Final Professional MBBS — Ophthalmology (complete, 12 chapters). Explanation-first answers with anatomical, optics, neuro & public-health diagrams, classifications, comparison tables, drug doses, clinical pearls and key-point recaps from Khurana's Comprehensive Ophthalmology, Parsons' Diseases of the Eye and Park's PSM.
12chapters144questions39High-Yield
THE CONCEPT
A chemical burn of the eye is a true ophthalmic emergency in which the single most important action — immediate, copious irrigation — must be taken before any formal assessment, because every minute of contact causes further, potentially irreversible damage. Crucially, alkalis are more dangerous than acids.
Blanched limbus(ischaemia → poor prognosis)
Perfused (pink) vessels
Extent of limbal ischaemia (clock hours) grades severity (Roper–Hall)
Chemical (alkali) burn with limbal ischaemia: the perilimbal blood vessels are blanched white over part of the limbus. The extent of limbal ischaemia (in clock hours) is the key prognostic factor, since the limbus houses the stem cells that heal the cornea.
ACID versus ALKALI
Alkalis (lime/plaster, ammonia, drain cleaner, cement) — more dangerous: they cause liquefactive necrosis and penetrate rapidly and deeply (into the anterior chamber, damaging the lens, ciliary body and drainage angle), so the injury continues after exposure.
Acids (sulphuric, battery acid) — usually less severe: they cause coagulative necrosis, and the coagulated surface proteins form a barrier that limits deeper penetration (except very strong acids and hydrofluoric acid).
MECHANISM & GRADING
The chemical destroys the corneal and conjunctival epithelium, the crucial limbal stem cells (whose loss prevents corneal healing and leads to conjunctivalisation of the cornea), and the perilimbal blood vessels (producing limbal ischaemia). The extent of limbal ischaemia is the key prognostic factor, and the Roper–Hall grading combines corneal haze with the clock-hours of limbal ischaemia to predict outcome.
MANAGEMENT
WHY ALKALIS ARE SO DANGEROUS
The reason alkalis are singled out as the worst chemical injuries lies in their chemistry. An alkali saponifies the fatty cell membranes and causes liquefactive necrosis, which — unlike the coagulated barrier an acid produces — does not stop the chemical; instead it opens a path for it to keep penetrating. The alkali therefore drives deep into the cornea and anterior chamber within minutes, damaging not only the surface but the lens, ciliary body and trabecular meshwork, and its effect continues long after the initial contact. This explains two clinical rules: that irrigation must be immediate and prolonged (to remove the ongoing reservoir of alkali), and that an alkali burn which looks deceptively 'white and quiet' may actually be severe, because blanching of the vessels signifies deep ischaemic damage rather than healing.
THE CENTRAL ROLE OF LIMBAL STEM CELLS
Understanding the limbal stem cells explains why limbal ischaemia dominates the prognosis. The corneal epithelium is continuously renewed by stem cells located at the limbus (the corneo-scleral junction); these cells also form a 'barrier' that stops conjunctival tissue growing onto the cornea. When a chemical injury destroys the limbal stem cells, the cornea cannot re-epithelialise normally, and conjunctival tissue with its blood vessels grows over it ('conjunctivalisation'), leaving a scarred, vascularised, opaque surface. This is why the extent of limbal (perilimbal vessel) ischaemia is the key prognostic sign, why severe burns need limbal stem-cell transplantation, and why simply grafting a clear cornea onto a stem-cell-deficient eye fails — the new cornea has no stem cells to maintain it.
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DANGER / REMEMBER:Irrigate immediately — before anything else — with copious water or saline for a prolonged period, everting the lids and removing any particulate matter (e.g. lime), and continuing until the pH is neutral (~7).
Subsequent treatment includes topical antibiotics, a cycloplegic, early topical steroids (to control inflammation), ascorbate/citrate, generous lubrication and control of intraocular pressure, with amniotic-membrane grafting and later limbal stem-cell transplantation or keratoplasty for severe injuries. Complications include corneal scarring, symblepharon, limbal stem-cell deficiency, glaucoma, dry eye and perforation.
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CLINICAL PEARL: A chemical burn is an emergency → immediate copious irrigation (before assessment) until the pH is neutral. Alkalis are worse than acids (liquefactive, penetrate deeply). Prognosis depends on limbal ischaemia (Roper–Hall grading). Then give antibiotics, steroids, cycloplegic and ascorbate, and watch for symblepharon, stem-cell deficiency and glaucoma.
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KEY POINTS / NUMBERS (viva)
Chemical burn = EMERGENCY → immediate copious irrigation (water/saline) BEFORE assessment, evert lids, remove particles, continue until pH ~7.
ALKALI (lime, ammonia, cement) worse than acid — liquefactive necrosis, deep penetration; acid — coagulative necrosis (self-limiting barrier).
Prognosis ∝ limbal ischaemia (Roper–Hall grading: corneal haze + clock-hours of limbal ischaemia). Then antibiotics, cycloplegic, early steroids, ascorbate/citrate, lubricants, IOP control; amniotic membrane / limbal stem-cell transplant / keratoplasty for severe.
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KEY POINTS TO REMEMBER
Chemical burn = true emergency: irrigate immediately (before assessment) with copious water/saline until pH neutral; evert lids, remove particulate matter.
Alkalis (lime, ammonia, cement) worse than acids — liquefactive necrosis + deep penetration; acids — coagulative necrosis limits penetration.
Damage to epithelium, limbal stem cells (→ failed healing/conjunctivalisation) and perilimbal vessels (limbal ischaemia = key prognostic factor).
Roper–Hall grading uses corneal haze + extent of limbal ischaemia to predict prognosis.
SOURCES: Khurana's Comprehensive Ophthalmology; Parsons' Diseases of the Eye.
THE CONCEPT
A hyphaema is blood in the anterior chamber, most often from blunt ocular trauma (which tears vessels of the iris or ciliary body). It typically settles inferiorly to form a visible fluid level, and it matters chiefly because of its complications — rebleeding, raised intraocular pressure and corneal blood staining.
Blood level (hyphaema) in the anterior chamber
Hyphaema: blood settles inferiorly in the anterior chamber, forming a visible level in front of the iris. It is graded by how much of the chamber it fills.
CAUSES & GRADING
The commonest cause is blunt trauma; others are post-surgical, spontaneous (rubeosis, tumour, blood dyscrasia, anticoagulants) and sickle-cell disease (which behaves worse). It is graded by how much of the anterior chamber the blood fills: microhyphaema (cells only), Grade I (<1/3), Grade II, Grade III, and Grade IV (total — the 'eight-ball' or blackball hyphaema).
MANAGEMENT
Rest with the head elevated (semi-recumbent) so the blood settles inferiorly, away from the visual axis, and clears; avoid strenuous activity.
Shield the eye; give a cycloplegic and topical steroids; avoid aspirin and NSAIDs (they promote bleeding).
Control the intraocular pressure (with caution regarding certain drugs in sickle-cell disease).
Monitor closely for a rebleed (typically days 2–5, and usually worse than the original) and for raised IOP.
Surgical evacuation is indicated for uncontrolled high pressure, a persistent total clot, or early corneal blood staining.
A NOTE ON THE REBLEED & RAISED PRESSURE
The two complications that dominate the management of hyphaema — rebleeding and raised intraocular pressure — deserve emphasis. A secondary bleed, typically between days two and five as the original clot retracts and lyses, is usually larger and more damaging than the first, which is why the eye is rested, shielded and kept free of aspirin/NSAIDs during this window, and reviewed closely. Raised pressure arises when red cells and debris block the trabecular meshwork; it is especially dangerous and harder to control in sickle-cell disease, where sickled cells clog the meshwork and the optic nerve tolerates pressure poorly (and where some pressure-lowering drugs are best avoided). Vigilant monitoring for both complications, and prompt treatment, is what protects vision after a hyphaema.
THE BOTTOM LINE
A hyphaema is blood in the anterior chamber, usually from blunt trauma, that is managed conservatively with rest, shielding and avoidance of anticoagulant drugs while watching vigilantly for the dangerous complications of rebleeding and raised pressure — with a lower threshold for concern in sickle-cell disease.
A NOTE ON THE SICKLE-CELL PROBLEM
Sickle-cell disease (and trait) deserves separate emphasis because it transforms a routine hyphaema into a high-risk one. In the relatively hypoxic, acidotic environment of the anterior chamber, red cells sickle and become rigid, clogging the trabecular meshwork far more readily than normal cells, so the pressure rises easily and is hard to control. At the same time the sickle optic nerve and retina tolerate raised pressure poorly, so even moderate elevations can cause damage, and some pressure-lowering drugs (such as carbonic-anhydrase inhibitors, which can worsen sickling, and hyperosmotics) must be used with caution. For all these reasons, at-risk patients are screened (sickle solubility test/electrophoresis) and managed with a much lower threshold for concern and intervention — a point examiners frequently probe.
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DANGER / REMEMBER:Sickle-cell disease greatly worsens the outlook (red cells sickle in the anterior chamber and raise the pressure, and the optic nerve is vulnerable), so African and other at-risk patients should be screened.
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CLINICAL PEARL: Hyphaema = blood in the anterior chamber, usually from blunt trauma; graded I–IV (IV = 'eight-ball'). Manage with rest and head elevation, an eye shield, a cycloplegic, avoidance of aspirin/NSAIDs and control of the IOP, while monitoring for a rebleed (days 2–5) and raised pressure. Operate for uncontrolled IOP or corneal staining. Sickle-cell disease worsens it — screen for it.
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KEY POINTS / NUMBERS (viva)
Hyphaema = blood in the anterior chamber; usually blunt trauma (also post-op, spontaneous, sickle cell).
Grading: microhyphaema (cells) → I (<1/3) → II → III → IV (total = 'eight-ball'/blackball).
Manage: rest + head elevation, eye shield, cycloplegic, topical steroids, avoid aspirin/NSAIDs, control IOP; monitor rebleed (days 2–5) + IOP; surgery for uncontrolled IOP/corneal staining/persistent clot. Sickle cell = worse (screen).
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KEY POINTS TO REMEMBER
Hyphaema = blood in the anterior chamber, usually from blunt trauma (iris/ciliary vessel tear); settles to a visible level.
Grades: microhyphaema → I (<1/3) → II → III → IV (total, 'eight-ball'/blackball).
Manage: rest + head elevation, eye shield, cycloplegic, topical steroids; avoid aspirin/NSAIDs; control IOP.
Monitor for rebleed (days 2–5, often worse) and raised IOP; surgical evacuation for uncontrolled IOP, persistent total clot, or corneal blood staining.
Sickle-cell disease worsens the outlook (sickling in the AC, optic-nerve vulnerability) — screen at-risk patients.
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SOURCES: Khurana's Comprehensive Ophthalmology.
THE CONCEPT
Mechanical ocular injuries are classified by whether the eye wall is breached: a closed-globe (blunt/contusion) injury leaves the wall intact, whereas an open-globe injury involves a full-thickness wound of the eye wall and is a surgical emergency.
Corneal laceration
Peaked pupil(iris drawn to wound)
Seidel +(aqueous leak)
Signs of an open globe: a full-thickness corneal laceration, a 'peaked' (teardrop) pupil drawn toward the wound by prolapsing iris, and a positive Seidel test (aqueous leaking through the wound, seen streaming through fluorescein).
CLOSED-GLOBE (BLUNT/CONTUSION) INJURIES
Blunt force can damage the eye from front to back: lid ecchymosis (a 'black eye'); corneal abrasion or oedema; hyphaema, traumatic mydriasis, iridodialysis and angle recession (which causes late glaucoma); Vossius ring, traumatic cataract and lens subluxation/dislocation; and posteriorly commotio retinae (Berlin's oedema), retinal tears/detachment, vitreous haemorrhage, choroidal rupture and traumatic optic neuropathy. Very severe force may cause a globe rupture at a weak point.
OPEN-GLOBE INJURIES
These are subdivided into penetrating (an entry wound only), perforating (entry and exit wounds), rupture (blunt force bursting the wall) and injuries with an intraocular foreign body. The signs of an open globe are a full-thickness wound, a peaked or distorted pupil (iris prolapsing toward the wound), a shallow or deep anterior chamber, a low intraocular pressure (a 'soft' eye), prolapse of uveal tissue or vitreous, a positive Seidel test (aqueous leaking on fluorescein), reduced vision and a 360° subconjunctival haemorrhage.
MANAGEMENT OF THE OPEN GLOBE
WHY THE OPEN GLOBE MUST NOT BE PRESSED
The cardinal rule in a suspected open globe — never to press on the eye — deserves emphasis because breaking it can be blinding. Once the eye wall is breached, any pressure on the globe (from examination, a tight pad, forced lid-opening, squeezing, vomiting or even crying) can raise the intraocular pressure and extrude the intraocular contents — iris, lens, vitreous or even retina — through the wound, converting a repairable injury into an unsalvageable one. This is why the injured eye is simply covered with a rigid protective shield (not a pad), the patient is kept calm and nil by mouth, and antiemetics are given to prevent the pressure spikes of vomiting. Every step in the pre-operative care of an open globe is designed to keep the intraocular pressure low and the contents inside until the surgeon can close the wound.
A NOTE ON SYMPATHETIC OPHTHALMIA
A distinctive late danger of penetrating eye injury (and of intraocular surgery) is sympathetic ophthalmia — a bilateral granulomatous uveitis in which, weeks to months after a penetrating injury to one eye (the 'exciting' eye), an autoimmune inflammation attacks the uvea of BOTH eyes, including the previously healthy 'sympathising' eye. Its importance is that it can blind the good eye, so it is a key reason to repair penetrating injuries meticulously, and, rarely, to consider enucleation of a blind, badly-disorganised injured eye within the first 1–2 weeks to prevent it. Once established, it is treated with systemic immunosuppression. Awareness of this complication underlies the careful follow-up of every penetrating ocular injury.
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DANGER / REMEMBER:Do NOT press on the eye (pressure can extrude the intraocular contents). Protect it with a rigid shield (no pad, no ointment), keep the patient nil by mouth, give systemic antibiotics and tetanus prophylaxis and antiemetics (to avoid a Valsalva), and arrange CT imaging (not MRI, if a metallic foreign body is possible) to localise any intraocular foreign body, followed by urgent surgical repair. Watch for endophthalmitis and sympathetic ophthalmia.
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CLINICAL PEARL: Classify trauma as closed-globe (blunt — hyphaema, angle recession, commotio retinae, lens injury) or open-globe (a full-thickness wound). Open-globe signs: a peaked pupil, a soft eye (low IOP), uveal/vitreous prolapse and a positive Seidel test. Manage the open globe by shielding it (no pressure, no pad), keeping the patient nil by mouth, giving systemic antibiotics and tetanus, CT to localise any foreign body (not MRI if metal) and urgent repair; beware endophthalmitis and sympathetic ophthalmia.
Open-globe management: don't press the eye; rigid shield (no pad/ointment), nil by mouth, systemic antibiotics + tetanus, antiemetics, CT (not MRI if metal), urgent surgical repair.
Complications: endophthalmitis and sympathetic ophthalmia.
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SOURCES: Khurana's Comprehensive Ophthalmology; Parsons' Diseases of the Eye.
THE CONCEPT
The 'red eye' is a very common presentation, and the key clinical skill is distinguishing the benign, self-limiting causes from the sight-threatening emergencies. This is done with a handful of discriminating features rather than the redness itself.
Conjunctivitis
diffuse redness,normal pupil/vision
Iritis / keratitis
ciliary flush, small pupil,pain + photophobia
Angle-closure
hazy cornea, mid-dilatedfixed oval pupil
Red flags = reduced vision, pain, photophobia, ciliary flush, abnormal pupil, hazy cornea
Sorting the red eye: conjunctivitis gives diffuse redness with a normal pupil and vision; iritis/keratitis gives a ciliary (circumcorneal) flush with pain; and acute angle-closure gives a hazy cornea with a fixed, mid-dilated oval pupil.
THE DISCRIMINATING FEATURES
Assess: vision (reduced vision is a red flag), pain (a deep ache is serious, whereas grittiness is not), the pattern of redness (diffuse conjunctival injection versus a ciliary/circumcorneal 'flush'), the pupil (size and reaction), the cornea (clarity and fluorescein staining), any discharge, and the intraocular pressure.
COMMON / BENIGN CAUSES
Conjunctivitis (bacterial/viral/allergic) — diffuse redness, discharge, grittiness, with normal vision, pupil and cornea (often bilateral).
Subconjunctival haemorrhage — a painless red patch with normal vision.
Episcleritis — sectoral, mild and self-limiting.
SIGHT-THREATENING CAUSES (red flags)
THE VALUE OF THE CILIARY FLUSH
One physical sign deserves special mention because it so reliably separates trivial from serious red eyes: the ciliary (circumcorneal) flush. In benign conjunctivitis, the redness is diffuse and most marked in the fornices, fading toward the cornea. In serious intraocular or corneal disease (keratitis, anterior uveitis, acute angle-closure), there is instead a deep, violaceous ring of dilated vessels concentrated around the cornea — the ciliary flush — reflecting inflammation of the deeper, cornea-adjacent tissues. Recognising a ciliary flush therefore immediately shifts the diagnosis toward the sight-threatening group and prompts a careful look at the cornea, pupil and intraocular pressure. It is one of the most useful discriminators at the bedside, distinguishing a red eye that can be treated simply from one that needs urgent referral.
ACUTE ANGLE-CLOSURE — THE EMERGENCY NOT TO MISS
Among the red-flag causes, acute angle-closure glaucoma is the one whose recognition is most time-critical, because delayed treatment causes rapid, permanent optic-nerve damage. Its picture is characteristic and worth committing to memory: a severely painful red eye with a hazy (cloudy) cornea, a fixed, mid-dilated, oval pupil, a stony-hard eye on palpation, haloes around lights, and marked systemic upset with nausea and vomiting — which can even mislead toward an abdominal or neurological diagnosis. The mechanism is a sudden closure of the drainage angle with a steep rise in intraocular pressure. Emergency treatment lowers the pressure medically (acetazolamide, topical agents, pilocarpine) and then relieves the block definitively with a laser iridotomy. Because this red eye can blind within hours, it must be identified and referred immediately — the reason it heads the list of sight-threatening red eyes.
A NOTE ON A STRUCTURED APPROACH
Because a red eye can be anything from trivial to blinding, a structured, always-the-same sequence prevents the serious causes being missed. A practical order is to check the vision first (a reduced acuity immediately flags a serious cause), then ask about the character of any pain and photophobia, inspect the pattern of redness (diffuse versus ciliary flush), examine the cornea with fluorescein (for an ulcer or abrasion), assess the pupil (size, shape, reaction), estimate or measure the intraocular pressure, and note any discharge. Running through this same checklist in every red eye ensures that the discriminating features are actively sought rather than assumed, and it reliably separates the patients who can be treated simply from the minority who need same-day specialist care.
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DANGER / REMEMBER: Reduced vision, deep pain and photophobia point to a serious cause: keratitis/corneal ulcer (pain, photophobia, a staining epithelial defect, ciliary flush ± hypopyon — think Pseudomonas/Acanthamoeba in contact-lens wearers); anterior uveitis (iritis) (ciliary flush, a small/irregular pupil, cells and flare); acute angle-closure glaucoma (severe pain, haloes, a hazy cornea, a mid-dilated fixed pupil, a hard eye and vomiting); scleritis (severe boring pain, deep violaceous injection, tenderness); and endophthalmitis (pain, hypopyon, visual loss after surgery/trauma).
THE APPROACH
Work through vision, pain, the pattern of redness, the pupil, the cornea (with fluorescein) and the intraocular pressure, and refer any red-flag features urgently.
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CLINICAL PEARL: A red eye is usually benign (conjunctivitis, subconjunctival haemorrhage, episcleritis — normal vision) but may be sight-threatening. Red flags = reduced vision, pain, photophobia, a ciliary (circumcorneal) flush, an abnormal pupil and a hazy cornea. These point to keratitis/ulcer, anterior uveitis, acute angle-closure glaucoma (haloes, hazy cornea, mid-dilated pupil, hard eye, vomiting), scleritis or endophthalmitis → urgent referral.
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KEY POINTS / NUMBERS (viva)
Assess a red eye by: vision, pain, redness pattern (diffuse vs ciliary flush), pupil, cornea (fluorescein), discharge, IOP.
Approach: assess vision/pain/redness/pupil/cornea (fluorescein)/IOP; refer red flags urgently.
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SOURCES: Khurana's Comprehensive Ophthalmology.
THE CONCEPT
A blow-out fracture is a fracture of the orbital floor (or medial wall) caused by a sudden increase in orbital pressure — typically from a blunt object larger than the orbital opening (a fist or ball). The pressure 'blows out' the thin floor into the maxillary sinus while the orbital rim stays intact, and orbital contents (fat, sometimes the inferior rectus) herniate downward.
'teardrop'
maxillary sinus
orbit (rim intact)
floor fractures
enophthalmos
Orbital blow-out fracture: a blow raises orbital pressure and fractures the thin floor, so orbital fat and the inferior rectus herniate into the maxillary sinus (the 'teardrop' sign), while the orbital rim stays intact — giving diplopia on upgaze, enophthalmos and cheek numbness.
FEATURES
Periorbital bruising and swelling, and surgical emphysema (air tracking in from the sinus, worse on nose-blowing).
Diplopia, especially on vertical gaze — from tethering/entrapment of the inferior rectus (or inferior oblique), giving restricted upgaze.
Enophthalmos — the eye sinks back as the orbital volume increases and contents herniate.
Infraorbital nerve anaesthesia — numbness of the cheek, upper lip and teeth (the nerve runs in the floor).
Restricted movements with a positive forced-duction test (mechanical entrapment).
INVESTIGATION & MANAGEMENT
A CT of the orbit (coronal) shows the floor fracture, the classic 'teardrop' sign of herniated contents hanging into the antrum, and tissue in the maxillary sinus. Management first assesses the globe (to exclude rupture, hyphaema or a retinal injury), advises the patient not to blow the nose, and gives antibiotics if the sinus is involved. Surgical repair (releasing entrapped tissue and repairing the floor with an implant) is indicated for significant enophthalmos, persistent diplopia, a large fracture or muscle entrapment — and urgently for the 'white-eyed blow-out' in children (a trapdoor fracture entrapping the muscle, which can trigger the oculocardiac reflex).
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CLINICAL PEARL: A blow-out fracture is an orbital floor fracture from blunt trauma (the rim staying intact), with contents herniating into the maxillary sinus. Features: diplopia on vertical gaze (inferior-rectus entrapment → restricted upgaze), enophthalmos, infraorbital-nerve numbness (cheek/lip) and emphysema on nose-blowing. CT orbit shows the 'teardrop' sign. Exclude a globe injury first; operate for entrapment, enophthalmos or persistent diplopia — and urgently for a child's 'white-eyed' trapdoor entrapment.
WHY THE FLOOR 'BLOWS OUT' AND WHAT GETS TRAPPED
The mechanism of a blow-out fracture is worth understanding because it explains all the signs. When a blunt object larger than the orbital opening strikes the eye, it cannot enter the orbit but instead compresses its contents and suddenly raises the pressure inside. This pressure is transmitted to the weakest walls — the paper-thin orbital floor and medial wall — which fracture and give way, decompressing the orbit into the maxillary or ethmoid sinus while the strong rim remains intact. As the floor breaks, orbital fat and the inferior rectus (or its connective-tissue sling) can herniate through and become trapped. This trapping is what causes the restricted upgaze and vertical diplopia, while the loss of orbital volume into the sinus causes the enophthalmos — so a single mechanism accounts for the whole clinical picture.
THE PAEDIATRIC 'WHITE-EYED' BLOW-OUT
A vital exception to the usual, unhurried management of blow-out fractures is the paediatric 'white-eyed' trapdoor fracture, which is a surgical emergency. A child's more elastic bone tends to snap open and then spring back ('trapdoor'), tightly entrapping the inferior rectus. The striking feature is that the eye may look deceptively white and quiet (little bruising or swelling) despite a markedly restricted upgaze and severe diplopia, and the entrapped muscle can trigger the oculocardiac reflex — nausea, vomiting, bradycardia and even syncope. Because prolonged entrapment causes ischaemic damage and permanent muscle dysfunction, this requires urgent surgical release within hours, unlike the adult fracture which is often observed for a week or two first. Recognising that a child with minimal signs but a stuck eye needs emergency surgery is a classic, high-stakes teaching point.
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KEY POINTS / NUMBERS (viva)
Blow-out fracture = orbital FLOOR (or medial wall) fracture from blunt trauma raising orbital pressure; rim intact; contents herniate into maxillary sinus.
Features: diplopia on vertical gaze (inferior-rectus entrapment → restricted upgaze), enophthalmos, infraorbital-nerve anaesthesia (cheek/lip/teeth), emphysema on nose-blowing, positive forced duction.
CT orbit (coronal) — floor fracture + 'teardrop' sign. Exclude globe injury first; don't blow nose; antibiotics if sinus involved. Surgery for enophthalmos/persistent diplopia/entrapment; urgent for paediatric 'white-eyed' trapdoor (oculocardiac reflex).
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KEY POINTS TO REMEMBER
Blow-out fracture = orbital floor (or medial wall) fracture from blunt trauma raising orbital pressure; the rim stays intact.
Contents (fat ± inferior rectus) herniate into the maxillary sinus.
CT orbit (coronal): floor fracture + 'teardrop' sign of herniated contents in the antrum.
Assess/exclude globe injury first; don't blow the nose; surgery for enophthalmos/persistent diplopia/entrapment; urgent for the paediatric 'white-eyed' trapdoor fracture (oculocardiac reflex).
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SOURCES: Khurana's Comprehensive Ophthalmology.
THE CONCEPT
Sudden painless loss of vision is an ophthalmic emergency requiring a rapid, structured differential, because several causes are treatable if acted on quickly. The fundus appearance and associated features usually separate them.
THE CAUSES
Central retinal artery occlusion — a pale retina with a cherry-red spot (an emergency).
Central retinal vein occlusion — a 'blood-and-thunder' fundus.
Vitreous haemorrhage — floaters and loss of the red reflex (often diabetic).
Retinal detachment — floaters, flashes and a 'curtain'.
Anterior ischaemic optic neuropathy — a swollen disc with an altitudinal defect (exclude giant cell arteritis).
Wet ARMD — sudden central distortion/loss; and amaurosis fugax (transient loss — a TIA/GCA warning).
ASSESSMENT
Take a focused history (onset, floaters/flashes/curtain, any pain), then check acuity, look for an RAPD, examine the fundus (disc and retina) and measure the IOP, and refer urgently. Distinguish it from sudden painful loss (acute angle-closure, uveitis, keratitis, or optic neuritis with pain on eye movement).
A NOTE ON THE PAINFUL DIFFERENTIAL
It is worth pairing this list with the causes of sudden painful visual loss, because the presence or absence of pain is a powerful early discriminator. Painful sudden loss suggests acute angle-closure glaucoma (with a red, hard eye, haloes and vomiting), anterior uveitis, microbial keratitis, or optic neuritis (pain on eye movement), whereas the classic painless causes are the vascular and retinal events above. Asking about pain, and then examining the front of the eye and the fundus, therefore rapidly narrows a frightening symptom to a manageable differential and directs the urgency of referral.
THE BOTTOM LINE
Sudden painless visual loss is an emergency worked up rapidly by fundus appearance and associated features, spanning CRAO, CRVO, vitreous haemorrhage, retinal detachment, AION and wet ARMD.
A practical safeguard is to remember that some 'sudden' losses are in fact transient — amaurosis fugax, a fleeting curtain of visual loss lasting minutes — which, although the vision recovers, is a serious warning of impending stroke (embolic) or giant cell arteritis and demands urgent vascular and inflammatory work-up rather than reassurance; treating a transient episode as a near-miss can prevent a permanent one.
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KEY POINTS TO REMEMBER
Sudden painless visual loss = emergency; separate the causes by fundus appearance + associated features.
Assess: history, acuity, RAPD, fundus, IOP → urgent referral; distinguish from sudden PAINFUL loss (angle-closure, uveitis, keratitis, optic neuritis).
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SOURCES: Khurana's Comprehensive Ophthalmology.
THE CONCEPT
An intraocular foreign body (IOFB) is a fragment retained inside the eye after a penetrating injury — classically from hammering metal on metal, which sends a small, high-velocity fragment through a tiny, easily-missed entry wound. A high index of suspicion is essential.
PRESENTATION & INVESTIGATION
There is a history of a high-velocity injury, sometimes with minimal symptoms; signs include an entry wound, hyphaema, lens or iris damage and vitreous haemorrhage. Investigation is with CT of the orbit to localise the fragment (NOT MRI if it may be metallic/ferromagnetic — the magnet could move it), plus B-scan ultrasound and X-ray.
COMPLICATIONS & MANAGEMENT
Complications include endophthalmitis (especially with organic/soil contamination — Bacillus), siderosis (from iron), chalcosis (from copper) and retinal detachment. Management is urgent surgical removal (vitrectomy with a magnet or forceps), with antibiotics and tetanus prophylaxis. Always suspect an IOFB after any hammering or high-velocity injury.
A NOTE ON THE MISSED DIAGNOSIS
The greatest danger with an IOFB is that it is simply missed, because the entry wound can be tiny and self-sealing and the patient may have surprisingly little pain or visual disturbance — often continuing to work after a hammering injury. This is why the history of hammering, grinding or any high-velocity metal-on-metal work is treated as a red flag, mandating a careful search for an entry wound and, crucially, imaging (CT) to look for a radio-opaque fragment even when the eye looks near-normal. A retained IOFB left in place risks endophthalmitis and the slow, blinding metallic degenerations, so the emphasis is firmly on suspecting and excluding it.
THE BOTTOM LINE
An intraocular foreign body follows a high-velocity (often hammering) injury, is easily missed, is localised by CT (not MRI if metallic), and needs urgent removal to prevent endophthalmitis and metallic degeneration.
It is also worth noting that the nature of the foreign material guides the risk: iron and copper threaten the slow metallic degenerations, organic and soil-contaminated fragments carry a high risk of aggressive endophthalmitis (notably Bacillus), while inert materials such as glass or certain plastics may occasionally be tolerated — but the default, especially for reactive metals and contaminated material, is prompt removal.
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KEY POINTS TO REMEMBER
IOFB = foreign body retained inside the eye after a penetrating injury; classically hammering metal on metal (small entry wound easily missed).
History of high-velocity injury (may be minimal symptoms); entry wound, hyphaema, lens/iris damage, vitreous haemorrhage.
Localise with CT orbit (NOT MRI if metallic — risk of movement), B-scan, X-ray.
A corneal abrasion is a defect of the corneal epithelium (from a fingernail, a foreign body, trauma or a contact lens). Because the cornea is richly innervated, it is very painful, with photophobia, watering, a foreign-body sensation and redness, and the defect stains with fluorescein.
FOREIGN BODY & EXAMINATION
A corneal foreign body is a particle on or embedded in the cornea; the lids must be everted to find a subtarsal foreign body, which causes vertical linear (ice-rink) abrasions as the lid moves over the cornea.
MANAGEMENT
Management is to remove the foreign body (with a needle or spud under the slit lamp), give a topical antibiotic and a cycloplegic for comfort; most abrasions heal in 24–48 hours. Avoid padding a contact-lens-related or organic injury (infection risk), and never give topical anaesthetic for ongoing use (it is toxic and delays healing). Watch for infection/ulcer, recurrent erosion and a rust ring (from a metallic foreign body — which must be removed).
A NOTE ON WHAT NOT TO DO
Two practical 'don'ts' make corneal-abrasion management safe. First, never send the patient home with topical anaesthetic drops: although they relieve pain instantly, repeated use is toxic to the epithelium, masks worsening disease and can lead to a non-healing 'anaesthetic' ulcer. Second, do not pad or bandage an abrasion associated with a contact lens or organic (vegetable) matter, because the warm, closed environment can encourage a sight-threatening infection (Pseudomonas or fungal keratitis); these are instead treated with antibiotic cover and left unpadded. Observing these rules turns a minor, quickly-healing injury into one that stays minor.
THE BOTTOM LINE
A corneal abrasion is a painful, fluorescein-staining epithelial defect that heals quickly with antibiotic cover — provided topical anaesthetics and inappropriate padding are avoided and a subtarsal foreign body is excluded.
A further practical point is that a corneal abrasion overlying the visual axis, or one that fails to heal within a couple of days, should be re-examined for an infective infiltrate or a retained foreign body (including a subtarsal one); and that recurrent, spontaneous morning abrasions suggest recurrent corneal erosion syndrome, which is managed differently with lubricants and epithelial-adhesion measures rather than as a fresh injury.
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KEY POINTS TO REMEMBER
Corneal abrasion = epithelial defect (fingernail, foreign body, contact lens); very painful, photophobia, watering, foreign-body sensation; stains with fluorescein.
Always evert the lids to exclude a subtarsal foreign body (causes vertical linear abrasions).
Remove foreign body (needle/spud), topical antibiotic + cycloplegic; heals in 24–48 h; remove any rust ring.
Don't pad a contact-lens/organic injury (infection risk); never prescribe topical anaesthetic for ongoing use (toxic, delays healing); watch for ulcer/recurrent erosion.
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SOURCES: Khurana's Comprehensive Ophthalmology.
THE CONCEPT
A subconjunctival haemorrhage is bleeding beneath the conjunctiva, producing a flat, bright-red, well-demarcated patch on the white of the eye. It is characteristically painless, with normal vision and no discharge, and although it looks alarming it is usually harmless.
CAUSES
It may be spontaneous (from a Valsalva — coughing, sneezing, straining, vomiting), from minor trauma, hypertension, a bleeding disorder or anticoagulants, or idiopathic. Importantly, after trauma a bullous or 360° subconjunctival haemorrhage may hide an underlying open globe (rupture), which must be excluded.
MANAGEMENT
It is benign and self-limiting, resolving over 1–2 weeks as the blood is reabsorbed (the colour fading). Management is reassurance, with a blood-pressure check and, if recurrent, assessment of clotting and anticoagulation — and always exclusion of a penetrating injury if it is traumatic.
A NOTE ON WHEN TO WORRY
Although the great majority of subconjunctival haemorrhages are entirely benign, a few situations warrant more attention. Recurrent haemorrhages should prompt a check of blood pressure, clotting and anticoagulant control, and occasionally point to a bleeding tendency. In the setting of trauma, a diffuse, bullous or 360° haemorrhage — especially with reduced vision, a soft eye or a deep/shallow chamber — may conceal an underlying globe rupture, which must be actively excluded. Distinguishing the reassuring, isolated, spontaneous haemorrhage from these warning presentations is the key clinical judgement, after which most patients need only an explanation and time.
THE BOTTOM LINE
A subconjunctival haemorrhage is a benign, painless, self-limiting red patch requiring only reassurance and a BP check — unless it is recurrent or traumatic, when a bleeding tendency or hidden globe rupture must be excluded.
For completeness, the natural evolution is reassuring and diagnostic: the blood changes colour from bright red through orange to yellow as it is reabsorbed over one to two weeks, without spreading into the cornea or affecting vision, so simply reviewing this expected course with the patient usually replaces any need for investigation in an isolated, spontaneous case.
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KEY POINTS TO REMEMBER
Subconjunctival haemorrhage = flat, bright-red, well-demarcated patch on the sclera; painless, normal vision, no discharge.
Benign, self-limiting — resolves over 1–2 weeks; reassure; check BP; if recurrent check clotting/anticoagulation.
In trauma, a bullous/360° haemorrhage may hide an open globe (rupture) — exclude a penetrating injury.
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SOURCES: Khurana's Comprehensive Ophthalmology.
THE CONCEPT
Commotio retinae is a transient greyish-white opacification of the outer retina following blunt ocular trauma. Despite the name, it is not true oedema but disruption of the photoreceptor outer segments by the shock wave of the injury.
FEATURES
It occurs at the site of impact or, by contrecoup, opposite it; when it involves the macula it is called Berlin's oedema and reduces central vision. The retina appears whitened, and at the macula this may give a pseudo-cherry-red spot.
COURSE & MANAGEMENT
It usually resolves spontaneously over days to weeks with recovery of vision, and needs no specific treatment (observation). However, severe cases can leave permanent photoreceptor damage, macular pigmentary change or a macular hole. It should be distinguished from a retinal detachment or retinal haemorrhage, and forms part of the spectrum of blunt-trauma injury.
A NOTE ON THE VISUAL PROGNOSIS
The prognosis of commotio retinae depends chiefly on whether the macula is involved and how severe the photoreceptor disruption is. Peripheral commotio is usually asymptomatic and resolves completely, and even macular (Berlin's) oedema often recovers well over days to weeks. However, severe macular involvement can leave permanent central visual loss through photoreceptor death, pigmentary scarring or a macular hole. Because the appearance at presentation does not always predict the outcome, and because it can coexist with other blunt-trauma injuries, the eye is examined fully (to exclude a retinal tear, detachment or haemorrhage) and followed until the retina and vision have stabilised.
THE BOTTOM LINE
Commotio retinae is a transient traumatic whitening of the outer retina that usually recovers, but severe macular (Berlin's) involvement can leave permanent central visual loss.
A useful distinction is that commotio retinae, unlike a retinal haemorrhage or detachment, is a whitening without blood or elevation and typically fades rather than progresses; if the retina instead becomes elevated, or if floaters and a field defect develop, a coexisting retinal tear or detachment must be sought, since blunt trauma can produce both at once.
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KEY POINTS TO REMEMBER
Commotio retinae = transient greyish-white opacification of the outer retina after blunt trauma (photoreceptor outer-segment disruption, not true oedema).
At the site of impact or contrecoup; at the macula = Berlin's oedema (reduced central vision, may give a pseudo-cherry-red spot).
Usually resolves spontaneously over days–weeks with visual recovery; no specific treatment (observe).
Severe cases: permanent photoreceptor damage, macular pigmentary change or macular hole; distinguish from retinal detachment/haemorrhage.
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SOURCES: Khurana's Comprehensive Ophthalmology.
THE CONCEPT
Both blunt and penetrating trauma can damage the lens. A Vossius ring is a ring of pigment imprinted on the anterior lens capsule when the pupillary margin of the iris strikes the lens during a blunt injury — it is harmless itself but is a marker of significant blunt trauma.
TRAUMATIC CATARACT
Traumatic cataract is lens opacification after injury. After blunt (concussion) injury it classically forms a 'rosette' (stellate, flower-shaped) subcapsular opacity; after penetrating injury with capsular rupture, aqueous enters the lens causing a rapid, total cataract with lens matter in the anterior chamber (which can cause lens-induced glaucoma or uveitis). The lens may also subluxate or dislocate (from zonular damage) into the anterior chamber or vitreous.
MANAGEMENT
Management is to assess the eye, treat any lens-induced glaucoma, and perform cataract surgery when appropriate — with an intraocular lens if the capsule and zonules are adequate, otherwise using alternative fixation.
A NOTE ON LENS-INDUCED COMPLICATIONS
The most urgent aspect of a traumatic cataract is not the opacity itself but the complications when the lens capsule is breached. Once lens material is released into the anterior chamber, it can provoke a lens-induced (phacomorphic or phacoantigenic) glaucoma and uveitis that raise the pressure and inflame the eye, sometimes needing prompt removal of the lens matter rather than elective surgery. A dislocated lens can likewise block the pupil or the angle and raise the pressure. So, beyond restoring vision, the assessment of a traumatic cataract specifically looks for raised pressure and inflammation from released or displaced lens material, which may dictate earlier surgical intervention.
THE BOTTOM LINE
Traumatic lens injury ranges from the harmless marker of a Vossius ring to a rosette or total cataract, and its urgent concern is lens-induced glaucoma or uveitis when the capsule is breached.
It is also worth appreciating that the timing of cataract surgery after trauma is individualised: an eye with capsular rupture and released lens matter causing raised pressure may need urgent lens removal, whereas a stable rosette cataract with good vision can be observed and operated electively once the eye is quiet and the visual need is clear, with careful pre-operative assessment of the capsule and zonules to plan lens fixation.
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KEY POINTS TO REMEMBER
Trauma damages the lens: Vossius ring = pigment imprinted on the anterior capsule by the iris (harmless, marks significant blunt trauma).
Traumatic cataract: blunt → 'rosette'/stellate subcapsular opacity; penetrating (capsular rupture) → rapid total cataract + lens matter in AC (lens-induced glaucoma/uveitis).
Lens may subluxate/dislocate (zonular damage) into the AC or vitreous.
Manage: treat lens-induced glaucoma; cataract surgery when appropriate (IOL if capsule/zonules adequate, else alternative fixation).
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SOURCES: Khurana's Comprehensive Ophthalmology.
THE CONCEPT
Siderosis and chalcosis are the toxic degenerative changes caused by a retained metallic intraocular foreign body. They are important because they cause progressive, preventable visual loss and are the reason a metallic IOFB must be detected and removed early.
SIDEROSIS BULBI (IRON)
A retained iron (ferrous) foreign body deposits iron throughout the ocular tissues, causing progressive damage: a rusty-brown iris (heterochromia), pupillary mydriasis, a cataract with rusty anterior-capsule deposits, retinal pigmentary degeneration and progressive visual loss/night blindness, with a declining ERG.
CHALCOSIS (COPPER)
A retained copper foreign body deposits copper, producing a Kayser–Fleischer-like ring in Descemet's membrane, a 'sunflower cataract' and retinal deposits; pure copper (>85%) causes an acute, sterile, endophthalmitis-like inflammation. Management of both is removal of the foreign body (which halts progression), with ERG monitoring — underlining the importance of early detection and removal of any metallic IOFB.
A NOTE ON PREVENTION BY EARLY REMOVAL
The clinical message of siderosis and chalcosis is essentially about prevention through early detection and removal. Both are slow, progressive and, once advanced, largely irreversible, but they can be halted — and the eye's function preserved — if the metallic foreign body is found and removed before the deposits accumulate. This is why any history of a possible metallic IOFB triggers imaging and, if a fragment is found, its removal, and why patients with a retained fragment are monitored with serial ERG to detect early toxicity. The conditions thus stand as a strong argument for taking every hammering or high-velocity metal injury seriously and never leaving an unexplained metallic fragment in the eye.
THE BOTTOM LINE
Siderosis (iron) and chalcosis (copper) are progressive, largely irreversible toxic degenerations from a retained metallic IOFB, preventable only by early detection and removal of the fragment.
Finally, these conditions reinforce a broader principle of ocular-trauma care: that a retained intraocular fragment is never simply 'left alone' without thought, because even a small, initially symptomless metallic body can, over months to years, silently degrade the retina and lens; documenting its presence, imaging it, and planning removal or at least serial ERG monitoring is therefore part of the long-term follow-up of any penetrating injury.
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KEY POINTS TO REMEMBER
Siderosis & chalcosis = toxic changes from a retained metallic intraocular foreign body (progressive, preventable visual loss).