Houston's First Bionic Eye - The Argus II Retinal Prosthesis Amir Mohsenin, M.D., Ph.D - The Robert Cizik Eye ...

Houston’s First Bionic Eye

The Argus II Retinal Prosthesis

           Amir Mohsenin, M.D., Ph.D.

    Department of Ophthalmology & Visual Science
  University of Texas Health Science Center at Houston

               Low Vision Education Day
                       July 2018

Retinitis Pigmentosa

                       From L. Yannuzzi’s “The Retinal Atlas”

Retinitis Pigmentosa
• Group of disorders characterized by:
   – Genetic inheritance
   – Progressive visual dysfunction
   – Retinal atrophy

• Different names:
   –   Tapetoretinal degeneration
   –   Primary pigmentary retinal degeneration
   –   Pigmentary retinopathy
   –   Rod-Cone dystrophy

• Vision changes:
   – Night blindness
   – Peripheral visual field loss
   – Central vision dysfunction

• Two broad categories: ”Typical RP” or ”Syndromic RP”

                                                         Image from L. Yannuzzi’s “The Retinal Atlas”

Retinitis Pigmentosa Types
          Typical                Syndromic
• Primarily ocular        • Associated with
  involvement               systemic disease

• Prevalence:             • Prevalence:
   – ~ 1:5000 worldwide      – Not well documented
                             – Usher syndrome: 1:6000

Retinitis Pigmentosa Management
• Maximize current vision
    – Refraction for new glasses
    – Remove cataracts if visually significant

• Treat macular edema if present
    – Topical or oral carbonic anhydrase inhibitors
    – Can consider intraocular steroid injection

• Nutritional supplements
    – Vitamin A palmitate: 15,000 IU/day
         • Slows the decline in ERG response by 20% per year
         • Has long-term adverse effects: Liver toxicity
         • Teratogenic: Can not be used in women who may become pregnant

    – Omega-3 Fatty Acids
         • Clinical trial failed to show clear benefit

    – Vitamin E at high dose may be harmful (?)

Retinitis Pigmentosa Management

• Sunglasses with UVA and UVB blocking

• Smoking cessation

• Low vision referral if appropriate

• Retinal prosthesis -> Argus II

What does the Bionic Eye do
            and who is it for?
§ Provides electrical stimulation of the retina to induce visual perception in
 blind patients

§ SELECTION CRITERIA:
  §   Severe advanced Retinitis Pigmentosa
  §   25 years of age or older
  §   Bare light or no light perception in both eyes
  §   Previous history of useful vision
  §   Able to perform post-implantation follow up and training

ARGUS II Retinal Prosthesis

Argus II Features
§ World’s first and only FDA approved retinal prosthesis for people blinded by
 outer retinal degenerations
§ Upgradeable camera, processor and software
§ Camera is external to the eye -> not affected by ocular opacity
§ Each electrode is individually programmable
§ Visual field of 20 degrees
§ MRI conditional
 § Can use 1.5 or 3.0 Tesla MRI machine with special instructions

§ Camera specs: 316,000 pixels element image sensor
§ Electrode array
 § 60 element stimulator
 § 5000:1 processing ratio

Argus II Early Clinical Trial
§ Clinical trial started in 2006
§ 5 year safety and performance results published in 2016
§ 30 participants in 10 centers across the US and Europe
§ Primary outcomes were safety and visual function
§ Secondary outcomes were functional visual performance on real-world tasks

§ RESULTS:
  § 24 of 30 patients remained implanted with functioning device at 5 years
  § 1 serious adverse event after the 3 year time point
  § Patients performed significantly better with the Argus on all visual function tests and
    functional vision tasks

Argus II Early Trial
                    Adverse Events
§ Conjunctival erosion (13%)
§ Low Eye Pressure (13%)
§ Conjunctival dehiscence (10%)
§ Endophthalmitis (10%)
§ Retack (7%)
§ Retinal Detachment (10%)
§ Retinal Tear (3%)
§ Uveitis (3%)
§ Keratitis, corneal melt, corneal opacity (each 1%)

Argus II Early Trial
 Reliability, Safety & Explantations
§ Reliability:
  § At 5 years
    § 2 implants failed at 4 years post implantation
    § Both because of progressive loss of ability to maintain radio-frequency link
    § Both devices remain implanted

§ Explantations:
  § 3 complete or partial explants
    § 1 implant removed at 14 months due to conjunctival erosion
    § 2 implants removed at 3.5 years and 4.3 years
      § One patient had recurrent conjunctival erosions and after 3rd occurrence the patient requested
         explantation
      § Other patient had chronic low eye pressure and drooping of the eyelid
        § Chose explantation for aesthetic reasons and to avoid additional surgeries

Argus II Early Trial
          Visual Function at Year 5
§ All tests performed with the Argus turned “on” and “off”

§ SQUARE LOCALIZATION
 § Ability to locate and touch a high-contrast white square of light on a
   black background on a touch screen
 § 80% performed significantly better with system ”on”

§ DIRECTION OF MOTION
 § Ability to determine and indicate the direction of a high-contrast bar
   that moved across the monitor
 § 50% performed significantly better with system “on”

§ GRATING VISUAL ACUITY
 § Visual acuity using square-wave gratings of different spatial
   frequencies on a computer monitor
 § 38% performed significantly better with system “on”

Steps to get the Bionic Eye
• 1. Screening visit in the clinic

• 2. Schedule surgery

• 3. Surgery day
   – Approximately 4 hour surgery
   – General anesthesia
   – Outpatient procedure

• 4. Post-operative appointments

• 5. Activation of device 1 month after surgery

• 6. Training

Bionic Eye Future Plans

•   Eye tracking

•   Infrared Thermal Sensor

•   2 cameras for depth perception

•   Artificial Intelligence
     • Object recognition
     • Ability to Read
     • Alexa type technology
     • GPS integration

•   Virtual Reality Games Improving the VPU

THANKS!