<prompt> Patient came with hydrops and scarring of cornea. What would be the treatment modality you would opt for him:Penetrating KeratoplastyEndothelial lamellar KeratoplastyDeep anterior lamellar keratoplastyCollagen cross linking  <response>: Penetrating keratoplasty has to be done in cases of deep corneal scar or hydrops. SURGICAL MODALITIES FOR KERATOCONUS Keratoplasty for Keratoconus DALK deep anterior Lamellar keratoplasty: when 12 of stroma is involved. ALTK Anterior lamellar therapeutic keratoplasty : When less than 12 of stroma is involved. Penetrating Keratoplasty: When full thickness of cornea is involved as in hydrops with scar. INTRASTROMAL CORNEAL RING SEGMENTS Reduce corneal steepening Made of PMMA. Femtolaser is used to make tunnel in cornea. Used in Pellucid Marginal Degeneration, post LASIK ectasia and keratoconus. 