A neonate is noted to have photophobia, epiphora, and blepharospasm. Corneal diameter measures 13 mm bilaterally. Examination under anaesthesia reveals elevated IOP of 30 mmHg, corneal oedema, and Haab's striae running horizontally. Which embryological structure fails to involute in congenital glaucoma?
- A Barkan's membrane (primordial endothelial tissue over the trabecular meshwork) ✓
- B Hyaloid artery
- C Pupillary membrane
- D Tunica vasculosa lentis
Explanation
Primary congenital glaucoma results from failure of regression of Barkan's membrane — an imperforate primordial endothelial sheet overlying the trabecular meshwork — which blocks aqueous outflow. Goniotomy or trabeculotomy is curative by incising this tissue. Haab's striae are horizontal breaks in Descemet's membrane from elevated IOP stretching the infant cornea (buphthalmos). The hyaloid artery, pupillary membrane, and tunica vasculosa lentis are unrelated embryological structures; their non-regression causes other conditions (persistent fetal vasculature, anterior polar cataract, etc.).
Reference: Khurana Comprehensive Ophthalmology, 7th ed.
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Written and medically reviewed by the StethoPrep medical team.