​Differential diagnosis of aqueous tear deficiency causing dry eyes are : 
-drugs
-secondary conjunctival scaring 
-infiltration of the lacunar glands 
-Sjorgen Syndrome 
-post radiation fibrosis of lacrimal gland 
-autoimmune disorders associating with Sjogren Syndrome 
-collagen vascular diseases 
-sensory denervation 
-lacrimal gland ablation 
-systemic vitamin A deficiency
-congenital alacrima 

​Differential diagnosis of lipid tear layer disorders causing dry eyes are : 
-rosacea
-blepharitis

​Differential diagnosis of mucin tear layer disorders causing dry eyes are : 
-topical drugs 
-mucocutaneous disorders 
-trachoma 
-vitamin A deficiency 
-diphtheric keratoconjuctivitis

​Differential diagnosis of dry eyes are : 
-mucin tear layer disorders 
-lipid tear layer disorders
-aqueous tear deficiency

​Differential diagnosis of drugs causing vesiculobullous are : 
-thiazides
-sulfonamdes –
-penicillin
-penicillamine
-NSAIDS
-griseofulvin 
-furosemide 
-cephalosporin 
-captopril 
-barbiturates 
-aspirin 

​Learn the differential diagnosis of drugs causing vasculitis are : 
-gold 
-cimetidine 
-allopurinol 
-aspirin 
-thiazides
-tetracycline 
-sulfonamide
-quinolones 
-propylthiouracil 
-phenytoin 
-penicillin
-quinolones 
-hydralazine

​Differential diagnosis of drugs causing urticarial are : 
-trazodone 
-ACE inhibitors 
-aspirins
-ranitidine
-radiocontrast media 
-polymixin 
-penicillins
-opiates 
-NSAIDS
-lithium 
-imipramine 
-fluoxetine 
-dextran 
-chlordiazepoxide
-cephalosporins 

​Differential diagnosis of drugs causing toxic epidermal necrolysis are : 
-vancomycin 
-allopurinol 
-trimethoprim – sulfamethoxazole 
-tetracycline
-sulfonamides
-anticonvulsant
-NSAIDS
-aspirin 
-isoniazid
-phenytoin 
-prazosin 

​Differential diagnosis of drugs causing Stevens Johnsons Syndrome are : 
-sulfamethoxazole
-trimethoprim 
-tetracycline 
-sulfonamide
-rifampicin 
-phenytoin 
-phenylbutazone 
-phenothiazine
-penicillin 
-hydantoin 
-allopurinol 
-aspirin 
-anticonvulsants
-NSAIDS
-codeine 
-griseofulvin 
-cimetidine 
-carbamazepine 
-barbiturates 

​Differential diagnosis of drugs causing pigmentation are :
-thioridazine 
-amitriptyline 
-haloperidol 
-clozapine 
-chlopromazine 
-perphenazine