Summary of recent applications of hydrogels as intravitreal DDS
| Disease | Hydrogel composition | Delivery route & active ingredients | Study phase | Release duration | Advantages & limitations | Reference |
| Retinal neovascularization | GelMA | Triamcinolone acetonide | In vitro; ex vivo | More than 90 days | The degradation process does not obstruct the trabecular meshwork; gelatin is an inexpensive material; no sudden release burst, reducing the risk of cytotoxicity; no measurements of kinetic release profile in vivo | [76] |
| Pluronic 127 | Ranibizumab | In vitro; in vivo (rabbits) | More than 7 weeks | The first study to create a Schiff-based injectable; dynamic reversible gel-sol conversion can be squeezed out of a syringe easily; self-healing properties that protect the drug while preventing dispersed particles from obstructing aqueous humor circulation | [74] | |
| PNM/PNF | Dexamethasone; anti-VEGF | In vitro; ex vivo (rabbits) | Dexamethasone: 35 days; anti-VEGF antibody: 13 days | Thermosensitive; prolonged degradation time under neutral pH; the optimal dosing regimen remains unclear; further preclinical and clinical trials are needed | [91] | |
| Wet AMD | Peptide amphiphile molecule (E-PA) | Ranibizumab | In vitro; in vivo (rabbits) | 10–150 hours | Dosage can be adjusted for each patient by changing peptide concentration; biodegradable | [87] |
| CaCl2 | anti-VEGF agent; betamethasone phosphate (BetP) disodium | In vitro; in vivo (mice) | 30 days | Antioxidant properties; the formulation is easy to prepare and is suitable for mass production; future clinical trials on human patients required; limited understanding of the mechanism behind BetP-based DDS | [88] | |
| F127/F68 | Rhein; baicalein | In vitro; in vivo | At least 14 days | Thermosensitive; inhibit choroidal neovascularization through anti-angiogenic and anti-oxidative stress pathways; alternative therapy for wet AMD patients who are unresponsive to anti-VEGF antibodies | [89] |
DDS: drug delivery systems; GelMA: gelatin methacryloyl; PNM/PNF: polynuclear metalloids/proprioceptive neuromuscular facilitation; VEGF: vascular endothelial growth factor; AMD: age-related macular degeneration