A formulation approved both for use in the eye/ear is classified in S03. Formulations approved for eye, ear and nose are also classified in S03. Formulations only licensed for use in the eye or the ear are classified in S01 and S02, respectively.

Most of the drugs in this group are topical preparations. Systemic preparations with clear ophthalmological indications are also classified in this group.
Small amounts of antiseptics in eye preparations do not influence the classification, e.g. benzalconium.
See also S03 - Ophthalmological and otological preparations.

This group comprises plain and combined antiinfective preparations for ophthalmological use.
Combinations with corticosteroids are classified in S01CA - Corticosteroids and antiinfectives in combination.

This group comprises antiinfective preparations for ophthalmological use, which cannot be classified in the preceding groups. Products containing boric acid, also in low strengths, are classified in this group.
Preparations containing benzalconium as the only active substance are classified here, on the 4th level.