1. Atropine eye drops
   • Antimuscarinic mechanism, cycloplegia and mydriasis
   • Indications: cycloplegic refraction, anterior uveitis, amblyopia penalisation, and low-dose myopia control
   • Preparations, effects, adverse effects, contraindications, and patient counselling
2. Corticosteroid eye drops
   • Agents and relative potency
   • Indications in anterior-segment inflammation
   • Dosing, tapering, monitoring, and adverse effects, especially raised intraocular pressure, cataract, delayed healing, and infection risk
   • Situations in which steroids are unsafe, including suspected epithelial herpes simplex keratitis
3. Proptosis
   • Definition and distinction from pseudoproptosis
   • Orbital anatomy, causes by age and time course, including thyroid eye disease, orbital cellulitis, tumor, vascular lesions, and trauma
   • Examination, red flags, imaging, investigation, and emergency management

1. Atropine Eye Drops

Classification and mechanism

• Drug class: Antimuscarinic (parasympatholytic), long-acting mydriatic and cycloplegic.
• Action: Blocks muscarinic receptors in:
  • Iris sphincter muscle → pupil dilatation (mydriasis)
  • Ciliary muscle → loss of accommodation (cycloplegia)
• It also reduces painful ciliary-muscle spasm in anterior uveitis and corneal disease.

Main ophthalmic uses

1. Cycloplegic refraction
   • Particularly useful in children, latent hypermetropia, accommodative esotropia, and suspected pseudomyopia.
   • Stronger and longer acting than cyclopentolate.
2. Anterior uveitis / iridocyclitis
   • Relieves photophobia and pain from ciliary spasm.
   • Prevents or breaks early posterior synechiae by keeping the pupil dilated.
   • Used along with treatment directed at the cause and topical anti-inflammatory therapy.
3. Amblyopia penalisation
   • Blurring accommodation in the better-seeing eye can encourage use of the amblyopic eye.
4. Myopia control
   • Low-concentration atropine is used in selected children to slow myopia progression. A recent systematic review found dose-dependent differences in efficacy; treatment choice and follow-up should be individualized by an eye specialist (2026 review and meta-analysis).

Preparations and duration

• Commonly available as 0.5% or 1% drops, and ointment in some settings.
• Atropine 1% produces profound cycloplegia and has a long duration:
  • Mydriasis may last about 7 to 10 days
  • Cycloplegia may persist for up to 2 weeks
• This long action makes it less convenient for routine adult refraction.

Adverse effects

Local

• Stinging, redness, allergic blepharoconjunctivitis
• Photophobia due to mydriasis
• Blurred near vision due to cycloplegia
• May precipitate acute angle-closure glaucoma in anatomically predisposed eyes

Systemic anticholinergic effects

• Dry mouth, flushing, fever
• Tachycardia
• Irritability, confusion, hallucinations
• Urinary retention

Contraindications / precautions

• Narrow anterior chamber angle or known angle-closure glaucoma, unless prescribed under specialist supervision
• Use cautiously in infants, elderly patients, and those susceptible to systemic anticholinergic effects
• Do not use for a red, painful eye without assessment, since pupil dilatation may mask or worsen angle closure.

Patient advice

• Blurred near vision and light sensitivity are expected.
• Wear sunglasses outdoors.
• Press the inner corner of the eye, over the lacrimal sac, for 1 to 2 minutes after instillation to reduce systemic absorption.
• Seek urgent review for severe eye pain, headache, halos around lights, vomiting, or sudden visual reduction.

2. Corticosteroid Eye Drops

Common preparations

Mechanism of action

• Suppress phospholipase A2 activity and reduce prostaglandin and leukotriene formation.
• Reduce vascular permeability, cellular infiltration, and cytokine-mediated inflammation.
• Control ocular inflammation but do not treat the underlying infection.

Indications

• Anterior uveitis / iridocyclitis
• Postoperative inflammation after cataract or other anterior-segment surgery
• Allergic or immune-mediated ocular surface inflammation
• Episcleritis and selected cases of scleritis, usually with specialist oversight
• Marginal keratitis and sterile inflammatory keratitis
• Chemical injury, after specialist assessment
• Adjunctive treatment in selected microbial keratitis cases, only after effective antimicrobial therapy has begun and the organism/clinical response is satisfactory. The AAO advises close review and IOP monitoring when topical steroids are started in this setting (AAO corneal guidance).

Principles of use

1. Make the diagnosis first. Never prescribe topical steroid simply for “red eye.”
2. Use adequate frequency initially for significant inflammation, then taper gradually according to response.
3. Monitor:
   • Visual acuity
   • Corneal status
   • Anterior chamber cells and flare
   • Intraocular pressure (IOP)
4. Combine with a cycloplegic, such as atropine or homatropine, when treating painful anterior uveitis.
5. Avoid abrupt cessation after prolonged intensive therapy because rebound inflammation may occur.

Major complications

1. Steroid-induced ocular hypertension and glaucoma

• Steroids can reduce aqueous outflow through the trabecular meshwork, raising IOP.
• Risk is greater with potent preparations, frequent use, longer duration, glaucoma, family history of glaucoma, diabetes, high myopia, and children.
• May be asymptomatic, so IOP measurement is required.

2. Cataract

• Prolonged use may cause posterior subcapsular cataract.

3. Infection and delayed healing

• Delayed epithelial healing.
• Increased susceptibility to bacterial, fungal, and viral infection.
• Can exacerbate fungal keratitis.
• Can worsen or reactivate herpes simplex epithelial keratitis, producing enlargement of dendritic ulcers.

4. Other

• Corneal thinning or melting in vulnerable corneas
• Ptosis, periocular skin changes, allergic reaction

Important contraindications

• Epithelial herpes simplex keratitis: classic dendritic ulcer
• Suspected fungal keratitis
• Undiagnosed corneal ulcer or purulent red eye
• Untreated ocular infection
• Significant corneal epithelial defect, unless the indication is clear and monitoring is close

Red-flag rule

3. Proptosis

Definition

• Exophthalmos is often used when the proptosis is caused by thyroid eye disease.
• Pseudoproptosis is apparent prominence without a true forward displacement, for example:
  • High axial myopia
  • Contralateral enophthalmos
  • Large globe
  • Lid retraction
  • Facial asymmetry

Clinical importance

Types and clues

Causes

A. Endocrine

• Thyroid eye disease
  • Autoimmune orbital inflammation with enlargement of extraocular muscles and orbital fat.
  • Features: lid retraction, lid lag, exposure keratopathy, restrictive myopathy, diplopia, and sometimes compressive optic neuropathy.

B. Infective

• Orbital cellulitis
  • Commonly follows sinusitis.
  • Presents with fever, painful swollen eyelids, chemosis, painful or restricted ocular movements, impaired vision, and proptosis.
  • Requires urgent hospital treatment with intravenous antibiotics and imaging.

C. Inflammatory

• Idiopathic orbital inflammation, also called orbital pseudotumor
• Sarcoidosis
• IgG4-related orbital disease

D. Neoplastic

• Lacrimal gland tumors
• Lymphoma
• Cavernous venous malformation
• Optic nerve glioma or meningioma
• Rhabdomyosarcoma in children
• Metastases, including neuroblastoma in children

E. Vascular

• Carotid-cavernous fistula
• Orbital varix
• Lymphangioma / venolymphatic malformation
• Cavernous venous malformation

F. Trauma

• Retrobulbar hemorrhage
• Orbital emphysema

Examination

History

• Onset and progression: acute, subacute, or chronic
• Pain, fever, sinusitis, trauma
• Diplopia and visual loss
• Thyroid symptoms
• Pulsation, bruit, worsening on bending or Valsalva
• Previous malignancy or systemic inflammatory disease

Examination points

• Compare globe prominence from above and below.
• Measure with an exophthalmometer.
• Assess:
  • Visual acuity and colour vision
  • Pupillary reactions, especially relative afferent pupillary defect
  • IOP, including in upgaze if thyroid eye disease is suspected
  • Ocular movements and diplopia
  • Lid position, lagophthalmos, exposure keratopathy
  • Fundus: disc edema, optic atrophy, choroidal folds
  • Direction of displacement:
    • Extraconal mass often displaces globe away from lesion
    • Intraconal mass often causes axial proptosis

Investigations

• Urgent CT orbit and paranasal sinuses for suspected orbital cellulitis, trauma, hemorrhage, or bony disease.
• MRI orbit/brain for soft-tissue lesions, optic nerve disease, orbital apex or cavernous sinus pathology.
• Thyroid function tests and thyroid autoantibodies if thyroid eye disease is suspected.
• CBC, inflammatory markers, cultures where infection is suspected.
• Biopsy for unexplained, progressive, or suspected neoplastic lesions.

Emergency red flags

• Reduced visual acuity or colour vision
• Relative afferent pupillary defect
• Severe pain or headache
• Marked restriction of eye movements
• Fever with lid edema
• Corneal exposure or ulceration
• Raised IOP
• Acute onset after trauma
• Tense orbit or rapidly worsening proptosis

Management principles

• Treat the cause, not proptosis alone.
• Orbital cellulitis: admission, IV antibiotics, ENT involvement, serial visual monitoring, and surgery if abscess or deterioration.
• Retrobulbar hemorrhage with optic nerve compromise: immediate orbital decompression, commonly lateral canthotomy and cantholysis, without delaying for imaging.
• Thyroid eye disease: smoking cessation, lubrication and corneal protection, control of thyroid status, prism or surgery for stable diplopia, immunomodulatory treatment or decompression for active or sight-threatening disease.
• Tumor/vascular lesion: imaging-directed referral to orbital specialist, with biopsy or definitive treatment as indicated.

Quick comparison: orbital cellulitis vs preseptal cellulitis