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Ocular Infections medical comic

This comic maps the eye as a battlefield, from the conjunctiva to the retina. It works through bacterial, chlamydial, viral, parasitic and fungal eye infections, linking each to its anatomical target, its history clue and its treatment, and flags the emergencies that threaten sight.

For MBBS, NEET-PG, FMGE, NEXT and USMLE revision.

Ocular infections: what the comic covers

High-yield points

  • Anatomy first: conjunctivitis, keratitis (cornea), uveitis, retinitis and endophthalmitis each have different causes; conjunctivitis is the commonest.
  • Hyperacute purulent conjunctivitis from Neisseria gonorrhoeae can perforate the cornea quickly and needs ceftriaxone.
  • Chlamydia trachomatis serotypes A–C cause trachoma, a leading infectious cause of blindness, controlled by the WHO SAFE strategy; serotypes D–K cause inclusion conjunctivitis.
  • Bacterial keratitis is a painful corneal ulcer, sometimes with hypopyon; Pseudomonas is the danger in contact lens wearers.
  • Endophthalmitis after surgery usually comes from the patient's own skin flora and needs intravitreal antibiotics.
  • Orbital cellulitis — proptosis, pain on eye movement and reduced vision — is an emergency, unlike preseptal cellulitis.
  • Adenovirus causes epidemic keratoconjunctivitis and pharyngoconjunctival fever; HSV gives dendritic corneal ulcers; CMV retinitis ('pizza pie' fundus) occurs in AIDS with CD4 below 50.
  • Acanthamoeba keratitis follows poor contact lens hygiene and causes pain out of proportion with a ring infiltrate; Toxoplasma causes chorioretinitis; Onchocerca causes river blindness; fungal keratitis follows injury with plant matter.

Mnemonics from the comic

  • Gonococcal conjunctivitis: Gonorrhoea is gone through the cornea in a flash — treat fast with ceftriaxone.
  • Adenovirus: A-deno goes on a boat (shipyard eye) and gets a sore throat (pharyngoconjunctival fever).
  • Discharge clue: Pus = bacteria, water = virus, wood = fungi.

Quick questions

How do you tell orbital cellulitis from preseptal cellulitis?

Orbital cellulitis lies behind the orbital septum and causes proptosis, pain on eye movement, restricted movement and reduced vision. It is an emergency needing admission and IV antibiotics. Preseptal cellulitis affects only the eyelid tissues in front of the septum.

What causes a dendritic corneal ulcer?

Herpes simplex virus keratitis. The branching ulcer stains with fluorescein.

Which eye infection is linked to contact lenses and tap water?

Acanthamoeba keratitis, which causes severe pain and a ring-shaped corneal infiltrate. Pseudomonas keratitis is the main bacterial risk for contact lens wearers.

Is this comic free to read?

The first pages are free to preview. Members read the full comic, and you can sign up free to read one comic in full.

Read next

From the blog

Topic map: Ocular infections in 7 branches

  1. Conjunctivitis
    • Discharge tells the cause
    • Commonest: adenovirus
    • Gonococcal: hyperacute
    • Ophthalmia neonatorum
    • Adenovirus syndromes
    • Acute haemorrhagic conjunctivitis
  2. Trachoma
  3. Keratitis
  4. Deeper infections
  5. Retina in HIV
  6. Parasites
  7. Key treatments

29 points, each linked to its comic page. Guests open the first branch; a free account opens two; Hero and Superhero members open the whole map.

Practice MCQs (34 questions, NEET-PG and USMLE style)

Question 1 (NEET-PG style)

Inflammation of the iris and ciliary body is called:

  1. Choroiditis
  2. Iridocyclitis (anterior uveitis)
  3. Retinitis
  4. Scleritis

Answer: B. Iridocyclitis (anterior uveitis)

The uvea has three parts: iris, ciliary body and choroid. Inflammation of the iris and ciliary body is iridocyclitis, or anterior uveitis; inflammation of the choroid is choroiditis (posterior uveitis), which often occurs with retinitis as chorioretinitis. The comic's map of the eye places each infection by its target: adnexa (blepharitis, stye, dacryocystitis), conjunctiva (conjunctivitis, the commonest), cornea (keratitis), uvea (uveitis), retina (retinitis) and the inside of the globe (endophthalmitis).

Question 2 (USMLE style)

A 35-year-old woman has had a red right eye for 2 days. Which of the following findings most strongly suggests a sight-threatening condition that needs urgent ophthalmology review rather than treatment as simple conjunctivitis?

  1. Mucopurulent discharge
  2. Lashes stuck together on waking
  3. A gritty feeling in the eye
  4. Redness that has spread to both eyes
  5. Reduced visual acuity with marked photophobia

Answer: E. Reduced visual acuity with marked photophobia

Conjunctivitis, the commonest eye infection, involves only the conjunctiva, the eye's outer coat, so vision is normal and pain is mild. Reduced visual acuity, marked photophobia, severe pain, a corneal opacity, a small or irregular pupil, or a hypopyon suggest disease of the cornea (keratitis), uvea or inside the eye (endophthalmitis), or acute glaucoma, all of which can threaten sight. Discharge, crusting, grittiness and spread to the other eye are typical of conjunctivitis. Comic mnemonic: conjunctiva is the coat, cornea is the clear window, uvea is underneath, retina is the receptor.

Practice questions written by Q World Medical Comics. Not affiliated with NBEMS, NBME or the USMLE program.

High-yield flash cards (41 cards)

Discharge clue to the cause of conjunctivitis
Purulent discharge suggests bacteria; watery discharge suggests a virus; itchy with stringy mucus suggests allergy; plant or vegetable injury suggests fungal keratitis — Mnemonic: pus = bacteria, water = virus, wood = fungi.
Commonest cause of conjunctivitis overall
Viral, mainly adenovirus; commonest bacterial causes are Staphylococcus aureus, Streptococcus pneumoniae, Haemophilus influenzae and Moraxella
Hyperacute purulent conjunctivitis: cause and danger
Neisseria gonorrhoeae — profuse pus, chemosis and lid swelling; it can penetrate an intact cornea and perforate it within 24–48 hours; needs IM ceftriaxone plus eye irrigation — Mnemonic: gonorrhoea is gone through the cornea in a flash.

Flip, rate and review with spaced repetition. Guests can study the first 3 cards; a free account unlocks 5 and saves your progress; Hero and Superhero members study every card.

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