The present paper examines the effect of the concentration of hydroxypropylmethylcellulose (HPMC 4000) 20–60 g/l in hydrogel on the density of lyophilised xerogel. Lamellae of a diameter of 5.5 mm were obtained by stamping from lyophilised foils and their density was estimated. With decreasing HPMC 4000 concentration in hydrogel, the density of lamellae decreases to values within 50–55 g/l. The causes of this phenomenon and its consequences for optimisation of technology of lyophilised ophthalmic lamellae are discussed.

        Key words: hydroxypropylmethylcellulose – hydrogel – lyophilisation – xerogel density