Some Guy Named Jake and His Live Eye Surgery! [Graphic, So, Um, FYI]

LASIK-Procedure

There’s a video on Vimeo posted by a user named JakeLV426.

Jake had eye surgery.  Jake got the video of his eye surgery!

For all of you out there who think this is as freaking cool as I do, check it out!  It’s ten minutes of delicate surgery on the eyeball.  This is so cool.  I pondered Ophthalmology as a career at one point in my life, so these kinds of operative videos blow my mind!

Just a heads up for the squeamish, this is a real, live eyeball undergoing a real, live eyeball surgery.

Jakes Eye surgery from JakeLV426 on Vimeo.

Holy Terminator Eyes! An LED Contact Lens That Gives Your Eyes A Display Overlay!

LED-contact-lens-fantasy

Can you imagine contact lenses that give you a see-through display that connects via Bluetooth into your iPhone?  Maybe something that allows you to get news stories as they pop up, see email notifications in your vision, or perhaps maybe even something actually useful?  The people at the University of Washington have developed a test case of this exact scenario — albeit in the eye of a rabbit.  But if Bugs Bunny can see like the Terminator, with images and text, then where’s the limit?  I submit it’s the SKY!

From the University of Washington’s press release, cross-posted from the Journal of Micromechanics and Microengineering:

We present the design, construction and in vivo rabbit testing of a wirelessly powered contact lens display. The display consists of an antenna, a 500 × 500 µm2 silicon power harvesting and radio integrated circuit, metal interconnects, insulation layers and a 750 × 750 µm2 transparent sapphire chip containing a custom-designed micro-light emitting diode with peak emission at 475 nm, all integrated onto a contact lens. The display can be powered wirelessly from ~1 m in free space and ~2 cm in vivo on a rabbit. The display was tested on live, anesthetized rabbits with no observed adverse effect. In order to extend display capabilities, design and fabrication of micro-Fresnel lenses on a contact lens are presented to move toward a multipixel display that can be worn in the form of a contact lens. Contact lenses with integrated micro-Fresnel lenses were also tested on live rabbits and showed no adverse effect.

Terminator-Lens-in-rabbit-eye

Let’s hit some key points here:

  • Part of the purpose of this most recent test was to test the safety of this device on a live subject.
  • Scientists tested a real, live, working video contact lens display on a real, live, BREATHING AND POOPING RABBIT (that’s what in vivo means, basically not diced up into dead tissue)
  • The device had wireless power, and everything needed is integrated into the tiny contact lens
  • No bad effects were observed on the rabbit, which was anesthetized
  • The contact lens had one pixel, but the next phase is a micro-Fresnel multi-pixel display lens, which were also tested on the bunnies, with no apparent bad effects.

led-contact-lens-detail

This is, by all accounts, AMAZING!  Can you imagine the implications of having a see-through display in your vision?!  From my lighting designer mind, I see things like photometric data or spectrophotometric data just updating as you look at something?  I hate to be the one to state this, but you KNOW the Defense Department is going to get their hands on this if they haven’t already — and we’ll see the next round of soldiers equipped with instant range finding and targeting displays right there in their vision as if it was nothing at all.  Seal Team 6, for example, was rumored to be wearing night vision contact lenses on the raid in Abbottabad, Pakistan on Osama Bin Laden.  A rumor of course, but is it really that inconceivable that something along those lines is possible?  I think not!

night-vision-contact-lenses

 

We’re still quite a bit away from the kinds of retina display technology we see in the movies — for example, in Mission Impossible 4 when Josh Holloway was in the train station looking at people’s faces as they passed by — but that technology is definitely going to be hitting our wallets in the next decade.  Call it intuition, call it a gut feeling, I don’t know.  But the interface is already there, Edward Snowden has made us very aware of that — and if it’s not already there by now, I have to believe that it isn’t way too far behind development.

retina-display-scanning

We already have license plate scanning cameras that police drive around with as they do their patrols.  We have data systems that can mine faces and scan instantly as people pass by the sensors.  What’s to say that soon we can’t have a device you go purchase at the local high end electronics retailer that allows you to shop for something anywhere, and while you’re looking at things in the store, you’re getting a display of the current price on Amazon versus what you’re seeing at Target?  Amazing thought, huh!

From an excellent article written in the IEEE Spectrum back in 2009, when the thought of monitoring someone’s blood glucose was an excellent reason for developing a technology like the one being tested today:

ieee-spectrum-bionic-eye

These lenses don’t need to be very complex to be useful. Even a lens with a single pixel could aid people with impaired hearing or be incorporated as an indicator into computer games. With more colors and resolution, the repertoire could be expanded to include displaying text, translating speech into captions in real time, or offering visual cues from a navigation system. With basic image processing and Internet access, a contact-lens display could unlock whole new worlds of visual information, unfettered by the constraints of a physical display.

Besides visual enhancement, noninvasive monitoring of the wearer’s biomarkers and health indicators could be a huge future market. We’ve built several simple sensors that can detect the concentration of a molecule, such as glucose. Sensors built onto lenses would let diabetic wearers keep tabs on blood-sugar levels without needing to prick a finger. The glucose detectors we’re evaluating now are a mere glimmer of what will be possible in the next 5 to 10 years. Contact lenses are worn daily by more than a hundred million people, and they are one of the only disposable, mass-market products that remain in contact, through fluids, with the interior of the body for an extended period of time. When you get a blood test, your doctor is probably measuring many of the same biomarkers that are found in the live cells on the surface of your eye—and in concentrations that correlate closely with the levels in your bloodstream. An appropriately configured contact lens could monitor cholesterol, sodium, and potassium levels, to name a few potential targets. Coupled with a wireless data transmitter, the lens could relay information to medics or nurses instantly, without needles or laboratory chemistry, and with a much lower chance of mix-ups.

Three fundamental challenges stand in the way of building a multipurpose contact lens. First, the processes for making many of the lens’s parts and subsystems are incompatible with one another and with the fragile polymer of the lens. To get around this problem, my colleagues and I make all our devices from scratch. To fabricate the components for silicon circuits and LEDs, we use high temperatures and corrosive chemicals, which means we can’t manufacture them directly onto a lens. That leads to the second challenge, which is that all the key components of the lens need to be miniaturized and integrated onto about 1.5 square centimeters of a flexible, transparent polymer. We haven’t fully solved that problem yet, but we have so far developed our own specialized assembly process, which enables us to integrate several different kinds of components onto a lens. Last but not least, the whole contraption needs to be completely safe for the eye. Take an LED, for example. Most red LEDs are made of aluminum gallium arsenide, which is toxic. So before an LED can go into the eye, it must be enveloped in a biocompatible substance.

terminator_vision_02More from the press release at the University of Washington:

At the moment, the contact lens device contains only a single pixel of information, but the researchers say it is a proof of the concept that the device could be worn by a person. Eventually it could display short emails and other messages directly before a wearers eyes.

“This is the first time we have been able to wirelessly power and control the display in a live eye,” said Babak Parviz, an author and UW associate professor of electrical engineering. Among his coauthors are Brian Otis, associate professor of electrical engineering, and Andrew Lingley, a graduate student.

“Looking through a completed lens, you would see what the display is generating superimposed on the world outside,” Parviz explained during a 2008  interview.

The researchers findings were published Nov. 22 in the Journal of Micromechanics and Microengineering.

Perhaps the best-known science fiction character to use such a display is the Terminator, and for almost seven years Parviz and others have worked on trying to make the display a reality.

Building the lenses required researchers to make circuits from metal only a few nanometers thick, about one-thousandth of a human hair. They built light-emitting diodes (LED) one-third of a millimeter in diameter. And to help focus the images, the researchers made arrays of tiny lenses that were put into the contacts.

The contact lens has an antenna to take power from an external source, as well as an integrated circuit to store this energy and transfer it to a transparent sapphire chip containing a single blue LED.

Otis called this successful wireless transmission to a lens “an extremely exciting project … that presents huge opportunities for health-care platforms.” The team is working on a way to monitor a diabetic patients glucose level using lenses.

Check this out, it’s three minutes worth of awesomesauce — some of this project from back in 2011:

GAH!  What an awesome project!

Contact_Lens_Designs

Crazy Friday Science: New “Dua’s Layer” Discovered in Human Eyes, Ophthalmology Changed Forever

From May 28, 2013 onward, the study of the human eye will forever be changed.  A doctor named Harminder S. Dua, Professor of Ophthalmology and Visual Sciences at the University of Nottingham has discovered a new layer of cells that lies just above Descemet’s Layer of the cornea and the corneal stroma.  Like so:

duas-layer

“Now hold on there cowboy, what’s the cornea?!”

The cornea is the covering for the iris, pupil, and the anterior chamber  – basically the spot in front of the eye’s lens.  It’s one of the body’s most nerve-filled tissues, and it’s filled with fluid for light transmission.  Check this out, it’s an excellent visual description of the cornea, anterior and vitreous chambers — for reference, Dua’s Layer is right between the rear edge of the cornea (closest to the iris) and the middle of the cornea:

Three_Main_Layers_of_the_Eye

 

What Dr. Dua has discovered is a layer within the cornea that seems to have something to do with failures in the cornea where misshaping takes place.  These kinds of diseases are thought to be caused by water becoming waterlogged within the cornea itself, perhaps caused by a tear in this new Dua’s Layer.  They give the person afflicted a cone-shaped cornea that can be corrected with glasses, contacts, or in extreme cases, corneal surgery.  I’ve never seen anything quite like this before, so I’m guessing you haven’t either:

Keratoconus_eye

keratoconus-eye

from http://thesclerallenscenter.com/wp-content/uploads/2010/10/IMG_8964.jpg

Dua’s Layer is the new tissue discovery that is thought to cause things like this crazy degenerative keratoconus, which looks very annoying and painful to me.  Keratoconus causes pretty awful headaches and eye strain for people afflicted, which nobody wants.  But, this discovery is being heralded as a potential game changer for corneal diseases and degenerative conditions.  From Sci News:

“This is a major discovery that will mean that ophthalmology textbooks will literally need to be re-written. Having identified this new and distinct layer deep in the tissue of the cornea, we can now exploit its presence to make operations much safer and simpler for patients,” said Dr Harminder Dua, Professor of Ophthalmology and Visual Sciences at the University of Nottingham and lead author of a paper published in the journal Ophthalmology.

“From a clinical perspective, there are many diseases that affect the back of the cornea which clinicians across the world are already beginning to relate to the presence, absence or tear in this layer.”

The human cornea is the clear protective lens on the front of the eye through which light enters the eye. Scientists previously believed the cornea to be comprised of five layers, from front to back, the corneal epithelium, Bowman’s layer, the corneal stroma, Descemet’s membrane and the corneal endothelium.

…and from Science Daily:

The scientists proved the existence of the layer by simulating human corneal transplants and grafts on eyes donated for research purposes to eye banks located in Bristol and Manchester.

During this surgery, tiny bubbles of air were injected into the cornea to gently separate the different layers. The scientists then subjected the separated layers to electron microscopy, allowing them to study them at many thousand times their actual size.

Understanding the properties and location of the new Dua’s layer could help surgeons to better identify where in the cornea these bubbles are occurring and take appropriate measures during the operation. If they are able to inject a bubble next to the Dua’s layer, its strength means that it is less prone to tearing, meaning a better outcome for the patient.

The discovery will have an impact on advancing understanding of a number of diseases of the cornea, including acute hydrops, Descematocele and pre-Descemet’s dystrophies.

The scientists now believe that corneal hydrops, a bulging of the cornea caused by fluid build up that occurs in patients with keratoconus (conical deformity of the cornea), is caused by a tear in the Dua layer, through which water from inside the eye rushes in and causes waterlogging.

This is the first time I am ever researching Keratoconus — I have a good friend who has Retinitis Pigmentosa, another degenerative disease of the eye (in that case the retina), but the conical cornea is quite an odd phenomena.  Have you ever had or know anyone who has had this disease?  I found some information at WebMD on Keratoconus on diagnosis and treatment:

Keratoconus changes vision in two ways:

  • As the cornea changes from a ball shape to a cone shape, the smooth surface becomes slightly wavy. This is called irregular astigmatism.
  • As the front of the cornea expands, vision becomes more nearsighted. That is, only nearby objects can be seen clearly. Anything too far away will look like a blur.

An eye doctor may notice symptoms during an eye exam. You may also mention symptoms that could be caused by keratoconus. These include:

  • Sudden change of vision in just one eye
  • Double vision when looking with just one eye
  • Objects both near and far looking distorted
  • Bright lights looking like they have halos around them
  • Lights streaking
  • Seeing triple ghost images

To be sure you have keratoconus, your doctor needs to measure the curvature of the. cornea. There are several different ways this can be done.

One instrument, called a keratometer, shines a pattern of light onto the cornea. The shape of the reflection tells the doctor how the eye is curved. There are also computerized instruments that make three-dimensional “maps” of the cornea.

How Is Keratoconus Treated?
Treatment usually starts with new eyeglasses. If eyeglasses don’t provide adequate vision, then contact lenses may be recommended.  With mild cases, new eyeglasses can usually make vision clear again. Eventually, though, it will probably be necessary to use contact lenses or seek other treatments to strengthen the cornea and improve vision.

A last resort is a cornea transplant.  This involves removing the center of the cornea and replacing it with a donor cornea that is stitched into place.

Congratulations to Dr. Harminder Dua and his team at the University of Nottingham for this amazing discovery!
Keep up the excellent game-changing work, good sir!

dr-harminder-dua

Check out the abstract at the journal Ophthalmology.

keratoconus-normal

from http://www.centralohioeyecare.com/user-files/PageImage206991.jpg

Thanks to Wikipedia on Keratoconus, Dua’s Layer, Traffic Shaper!

How Well Do YOU Know Light? Take Our Quiz, Come Find OUT! COME ON!

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From the OMG WTF Files – The Ancient Art of EYEBALL SHAVING

eyeball-shavingI still can barely believe this — I researched “eyeball shaving hoax” extensively before posting this.  It is in fact a real thing, practiced in China, and apparently for hundreds of years if not thousands.

Meet Liu Deyuan, a barber (yes, a BARBER does this) who offers the ancient (and albeit abandoned) art of Eyeball Shaving at his little barber shop in Chengdu City, in west Sichuan Province, China:

615x330_china-eye-shaving

Let’s recap really quickly here:

  • There’s a barber in China who shaves people’s eyelids and eyeballs for about 5 yuan, which is $0.81 USD
  • A BARBER IS SHAVING PEOPLE’S EYES AND FACES WITH THE SAME KNIFE
  • A BARBER IS SHAVING PEOPLE’S EYES
  • PEOPLE PAY TO HAVE THIS DONE.

From an article at ChiEnglish.com, bolding is mine:

First, Liu uses some water to rinse off the knife that he had just used to shave a customer’s head and pulled up a stool. Using his fingers to hold open the customer’s eyelids, he scraped the blade back and forth over the eyelid and then the eyeball. Then he took out another tool — a small rod, which he placed in the customer’s eye, sliding it back and forth in the upper eyelid like a windshield wiper. Liu repeated the process on the lower eyelid. When the left eye was done, he did the whole thing again on the right eye. The whole process took about 5 minutes.

Holy mother.  Look at these tools – yeah, they look really sterile, don’t they!

eyeball-shaving-tools

I’m not sure what else to say but GAAAAAAAAAAAAAAAH.  This practice has been abandoned by most, and is shunned by doctors for the risk of cross-contamination.  Yeah, like cross-contamination is the only real issue here.  WHat happens when ol’ Liu there sneezes while shaving ze eyeballs?!

eyeball_shaving_eyelids

I love the look on that dude’s face on the right in the photo above.  That is the perfect “Caption THIS” image!

Eyeball-Shaving-China

EYEBALL_SHAVING

 

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.

Bionic Eye Man Wirelessly Records His World

rob-spence

This is an awesome quick minute of video of a man who lost his eye in a shooting accident.  He had his eye socket fitted with a wirelessly transmitting video recorder.  Now this is an idea that I can totally get behind, especially if we give it to Howard Stern or Mancow…

I kid about the Howard Stern thing.  Misogyny stopped being funny when I was 5 or 6.  Meet Rob Spence, the man behind the “Bionic Eye” he’s created to go in the empty eye socket.  Here’s Rob with version 2.0 of the Bionic Eye:

Eyeborg Phase II from eyeborg on Vimeo.

LED eye bionic jumping, teaser footage of experimenting with eye-camera prototype, action!  Rob Spence is a filmmaker who lost his eye and decided to replace it with a wireless video camera.  Check out Kosta Grammatis glancing about nervously as Fox News guffaws about our bionic lab.

An article from IEEE Spectrum talks about Spence’s internal eye equipment:

The bionic eye is simply designed, and components are constantly changing. It basically contains a 1.5mm-square, low-res video camera, a small round printed circuit board, video transmitter, and a 3-volt rechargeable Varta microbattery. The components are contained in resealable clear acrylic used in false eyes, but it has two holes for wires to recharge the battery.

“I can recharge my eye via USB off my laptop,” says Spence.

The Eyeborg prototype in the video, the third, can only work for an hour an a half on a fully charged battery. Its transmitter is quite weak, so Spence has to hold a receiving antenna to his cheek to get a clear signal. He muses that he should build a Seven of Nine-style eyepiece to house it. He’s experimenting with a new prototype that has a stronger transmitter, other frequencies and a booster on the receiver.

This is an example of sacrifice for the good of all mankind.  Rob, we salute you.

What Exactly are Eye Floaters?

“I’ll look over there!”

“I’ll move over HERE!”

“You got an answer for everything.”

So.  Have you ever been looking at a book, the sky, or anything really, and seen what most people call “eye floaters?”  You know, the really weird almost chromosome-looking things that seem to just effortlessly and painlessly dance across our vision whenever the hell they want?  Like so:

These little buggers are the product of eye aging and the disintegration of the goo inside the eyeball itself.  If you’ve ever spent any time at all staring at eye floaters, you know that they can be fairly entertaining!

Inside of the eye ball, there is a liquid that gives the eye its shape and acts as a light medium (consequently with a Refractive Index of 1.336) to get light to the retina.  This liquid isn’t quite a liquid and isn’t quite a gel, but the consistency of it is sort of like that of Jell-O.  it’s called the Vitreous Humor, or the Vitreous body, or simply just the Vitreous.  This stuff is pretty neat, as it’s completely transparent as we’re born through teen-hood.  The vitreous is made of about 99% water, along with some sugars, some salts, some collagen fibers, and these pretty cool cells called phagocytes.  The phagocytes’ main purpose is to hunt down and kill foreign bodies in the eye’s vitreous body and visual field.  Pretty cool, eh?

The vitreous body is a stagnant body of fluid; it does not have a regeneration process either, which means if you sustain some damage to an eye or both, they’re gone, as once the vitreous is gone, it is gone forever.  This is a great reason to ALWAYS wear safety goggles and eye protection whenever you’re doing something that could impact the eye ball.  I had a pretty scary experience one summer when I was still in undergraduate study, away on an opera tour.  I was building the set we were touring, and a piece of a table saw blade sheared away and shot itself right into my eyeball.  I spent several hours at the hospital as the doc tried to grab that piece of metal and dislodge it from my eyeball, about 3 millimeters from the edge of my pupil.  I got lucky.  I did have safety glasses on, too – which goes to show you that you can never be too careful.  After the ER doc dug that piece of blade out of my eye, they inserted a plastic lens attached to a bag of saline that drained around my eyeball to clean out any extra debris.  The resulting pic was pretty hilarious, and I was in good spirits, making jokes.  Ann Davis, thingmaker extraordinaire, took the photo, circa 1998:

As we get older, parts of the Vitreous degenerate and clump, creating the little eye floaters we’re so fond of seeing.  These things remain in the eye for as long as we are old, until we either A) die, or B) have them surgically removed.  For most people these things aren’t a problem at all, we just deal with them.  For some, however, they become so numerous and so vision-impairing that surgery IS required for removal of all of the clumped bits of whatever matter the eye floaters are made from — old proteins, bits of clumped collagen cell bundles, foreign bodies, retinal cells, etcetera.

Eye floaters do have some different types — from Wikipedia’s entry on floaters:

The common type of floater, which is present in most people’s eyes, is due to degenerative changes of the vitreous humour. The perception of floaters is known as myodesopsia, or less commonly as myiodeopsiamyiodesopsia, or myodeopsia.  They are also called Muscae volitantes (from the Latin, meaning “flying flies”), or mouches volantes (from the French). Floaters are visible because of the shadows they cast on the retina or their refraction of the light that passes through them, and can appear alone or together with several others in one’s field of vision. They may appear as spots, threads, or fragments of cobwebs, which float slowly before the observer’s eyes.  Since these objects exist within the eye itself, they are not optical illusions but are entoptic phenomena.

What I find cool about eye floaters is that you’re actually seeing the shadow of the floaters on your retina, like a Linnebach projector.  Remember those?  As the light passes through the iris, it blows through the vitreous body and the floaters get in the way, causing shadows on the retina that your brain decodes as the floaters’ shape and size.

Now let me say this — most times, eye floaters are harmless bits of entertainment that all people have in some form or another.  However, sometimes eye floaters can be indications of a larger problem, like eye disease brought around by diabetes, carotid artery disease, or even as an indicator of a stroke or heart attack that may be imminent.  Sometimes eye floaters might be accompanied by flashes of light; this is a certain time to hit the doctor’s office.  A lesser known ailment, one that keeps on giving, per se, is ocular herpes.  As scary as that sounds, it is!  The vitreous can also become detached, too — as you age, the vitreous body sort of liquefies and detaches from the retina, which also causes eye floaters.  I’m certainly not a doctor, and you should use your own judgement when it comes to your health.  But if you have lots and lots and lots of floaters, perhaps it’s time to visit your doc.

A detailed article about determining when your eye floaters might indicate a larger problem is here – check it out.

Some fun facts on eye floaters, from Today I Found Out:

  • Interestingly, if the eye floaters would just stay still instead of floating around, your brain would automatically tune them out and you’d never consciously see them.  Your brain does this all the time with things both in and outside of your eyes.  One example of this inside your eye are blood vessels in the eye which obstruct light; because they are fixed in location, relative to the retina, your brain tunes them out completely and you don’t consciously perceive them.
  • The reason you can see floaters better when looking at, for instance, a bright blue sky, is because your pupils contract to a very small size, thus reducing the aperture, which in turn makes floaters more apparent and focused.
  • Individual floaters often won’t change much throughout your lifetime, typically retaining their basic shape and size.
  • The perception of eye floaters is known as myodesopsia.
  • The reason the floating specs never seem to stay still is because floaters, being suspended in the vitreous humor,  move when your eye moves.  So as you try to look at them, they will appear to drift with your eye movement.
  • Eye floaters are examples of entoptic phenomena.  Entoptic phenomena are things we see where the source is within the eye itself.
  • If you ever see a ton of floaters appear out of no where, possibly with some light flashes, you should get to an eye doctor immediately.  There is a chance (1 in 7) that your retina is about to detach from the back of your eye.  If that happens, you have very little time to get it fixed before it effectively dies and you go blind from that eye.
  • Floaters can damage the retina by tugging on it, sometimes producing a tear.  When a tear happens, vitreous can invade the opening in the tear, which will ultimately widen the gap and in 50% of these cases will result in the retina eventually becoming fully detached if not repaired via surgery.
  • “Light flashes” not caused by actual light, also known as photopsia, will often occur when the photoreceptors in the retina receive stimulation from being touched or from being torn.  This produces an electrical impulse to your brain, which your brain more or less interprets as a light flash.  This physical stimulation is often caused when traction is being applied while the vitreous detachment is taking place.  The flashes should subside when the vitreous finally detaches.
  • These flashes will also often temporarily occur when you get a sharp blow to the head.  The sudden jarring causes pressure on the retina; this in turn creates an electrical impulse to the brain which the brain interprets as a flash.

Thanks to About, Earth Clinic, eHow, WiseGeek, All About Vision, WikiDoc, LoveEyeFloaters, and TheBrain!

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?

After-Image Woman – Check It Out!

Alright, alright, this is the last optical illusion for a few days.  Otherwise, Brad Schiller is gonna be breaking down my door with a baseball bat!  [love you, sugar Brad!]

Ok – stare at the red dot on this woman’s schnoz for about a half a minute as hard as you can.  Once the 30 or so seconds are up, stare at something white.  Allow the flippage to ensue.  The longer you stare, the longer your vision has a chance to burn in, and the closer you stare at that red dot the better – try to get your eyes around 12″ away.

Is that not just totally f*cking trippy or WHAT?!  It’s called an afterimage.  it’s what happens when we over-stimulate our cones – they essentially go on break, and the cones around them, which aren’t overstimulated, kick into gear, allowing the brain to interpret the exact opposite of the image.

HAPPY THURSDAY MORNING!