This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Cornea and sclera, Subject name: Ophthalmology
Dellen is- 
Select and explain. 
A. Localized thinning of peripheral cornea, B. b) Raised lesions in corneo limbal junction, C. Age related macular degeneration, D. Marginal keratitis
A: Localized thinning of peripheral cornea
Answer: A: Localized thinning of peripheral cornea 
Explanation: Impaired eyelid function. It is seen in patientswith Bell's palsy, exposure keratitis, dellen,symblepharon, pterygium, nocturnal lagophthalmosand ectropion. REF:Comprehensive ophthalmology,20th edition,AK Khurana,pg no.365.