Calculated Drug Concentrations in Currently Available Intravitreal Therapies: Determination of Dilution Factor and Deviation From Recommended Doses.

In ophthalmology, intravitreal therapies are currently not personalized/customized and are not adjusted to the individual vitreous volume. With reference to the recently published calculation formula for a more accurate estimation of the vitreous body, we determined the dose of intravitreal medication for different vitreous volumes and compared them with the average volume. Using the axial length of the eye, the formula for the vitreous volume exact (VIVEX) can provide a more accurate indication of the vitreous volume in individual cases than an assumed standard volume of 4 mL. The concentration of active substances in small eyes may be twice as high as that in normal-sized emmetropic eyes. In contrast, large eyes may show less than half of the recommended drug concentration. The calculated concentrations of the investigated intravitreal drugs in small and large eyeballs showed impressive differences with large deviations from the recommended doses. Further systematic studies should follow to find out whether this has any impact on the effectiveness or side effects of the injected drugs.