Dellen is-
Localized thinning of peripheral cornea
b) Raised lesions in corneo limbal junction
Age related macular degeneration
Marginal keratitis
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.
Cornea and sclera