Purpose
The iMvalv is an ocular implant with MEMS technology to produce aqueous humor drainage. It was built with silicone multiple layers, (for their plate and tube) and has the capability of an active mechanism powered by a spiral antenna and a hybrid microcircuit. This is the first exploratory in-vivo study in rabbits to implant it and to describe and evaluate its surgical, clinical and histological performance.
Methods
Five New Zeland male rabbits were anesthetized and his right eyes were operated (left eyes were controls) with similar equipment and technique utilized for humans glaucoma implants procedures. Briefly, after conjunctiva and tenon were opened (4 millimeters at the limbus), a pocket was created and the iMvalv plate was implanted. Then, the tube was introduced in the anterior chamber and conjunctiva was closed (sutured with nylon 10.0). Previousy, intraocular pressure (IOP) were measured with Perkins tonometer (for both eyes) and measurements were taken again 1, 7, 21 and 50 days after surgeries. Also, clinical evolution were evaluated at the same time-points. Post-operative topical drops (gatifloxacin 0,3; dexametasone 1%) were instilled four times a day during 10 days. At day 50, animals were euthanized, right eyes were enucleated and the histological study were performed (heatoxilin-eosine).
Results
From the five eyes, the first has suffered the tube extrusion one day after surgery and the animal were euthanized and excluded from the study. The remains four operated eyes finished the complete study and their IOP were lower than controls at all the different time-points (2-3mmHg versus 5-6mmHg in controls). However, one eye reach 6 mmHg one day after surgery (clinical evaluation shows fibrin reaction in the anterior chamber), which spontaneously decrease to 3 mmHg one week after (anterior chamber reaction disappear). No other clinical alteration were described in all of the eyes. The histological study shows foreign body tissue reaction in the implant area (the same in all of the eyes).
Conclusions
The iMvalv device were successfully implanted in four eyes from five and IOP were lower than controls during all of the study. Clinical and histological evolution were similar than could be observed in non complicated humans glaucoma valves implants surgeries. New studies will be necessary to improve the design and to probe all of the potential advantages of this new conceptual technology for glaucoma devices.