Bringing Galileo into the 21st Century

Age-related macular degeneration (AMD), a progressive disease of the retina impacting millions of older adults around the world, is the number one cause of blindness in people 65 years and older. Addressing this disease is Samsara Vision (previously known as VisionCare Inc.) and its first and only U.S. Food and Drug Administration (FDA) approved Implantable Miniature Telescope (IMT). Developed by Isaac Lipshitz, IMT is a device proven to restore vision and improve quality of life. IMT also has the CE mark for the European Union, Therapeutic Goods Administration register certificate from Australia, and Health Canada medical device license.

Reducing the blind spot

The IMT technology platform is based on wide-angle micro-optics that, in combination with the optics of the cornea, create a telephoto system that magnifies objects in view (2.2x/2.7x, depending on model). The magnification projects images seen straight-ahead onto healthy perimacular areas of the retina instead of the macula alone, where AMD caused a breakdown of photoreceptors and loss of vision. (The nominal field of view of 24° is projected onto approximately 54° of the retina.) This reduces the impact of the blind spot (central scotoma) in central vision. The blind spot doesn’t go away, but it appears smaller to the patient who can see around it.

In an outpatient procedure, the corneal surgeon will remove the eye’s natural lens and place the IMT in the capsular bag, using haptic loops to keep it stationary. Monocular implantation inside one eye allows the patient to see using natural eye movements in stationary and dynamic environments. Since there’s no relative movement between the eye and the telescope, there are no optical aberrations. The implanted eye provides central vision, while the fellow eye remains as-is to be used for peripheral vision, despite also being impacted by late-stage AMD. Working with an occupational therapist and low-vision specialists post-operatively, patients learn to use their new vision, retraining their brain to see images previously unrecognizable, such as faces. IMT candidates must also meet specific age and eye health requirements and aren’t eligible if they had previous intraocular or corneal surgery in the operative eye, including any type of surgery for either refractive or therapeutic purposes (e.g., cataracts).

High tech components

Despite being smaller than a pea, the wide angle (WA) IMT uses Galileo’s telescope principles with its fixed-focus telescopic system comprising an ultraprecision glass wide-angle micro-optics design.

The WA IMT prosthetic device includes three primary components: a fused silica glass capsule that contains wide-angle micro-optical elements; a clear polymethylmethacrylate (PMMA) carrier; and a blue PMMA light restrictor which prevents peripheral light from entering the eye. The sealed optical component is snap-fitted into the carrier plate. All materials are biocompatible for long-term ocular implantation, and one of the internal pieces that’s not in contact with body fluids or tissue but contains stainless steel, has been evaluated for MRI compatibility and determined to be MR-conditional.

Individual components of the IMT are selected carefully based on quality and the manufacturers’ expertise. For example, the optical lenses are sourced from Swiss or German firms and the plastics and silicone materials are know-how of other manufacturers in EU or U.S. markets. In our Israeli lab, our specially trained professionals combine the components, check each piece, and use sophisticated technology that is precisely designed for the IMT. In our cleanroom, we also have proprietary machines that assemble the telescope to ensure high quality. For example, there is a special assembling machine that enables precise integration of optics up to 2µm in tolerance – a special technology of telescope capsule glass welding. During device manufacturing, engineers also use quality control machines that check each telescope capsule for integrity and sealing, and optical benches that mimic human eyes to confirm device performance and its collaboration with the human eye testing criteria. Each device is tested individually to confirm quality before it’s shipped.

Next-generation, smaller incision device

Clinical study results demonstrate that the WA IMT improves Best Corrected Visual Acuity (BCVA) by three to four lines and that this gain in visual acuity is retained for more than 60 months. The WA IMT dimensions require corneal surgeons to perform a 12mm limbal incision, 12 sutures, and 7mm capsulorhexis for implantation to minimize the risk of endothelial cell (ECD) loss.

Already available in Europe and under evaluation in the U.S., the Samsara Vision Tsert SI IMT resolves some of these issues. This next-generation device comes in a single-use, sterile, disposable preloaded injectable system, which, after removal of the ocular crystalline lens, allows the device to be injected into the eye’s capsular bag in a conventional surgical procedure similar to intraocular lens (IOL) implantation. This eases the surgical procedure, eliminates safety issues, reduces astigmatism by a minimum number of sutures, significantly reduces trauma, eliminates intraocular device manipulation, and halves surgery time (down to about 25 minutes). All these are related to significant reduction of the incision size (6.5mm). The Tsert SI IMT has optical performances and elements identical to that of the IMT and 2.7x magnification.

One limitation of the IMT is that it’s currently contraindicated in those with previous intraocular or any corneal surgery in the operative eye. This eliminates the significant number of older adults who underwent cataract surgery. Cataracts can develop before or concurrently with AMD. Despite the improved design of the Tsert SI IMT, it doesn’t lend itself to be surgically exchanged for a previously implanted IOL. One of the major challenges in the company development pipeline is a small incision IMT for this patient population, modifying our technology to serve the needs of pseudophakic patients.

Modern medicine has vastly increased life expectancy, but with that comes increasing prevalence of progressive conditions, such as AMD, which impact the health and well-being of older adults. Samsara Vision remains a small company focused on improving the vision of people living with serious retinal diseases. In developing the IMT and the patient-centric technology, the company has positively contributed to an improved quality of life in our target patient population, but won’t be satisfied until a larger section of that community can access our novel technology.

Samsara Vision
https://www.samsaravision.com

About the author: Eli Aharoni is vice president research & development, general manager at Samsara Vision.