Entoptic PhenomenaOptometry 662, Spring 2010Pacific University College of OptometryJames Kundart, O.D., M.Ed., F.A.A.O.http://www.migraine-aura.org/content/e27891/e27265/e42285/e42442/e54887/index_en.html

Focus Questions Why do we see the Purkinje Tree under the slit lamp, but not in the sunshine? Why are flying corpuscles better described as flying spots?Which entoptic phenomena can be used by an observant patient to monitor glaucoma? Which can be used to monitor diabetic retinopathy?What part of the retinal causes the polarization responsible for the Hadinger Brush effect? What is Maxwells spot? When is it seen?

What Are Entoptic Images?Visual perceptions that are produced or influenced by native structures in your own eyes are entoptic phenomenaFor example, you have all seen your retinal vessels when sitting for slit lamp exams. This is called the Purkinje tree.Why dont you see it all the time?Why should you care?We will answer these question today

Why Havent I Heard About This Before?Its not just because you are second years! Hart and Westheimer (in Adler) say:Because of their subjective nature, entoptic phenomena require a savvy, articulate patient to observe and describe them.They also cant be photographed, so I can only show you drawingsWe will cover these phenomena from anterior to posterior eye structuresBecause entoptic phenomena improve your understanding of the physiology of vision and visual perception, and can sometimes be used to monitor ocular disease

Some Entoptic Phenomena Corneal Mosaic Physiologic Halos Vitreous Floaters Retinal Phosphenes Purkinje Tree Flying Spots Blue Retinal Arcs Haidingers Brushes

1) Corneal MosaicYou have seen what sodium fluorescein looks like on the tear film of your classmates, and the corneal epithelium by nowDid you know you can see your own corneal mosaic without a slit lamp?If a small (0.1 mm) pinhole is placed at the spectacle plane (17 mm in front of the eyes) and backlit, you can see your own tear film, and irregularities in the corneaThe resulting image is limited in size by the pupil, not the pinhole

Imagining the Corneal MosaicAdler, figure 16-4Corneal Guttatahttp://www.flickr.com/photos/12212056@N04/2035013811/

What Can Be Seen with the Pinhole Technique?According to Adler, folds in corneal epithelium appear as horizontal bandsExcessive oil or mucus in the tear film look like bright blobs surrounded by a dark ring which swim up and down on blinkShallow, linear channels made by ridges in Bowmans membrane can be seen with sodium fluorescein, as are sometimes caused by contact lens wear

Endothelial Dystrophyand the Corneal Mosaichttp://www.opt.pacificu.edu/ce/catalog/10603-AS/Cornea.htmlhttp://www.flickr.com/photos/jrmod/221356083/

Tattooing the CorneaWhat is the treatment for symptomatic partial corneal scarring where transplants (penetrating keratoplasty or DSEK) are not available?With a translucent scar, patient symptoms would decrease when the scar was made opaque by surgical tattoo of the corneaThis is because a true opacity reduces the light that reaches the retina, but does not reduce overall contrast like a translucent defect doesSpecial pigments can be embedded in the cornea to hide corneal scars and to block light from entering the eye through iris defectshttp://www.michigancornea.com/tech_Iris.htm

2) Physiologic HalosYou may have learned about pathologic halos, such as those from a steamy, edematous cornea, from contact lens overwear or ocular hypertensionPhysiologic halos are different -- they are colored rings from chromatic aberration caused by the corneal mosaic -- but they still come from the corneaThey are dimmer, and their size varies with wavelength (color) of the lightAll colors of the rainbow are present -- which are smallest, and which biggest? _______________ (Remember: blue bends best!)

Which of These Will Cause a Pathologic Halo? http://www.atlasophthalmology.com/atlasimg/Img0086_51_low.jpghttp://www.flickr.com/photos/jrmod/339707643/Nuclear sclerotic cataract vs. corneal opacityThe cornea causes haloes, and the lens

LenticularDiffraction SpikesInstead of haloes, the surface of the crystalline lens causes diffraction of pinpoint light, such as starlightEveryone knows that you dont need a cataract to see starbursts around lights this way, soThey must originate from a healthy lens, tooPhysiologic sutre lines are the likely culpritThe same pinhole technique used for the corneal mosaic can be used to image lens opacities, which otherwise simply dampen lighthttp://www.astronomie.de/astropraxis/starhopper/canis-major/sirius.jpg

Why Patients Dont See Their Cataracts DirectlyAdler, figure 16-4Chttp://www.flickr.com/photos/whvick/132165203/

Early Cataract as It Appears Through a PinholeAdler, 9th edition, figure 15-4http://www.flickr.com/photos/mak506/283085523/Please resist temptation to use the abbreviation cats for cataracts

3) Vitreous FloatersWe are all familiar with the muscae volitantes (flitting flies) that patients believe are in their tear film, but you know are actually in the vitreousSome of these are remnants of the hyaloid artery that feeds the fetal lens. Others may be due to retinal tears or hemorrhage, like so-called tobacco dust floatersWhen they settle to the inferior vitreous due to gravity, we dont see themRemember, the vitreous never circulates or gets replenished, so floaters are forever. Learn to love them.

Why Patients Do See Vitreous FloatersAdler, figure 16-4B

Which Floaters Are Harmless?We quickly become accustomed to reassuring patients that floaters are normal, but sometimes they are notFamiliar, countable floaters can be normal might as well become your friendsRecent-onset, innumerable floaters often are due to retinal tear or detachment Likewise, large, new spider-shaped floaters can be a retinal hemorrhage, so ask your patients to describe what they seeWill patients with active uveitis see their cells and flare? What about asteroid hyalosis? Why not? ___________

Are These Floaters Symptomatic?Some Treat Asteroid Hyalosis with Laser http://dro.hs.columbia.edu/asthyalosis.htm

When Do You Expect To See Floaters?When the lighting is bright and there is stationary background, floaters are most visibleFor example, you might see your floaters against the blue sky or snow on the SOA ski tripAs we have seen, they also have to be close to the retina to cause a penumbra (shadow)Holding a pen tip so that it casts a shadow on a paper gives you an idea, as the shadow fades the further away you hold the pen from the paper

4) Retinal PhosphenesWe are all familiar with the bright glow you see when rubbing your closed eyesThis is known to occur due to increase in vitreal pressure on, and deformation of, the retinaThis causes the photoreceptors to fire, and for you to perceive light, especially if you are in a dark roomWhy dont you feel pain? Hint: where are pain sensors in the eye? How high does your IOP have to be to feel painful?These are different than other entopic phenomena as they require a nonlight stimulus -- rubbing or quick eye or head movements (flick phosphenes)Infants with low vision are thought to rub their eyes incessantly in order to trigger phosphenes and stimulate the optic nerve (this helps diagnosis)

Phosphenes and the B&L Proview Eye Pressure MonitorAdler, figure 16-6http://coopereyecare.com/glaucoma.htm

Moores Lightning StreaksThese are entoptic phenomena that occur at the vitreal-retinal interfaceThey are most often seen in the temporal visual field and are vertically orientedThey were first described in 1935, but are very common in middle-aged patientsIt is now thought that they are brought on by posterior vitreous detachment, or PVDThis is a universal condition that some patients never see because it happens in the periphery

Posterior Vitreous Detachment (PVD) vs. RDhttp://www.flickr.com/photos/nrgthedude/3359660841/

Why Do We Get PVD?Since the vitreous never replenishes, it degenerates over a lifetime in all patientsThink of it like a bowl of jello left out of the refrigerator on a warm day. What happens?The jello is the vitreous, and the bowl is the retina from which it can become detachedThe jello becomes liquified and separates from the bowl the longer it sits out (or the older your patient is)This liquefaction is called vitreous syneresis

5) Purkinje TreeThe Purkinje tree is a good example of how the visual cortex separates self from non-self Its there, but we dont see it most of the time, EXCEPTThe retinal arteries (arterioles) and veins (venuoles) show up in stark relief when you sit in the slit lamp for your classmates. Have you seen it?Why??? The slit lamp isnt brighter than, say, the sun, and the sun doesnt make it appear, right?When you see the Purkinje Tree, one part of the biomicroscope is moving faster than the sun moves in the sky -- which part? light

Jan Evangelista Purkyn (1787-1869)A monk who raised flowers, like Mendelhttp://en.wikipedia.org/wiki/Jan_Evangelista_Purkyn%C4%9B

The Purkinje Treehttp://www.snof.org/vue/entoptique.html

How the Purkinje Tree is Similar to PVDBoth are seen only when conditions change, like when the light moves, or when the vitreous becomes liquifiedWe see them because they are close to the retina, unlike corneal or lens defectsSo, can O.D.s use this phenomenon so that their diabetic patients can check themselves for retinal hemorrhages at home?If you instruct the patient to move a penlight over their closed lids in a dark room, you can!You can also use a blue light, as in the next example

6) Flying Spots(not in Adler)When looking at a brightly-lit blue field with no background (moving or stationary), a series of fast-moving whitish spots are seen that move along curves and leave a trail, like a cometSince blue light is the type absorbed by hemoglobin, these flying spots are thought to be white blood cells in the retinal vesselsThus, the flying spots are sometimes called flying corpuscles (an old name for blood cells), or the blue field entoptic phenomenon

Which Cells Cause the Flying SpotsEntoptic Phenomenon?http://www.citylightsnews.com/randy/glossary/glossary_tuvwxyz.htmHint: it looks green here, but it isnt really green

Other Facts About Entoptic Flying SpotsThe spots move in pulsatile fashion that accelerates with increased heart rate, as after exerciseTheir arent enough of them to be caused by red blood cells and they are the wrong color (whitish)Applying pressure to the eye may make them as easy to see as the Purkinje treeThey can potentially be used to monitor for clinically significant macular edema (CSME), because there should be no blood vessels in the foveal avascular zone

No Spots Seen in the Foveal Avascular Zone (FAZ)Source: Adler, page 493, 9th edition

From Which Vascular Beds Do the Spots Arise?There are two possibilitiesOne is the precapillary arterioles of the nerve fiber layerThe other is the capillary loops of the inner nuclear/outer plexiform layersMarshall determined long ago that it cant be the nerve fiber layer, by using different blue lights to illuminate the Purkinje tree in one eye, and spots in the otherSo its the capillary loops that make the spots appear

7) Blue Retinal ArcsThe nerve fiber layer itself can cause entoptic images, also found by PurkinjePurkinje used a glowing tinder taken from a fire, (dont try this at home)Red, rectangular lights apparently the most effective stimuli, held parallel to NFL bundlesFor example, when a red target was seen by nasal field, two arcs were seen, and would change apparent distance from each other with target movementThe arcs are dim gray in the dark, and bright blue in the light, like an afterimage

What Blue Retinal ArcsLook Like OSAdler, figure 16-8

How Does Retinal Anatomy Explain Blue Arcs?The nerve fiber layer (NFL) radiate from the optic nerve in bundles toward and around the foveaThey respect the horizontal midline and do not cross it, making a seam of sortsRecall that this midline is called the horizontal rapheThe perceptual phenomenon lateral inhibition likely plays a significant roleMuch more on lateral inhibition later!

Nerve Fibers Bundles and the Horizontal Raphe ODSee also Adler, figure 16-7http://www.glaucomaworld.net/english/010/e010i12.html

8) Haidingers BrushOur last type of entoptic phenomenon, these come from the fovea when a spinning polarized target is usedThey are best seen with magnification and a glass cobalt blue filter (same color as the slit lamp filter for fluorescein)You can see a brush that spins like an airplane propeller and moves with your eye, looking like a Maltese cross

The Maltese Cross -- Can You See It On Your Laptop Screen?You need to use polaroid glasses to see it on a laptophttp://world.std.com/~mmcirvin/haidinger.htmlhttp://www.bernell.com/product/4092/184

Why Do We See the Haidinger Brush?Plane-oriented molecules of pigment in the fovea causes some plane-polarized light to be absorbed, especially if its blueSo when a spinning polarizer is put in front of a blue light, you see a propellerSubtle macular edema and other retinal disease may cause the brush to disappear, even if the retina looks normal to your ophthalmoscopeIt is used in vision therapy to track the location of the fovea in patients with amblyopia and eccentric fixation

Which Part of the Retina Sees the Brush?http://cheme.che.caltech.edu/groups/jak/research/eyes/

Maxwells SpotMaxwells Spot is a close relative to Haidingers BrushesSeen as a dark reddish circle surrounded by a clear ring and brighter blue halo when looking at a diffuse flickering blue lightThe size is 2-3 degrees, oval horizontally, and may look grainyXanthophyll foveal pigment is responsible for Maxwells SpotWhich color is xanthophyll? Hint: which color is the macula lutea? ______________http://www.nature.com/nature/journal/v175/n4450/abs/175306a0.html

Review CapsuleWhy do we see the Purkinje Tree under the slit lamp, but not in the sunshine? Why are flying corpuscles better described as flying spots?Which entoptic phenomena can be used by an observant patient to monitor glaucoma? Which can be used to monitor diabetic retinopathy?What part of the retinal causes the polarization responsible for the Hadinger Brush effect? What is Maxwells spot? When is it seen?

References & ReadingsTodays material can be found in chapter 16 (in the 10th edition) of Adlers Physiology of the Eye, the chapter with the same title as this lecture, by Hart and Westheimer. Thanks to them!Next time, we will start Schwartz, chapters 1 and 2. Better buy now and keep up!I recommend a used copy since a new edition is coming out by next year, and you may want to keep your copy until after your Boards

James Kundart, OD, MEd, FAAO Optometry 662, Spring 2010James Kundart, OD, MEd, FAAO Optometry 662, Spring 2010*James Kundart, OD, MEd, FAAO Optometry 662, Spring 2010James Kundart, OD, MEd, FAAO Optometry 662, Spring 2010*James Kundart, OD, MEd, FAAO Optometry 662, Spring 2010James Kundart, OD, MEd, FAAO Optometry 662, Spring 2010*James Kundart, OD, MEd, FAAO Optometry 662, Spring 2010James Kundart, OD, MEd, FAAO Optometry 662, Spring 2010*James Kundart, OD, MEd, FAAO Optometry 662, Spring 2010James Kundart, OD, MEd, FAAO Optometry 662, Spring 2010*James Kundart, OD, MEd, FAAO Optometry 662, Spring 2010James Kundart, OD, MEd, FAAO Optometry 662, Spring 2010*Use specular reflection to see endotheliumIf corneal edema, look at endothelium

James Kundart, OD, MEd, FAAO Optometry 662, Spring 2010James Kundart, OD, MEd, FAAO Optometry 662, Spring 2010*If u have a patient with corneal dropout, can use pinhole to monitor own cornea

James Kundart, OD, MEd, FAAO Optometry 662, Spring 2010James Kundart, OD, MEd, FAAO Optometry 662, Spring 2010*James Kundart, OD, MEd, FAAO Optometry 662, Spring 2010James Kundart, OD, MEd, FAAO Optometry 662, Spring 2010*James Kundart, OD, MEd, FAAO Optometry 662, Spring 2010James Kundart, OD, MEd, FAAO Optometry 662, Spring 2010*James Kundart, OD, MEd, FAAO Optometry 662, Spring 2010James Kundart, OD, MEd, FAAO Optometry 662, Spring 2010*James Kundart, OD, MEd, FAAO Optometry 662, Spring 2010James Kundart, OD, MEd, FAAO Optometry 662, Spring 2010*James Kundart, OD, MEd, FAAO Optometry 662, Spring 2010James Kundart, OD, MEd, FAAO Optometry 662, Spring 2010*James Kundart, OD, MEd, FAAO Optometry 662, Spring 2010James Kundart, OD, MEd, FAAO Optometry 662, Spring 2010*James Kundart, OD, MEd, FAAO Optometry 662, Spring 2010James Kundart, OD, MEd, FAAO Optometry 662, Spring 2010*James Kundart, OD, MEd, FAAO Optometry 662, Spring 2010James Kundart, OD, MEd, FAAO Optometry 662, Spring 2010*Worry about floaters because of retinal detachment / retinal tears

Retinal Detachment new floaters, a lot of them (too many to count), little floatersJames Kundart, OD, MEd, FAAO Optometry 662, Spring 2010James Kundart, OD, MEd, FAAO Optometry 662, Spring 2010*Can replace vitreous with saline if its warranted (only in severe cases)James Kundart, OD, MEd, FAAO Optometry 662, Spring 2010James Kundart, OD, MEd, FAAO Optometry 662, Spring 2010*Patients dont see floaters in anterior chamber (cells + flare) because so far from retina that the patient is never aware of itJames Kundart, OD, MEd, FAAO Optometry 662, Spring 2010James Kundart, OD, MEd, FAAO Optometry 662, Spring 2010*Asteroid Hyalosis looks like Christmas snow globe filled with glitter associated with pre-diabetics/diabetics leakage, mineral deposition in the vitreous James Kundart, OD, MEd, FAAO Optometry 662, Spring 2010James Kundart, OD, MEd, FAAO Optometry 662, Spring 2010*James Kundart, OD, MEd, FAAO Optometry 662, Spring 2010James Kundart, OD, MEd, FAAO Optometry 662, Spring 2010*James Kundart, OD, MEd, FAAO Optometry 662, Spring 2010James Kundart, OD, MEd, FAAO Optometry 662, Spring 2010*James Kundart, OD, MEd, FAAO Optometry 662, Spring 2010James Kundart, OD, MEd, FAAO Optometry 662, Spring 2010*High myopes more likely to get thisJames Kundart, OD, MEd, FAAO Optometry 662, Spring 2010James Kundart, OD, MEd, FAAO Optometry 662, Spring 2010*James Kundart, OD, MEd, FAAO Optometry 662, Spring 2010James Kundart, OD, MEd, FAAO Optometry 662, Spring 2010*James Kundart, OD, MEd, FAAO Optometry 662, Spring 2010James Kundart, OD, MEd, FAAO Optometry 662, Spring 2010*Perceptual system is good at filtering things out when light is stationary and you are moving around. Worse when light is moving around such as in a slit lampJames Kundart, OD, MEd, FAAO Optometry 662, Spring 2010James Kundart, OD, MEd, FAAO Optometry 662, Spring 2010*James Kundart, OD, MEd, FAAO Optometry 662, Spring 2010James Kundart, OD, MEd, FAAO Optometry 662, Spring 2010*James Kundart, OD, MEd, FAAO Optometry 662, Spring 2010James Kundart, OD, MEd, FAAO Optometry 662, Spring 2010*James Kundart, OD, MEd, FAAO Optometry 662, Spring 2010James Kundart, OD, MEd, FAAO Optometry 662, Spring 2010*James Kundart, OD, MEd, FAAO Optometry 662, Spring 2010James Kundart, OD, MEd, FAAO Optometry 662, Spring 2010*James Kundart, OD, MEd, FAAO Optometry 662, Spring 2010James Kundart, OD, MEd, FAAO Optometry 662, Spring 2010*James Kundart, OD, MEd, FAAO Optometry 662, Spring 2010James Kundart, OD, MEd, FAAO Optometry 662, Spring 2010*James Kundart, OD, MEd, FAAO Optometry 662, Spring 2010James Kundart, OD, MEd, FAAO Optometry 662, Spring 2010*James Kundart, OD, MEd, FAAO Optometry 662, Spring 2010James Kundart, OD, MEd, FAAO Optometry 662, Spring 2010*James Kundart, OD, MEd, FAAO Optometry 662, Spring 2010James Kundart, OD, MEd, FAAO Optometry 662, Spring 2010*James Kundart, OD, MEd, FAAO Optometry 662, Spring 2010James Kundart, OD, MEd, FAAO Optometry 662, Spring 2010*James Kundart, OD, MEd, FAAO Optometry 662, Spring 2010James Kundart, OD, MEd, FAAO Optometry 662, Spring 2010*James Kundart, OD, MEd, FAAO Optometry 662, Spring 2010James Kundart, OD, MEd, FAAO Optometry 662, Spring 2010*James Kundart, OD, MEd, FAAO Optometry 662, Spring 2010James Kundart, OD, MEd, FAAO Optometry 662, Spring 2010*James Kundart, OD, MEd, FAAO Optometry 662, Spring 2010James Kundart, OD, MEd, FAAO Optometry 662, Spring 2010*James Kundart, OD, MEd, FAAO Optometry 662, Spring 2010James Kundart, OD, MEd, FAAO Optometry 662, Spring 2010*James Kundart, OD, MEd, FAAO Optometry 662, Spring 2010James Kundart, OD, MEd, FAAO Optometry 662, Spring 2010*James Kundart, OD, MEd, FAAO Optometry 662, Spring 2010James Kundart, OD, MEd, FAAO Optometry 662, Spring 2010*James Kundart, OD, MEd, FAAO Optometry 662, Spring 2010James Kundart, OD, MEd, FAAO Optometry 662, Spring 2010*