Topotecan Microneedle Scleral Patch: A Transscleral Drug Delivery Study for Retinoblastoma.

The dimensions of microneedles were uniform across the array measuring 548 ± 3.7 μm length, 336 ± 7.5 μm width, and 18 μm tip diameter.

In the ex vivo goat eye model, the required insertion force was 0.026 N per needle, which was 50 times lower than the compression strength of 1.27 N per needle.

The microneedles were inserted up to a depth of 225 μm.

At 8 hours, the drug level was undetectable (0.02 ± 0.01 μg/g).