Free Powerpoint Templates

The “Bionic Eye”: A Ray of Vision For the Blind…

Presented by: Rimjhim Roy Choudhury

Roll No.: 11410609

(Current Research and Future Prospects)

ScleraChoroid

Fovea / Yellow Spot (center

of visual field)

Optic Nerve

Retina

Central Artery and vein of the

retina

Blind Spot

Lens

Pupil

Iris

Cornea

Suspensary Ligament

Ciliary Body

Aqueous Humor

Vitreous Humor

The Retina

The Retina

Diseases of the Eye

Retinitis PigmentosaMacular Degeneration

Retinitis Pigmentosa

Hereditary Genetic Disease

Peripheral Rods degenerate

Gradually progresses towards center of eye

Spares the foveal region

Tunnel vision results

Macular Degeneration

Genetically RelatedCones in Macula

region degenrateLoss or damage of

central visionPeripheral Retina

sparedCommon among old

people

G.S. Brindley’s Research

Breakthrough in 1968Implaned electrodes into the visual cortexFirst electrical stimulation of Visual CortexBright spots called phosphene was producedPhosphene is a visual phenomenon characterized

by experience of seeing light without light actually entering the eye.

Dr. Mark Humayun’s Research (USC)

In 1998 demonstrated that a blind person could be made to see light by stimulating the nerve ganglia behind the retina with an electrical current.

This test proved that the nerves behind the retina still functioned even when the retina had degenerated.

Based on this information, scientists set out to create a device that could translate images and electrical pulses that could restore vision.

Mark Humayun himself is involved with the research on Second Sight’s Argus II.

Optimism: Advances in biomaterials, micro fabrication, electronics

The Success of :Cardiac pacemakers as neural prosthesisCochlear implants to restore hearing to the deaf

The development of DRDO’s indigenous and affordable cochlear implant monitored by Dr. Kalam

Rapid developments in : VLSI design Micro- fabrication technology

Bionic Eye?

Visual Prostheses including:Retinal Prosthesis: Artificial Silicon Retina:

Epiretinal (Argus II by Second Sight Medical Products Inc) , Subretinal (Artificial Silicon Retina microchip by Optobionics Corporation; Retina Implant AG, Germany).

Optic Nerve Prosthesis: Lateral geniculate nucleus, Optic nerve and Optic disc (early experimental stage)

Cortical prosthesis: Only therapeutic approach for individuals with non-functioning retinae or optic nerves (Utah Electrode Array – experimental stage)

Approaches Towards Retinal Prosthetic Implantation

Epiretinal Approach involves a semiconductor based device positioned on the surface of the retina to try to simulate the remaining overlying cells of the retina.

Subretinal Approach involves implanting the chip behind the retina to simulate the remaining viable cells.

Device 1: Retina Implant AG, Germany

Augmented Reality: Retina Implant AG, Germany

On the retina implant, next to the 1500 photodiode array, was a 4x4 matrix of direct stimulation points. (No photodiodes, just electrical contacts).

Using that 4x4 pattern, doctors were able to get their newly implanted patients to see small dots, vertical and horizontal lines, and even simple shapes (like 'L').

Device 2: Second Sight’s Argus, close to becoming commercially available.

• .

On-Going Development:Argus III

The Argus III will work by taking the image from a camera and wirelessly transmitting it to an electronics package. That package will stimulate undamaged retinal tissue using a thin film transistor electrode array.

Augmented Reality: Argus II

Sent it to the eye implant

Process the new image

Add the graphics

Take the input from the camera

Challenges

Visual Acuity:Visual acuity is a

measure of the spatial resolution

The best reported visual acuity was 20/1,000

The cutoff for legal blindness is 20/200

Normal vision is 20/20

Schnellen Chart

Challenges (Contd.)

Field of ViewThe extent of the observable world that is seen at any given

moment.For ARGUS II extends to 20 degrees (the limit for legal

blindness)Natural vision has a 180-degree field of view. The subretinal implants provide a field of view of less than

15 degrees. More than 1000 pixel display (large no. of electrodes) is

required for near normal vision.

We are a long way from being able to claim “restored vision.”

Drawbacks of Silicone

Silicon based microdetectors continues to suffer from problems of deterioration of the chip, contamination of the eye and atrophy of the retina.

Silicon needs to be encapsulated in thin biocompatible polyimmide film because of its toxicity in the human body.

Drawbacks of Silicone (cont.)

Scientists at NASA’s Space Vacuum Epitaxy Centre (SVEC), have developed a new material, a non toxic ceramic microdetectors.

The arrays are stacked in a hexagonal structure that mimics the arrangement of the rods and cones.

It’s naturally porous structure allows nutrients to flow from the back to the front of the eye, preventing atrophication of the retina.

Conclusion

Hans Keirstead (UC Irvine) is already working on a stem cell treatment, succeeded in getting stem cells to differentiate into a retina.

He created a 3D retina (first 3D tissue structure) derived from hESCs for the treatment of retinal diseases.

By the time we get retina implants up to the levels of human vision, we may no longer need to rely on them for vision restoration.

Augmentation may ultimately be the only real reason to get an implant.

References

Mark Humayun et al. “Artificial vision through neuronal stimulation” Neuroscience Letters 25 June 2012, Vol 519(2), pp. 22-128

Mark S. Humayun et al. “Pattern electrical stimulation of the human retina” Vision Research July 1999, Vol 39(15), pp. 2569-2576

G.S. Brindley et al. “The sensations produced by electrical stimulation of the visual cortex” Journal of Physiology 1968, Vol 96, pp. 479–493

Zhilian Yue et al. “Controlled delivery for neuro-bionic devices” Advanced Drug Delivery Reviews, In Press, Corrected Proof, Available online 13 June 2012

James D. Weiland and Mark S. Humayun. "Retinal Prosthetic Systems for Treatment of Blindness” Frontiers of Engineering 2011: Reports on Leading-Edge Engineering from the 2011 Symposium. Washington, DC: The National Academies Press, 2012, pp. 115–121

Keirstead HS et al.“Three-dimensional early retinal progenitor 3D tissue constructs derived from human embryonic stem cells.” J Neurosci Methods. 2010 Jun 30;190(1):63-70.

2-sight.eu retina-implant.de http://spectrum.ieee.org/biomedical/bionics/augmented-reality-in-a-contact-lens http

://www.dailymail.co.uk/sciencetech/article-2138775/The-eye-borg-First-successful-implant-bionic-eye-restore-sight-blind.html

Thank You!