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Update your Knowledge with MKSAP 19 Q&A: Answer and Critique

Answer

A: Acute bacterial conjunctivitis

Educational Objective

Diagnose acute bacterial conjunctivitis.

Critique

The most likely diagnosis is acute bacterial conjunctivitis (Option A). In adults, Staphylococcus aureus is most commonly implicated. Bacterial conjunctivitis is highly contagious and is usually spread by person-to-person contact or through contact with contaminated surfaces. Patients most commonly present with several days of unilateral diffuse conjunctival redness and discharge, although bilateral involvement may occur. The discharge is frequently mucopurulent and accompanied by eyelid debris and matting, which is worse upon awakening. Patients, such as this one, may also have visual blurring that improves with blinking; overt changes in visual acuity do not occur.

Patients with blepharitis (Option B) typically present with chronic symptoms characterized by red, swollen, or itchy eyelids; ocular gritty sensation; and crusting of eyelashes in the morning. Because of the accompanying disordered tear composition, affected patients may develop eye irritation and excessive tear production. This patient's primary symptoms are acute eye redness and discharge without eyelid involvement, which is not consistent with blepharitis.

Hyperacute bacterial conjunctivitis (Option C) is a potentially vision-threatening condition caused by Neisseria gonorrhea infection. It is characterized by rapid onset of profuse purulent discharge and diffuse bright red conjunctival hemorrhage. If untreated, it can progress to corneal ulceration. This patient's symptoms are relatively mild and do not support a diagnosis of hyperacute bacterial conjunctivitis.

Although scleritis (Option D) causes diffuse eye redness, it is typically accompanied by severe eye pain, visual disturbance, photophobia, and watery discharge, which are not present in this patient.

Viral conjunctivitis (Option E), most commonly caused by adenovirus, frequently occurs in the setting of upper respiratory tract symptoms. Patients with viral conjunctivitis often present with eye redness and clear, watery discharge that frequently begins unilaterally and eventually progresses to bilateral ocular involvement. On examination, preauricular lymphadenopathy is common. This patient has unilateral purulent discharge, which is not consistent with viral conjunctivitis.

Key Points

Acute bacterial conjunctivitis, most commonly caused by Staphylococcus aureus, typically presents with several days of unilateral diffuse conjunctival redness and mucopurulent discharge.

Hyperacute bacterial conjunctivitis is a potentially vision-threatening condition caused by Neisseria gonorrhea infection and is characterized by rapid onset of profuse purulent discharge and diffuse bright red conjunctival hemorrhage.

Bibliography

Varu DM, Rhee MK, Akpek EK, et al; American Academy of Ophthalmology Preferred Practice Pattern Cornea and External Disease Panel. Conjunctivitis Preferred Practice Pattern庐. Ophthalmology. 2019;126:P94-169. [PMID: 30366797] doi:10.1016/j.ophtha.2018.10.020

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