Experimental Implantation and Long-term Testing of an Intraocular Vision Aid in Rabbits

Abstract

To develop an intraocular vision aid to provide artificial vision in severely traumatized eyes, where neuroretinal function could be preserved but irreversible anterior segment opacification resulted in blindness. Methods: The basis of an intraocular vision aid is in principle a telemetric circuit to bridge the opaque cornea and to allow for artificial light stimulation of the retina. The visual prosthesis comprises an external high-dynamic range complementary metal oxide semiconductor camera and digital signal processing unit and an intraocular miniaturized light-emitting diode array to project the image onto the retina. For in vivo testing of long-term function and biocompatibility, silicone-encapsulated active photodiodes were implanted in 13 pigmented rabbits and were followed up for up to 21 months. Results: Lens extraction and stable fixation of the device in the ciliary sulcus were successful in all cases. For up to 21 months inductive energy transmission and wireless stimulation of the implants could be maintained. Electrophysiologic data and histology demonstrated a good tissue biocompatibility in the long-term follow-up. Conclusion: The results demonstrate the general feasibility and biocompatibility to implant and fixate an intraocular light-emitting diode prosthesis. Inductive energy transmission to the intraocular device and wireless light stimulation are assured in the long term but depend on meticulous water-impermeable encapsulation of the delicate microelectronic components. Clinical Relevance: An intraocular vision aid compound system with a high-resolution light-emitting diode matrix might be a future treatment option to restore vision in blind eyes with severe anterior segment disorders.

A Step by Step Protocol for Subretinal Surgery in Rabbits

“…Lubricant should be added every 5 -10 min to prevent corneal, scleral and conjunctival damage during the operation, and to maintain a clear intraocular media, as dried/blackened sclera may be a cause of wound dehiscence, which in turn leads to ocular hypotony and/ or intraoperative leakage from sclerotomies. Heparin should be added to prevent the formation of a fibrin film that makes particularly subretinal implantation challenging and simultaneously adding epinephrine to reduce bleeding under heparin 16 . Too long heparin/ epinephrine exposure times (>1 hour) should be avoided to prevent corneal edema by endothelial decompensation 33 , hypertensive crisis or intraoperative fatality.…”

A Step by Step Protocol for Subretinal Surgery in Rabbits

“…Lubricant should be added every 5 -10 min to prevent corneal, scleral and conjunctival damage during the operation, and to maintain a clear intraocular media, as dried/blackened sclera may be a cause of wound dehiscence, which in turn leads to ocular hypotony and/ or intraoperative leakage from sclerotomies. Heparin should be added to prevent the formation of a fibrin film that makes particularly subretinal implantation challenging and simultaneously adding epinephrine to reduce bleeding under heparin 16 . Too long heparin/ epinephrine exposure times (>1 hour) should be avoided to prevent corneal edema by endothelial decompensation 33 , hypertensive crisis or intraoperative fatality.…”

Wireless image transfer across opaque cornea: A novel approach to visual rehabilitation

“…One of the early examples of an anterior-segment-focused electronic vision model was the Intraocular Vision Aid (IOVA), which incorporated a spectacle-mounted camera and a wireless intraocular display, with feasibility demonstrated in animal models. [ 8 ] Though literature is scant on the subject, older prototypes used CMOS camera and infrared light followed later by blueprints for wireless image transfer across the cornea using modern transfer protocols. [ 9 10 11 ] Some experiments involve data transfer across clear cornea using electronic chips embedded in contact lenses.…”

Feasibility of Intraocular Projection for Treatment of Intractable Corneal Opacity

“…As a proof of concept and safety test, implants with a single wirelessly powered LED were placed successfully into the anterior segments of 13 rabbits for up to 21 months. 22 No further work since 2005 was found on this subject.…”

A Step by Step Protocol for Subretinal Surgery in Rabbits

“…Lubricant should be added every 5 -10 min to prevent corneal, scleral and conjunctival damage during the operation, and to maintain a clear intraocular media, as dried/blackened sclera may be a cause of wound dehiscence, which in turn leads to ocular hypotony and/ or intraoperative leakage from sclerotomies. Heparin should be added to prevent the formation of a fibrin film that makes particularly subretinal implantation challenging and simultaneously adding epinephrine to reduce bleeding under heparin 16 . Too long heparin/ epinephrine exposure times (>1 hour) should be avoided to prevent corneal edema by endothelial decompensation 33 , hypertensive crisis or intraoperative fatality.…”

Wireless image transfer across opaque cornea: A novel approach to visual rehabilitation

“…One of the early examples of an anterior-segment-focused electronic vision model was the Intraocular Vision Aid (IOVA), which incorporated a spectacle-mounted camera and a wireless intraocular display, with feasibility demonstrated in animal models. [ 8 ] Though literature is scant on the subject, older prototypes used CMOS camera and infrared light followed later by blueprints for wireless image transfer across the cornea using modern transfer protocols. [ 9 10 11 ] Some experiments involve data transfer across clear cornea using electronic chips embedded in contact lenses.…”

Feasibility of Intraocular Projection for Treatment of Intractable Corneal Opacity

“…As a proof of concept and safety test, implants with a single wirelessly powered LED were placed successfully into the anterior segments of 13 rabbits for up to 21 months. 22 No further work since 2005 was found on this subject.…”

A Step by Step Protocol for Subretinal Surgery in Rabbits

“…Lubricant should be added every 5 -10 min to prevent corneal, scleral and conjunctival damage during the operation, and to maintain a clear intraocular media, as dried/blackened sclera may be a cause of wound dehiscence, which in turn leads to ocular hypotony and/ or intraoperative leakage from sclerotomies. Heparin should be added to prevent the formation of a fibrin film that makes particularly subretinal implantation challenging and simultaneously adding epinephrine to reduce bleeding under heparin 16 . Too long heparin/ epinephrine exposure times (>1 hour) should be avoided to prevent corneal edema by endothelial decompensation 33 , hypertensive crisis or intraoperative fatality.…”

Wireless image transfer across opaque cornea: A novel approach to visual rehabilitation

“…One of the early examples of an anterior-segment-focused electronic vision model was the Intraocular Vision Aid (IOVA), which incorporated a spectacle-mounted camera and a wireless intraocular display, with feasibility demonstrated in animal models. [ 8 ] Though literature is scant on the subject, older prototypes used CMOS camera and infrared light followed later by blueprints for wireless image transfer across the cornea using modern transfer protocols. [ 9 10 11 ] Some experiments involve data transfer across clear cornea using electronic chips embedded in contact lenses.…”

Feasibility of Intraocular Projection for Treatment of Intractable Corneal Opacity

“…As a proof of concept and safety test, implants with a single wirelessly powered LED were placed successfully into the anterior segments of 13 rabbits for up to 21 months. 22 No further work since 2005 was found on this subject.…”