Steroid isolation , depending on context, is the isolation of chemical matter required for chemical structure elucidation, derivitzation or degradation chemistry, biological testing, and other research needs (generally milligrams to grams, but often more  or the isolation of "analytical quantities" of the substance of interest (where the focus is on identifying and quantifying the substance (for example, in biological tissue or fluid). The amount isolated depends on the analytical method, but is generally less than one microgram.  [ page needed ] The methods of isolation to achieve the two scales of product are distinct, but include extraction , precipitation, adsorption , chromatography , and crystallization . In both cases, the isolated substance is purified to chemical homogeneity; combined separation and analytical methods, such as LC-MS , are chosen to be "orthogonal"—achieving their separations based on distinct modes of interaction between substance and isolating matrix—to detect a single species in the pure sample. Structure determination refers to the methods to determine the chemical structure of an isolated pure steroid, using an evolving array of chemical and physical methods which have included NMR and small-molecule crystallography .  : 10–19 Methods of analysis overlap both of the above areas, emphasizing analytical methods to determining if a steroid is present in a mixture and determining its quantity. 
Steroid and antibiotic eye drops - hydrocortisone/neomycin/polymixin B; loteprednol/tobramycin; prednisolone/gentamycin; prednisolone/sulfacetamide; hydrocortisone /neomycin/bacitracin/ polymyxin B (Blephamide, Catapred [discontinued], Isopto, Pred-G, Poly-Pred [discontinued], Tobradex, Zylet and many other brands) are steroid and antibiotic eye drops prescribed to prevent or treat eye infections that are associated with inflammation. Side effects, drug interactions, dosage, and pregnancy safety information should be reviewed prior to using these medications.
The second major complication is a steroid related rise in eye pressure, also known as being a "steroid responder". This usually requires at least 2 weeks of continuous steroid use, and is reversible if the steroid is discontinued. The rise in pressure can be very high but if often asymptomatic. It may be more common in people already being treated for glaucoma. If a person has glaucoma or has a history of steroid related eye pressure problems, they should consult with an ophthalmologist for monitoring of eye pressure if steroid treatment is being contemplated.