Autologous serum eye drops (ASED) are an established treatment for various dry eye conditions. However, the amount of whole blood collected for ASED is often restricted, as patient-specific factors (e.g. Hb/Hct) have a limiting effect. Adjusting the serum volume per vial to the patient's actual needs could minimize the waste of residual serum and thus increase the size of each ASED batch. For this reason, we analyzed used ASED vials to determine the consumption of ASED more precisely.

ASED are obtained from a patient-specific amount of whole blood. As a standard 1.5 mL serum is cryopreserved per vial (ATS12, ATS36, Heinz Meise GmbH, Germany). 11 batches of vials with residual serum were returned to us by 8 patients for consumption determination (n= 478, min 13/max 50; mean 43): each vial was weighed to calculate the difference to the average filling weight. The latter is based on data from 245 vials weighed directly after manufacturing. The calculations of the optimal ASED filling volume were carried out based on a new technology with filling volumes in the range from 0.1 to 2.0 mL that can be adjusted in 0.1 increments. Furthermore, the avoidable blood loss was calculated.

245 ASED vials were analyzed directly after production containing an average serum filling weight of 1.56 g (min. 1.20 g/max. 1.70 g). 478 vials from 11 batches used by patients showed an average total consumption of 0.86 g serum per vial (min. 0.43 g/max. 1.24 g), which corresponds to an average proportion of 55 % (min. 28 %/max. 80 %). This results in an average loss of 45 % serum per vial (min. 20 %/max. 72 %) and an extrapolated loss of 182 ml whole blood (min. 52 ml/max. 317 ml) per collection for the patient. Adjusting the serum volume to the actual consumption to the nearest 0.1 mL would increase the absolute number of vials available by an average of 104 (min. 21/ max. 248), which corresponds to 6.7 % more vials per 0.1 mL of serum saved.

An individualized filling quantity for ASEDs corresponds to the principle of fundamentally economical use of blood as a resource and minimizes serum loss. Significantly larger batches not only reduce the burden on patients due to a lower frequency of whole blood donation but can also reduce costs. Finally, it should be noted that appropriate validations must be carried out so that the shelf life does not represent a restriction on availability.

The authors declare no conflicts of interest.