Oculoplastics
This section covers oculoplastics: eyelid malposition, ptosis, eyelid tumours, and reconstructive principles. The exam tests anatomical assessment and matching the operation to the defect.
Core rules and concepts
- Ptosis is classified as congenital, aponeurotic, myogenic, neurogenic, mechanical, or traumatic; levator function and marginal reflex distance guide surgery.
- Good levator function favours levator resection; poor function, especially in congenital ptosis, may need a frontalis sling.
- Involutional entropion involves horizontal laxity and lower lid retractor dehiscence; repair addresses laxity and retractors.
- Involutional ectropion also involves laxity; medial canthal tendon laxity and punctal position must be assessed.
- Basal cell carcinoma is the commonest eyelid malignancy; it has pearly margins and telangiectasia. Mohs surgery or margin-controlled excision is used near the canaliculus.
Worked example
A 6-year-old has a unilateral droopy upper lid since birth. The lid covers the pupil, and levator function is 3 mm. Visual acuity is reduced in that eye. The diagnosis is congenital ptosis with anisometropic or deprivation amblyopia risk. Because levator function is poor, a frontalis sling procedure is planned. Amblyopia therapy is coordinated before and after surgery. The pupil and fundus are checked to exclude masquerade causes, and the child is warned about exposure keratopathy after surgery.
Traps that cost marks
Do not operate for ptosis without checking levator function and pupil size. A pupil-involving ptosis may be a third-nerve palsy. Missing a marginal basal cell carcinoma near the lacrimal system changes reconstruction. Over-resection in congenital ptosis can cause lagophthalmos and corneal exposure.