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OP3.1-7 | Conjunctiva and Red Eye — Practice Quiz
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A 28-year-old construction worker presents with a sudden-onset red right eye for 2 days. He reports profuse sticky yellow-green discharge that seals his eyelids shut in the morning, with mild grittiness but no significant pain or photophobia. Vision is unaffected. On eversion of the upper eyelid you see flat, polygonal elevations on the tarsal conjunctiva. What is the most likely diagnosis?
Correct. Mucopurulent discharge, papillary reaction, and absence of a preauricular lymph node are the hallmarks of bacterial conjunctivitis. Common organisms include Staphylococcus aureus and Haemophilus influenzae.
Mucopurulent discharge with papillary reaction (flat, polygonal elevations) on the tarsal conjunctiva and no preauricular node is the classic presentation of acute bacterial conjunctivitis.
Incorrect. The key distinguishing features here are the mucopurulent discharge and the papillary reaction on tarsal conjunctiva. Viral conjunctivitis produces watery discharge and a follicular reaction; anterior uveitis causes photophobia and ciliary injection; VKC causes intense itching with giant papillae.
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A 19-year-old college student presents with a red, watery right eye for 3 days. He has a tender, enlarged preauricular lymph node. On examination, you find small translucent dome-shaped elevations on the lower palpebral conjunctiva. He mentions several classmates have had similar symptoms this week. Which feature most strongly distinguishes this from bacterial conjunctivitis?
Correct. Tender preauricular lymphadenopathy is virtually pathognomonic of viral (especially adenoviral) conjunctivitis. Follicles on the lower palpebral conjunctiva further support the viral diagnosis. Bacterial conjunctivitis does not produce preauricular lymphadenopathy.
Preauricular lymphadenopathy is the single most reliable clinical sign distinguishing viral from bacterial conjunctivitis. The dome-shaped elevations are follicles, confirming the viral aetiology.
Incorrect. While watery discharge and follicles are also clues, the preauricular lymph node is the single most reliable differentiating feature between viral and bacterial conjunctivitis. Bacterial conjunctivitis characteristically does NOT cause preauricular lymphadenopathy.
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A 35-year-old patient with red eye has photophobia, reduced vision, and periocorneal (ciliary) injection. She denies any discharge. Which of the following diagnoses should be considered FIRST given these features?
Correct. Photophobia, reduced vision, and ciliary injection without discharge are the red-eye danger signs indicating anterior uveitis (or keratitis). These presentations must never be dismissed as simple conjunctivitis and require urgent specialist review.
Photophobia, reduced vision, and circumcorneal (ciliary) injection without discharge constitute the danger-sign triad for anterior uveitis and demand urgent ophthalmic referral.
Incorrect. Conjunctivitis (bacterial or allergic) does not typically cause photophobia or reduced vision. Subconjunctival haemorrhage causes a painless bright-red eye without any visual disturbance or discharge. The danger-sign pattern here — photophobia + reduced vision + ciliary injection — points to anterior segment pathology beyond the conjunctiva.
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A community health worker in a trachoma-endemic rural area examines a 10-year-old girl. She finds five or more follicles (each 0.5 mm diameter) on the upper tarsal conjunctiva. Using the WHO simplified trachoma grading, what grade should she record?
Correct. TF is the WHO grade for five or more follicles (each at least 0.5 mm) on the upper tarsal conjunctiva. It represents active trachoma at the follicular stage and is the trigger for antibiotic treatment under the SAFE strategy.
TF (Trachomatous Inflammation — Follicular) is defined as five or more follicles, each at least 0.5 mm, on the upper tarsal conjunctiva — the earliest WHO grade indicating active trachoma requiring treatment.
Incorrect. The five grades of the WHO simplified trachoma grading system are TF, TI, TS, TT, and CO. TF specifically requires five or more follicles each at least 0.5 mm on the upper tarsal conjunctiva. TI involves intense inflammation obscuring more than half the deep tarsal vessels; TS involves scarring; TT involves trichiasis; CO involves corneal opacity.
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A 9-year-old boy from South India presents each summer with intense bilateral itching, photophobia, and a ropy mucoid discharge. Examination reveals large, flat-topped papillae (cobblestone appearance) on the upper tarsal conjunctiva and gelatinous limbal thickening with white deposits. Which of the following is the MOST APPROPRIATE first-line treatment for an acute exacerbation?
Correct. VKC is driven by mixed Type I (IgE/mast cell) and Type IV (T-cell) hypersensitivity. Acute exacerbations require a short course of topical corticosteroids for rapid control, combined with a mast cell stabiliser for maintenance. Antihistamines alone are insufficient. Antibiotics have no role.
VKC acute exacerbations require topical corticosteroids (for rapid anti-inflammatory effect) combined with mast cell stabilisers (for maintenance). Antihistamines alone are inadequate for the mixed Type I and Type IV hypersensitivity of VKC.
Incorrect. The cobblestone papillae, limbal Trantas dots, and ropy discharge describe VKC (vernal keratoconjunctivitis), not bacterial infection (no role for antibiotics). Antihistamines alone are inadequate for VKC's mixed immune mechanism. Mast cell stabilisers work for prevention but not acute flares. The combination of a short corticosteroid course plus mast cell stabiliser is standard acute management.
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A 40-year-old fisherwoman from coastal Andhra Pradesh presents with a wing-shaped fleshy growth on the nasal side of her left eye that has been slowly growing toward the pupil. She reports mild redness and occasional tearing. A probe passed under the growth slides freely along the entire length. What is the most important implication of this finding?
Correct. The probe test distinguishes true pterygium from pseudopterygium. In a true pterygium the probe cannot pass under the growth at the limbus (it is adherent there), while in pseudopterygium the probe passes freely under the entire lesion. The question stem indicates the probe slides freely, which confirms pterygium (the probe passes under the body) but cannot pass at the head — confirming limbal attachment of a true pterygium.
In the probe test, a probe passed under a true pterygium cannot pass through (the growth is attached at the limbus). A probe that passes freely under the entire length indicates pseudopterygium. Here, 'slides freely along the entire length' identifies this as a true pterygium confirming intact limbal attachment (the probe passes under the body but not through the head at the limbus). Note: the classic probe test finding for TRUE pterygium is that the probe CANNOT be passed at the limbal end.
Incorrect. The probe test is performed to distinguish true pterygium (probe cannot pass through at the limbus — adherent) from pseudopterygium (probe passes freely at all points). A nasal fleshy growth in a UV-exposed patient is most consistent with pterygium. Pseudopterygium typically follows a localised corneal insult (chemical burn, corneal ulcer) and the probe passes freely at all points.
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While assessing a patient with a suspected conjunctival foreign body after wind exposure, you notice the patient has high axial myopia and a history of a direct blow to the eye 2 hours ago. You also find the anterior chamber appears shallow with decreased visual acuity. What is the correct immediate action?
Correct. Any features suggesting open globe injury (trauma + reduced VA + shallow AC) mandate immediate cessation of assessment, application of a protective shield (not a pressure pad — pressure can extrude vitreous through an open wound), and urgent ophthalmology referral. Never attempt FB removal when penetrating injury is possible.
A suspected open globe injury (reduced VA, shallow AC, trauma) is an absolute contraindication to any manipulation. The eye should be protected with a rigid shield (never a pressure pad) and urgently referred. Pressure applied over an open globe can extrude intraocular contents.
Incorrect. The features described — trauma, reduced VA, and shallow anterior chamber — raise serious concern for an open globe injury. Attempting FB removal, irrigation, or applying a pressure pad risks extrusion of intraocular contents through an open wound. The correct action is to apply a rigid shield without pressure and arrange emergency referral.
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A patient is prescribed two eye drops for glaucoma. Which of the following instructions regarding instillation of multiple eye drops is CORRECT?
Correct. The conjunctival sac can hold only 7–10 μL — far less than a single drop (30–50 μL). If a second drop is instilled immediately, it physically washes the first drop out of the conjunctival sac before it can be absorbed. A minimum wait of 5 minutes between drops ensures adequate absorption of the first before the second is instilled. Ointment is always last in any sequence.
The conjunctival sac holds only 7–10 μL. A standard eye drop is 30–50 μL. When two drops are given without a wait, the second drop washes out the first. A minimum 5-minute gap between drops is required. Ointments are always instilled AFTER drops as they form a barrier to drop penetration.
Incorrect. The conjunctival sac capacity is only 7–10 μL. Instilling two drops together or immediately one after the other causes the second drop to wash out the first, reducing therapeutic efficacy. The correct instruction is to wait at least 5 minutes between drops. Eye ointment should always be instilled LAST (after all drops) because it forms a barrier that prevents subsequent drops from penetrating.
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A 25-year-old presents with chronic bilateral red eyes for 6 weeks. Slit-lamp examination reveals small depressions at the superior limbus. He also has conjunctival scarring visible on eyelid eversion. There is no active follicular reaction. Which finding is PATHOGNOMONIC of past trachoma infection?
Correct. Herbert's pits are small depressions at the upper limbus representing the cicatricial remnants of trachomatous limbal follicles. They are pathognomonic of trachoma — no other condition produces this finding — and persist for life even after all active infection has cleared.
Herbert's pits — small depressions at the superior limbus representing scars of healed limbal follicles — are pathognomonic of trachoma and remain even after active infection has resolved. Arlt's line is a conjunctival scar, not pathognomonic; pannus and follicles occur in other conditions.
Incorrect. Herbert's pits (depressions at the superior limbus from healed limbal follicles) are pathognomonic of trachoma. Arlt's line (horizontal scar on tarsal conjunctiva) is characteristic but not pathognomonic. Pannus and superior limbal follicles occur in several other conditions including chlamydial inclusion conjunctivitis and phlyctenular disease.
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Which of the following features, if present in a patient with red eye, would mandate URGENT ophthalmology referral rather than primary care management?
Correct. Photophobia with reduced VA and circumcorneal injection are classic danger signs of anterior uveitis or keratitis. These require urgent specialist evaluation. Mucoid discharge suggests conjunctivitis; bilateral itching with ropy discharge suggests VKC; painless subconjunctival haemorrhage is usually benign and self-resolving.
The red-eye danger signs mandating urgent referral are: reduced visual acuity, severe photophobia, ciliary (circumcorneal) injection, corneal haze, and severe pain unresponsive to analgesia. These indicate anterior uveitis, keratitis, or acute glaucoma — not conjunctivitis.
Incorrect. The danger signs that mandate urgent referral from primary care are: reduced visual acuity, marked photophobia, circumcorneal (ciliary) injection, corneal haze or opacity, and severe unrelenting pain. Discharge (option A), itching (option B), and painless subconjunctival haemorrhage (option C) do not indicate a sight-threatening condition requiring urgent referral.
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A 16-year-old male presents with recurrent seasonal bilateral eye irritation each March–April. He has intense itching, photophobia, and a stringy mucoid discharge. You find giant papillae (>1 mm) on the upper tarsal conjunctiva and white chalky dots at the limbus (Trantas dots). What is the CORRECT description of the immune mechanism responsible for the giant papillae?
Correct. VKC involves both Type I (IgE-mediated, mast-cell degranulation → immediate itching, ropy discharge) and Type IV (T-cell/eosinophil-mediated, delayed → giant papillae, eosinophilic infiltration). This dual mechanism is why treatment requires both mast-cell stabilisers and anti-inflammatory agents (corticosteroids or calcineurin inhibitors).
VKC is driven by a dual immune mechanism: Type I (immediate, IgE-mast cell) producing the acute itch and watery component, and Type IV (delayed-type, T-cell eosinophil) producing the chronic papillary hypertrophy and corneal complications. This mixed mechanism explains why antihistamines alone are insufficient.
Incorrect. VKC is unique among allergic conjunctivitides in being driven by a mixed Type I and Type IV immune response. Simple SAC/PAC is purely Type I. The Type IV component in VKC accounts for the chronic papillary hypertrophy, eosinophil infiltration, and risk of corneal shield ulcer — features absent in simple allergic conjunctivitis.
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A patient who has undergone successful pterygium excision is being counselled about recurrence prevention. Which of the following is the most evidence-based recommendation?
Correct. UV-B exposure is the dominant pathogenic factor in pterygium. After excision, UV protection with wraparound sunglasses and hats substantially reduces recurrence risk. Avoiding all outdoor activity is unnecessary and impractical. Indefinite topical corticosteroids are not indicated for prevention and risk steroid side effects.
Since UV-B radiation is the dominant aetiological factor in pterygium, UV protection (wraparound UV-blocking sunglasses, wide-brimmed hats) is the most important evidence-based preventive measure after excision. Indefinite topical steroids have no proven role in recurrence prevention and carry risks of glaucoma and cataract.
Incorrect. Pterygium is caused by UV-B-induced limbal stem cell dysfunction. The most important preventive measure is UV protection outdoors using wraparound sunglasses and wide-brimmed hats. Avoiding all outdoor activity is excessive. Indefinite topical corticosteroids are not proven preventive agents and carry risks of ocular hypertension and posterior subcapsular cataract.
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