A 70-year-old patient with primary open-angle glaucoma was implanted with a second-generation EYEMATE-IO  device during cataract surgery in the right eye as part of a clinical trial in 2015. At that time, he had been diagnosed with glaucoma for 29 years. He had not undergone previous eye surgery at the time of EYEMATE-IO  implantation. Glaucoma was mild in both eyes, with a mean visual field defect of 4.8 and 2.4 dB in the right and left eye, respectively. The IOP was well regulated with local latanoprost and brimonidine. We followed the patient regularly until the outbreak of the COVID-19 pandemic in 2020. During that time, visits to the clinic were highly restricted, and the patient was seen only twice per year. In addition, the patient's wife had a serious illness and was in constant need of care, so the patient was additionally restricted in his visits the Eye Hospital. In May 2021, the EYEMATE-IO  recorded an increase in the IOP in the right eye. During a visit arranged at short notice, the EYEMATE-IO  measurements revealed IOP values between 24.8 and 26.6 mmHg, which were verified by three GAT measurements showing values between 26.0 and 28.0 mmHg in the right eye. The antiglaucoma medication was changed to a preservative-free combination of bimatoprost/timolol and dorzolamide; however, severe allergic eczema of the eyelids and the periocular skin developed. In December 2021, the patient's GAT IOP values were between 34.0 and 37.0 mmHg (three measurements). Self-measurements obtained via the EYEMATE-IO  during the same visit showed IOP values between 41.3 and 42.0 mmHg (three measurements). On gonioscopy, the anterior chamber angle was Shaffer grade IV in all quadrants, with normal pigmentation of the trabecular meshwork. Furthermore, there was no change in the position of the EYEMATE-IO , which could have explained the IOP elevation. Several mechanisms might have caused the increase in IOP, including the course of the disease, loss of IOP reduction capacity of the antiglaucoma medications, and loss of adherence to therapy due to the adverse effects caused by the medications. In addition, optical coherence tomography (OCT) demonstrated progressive loss of the retinal nerve fiber layer of 2.9 microm per year in the last 2 years.
Because the glaucoma was progressive on OCT and the IOP was elevated on maximal-tolerated medication, the decision was made to perform minimally invasive bleb surgery in the right eye with the PreserFlo  MicroShunt. Antiglaucoma medications were stopped in the right eye 2 weeks prior to surgery, and systemic acetazolamide 250 mg twice daily was given instead. Unpreserved dexamethasone eye drops were given three times daily in the right eye 1 week before surgery. The surgery was uncomplicated, and the postoperative care was unremarkable. Moxifloxacin eye drops were given for 1 week four times daily, and unpreserved dexamethasone eye drops were tempered over 6 weeks. The patient continued to conduct IOP self-measurements with the EYEMATE-IO  postoperatively. At 3-month follow-up, we observed a moderately elevated, posterior, well-functioning filtering bleb in the right eye. The IOP was 14.5 mmHg (mean of two measurements) with GAT and 15.5 mmHg (mean of two measurements) with the EYEMATE-IO . The patient was medication free in the operated eye. A further follow-up was scheduled in 6 months, and the patient was instructed to continue the IOP self-measurements. The patient was prompted to contact the clinic immediately if his IOP increased over 20.0 mmHg to arrange an earlier visit. The telemetrically obtained IOP data between January 2021 and the time of publication of this report are presented in Figure 1.
Statistical analysis was performed to compare the mean IOP values collected by the EYEMATE-IO  during follow-up. IOP decreased significantly from 28.7 +- 8.3 mmHg at baseline (range = 13.5-49.1 mmHg, 76 measurements) to 14.6 +- 2.7 mmHg at 3 months (range = 8.1-22.4 mmHg, 137 measurements), 12.7 +- 2.2 mmHg at 5 months (range = 6.8-17.9 mmHg, 120 measurements), 14.1 +- 2.2 mmHg at 7 months (range = 8.6-19.7 mmHg, 81 measurements), and 14.6 +- 2.7 mmHg at 9 months after surgery (range = 8.4-22.3 mmHg, 73 measurements), respectively. The self-measured IOP values during the preoperative month and postoperative months 3, 5, 7, and 9 - depending on the time of the day - are presented in Tables 1 and 2 and Figure 2. In addition, the 24-h IOP fluctuations were considerably lower at all follow-up time points compared with the fluctuations recorded during the preoperative month (Figures 2 and 3).