The purpose of this study by Weinreb and colleagues was to evaluate the biodegradation of the bimatoprost 10-µg implant in the phase 3 ARTEMIS studies. Patients enrolled in this study had a diagnosis of open-angle glaucoma or ocular hypertension, with washout IOP between 22-32 mmHg and an open inferior iridocorneal angle. Gonioscopy was used to assess the size of the implant compared to the initial size at implantation and the location of the implant in the angle. Implant size of absent to ≤ 25% was considered to be clinically significant implant biodegradation. The study found that most implants increased in size from week two to 28, typically increasing about 50%, but some implants doubling in size. By week 28 about half of implants were found to be ≤ 75% and a third were estimated to be ≤ 50% of the initial size. Only about 12% reached clinically significant biodegradation. However, by weeks 31 to 52 most implants reached clinically significant biodegradation and 92% were ≤ 50% of their initial size. By month 20, 95% were absent or ≤ 25%.
Additional studies are needed to better understand the relationship between implant biodegradation and intraocular pressure control to determine timing of retreatment
Gonioscopy showed that most implants were located in the inferior iridocorneal angle. It is unclear how the administration of the second and third implant in the ARTEMIS study at week 16 and 32 may have affected the degradation of the first implant. Also, the grading of the implant size is somewhat subjective with unknown intrasubject variability. Furthermore, it is unclear what clinical significance the rate of degradation has on intraocular pressure control as implant remnant may be present for months after complete drug release and IOP may continue to be controlled after the implant is completely biodegraded. Additional studies are needed to better understand the relationship between implant biodegradation and intraocular pressure control to determine timing of retreatment.