<prompt> A patient is presenting with co itching at the lid and swelling for the past 1 month. On examination, there are crusting, scaling with small ulcers near eyelid margin. If untreated, it can lead to:Orbital cellulitisEctropion and EpiphoraChalazionOrbital abscess formation  <response>: Ans: b Ectropion and EpiphoraRef: A.K. Khuranas Comprehensive Ophthalmology, 6th edition, Page 365 and 368; Parsons Diseases of the Eye, 22nd edition, Page 451The diagnosis is ulcerative blepharitis.BLEPHARITISSubacute or chronic inflammation of the lid margins. TypesEtiology and pathogenesisClinical featuresTreatmentSquamous. Associated with seborrhea of the scalp. Zeiss gland - abnormal excessive neutral lipids which are split by corynebacterium acne into irritating free fatty acids. White dandruff like deposition among the lashes. On removal, no ulcer. Lid hygiene. Treat the seborrheaUlcerative staphylococcalDue to staphylococcal infection. Yellow crusts at the root of the cilia with matting of lashes. On removal of the crusts, bleeding small ulcers are seen. Red, thickened lid margins. Lid hygiene. Topical and systemic antibioticsPosteriorMeibomianitis. Associated with acne rosacae. Meibomian gland dysfunction. Bacterial lipases play a role. Meibomian Seborrhea - white frothy discharge at the lid margin. Toothpaste like thick secretion on expressing the meibomian gland. Meibomian gland appears like vertical yellow streaks due to thick secretion. Lid hygiene and warm compress. Topical and systemic antibioticsParasitic. Phthiriasis palpebrum - Phthirus pubis crab louse. It is sexually transmitted. Peduculosis-pediculus humanis corporiscapitus head louse. Spill over from the head if severely infested Lice and Nits anchoring the lashes. Mechanical removal of the lice and nits with forceps. Yellow mercuric oxide 1 application. Delousing the whole familyComplications of chronic blepharitis:Lash abnormalities: Madarosis, trichiasis, poliosis.Tylosis.Punctual eversion - chronic watering of the eyes - eczema of the surrounding skin - cicatrization - ectropion.Recurrent hordeolum externum.Marginal keratitis.Dry eyes.Chronic inflammatory changes in the cornea and conjunctiva. 