   • Thyroid ophthalmopathy

MBBS Ophthalmology - 5-Mark Answers

1. Anatomy of Cornea

Definition

Dimensions

• Horizontal diameter: about 11.5-12 mm
• Vertical diameter: about 10.5-11 mm
• Central thickness: about 0.5-0.55 mm
• Peripheral thickness: about 0.65 mm
• Refractive power: about +43 D

Layers of cornea

1. Epithelium
   • Non-keratinized stratified squamous epithelium, about 5-6 cell layers.
   • Rapid regeneration.
   • Acts as a protective barrier.
2. Bowman’s membrane
   • Acellular anterior limiting membrane.
   • Does not regenerate after injury and heals by scar formation.
3. Stroma (substantia propria)
   • Forms about 90% of corneal thickness.
   • Consists of regularly arranged collagen lamellae, keratocytes, and ground substance.
   • Regular arrangement maintains transparency.
4. Descemet’s membrane
   • Basement membrane of corneal endothelium.
   • Elastic and resistant to injury.
   • Regenerates after damage.
5. Endothelium
   • Single layer of hexagonal cells.
   • Maintains corneal deturgescence by pump function.
   • Does not significantly regenerate.

Nutrition

• Aqueous humour
• Tear film
• Perilimbal capillary plexus

Nerve supply

• Sensory supply: long ciliary nerves, branches of ophthalmic division of trigeminal nerve.
• Cornea is highly sensitive.

Functions

• Refraction of light
• Protection of intraocular structures
• Transparent optical window of the eye

2. Classification of Trachoma

WHO simplified trachoma grading

1. TF - Trachomatous inflammation, follicular
   • Five or more follicles, each at least 0.5 mm, on the upper tarsal conjunctiva.
2. TI - Trachomatous inflammation, intense
   • Marked inflammatory thickening of upper tarsal conjunctiva obscuring more than half of the deep tarsal vessels.
3. TS - Trachomatous scarring
   • Presence of easily visible tarsal conjunctival scars.
4. TT - Trachomatous trichiasis
   • At least one eyelash touches the eyeball, or evidence of recent removal of inturned lashes.
5. CO - Corneal opacity
   • Easily visible corneal opacity over the pupil margin, affecting vision.

Sequelae

• Entropion
• Trichiasis
• Corneal ulceration and opacity
• Visual impairment or blindness

3. Antiglaucoma Drugs

1. Decreasing aqueous humour formation, or
2. Increasing aqueous humour outflow.

A. Drugs reducing aqueous production

1. Beta-blockers

• Timolol
• Betaxolol
• Levobunolol

2. Carbonic anhydrase inhibitors

• Topical: Dorzolamide, brinzolamide
• Oral/systemic: Acetazolamide

3. Alpha-2 adrenergic agonists

• Brimonidine
• Apraclonidine

B. Drugs increasing aqueous outflow

1. Prostaglandin analogues

• Latanoprost
• Travoprost
• Bimatoprost

2. Cholinergic drugs or miotics

• Pilocarpine
• Carbachol

3. Rho-kinase inhibitor

• Netarsudil

C. Hyperosmotic agents

• Intravenous mannitol
• Oral glycerol or isosorbide

4. Aphakia: Definition, Causes and Management

Definition

Causes

1. Surgical aphakia

• Following intracapsular cataract extraction
• Following extracapsular cataract extraction without intraocular lens implantation
• Following removal of dislocated lens

2. Traumatic aphakia

• Penetrating injury with extrusion of lens
• Blunt trauma causing lens dislocation or absorption

3. Congenital aphakia

• Rare developmental anomaly due to failure of lens formation.

Clinical features

• Marked hypermetropia, approximately +10 D
• Loss of accommodation
• Deep anterior chamber
• Iridodonesis - tremulous iris
• Purkinje image of posterior lens surface is absent
• Aphakic spectacles cause image magnification, peripheral distortion and ring scotoma

Management or optical correction

1. Posterior chamber intraocular lens implantation
   • Best method where capsular support is adequate.
   • May be primary or secondary implantation.
2. Contact lens
   • Preferred in unilateral aphakia and children.
   • Gives better image quality than spectacles.
3. Aphakic spectacles
   • Used mainly in bilateral aphakia when contact lens or IOL is unsuitable.
   • Usually require about +10 D spherical correction for distance, with near addition.
4. Secondary IOL options
   • Sulcus-fixated posterior chamber IOL
   • Scleral-fixated IOL
   • Iris-claw IOL
   • Anterior chamber IOL in selected cases

5. Phacolytic Glaucoma

Definition

Pathogenesis

• In a hypermature cataract, lens proteins leak into the aqueous humour.
• Macrophages engulf these proteins.
• Protein-laden macrophages and lens proteins obstruct the trabecular meshwork.
• This causes a sudden rise in intraocular pressure.

Clinical features

• Elderly patient with long-standing mature or hypermature cataract
• Sudden pain, redness, watering and defective vision
• Corneal edema
• Deep anterior chamber
• Open angle on gonioscopy
• Markedly raised IOP
• Mild to moderate anterior uveitis
• Flare, cells, and sometimes pseudohypopyon of macrophages
• White, mature or hypermature cataract

Treatment

Medical treatment

• Topical beta-blocker, alpha-agonist and carbonic anhydrase inhibitor
• Oral acetazolamide if not contraindicated
• Hyperosmotic agent if IOP is very high
• Topical corticosteroid to control inflammation
• Cycloplegic agent

Definitive treatment

• Cataract extraction with intraocular lens implantation, once IOP and inflammation are controlled.

6. Keratoconus

Definition

Etiology and associations

• Usually begins around puberty and progresses until the third or fourth decade.
• Often bilateral but asymmetric.
• Associated with:
  • Atopy and eye rubbing
  • Down syndrome
  • Vernal keratoconjunctivitis
  • Connective-tissue disorders

Clinical features

• Progressive diminution of vision
• Frequent change of spectacles
• Increasing irregular astigmatism and myopia
• Glare, photophobia, monocular diplopia

Signs

• Conical protrusion of cornea
• Fleischer ring: iron deposition at base of cone
• Vogt striae: fine vertical stromal lines that disappear on pressure
• Munson sign: V-shaped indentation of lower lid on downgaze
• Oil-droplet reflex on retinoscopy
• Scissoring reflex on retinoscopy
• Acute hydrops due to rupture of Descemet’s membrane may occur.

Investigations

• Keratometry
• Corneal topography or tomography
• Pachymetry for corneal thickness

Treatment

1. Spectacles in early disease
2. Rigid gas-permeable contact lens for irregular astigmatism
3. Corneal collagen cross-linking to halt progression
4. Intracorneal ring segments in selected cases
5. Deep anterior lamellar keratoplasty or penetrating keratoplasty in advanced disease/scarring

7. HSV Keratitis and Herpes Zoster Ophthalmicus

A. Herpes Simplex Virus Keratitis

Etiology

Clinical features

• Pain, photophobia, watering and blurred vision
• Corneal sensation is reduced
• Conjunctival congestion

Corneal manifestations

1. Epithelial keratitis
   • Punctate epithelial lesions
   • Dendritic ulcer with branching pattern and terminal bulbs
   • Stains with fluorescein
   • Geographic ulcer in severe disease
2. Stromal keratitis
   • Disciform keratitis
   • Stromal edema, keratic precipitates, reduced vision
3. Endotheliitis and anterior uveitis

Treatment

• Epithelial disease: topical antiviral or oral antiviral therapy.
• Debridement may be considered in selected epithelial lesions.
• Stromal disease: topical corticosteroid only under antiviral cover and specialist supervision.
• Topical steroids are contraindicated in active epithelial dendritic ulcer.

B. Herpes Zoster Ophthalmicus

Definition

Clinical features

• Severe unilateral pain followed by vesicular rash over forehead, upper lid and scalp.
• Rash does not cross the midline.
• Lid edema, conjunctivitis, episcleritis, keratitis, uveitis and secondary glaucoma may occur.
• Hutchinson sign: vesicles on tip or side of nose, indicating nasociliary nerve involvement and increased risk of ocular complications.

Ocular manifestations

• Punctate epithelial keratitis
• Pseudodendritic keratitis
• Stromal keratitis
• Anterior uveitis
• Raised IOP
• Corneal hypoesthesia and neurotrophic keratopathy

Treatment

• Prompt systemic antiviral therapy, ideally early in disease.
• Analgesics and treatment of post-herpetic neuralgia.
• Lubricants.
• Topical steroid and cycloplegic for stromal keratitis/uveitis under ophthalmic supervision.
• Treat raised IOP if present.

8. Thyroid Ophthalmopathy

Definition

Pathogenesis

• Enlargement of extraocular muscles
• Accumulation of glycosaminoglycans
• Orbital fat expansion
• Proptosis, restricted ocular movements and optic nerve compression in severe cases

Clinical features

Symptoms

• Foreign-body sensation
• Watering, photophobia and redness
• Diplopia
• Cosmetic prominence of eyes
• Reduced vision in severe disease

Signs

• Lid retraction
• Lid lag on downgaze
• Stare and infrequent blinking
• Proptosis or exophthalmos
• Conjunctival congestion and chemosis
• Restrictive myopathy, commonly inferior rectus involvement causing limitation of elevation
• Diplopia
• Exposure keratopathy
• Raised IOP, especially in upgaze
• Compressive optic neuropathy in severe disease

Investigations

• Thyroid function tests: T3, T4 and TSH
• Thyroid autoantibodies where required
• Visual acuity, color vision and visual fields
• Exophthalmometry
• CT or MRI orbit: enlarged extraocular muscle bellies with tendon sparing

Management

1. Achieve euthyroid state and advise smoking cessation.
2. Lubricant drops and ointment for exposure symptoms.
3. Prisms for diplopia in selected patients.
4. Systemic corticosteroids or other immunomodulatory treatment for active moderate-to-severe disease.
5. Urgent orbital decompression for dysthyroid optic neuropathy or severe exposure keratopathy.
6. After disease becomes inactive:
   • Orbital decompression
   • Squint surgery
   • Eyelid surgery, in that order

9. Cataract Surgeries and Types

1. Intracapsular cataract extraction (ICCE)

• Entire lens with capsule is removed.
• Large incision is needed.
• No posterior capsular support for posterior chamber IOL.
• Now rarely performed.
• May be used in selected cases of subluxated lens.

2. Extracapsular cataract extraction (ECCE)

• Anterior capsule is opened.
• Lens nucleus and cortex are removed.
• Posterior capsule is retained.
• Allows implantation of posterior chamber IOL.
• Requires a relatively large incision and sutures.

3. Manual small-incision cataract surgery (MSICS)

• Self-sealing sclero-corneal tunnel incision.
• Nucleus is delivered manually.
• Posterior chamber IOL is implanted in capsular bag.
• Common, economical, and useful for dense mature cataracts.

4. Phacoemulsification

• Most common modern technique.
• A small corneal incision is made.
• Lens nucleus is emulsified using ultrasound and aspirated.
• Foldable posterior chamber IOL is implanted.
• Advantages: small incision, less astigmatism, early visual rehabilitation.

5. Femtosecond laser-assisted cataract surgery

• Laser assists corneal incisions, capsulotomy and lens fragmentation.
• It is an advanced variation of phacoemulsification.

Types of intraocular lenses

• Posterior chamber IOL: most commonly used
• Anterior chamber IOL
• Iris-fixated or iris-claw IOL
• Scleral-fixated IOL
• Monofocal, multifocal, toric, and extended-depth-of-focus IOLs

10. Anatomy of Eyelid, Diagram and Congenital Anomalies

Functions of eyelids

• Protect globe from trauma and excessive light
• Spread tear film during blinking
• Prevent drying of cornea
• Assist tear drainage by lacrimal pump action

Layers of eyelid

1. Skin
2. Subcutaneous areolar tissue
3. Orbicularis oculi muscle
4. Submuscular areolar tissue
5. Fibrous layer:
   • Tarsal plate
   • Orbital septum
6. Retractor layer:
   • Levator aponeurosis and Müller muscle in upper lid
   • Capsulopalpebral fascia in lower lid
7. Palpebral conjunctiva

Lid margin

• Anterior part
  • Eyelashes
  • Glands of Zeis
  • Glands of Moll
• Posterior part
  • Meibomian gland openings
  • Mucocutaneous junction

Tarsal glands

• Meibomian glands are modified sebaceous glands embedded in tarsal plate.
• Their secretion contributes to the lipid layer of tear film.

Blood supply

• Medial and lateral palpebral branches form marginal and peripheral arterial arcades.

Nerve supply

• Sensory: ophthalmic and maxillary divisions of trigeminal nerve.
• Motor:
  • Facial nerve supplies orbicularis oculi.
  • Oculomotor nerve supplies levator palpebrae superioris.
  • Sympathetic supply to Müller muscle.

Congenital eyelid anomalies

1. Congenital ptosis
   • Drooping of upper lid due to levator muscle dysgenesis.
   • Can cause amblyopia.
   • Treated by levator resection or frontalis sling depending on levator function.
2. Congenital lid coloboma
   • Full-thickness defect of eyelid, commonly upper lid.
   • May be associated with facial syndromes.
   • Requires surgical repair.
3. Epicanthus
   • Vertical skin fold over medial canthus.
   • May produce pseudostrabismus.
4. Epiblepharon
   • Extra fold of skin and orbicularis causes lashes to turn inward, usually in lower lid.
   • Often improves with growth; surgery if cornea is affected.
5. Blepharophimosis syndrome
   • Narrow horizontal palpebral fissures, ptosis, epicanthus inversus, and telecanthus.
   • Requires staged surgical correction.
6. Cryptophthalmos
   • Rare condition in which eyelid folds fail to develop and skin passes continuously over the globe.

10-Mark Answers: MBBS Ophthalmology

1. Corneal Ulcer

Definition

Etiology

A. Infective causes

1. Bacterial
   • Staphylococcus aureus
   • Streptococcus pneumoniae
   • Pseudomonas aeruginosa
   • Moraxella
2. Fungal
   • Aspergillus
   • Fusarium
   • Candida
3. Viral
   • Herpes simplex virus
   • Varicella-zoster virus
4. Protozoal
   • Acanthamoeba, especially in contact-lens users.

B. Predisposing factors

• Trauma, especially with vegetative matter
• Contact-lens wear and poor lens hygiene
• Corneal foreign body or abrasion
• Chronic dacryocystitis
• Blepharitis, trichiasis, entropion
• Lagophthalmos and exposure keratopathy
• Dry eye and neurotrophic cornea
• Use of topical corticosteroids
• Diabetes mellitus, malnutrition, and immunosuppression
• Previous corneal disease or surgery

Clinical Features

Symptoms

• Pain
• Redness
• Watering
• Photophobia
• Blepharospasm
• Foreign-body sensation
• Purulent discharge
• Diminution of vision

Signs

• Lid edema and blepharospasm
• Circumcorneal or ciliary congestion
• Epithelial defect staining with fluorescein
• White, yellow, or gray stromal infiltrate
• Corneal edema and stromal necrosis
• Mucopurulent discharge
• Anterior chamber reaction with cells and flare
• Hypopyon in severe ulcer
• Raised intraocular pressure may occur
• Descemet folds in severe inflammation

Clinical Types and Their Features

Investigations

1. Visual acuity testing.
2. Slit-lamp examination
   • Size, site, depth, margins, and base of ulcer
   • Degree of stromal infiltrate and thinning
   • Presence of hypopyon and anterior uveitis
3. Fluorescein staining to delineate epithelial defect.
4. Corneal scraping before antimicrobial therapy, especially in large, central, deep, atypical, or nonresponsive ulcers.
5. Smear examination:
   • Gram stain for bacteria
   • KOH wet mount for fungi
   • Giemsa stain where required
6. Culture and sensitivity on suitable media.
7. Culture the contact lens, lens case, and solution in contact lens-associated ulcers.
8. Measure intraocular pressure, if safe.

Treatment

A. General Measures

• Treat as an ophthalmic emergency.
• Stop contact-lens use immediately.
• Do not patch the eye.
• Do not use topical corticosteroids in an untreated infective ulcer.
• Obtain corneal scrapings before treatment where indicated.
• Daily follow-up is needed in severe ulcers.
• Admit if ulcer is large, central, progressive, associated with hypopyon, thinning, perforation, or poor compliance.

B. Medical Treatment

1. Bacterial ulcer

• Intensive topical broad-spectrum antibiotics.
• Mild peripheral ulcer: topical fluoroquinolone, for example moxifloxacin.
• Severe or central ulcer: fortified antibiotics, such as:
  • Fortified cephalosporin for Gram-positive organisms
  • Fortified aminoglycoside for Gram-negative organisms
• Initially, drops may be administered hourly, then tapered according to response and culture report.

2. Fungal ulcer

• Topical natamycin 5% for filamentous fungi.
• Topical amphotericin B for Candida keratitis.
• Systemic antifungal therapy may be required in deep or refractory ulcers.
• Treatment is usually prolonged.

3. Herpes simplex epithelial keratitis

• Topical or oral antiviral therapy.
• Do not use topical steroids in active dendritic epithelial keratitis.

4. Acanthamoeba keratitis

• Prolonged antiamoebic treatment with biguanides and diamidines under specialist supervision.

C. Supportive Treatment

• Cycloplegic, such as homatropine or atropine, to relieve ciliary spasm and prevent posterior synechiae.
• Oral analgesics.
• Antiglaucoma drugs if IOP is raised.
• Treat associated blepharitis, dacryocystitis, trichiasis, dry eye, or lid abnormality.

D. Surgical Treatment

• Impending perforation
• Corneal perforation
• Uncontrolled progressive ulcer
• Nonhealing ulcer
• Dense corneal scar after healing

• Cyanoacrylate tissue adhesive with bandage contact lens for small perforation
• Amniotic membrane graft in selected cases
• Therapeutic penetrating keratoplasty in perforation or uncontrolled infection
• Optical keratoplasty later for visually significant corneal opacity

Complications

• Corneal scar and opacity
• Irregular astigmatism
• Descemetocele
• Corneal perforation
• Iris prolapse
• Adherent leukoma
• Anterior synechiae
• Secondary glaucoma
• Endophthalmitis or panophthalmitis
• Permanent loss of vision

Diagram to Draw

• Corneal ulcer
• Epithelial defect
• Stromal infiltrate
• Corneal edema
• Hypopyon
• Ciliary congestion

2. Anatomy of Anterior Chamber Angle and Acute Angle-Closure Glaucoma

A. Anatomy of the Anterior Chamber Angle

Definition

Structures Seen on Gonioscopy

1. Schwalbe’s line
   • Peripheral termination of Descemet’s membrane.
   • Appears as a fine glistening line.
2. Trabecular meshwork
   • Lies posterior to Schwalbe’s line.
   • Has anterior non-pigmented and posterior pigmented portions.
   • The posterior pigmented trabecular meshwork is the main site of aqueous drainage.
3. Scleral spur
   • White circumferential ridge posterior to trabecular meshwork.
   • Site of attachment of longitudinal fibres of ciliary muscle.
4. Ciliary body band
   • Gray-brown band posterior to scleral spur.
   • Represents anterior surface of ciliary body.
5. Root of iris
   • Most posterior structure of the angle.
   • Peripheral anterior synechiae may form here in angle-closure glaucoma.

Aqueous Drainage Pathway

Examination

• The angle is examined by gonioscopy.
• A narrow angle may be identified by slit-lamp assessment, Van Herick method, and gonioscopy.
• Gonioscopy is the definitive method for assessing angle openness and angle structures.

Diagram to Draw

B. Acute Angle-Closure Glaucoma

Definition

Predisposing Factors

• Age above 40 years
• Female sex
• Hypermetropia
• Short axial length and small eye
• Shallow anterior chamber
• Thick or anteriorly positioned lens
• Narrow angle in fellow eye
• Family history
• Asian and Inuit ancestry
• Emotional stress
• Dim illumination
• Pharmacological mydriasis
• Anticholinergic and sympathomimetic drugs

Etiopathogenesis

1. Pupillary Block Mechanism

• Aqueous humour normally flows from posterior chamber through pupil into anterior chamber.
• In susceptible eyes, contact between the lens and posterior iris obstructs flow at the pupil.
• Pressure rises in posterior chamber.
• Peripheral iris bows forwards, called iris bombe.
• The peripheral iris blocks the trabecular meshwork.
• Aqueous outflow is obstructed.
• IOP rises rapidly.

2. Plateau Iris Mechanism

• Anteriorly placed ciliary processes push peripheral iris forward.
• Angle may remain narrow even after peripheral iridotomy.

Clinical Features

Symptoms

• Sudden severe ocular pain
• Headache, usually frontal
• Blurring of vision
• Coloured halos around lights
• Red eye
• Nausea and vomiting
• Abdominal pain may occur and can mimic acute abdomen

Signs

• Visual acuity is decreased
• Marked circumcorneal congestion
• Corneal edema causing hazy cornea
• Shallow anterior chamber
• Fixed, vertically oval, mid-dilated pupil
• Iris atrophy may be present later
• Markedly raised IOP, often 40-60 mmHg or more
• Globe feels hard on digital palpation
• Closed angle on gonioscopy
• Optic disc hyperemia and later glaucomatous cupping, if prolonged

Differential Diagnosis

• Acute anterior uveitis
• Acute conjunctivitis
• Keratitis or corneal ulcer
• Endophthalmitis
• Migraine
• Acute gastrointestinal disease due to vomiting

Management

1. Immediate Treatment

Reduce IOP

• Topical beta-blocker, such as timolol, unless contraindicated.
• Topical alpha-2 agonist, such as brimonidine.
• Topical carbonic anhydrase inhibitor, such as dorzolamide.
• Oral or intravenous acetazolamide, if not contraindicated.
• Intravenous mannitol in severe cases or when IOP is markedly elevated.

Produce Miosis

• Pilocarpine is given after IOP starts falling.
• It may be ineffective initially when the iris sphincter is ischemic due to very high IOP.

Control Inflammation and Pain

• Topical corticosteroid to control anterior chamber inflammation.
• Cycloplegic may be used in selected cases after ophthalmic assessment.
• Analgesics and antiemetics.

Additional Measures

• Laser peripheral iridoplasty may be used if the angle remains closed, including plateau iris or an attack not responding adequately to initial therapy.
• Anterior chamber paracentesis may be considered in selected emergency situations by an ophthalmologist.

2. Definitive Treatment

Laser Peripheral Iridotomy

• Creates a small opening in peripheral iris.
• Bypasses pupillary block by allowing aqueous to pass directly from posterior to anterior chamber.
• It is the definitive treatment in primary pupillary-block angle closure.
• Performed after corneal clarity improves enough for laser treatment.

Surgical Peripheral Iridectomy

• Used when laser iridotomy cannot be performed.

Lens Extraction

• Considered in lens-related crowding, cataract, or persistent angle closure.

Treatment of Fellow Eye

• The fellow eye is usually anatomically predisposed.
• Prophylactic laser peripheral iridotomy is generally indicated in the fellow phakic eye.

Complications

• Peripheral anterior synechiae
• Chronic angle-closure glaucoma
• Iris atrophy
• Glaucomatous optic atrophy
• Permanent visual-field loss
• Blindness

Diagram to Draw

• Shallow anterior chamber
• Forward bowing of peripheral iris
• Iris bombe
• Blocked trabecular meshwork
• Lens
• Raised pressure in posterior chamber