Stamp, oculist's stamp

This stone block belonged to Gaius Silvius Tetricus. He was an eye doctor 'oculist’ from Gaul. Medical men like him travelled around the country selling their potions. Tetricus used this block as a palette to mix ointments to cure eye diseases. Each narrow side of the block is carved with a different prescription to cure diseases such as corneal scars and conjunctivitis. The prescriptions are written back-to-front so they could be stamped onto the sticks of ointment.
The inscriptions are:
1) C SILV[...]RICIDIAMI/SVSADDIATHESETCICAT: G(ai) Silv[i Te]rici diamisus ad diathes(es) et cicat(rices) 'Gaius Silvius Tetricus's salve made from Misy for affections and scars (of the eye)'
2) CSILVITETRICIPENICILL ADIMPETLIPPITVDIN: G(ai) Silvi Tetrici penicill(um) ad impet(um) lippitudin(is) 'Gaius Silvius Tetricus's ointment for the onset of ophthalmia'
3) CSILVITETRICIEVODES AD ASPRITVDINES (palm branch): G(ai) Silvi Tetrici euodes ad aspritudines 'Gaius Silvius Tetricus's fragrant salve for granulations (of the eyelids)'
4) CSILVITETRICIBIPROSO PVMADIM[...]: G(ai) Silvi Tetrici biprosopium ad im[petum lippitudines?] 'Gaius Silvius Tetricus's biprosopum for the onset [of opthalmia?]