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Background and Importance Age-related eye diseases, such as macular degeneration, diabetic macular oedema and venous occlusion, have increased significantly in recent decades, driving demand for anti-vascular endothelial growth factor (VEGF) therapies. Compounding these agents into prefilled syringes optimises resources, leading to significant savings. Ensuring the physicochemical integrity of each locally produced syringe, prepared from both reference biological product and biosimilars, is essential to maintain efficacy and patient safety throughout the assigned 28-day shelf life.Aim and Objectives To evaluate the stability and environmental impact of hospital compounding of intravitreal injections of aflibercept Eylea (8 and 40 mg/mL), bevacizumab MVASI (25 mg/mL), ranibizumab Ranivisio (0.6 mg/mL) and faricimab Vabysmo (120 mg/mL) stored in silicone-free and oil-free polypropylene syringes (Henke-Ject, ) with low dead space.Material and Methods Syringes were stored at 2-8°C under light protection and analysed after 0, 7, 28 and 90 days. Analyses, performed in triplicate, included VEGF-binding affinity and biophysical stability tests using dynamic light scattering (DLS) and thermal-ramp analysis (25-100°C) to assess particle size and thermal behaviour. For statistical analysis (p < 0.01) one-way ANOVA was used.Results In 2025, 6015 injections were prepared for 991 patients, resulting in an estimated savings of EUR 1 494 584. No visual changes in colour, opalescence or particles were observed up to 90 days. Ranibizumab showed the best thermal stability (unfolding 75-79°C) with minimal particle variation (2.69-2.84 nm). Bevacizumab remained stable (7.75-7.86 nm; 64-70°C), and aflibercept 40 mg/mL showed better stability than 8 mg/mL (6.61-7.26 nm). Faricimab exhibited early aggregation (peak particle size at 187 nm after 1 week; 42-64°C) and progressive VEGF affinity loss after 7 days. The others showed ≤10% affinity variation within 28 days.Conclusion and Relevance Except for faricimab, all anti-VEGF injections seem to maintain their physical, chemical and biological stability throughout the 28-day shelf life, supporting the reliability of the hospital compounding and storage process. The analytical sensitivity applied enabled early detection of aggregation risk, justifying the decision to shorten faricimab’s validity period to one week. Continuous validation after any production change ensures consistent safety and efficacy. The demonstrated cost savings highlight the pharmacist’s role in promoting quality, sustainability and rational use of hospital prepared intravitreal preparations.Conflict of Interest No conflict of interest