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Subretinal implantation of semiconductor-based photodiodes: durability of novel implant designs.
J Rehabil Res Dev 2002 May-Jun; 39(3):313-21JR

Abstract

Selective degeneration of the retinal photoreceptor layers underlies blindness in retinitis pigmentosa (RP) and other inherited retinal disorders. Because there are no therapies for these patients, we are evaluating the possibility that electrical stimulation delivered to the subretinal space by a microphotodiode array (MPA) could replace, in some aspect, the function of diseased photoreceptors. Early MPA prototypes utilized gold as the electrode material, which gradually dissolved during the postoperative period following subretinal implantation. Here we present the results obtained when different MPA materials were used. Semiconductor-based silicon MPAs (2 mm in diameter; 50 microm in thickness), incorporating iridium/iridium oxide (IrOx) or platinum (Pt) electrodes, were implanted into the subretinal space of the right eye of normal cats with the use of vitreoretinal surgical techniques. Indirect ophthalmoscopy, fundus photography, ganzfeld electroretinography, and histology were used for the evaluation of the implanted retinas postoperatively. Infrared (IR) stimulation was used to isolate electrical responses generated by the MPA. The unimplanted left eyes were used for control purposes. After the implantation surgery, subretinal MPAs retained a stable position in the subretinal space. Up to 12 months after surgery, there was little change in the magnitude of the electrical response of IrOx- and Pt-based MPAs to a standard IR light stimulus. Overlying the implant, there was a near-complete loss of the outer retinal layer, which is likely to reflect obstruction of choroidal nourishment to these layers by the solid disk implant. In addition, the inner retinal layers showed variable disorganization. Away from the implant, the retina displayed a normal appearance. In comparison to electroretinograms (ERGs) obtained from unimplanted eyes, responses recorded from implanted eyes had a normal waveform but were slightly smaller in amplitude. These results indicate that IrOx and Pt improve implant electrode durability and that implants incorporating these materials into the electrode layer do not induce panretinal abnormalities.

Authors+Show Affiliations

Optobionics Corporation, Wheaton, IL 60187, USA. alanykc@aol.comNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info available

Pub Type(s)

Comparative Study
Journal Article
Research Support, Non-U.S. Gov't
Research Support, U.S. Gov't, Non-P.H.S.

Language

eng

PubMed ID

12173752

Citation

Chow, Alan Y., et al. "Subretinal Implantation of Semiconductor-based Photodiodes: Durability of Novel Implant Designs." Journal of Rehabilitation Research and Development, vol. 39, no. 3, 2002, pp. 313-21.
Chow AY, Pardue MT, Perlman JI, et al. Subretinal implantation of semiconductor-based photodiodes: durability of novel implant designs. J Rehabil Res Dev. 2002;39(3):313-21.
Chow, A. Y., Pardue, M. T., Perlman, J. I., Ball, S. L., Chow, V. Y., Hetling, J. R., ... Peachey, N. S. (2002). Subretinal implantation of semiconductor-based photodiodes: durability of novel implant designs. Journal of Rehabilitation Research and Development, 39(3), pp. 313-21.
Chow AY, et al. Subretinal Implantation of Semiconductor-based Photodiodes: Durability of Novel Implant Designs. J Rehabil Res Dev. 2002;39(3):313-21. PubMed PMID: 12173752.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Subretinal implantation of semiconductor-based photodiodes: durability of novel implant designs. AU - Chow,Alan Y, AU - Pardue,Machelle T, AU - Perlman,Jay I, AU - Ball,Sherry L, AU - Chow,Vincent Y, AU - Hetling,John R, AU - Peyman,Gholam A, AU - Liang,Chanping, AU - Stubbs,Evan B,Jr AU - Peachey,Neal S, PY - 2002/8/14/pubmed PY - 2003/1/8/medline PY - 2002/8/14/entrez SP - 313 EP - 21 JF - Journal of rehabilitation research and development JO - J Rehabil Res Dev VL - 39 IS - 3 N2 - Selective degeneration of the retinal photoreceptor layers underlies blindness in retinitis pigmentosa (RP) and other inherited retinal disorders. Because there are no therapies for these patients, we are evaluating the possibility that electrical stimulation delivered to the subretinal space by a microphotodiode array (MPA) could replace, in some aspect, the function of diseased photoreceptors. Early MPA prototypes utilized gold as the electrode material, which gradually dissolved during the postoperative period following subretinal implantation. Here we present the results obtained when different MPA materials were used. Semiconductor-based silicon MPAs (2 mm in diameter; 50 microm in thickness), incorporating iridium/iridium oxide (IrOx) or platinum (Pt) electrodes, were implanted into the subretinal space of the right eye of normal cats with the use of vitreoretinal surgical techniques. Indirect ophthalmoscopy, fundus photography, ganzfeld electroretinography, and histology were used for the evaluation of the implanted retinas postoperatively. Infrared (IR) stimulation was used to isolate electrical responses generated by the MPA. The unimplanted left eyes were used for control purposes. After the implantation surgery, subretinal MPAs retained a stable position in the subretinal space. Up to 12 months after surgery, there was little change in the magnitude of the electrical response of IrOx- and Pt-based MPAs to a standard IR light stimulus. Overlying the implant, there was a near-complete loss of the outer retinal layer, which is likely to reflect obstruction of choroidal nourishment to these layers by the solid disk implant. In addition, the inner retinal layers showed variable disorganization. Away from the implant, the retina displayed a normal appearance. In comparison to electroretinograms (ERGs) obtained from unimplanted eyes, responses recorded from implanted eyes had a normal waveform but were slightly smaller in amplitude. These results indicate that IrOx and Pt improve implant electrode durability and that implants incorporating these materials into the electrode layer do not induce panretinal abnormalities. SN - 0748-7711 UR - https://www.unboundmedicine.com/medline/citation/12173752/Subretinal_implantation_of_semiconductor_based_photodiodes:_durability_of_novel_implant_designs_ L2 - https://www.rehab.research.va.gov/jour/02/39/3/pdf/Chow.pdf DB - PRIME DP - Unbound Medicine ER -