Abstract
Purpose :
Present-day treatments for corneal blindness are limited by a high rate of complications. Moreover, such approaches may not be as effective in particularly severe cases of ocular surface damage. The purpose of this work is to create a complete functional intraocular microdisplay projector system that projects light directly onto the retina by bypassing the damaged cornea, and to test whether this alternative approach for treating corneal opacity can potentially restore high levels of functional vision.
Methods :
The intraocular microdisplay projection systems (IMPS) were constructed from commercially available electronic components. These devices work by capturing light via an external camera, processing the data wirelessly, and projecting an in-focus image onto the retina via an intraocular microdisplay. The IMPS were encased in biocompatible plastic housing, then sealed and waterproofed in biocompatible silicone. Image quality and visual acuity of the device were measured with a calibrated eye chart. The biocompatibility of the external projector components was assessed using MTT cell proliferation assay. Accelerated wear testing was performed in 0.9% normal saline at 70°C. Heat dissipation from the device was measured externally and after implantation in a living rabbit eye.
Results :
Functioning implants (9.5 x 7 mm x 7 mm; ~360 mg) consisting of projecting and processing units were successfully constructed. With a lens (focal length of 3 mm) placed 4 mm from the microdisplay (10.5 µm pixel pitch), the device can produce a visual acuity of up to 20/127. The external materials were shown to be non-toxic, and three of four devices remained functional after three months in accelerated wear conditions. External temperature testing demonstrated a 1.78°C increase after one hour; a 75 mW device implanted in a living rabbit eye for 30 minutes exhibited a peak temperature increase of 1°C.
Conclusions :
Intraocular microdisplay projectors could be used to restore vision in people blinded by corneal opacity. In the future, such a device could provide a more accessible solution to patients who may not be ideal candidates for cornea transplants or keratoprostheses.
This abstract was presented at the 2019 ARVO Annual Meeting, held in Vancouver, Canada, April 28 - May 2, 2019.