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Second Sight Medical Products Delivers a Kick to the Giftbag for Retinitis Pigmentosa

This is very exciting news for the realm of artificial vision.  I have someone I look up to that suffers from Retinitis Pigmentosa, and it sucks to see this degenerative disease affect this man’s sight.

But:  advances are being made in “bionic” tech all the time that tries to bridge the gap between natural vision and artificially enhanced vision – and since we don’t understand that much about how the brain translates sight into information for the brain, every time there is a breakthrough in technology in this arena, it’s a big deal!

First, what is Retinitis Pigmentosa?  It sounds like something that is not very good, and in fact it is not.  From Wikipedia and the NIH:

Fundus of patient with retinitis pigmentosa, mid stage (Bone spicule-shaped pigment deposits are present in the mid periphery along with retinal atrophy, while the macula is preserved although with a peripheral ring of depigmentation. Retinal vessels are attenuated.) Hamel Orphanet Journal of Rare Diseases 2006

Fundus of patient with retinitis pigmentosa, mid stage (Bone spicule-shaped pigment deposits are present in the mid periphery along with retinal atrophy, while the macula is preserved although with a peripheral ring of depigmentation. Retinal vessels are attenuated.) Hamel Orphanet Journal of Rare Diseases 2006

Retinitis pigmentosa (RP) is an inherited, degenerative eye disease that causes severe vision impairment and often blindness.[1] Sufferers will experience one or more of the following symptoms:

  • Night blindness or nyctalopia;
  • Tunnel vision (no peripheral vision);
  • Peripheral vision (no central vision);
  • Latticework vision;
  • Aversion to glare;
  • Slow adjustment from dark to light environments and vice versa;
  • Blurring of vision;
  • Poor color separation; and
  • Extreme tiredness.

The progress of RP is not consistent. Some people will exhibit symptoms from infancy, others may not notice symptoms until later in life.[2] Generally, the later the onset, the more rapid is the deterioration in sight. Also notice that people who do not have RP have 90 degree peripheral vision, while some people that have RP have less than 90 degree.

A form of retinal dystrophy, RP is caused by abnormalities of the photoreceptors (rods and cones) or the retinal pigment epithelium (RPE) of the retina leading to progressive sight loss. Affected individuals may experience defective light to dark, dark to light adaptation or nyctalopia (night blindness), as the result of the degeneration of the peripheral visual field (known as tunnel vision). Sometimes, central vision is lost first causing the person to look sidelong at objects.

The effect of RP is best illustrated by comparison to a television or computer screen. The pixels of light that form the image on the screen equate to the millions of light receptors on the retina of the eye. The fewer pixels on a screen, the less distinct will be the images it will display. Fewer than 10 percent of the light receptors in the eye receive the colored, high intensity light seen in bright light or daylight conditions. These receptors are located in the center of the circular retina. The remaining 90 percent of light receptors receive gray-scale, low intensity light used for low light and night vision and are located around the periphery of the retina. RP destroys light receptors from the outside inward, from the center outward, or in sporadic patches with a corresponding reduction in the efficiency of the eye to detect light. This degeneration is progressive and has no known cure as of June 2012.

That sucks so much.  However, now you have to meet Second Sight Medical Products’ Argus® II Retinal Prosthesis System, which just got FDA approval for patent this week:

All I can say about this is holy crap.

argus-2-system-overview

From the MedGadget article on the Argus II system:

The bionic eye works by replacing the disease-damaged photoreceptors of the eye with tiny chips that translate light into electrical signals, which in turn stimulate the optic nerve. The normal retina is really not a camera, and the optic nerve does not send pixels, per say, to the brain, but rather a highly processed and optimally encoded representation of the visual scene. The fact that bionic eyes like the Argus II can work at all — and indeed so well — is due more to the brain’s ability to make sense out of whatever relevant signals it receives, than to current understanding of how the retina actually works. As researchers advance their understanding of  the retina, bionic eye technology will continue to advance hand-in-hand to provide new vision to the blind at ever higher resolution.

This is amazing technology.  I hope that the Argus II system can restore vision in those who have lost it due to terrible degenerative diseases like RP.

To my buddy:  hang in there, big man.  I’m always on the lookout.

Side note:  under the Did You Know? section of the Argus II System website:

The Latin word “Argus” refers to a giant in Greek mythology with 100 eyes, Argus Panoptes, who was considered all-seeing. Argus was the servant of Hera, goddess of women and marriage as well as the wife of Zeus. Zeus seduced the nymph Io who was also the priestess of Hera.  In order to hide her from Zeus, Hera transformed her into a white heifer and asked Argus to watch over Io and protect her from Zeus.

Too cool, Second Sight.

Moonlight Mini-Lesson

The above photo by Andrew Tallon was taken at 10:30 pm! What I love about this image is it perfectly exemplifies that our moon is just a reflector for sunlight.

So why don’t we see our night landscape this way, if a camera can capture it?

A number of fascinating factors!

Our moon’s albedo (the measurement of amount of light reflected by astronomical objects) is 0.12, which means about 12% of light which hits the moon is reflected. This amount is subject to fluctuation by numerous factors, including the phase of the moon. The amount which hits the earth’s surface can be–and frequently is–significantly less.

To capture the above image, the shutter was open for 30 seconds. Our eyes have our own tricks for seeing in low-light scenarios, which involve our fantastic friends the rods and cones. The outer segment of rods contain the photosensitive chemical rhodopsin (you might know this as visual purple). Cones contain color pigments in their outer segment. Our rods predominantly help us in low light level environments, which means that we have significantly decreased color perception in moonlight.

Cones are located in the center of the eye and are high-density. Rods meanwhile are located around the cones, so in extreme darkness, a 1° blind spot is developed in the central region of the eye where there are only cones. Rods reach their maximum concentration around 17° each direction from the center line, so sneaking some sideways glances actually improves your nighttime perception.

Our rods are not equally sensitive to all wavelengths of light. They are far more sensitive to blue light, and at around 640 nm, are pretty much useless! Click this graph from the University of New Mexico to check it out:

This means that the color of light the moon is actually reflecting appears significantly different to us because of its low intensity.

A neat example I found on the American Optometric Association’s Website which caught my interest was:

For example, in a darkened room, if one looks at two dim lights of equal illumination (one red and one green) that are positioned closely together, the red light will look brighter than the green light when the eyes are fixating centrally. If one looks to the side of the dim lights about 15-20 degrees, the green light will appear brighter than the red.

If you’re planning on shooting your own moonlight landscapes, be a light geek! It is hard to find focus at night, so place a luminous object near your focus, whether it’s a lantern, or a friend with their cell phone! If you want to be super geeky, tape a laser pointer to the top of your camera, then manually focus on the dot.

 

So, with all of this science in mind, how would you replicate moonlight now, vs how you did previously?

Preliminary Report Shows Stem Cells Reversed Macular Degeneration

This is crazy.  I just read a report in the journal The Lancet about a trial that’s taking place with embryonic stem cells and human subjects with macular degeneration.  The preliminary report actually shows that the patients have experienced some restoration of their vision.  Two patients are being utilized in this study – one with Stargardt’s macular dystrophy and one with dry age-related macular degeneration.  From the study:

Although there is little agreement between investigators on visual endpoints in patients with low vision, it is encouraging that during the observation period neither patient lost vision. Best corrected visual acuity improved from hand motions to 20/800 (and improved from 0 to 5 letters on the Early Treatment Diabetic Retinopathy Study [ETDRS] visual acuity chart) in the study eye of the patient with Stargardt’s macular dystrophy, and vision also seemed to improve in the patient with dry age-related macular degeneration (from 21 ETDRS letters to 28).

Hey, did you hear?  Lemme just make sure that everybody heard:  STEM CELLS ARE BEING USED TO HELP RESTORE VISION AND ARE SHOWING SIGNS OF SUCCESS.  AWE-SOME!

OK – first, what is macular degeneration?  We’re basically talking about vision loss here that results from some sort of degeneration of the maculaThese two macular degeneration subjects have interesting vision deficiencies.  Presentation on Stargardt’s Dystrophy, from Wikipedia:

Those with Stargardt disease are sensitive to glare; overcast days offer some relief. Vision is most noticeably impaired when the macula (center of retina and focus of vision) is damaged, leaving peripheral vision more intact. Symptoms usually appear before age 20. Symptoms include wavy vision, blind spots, blurriness, impaired color vision, and difficulty adapting to dim lighting.  Some patients are able to drive. Many patients use magnifiers to help them see, and wear sunglasses to slow the development.

The other one, in this case, is a general dry age-related macular degeneration.  There are two kinds of this vision-killing degeneration, a wet kind and a dry kind:

Age-related macular degeneration (AMD) is a medical condition which usually affects older adults and results in a loss of vision in the center of the visual field (the macula) because of damage to the retina. It occurs in “dry” and “wet” forms. It is a major cause of blindness and visual impairment in older adults (>50 years). Macular degeneration can make it difficult or impossible to read or recognize faces, although enough peripheral vision remains to allow other activities of daily life.

Starting from the inside of the eye and going towards the back, the three main layers at the back of the eye are the retina, which contains the nerves; the choroid, which contains the blood supply; and the sclera, which is the white of the eye.

The macula is the central area of the retina, which provides the most detailed central vision.

In the dry (nonexudative) form, cellular debris called drusen accumulate between the retina and the choroid, and the retina can become detached. In the wet (exudative) form, which is more severe, blood vessels grow up from the choroid behind the retina, and the retina can also become detached. It can be treated with laser coagulation, and with medication that stops and sometimes reverses the growth of blood vessels.[1][2]

Although some macular dystrophies affecting younger individuals are sometimes referred to as macular degeneration, the term generally refers to age-related macular degeneration (AMD or ARMD).

Age-related macular degeneration begins with characteristic yellow deposits (drusen) in the macula, between the retinal pigment epithelium and the underlying choroid. Most people with these early changes (referred to as age-related maculopathy) have good vision. People with drusen can go on to develop advanced AMD. The risk is considerably higher when the drusen are large and numerous and associated with disturbance in the pigmented cell layer under the macula. Recent research suggests that large and soft drusen are related to elevated cholesterol deposits and may respond to cholesterol-lowering agents.

Ok, now I’mma let you finish, Taylor Swift, but STEM CELLS ARE BEING USED TO HELP RESTORE VISION AND ARE SHOWING SIGNS OF SUCCESS.

Check out the original article at The Lancet.  Very, very cool news.

Thanks, Wikipedia, Wikipedia, and WebVision!

My God, It’s Full of Stars! What You See When Your Eyes are Closed – Phosphenes

As much as I love light, I love to close my eyes and stare at the back of my eyelids.  Have you ever noticed how amazing, how beautiful the events that occur are when you rub your eyes and notice the instant star and explosion show that occurs in your vision?  I always imagine it as I’m looking into the birth of a universe – each time I stare at my eyelids I see little exploding stars that each take about 2-3 seconds to fully ignite, explode, and become part of the other stars waiting for me to focus my gaze on them.  Try it, it’s a lot of fun!  It is for me, at least.  Perhaps I’m nutso.  Still, AWESOME!

These little events are called entopic phenomena, meaning that they come directly from the eye itself.  I’m pretty sure everyone’s experienced the most common form of entopic phenomena, eye floaters.  Right?

 

Eye floaters, whether or not they have a sarcastic retort like the ones in Family Guy, are entopic phenomena.

The light that you see when you don’t see any light – whether it’s the random star birth and death that I see when I close my eyes, or if I rub my eyes, or any of a few things that trigger it for me – are called phosphenes.  That word is from two greek words, phos (light) and phainein (to show), and goes to explain most of the “hey there is light in my vision but there’s no source” mysteries.  The phrase “seeing stars,” like from getting whacked in the head or from being dizzy is phosphenic.  When people are deprived of light for long periods of time, phosphenes occur in the person’s vision as well – this is referred to as “the prisoner’s cinema.”  Isn’t that just creepy and horrible?  Apparently phosphenes can occur through several methods, from strong magnetic fiends, to just rubbing your eyes, to reports of astronauts seeing them when exposed to radiation in space.

Here’s a good account of the Prisoner’s Cinema, which also happens apparently to truck drivers, pilots, and other folk who have to concentrate on something for very long periods of time:

It has been widely reported that prisoners confined to dark cells often see brilliant light displays, which is sometimes called the “prisoner’s cinema.” Truck drivers also see such displays after staring at snow-covered roads for long periods, and pilots may experience phosphenes, especially when they are flying alone at high altitudes with a cloudless sky. In fact, whenever there is a lack of external stimuli, these displays can appear. They can also be made at will by simply pressing your fingertips against closed eyelids. In addition, they can also be produced by an electrical shock. In fact, reportedly, it was high fashion in the eighteenth century to have a phosphene party. It is noted that Benjamin Franklin once took part in such an encounter where a circle of people holding hands would be shocked by a high-voltage electrostatic generator, so that phosphenes were created each time the circuit was completed or broken.

The earliest account of phosphenes is given by the Bohemian physiologist Johannes Purkinje in 1819. These subjective images are called phosphenes (from the Greek phos, light, and phainein, to show). Oster (1970) suggests that, because phosphenes originate within the eye and the brain, they are a perceptual phenomenon common to all mankind. The visual areas of the brain at the back of the head (occipital lobe) can also be stimulated to produce phosphenes.

I find these very fascinating, these entropic events.  Do you have them?  How would you describe them?  Please, leave a message in the comments, I am very interested in your phosphene experiences!

Check out this beautiful video representation of phosphene events portrayed artistically.  So pretty!

Thanks to Wikipedia, and again, and Multiple Sclerosis Info, WiseGeek, MadSci, and MotiFake!   

How It’s Made – Contact Lenses!

I have to admit – I have never been able to stick a contact lens on my own eye.  Therefore, I just don’t try to wear them!

The process of making a contact lens is pretty neat, actually – 15 steps in total (minus a hydrating procedure that takes about a day) can be preformed in about 15-20 minutes total.  Pretty interesting!  The computerized, mechanized aspect of the contact lens manufacturing is exactly how you’d imagine it to be – extremely precise.

Check out this video from the How It’s Made (JimOnLight.com LIGHT related) series on making these contact lenses.  Very interesting!

Also, not to be outdone, the making of SPECTACLES!