Oculenta. Eye Ointments.
Eye ointments are made with soft paraffin, of uniform consistence, free from granular particles, and having a melting-point of about 35°, so that the ointments melt readily when introduced into the eye. The soft paraffin should first be carefully examined to ensure its neutrality, then melted, strained through fine muslin, and set aside in a covered vessel to cool. The material to be incorporated in the ointments should be in the finest possible powder, and should be triturated with a small portion of the soft paraffin until a perfectly smooth mixture is obtained. The mixtures of alkaloids and paraffin may be warmed just above the melting-point of the latter (not above 50°) until solution is effected. In the alkaloidal eye ointments the free alkaloids are used, and not their salts, as the latter are mostly insoluble in fats and soft paraffin. The use of oleic acid as a solvent for alkaloids in eye ointments is not desirable, as many samples of oleic acid are rancid and have an irritant action. Eye ointments are best dispensed in collapsible tubes. Where it is necessary for the eye ointment to set immediately to prevent separation of some of the component parts the collapsible tubes may be filled by pouring the ointment, previously melted at a low temperature, into the tubes, surrounded with ice. In cases where the ointment should not be melted, it may be rolled in grease-proof paper and placed with the paper in the tube, which should then be closed. The soft paraffin and the utensils employed in making eye ointments should be sterilised immediately before use. Eye ointments are best applied by means of a glass rod with a properly rounded end; the rod may be sterilised before use, an advantage not possessed by camel-hair brushes.