BY DR. DANIEL L.JOHNSON

Eye FloatersOne early spring evening after work,

Darrell turned off his office lights,and against the dark saw little flasheslike lightning in his peripheral vision.He instantly remembered that his momhad told him she saw flashes when shehad a retinal detachment. This had beensort of an unhappy time for her, so hefelt anxious.

But his vision seemed clear as he wenthome, and his eye was comfortable, sohe slept on it. He was relieved when hiseye doctor said to come right in when hephoned the next morning.

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After much peering and examining,she said, "You have a vitreous detach-ment. It's just an aging change, butsometimes it leads to retinal detachment,so I want to see you again next week."

He felt a little hurt to hear that Agehad cut one more small notch in his beltand felt glad that nothing devastatinghad happened.

But he did notice, after that, somespecks dancing gracefully around, get-ting somewhat in the way of fine print,especially on his computer screen orin bright light. Then, when the soar-ing season began, there were lots oflittle specks dancing gracefully againstthe sky. As he flew, every so often, hethought one was a bird or distant plane.

He began to wonder whether this wasa risk for seeing other aircraft.

Are Ocular Floaters Important toPilots?

If you're wondering what an ocularfloater is, then you're still young, withoptically pure clear eyes.

From the point of view of the victim,a "floater" is any little spot or blur in ourvision that shows up when we look ata featureless background, especially inbright light, and that moves or jiggleswhen our eyes move.

From the point of view of the eyedoctor, floaters are various little imper-fections in the watery core of the eye-ball, the vitreous humor. As in the archaicsense of humor, "fluid or juice of ananimal or plant," which is not comical.Especially if your vitreous is not glassyclear ("vitreous" means "glassy").

To make this plainer, the eyeball isfilled with a clear-as-glass (vitreous)wet gel (humor). Various imperfectionscause motes to form within it when ag-ing causes the proteins which form the

gel to clump. When light shines intothe eye (something we seek out, becausevision is a Good Thing), any speck maycast its tiny shadow on the retina.

We see this as a (hold your breath)shadowy speck. The eye is continuallyin motion, and the gel jiggles accord-ingly, making the shadows seem to floataround.

This feels like a problem only if thefloaters are in front of the fovea, thetiny spot in the central retina that givesus detailed vision. Then it can be an-noying, or can cripple our ability to seefine detail if there is a flock of centralfloaters.

The Problem with FloatersSadly, the brain is so very good at fill-

ing in gaps in our conscious picture ofwhat's around us that it will invent stuff,filling in gaps with familiar patterns oradjoining textures.

On the favorable side, this lets us readdegraded text and respond instantlywhen that is urgent without having towait for all the dots to be connected. Onthe other hand, the filled-in gaps some-times contain important detail. We'veprobably all had a car on the cross-streetemerge unexpectedly from our wind-shield A-pillar.

This is important for see-and-avoidbecause the airplane we're going to col-lide with begins as a gnat-sized speck- insect, bird, or airplane dependingon the distance our brain assumes. Thisis made more difficult if we have tinybits in the eye that hide this speck, orthat cast their own shadow and mimicsomething.

False ImpressionsWe understand that "first impressions"

are often correct. Yet our instantaneous"eureka" experiences are not reliable. Wemake mistakes repeatedly if we do notverify what we think at first is true.

In medicine, decades ago, Germanphysicians admired those who couldreach a diagnosis instantly by recogniz-ing parts of a familiar pattern. This isgreat fun, and makes us look magicallysmart. They called it blinkreit, whichseems to have spawned the MalcolmGladwell book, Blink.

October 2015 • www.ssa.org

Yet in medicine, and in every occu-pation in which accuracy is crucial (orerror damaging), self-doubt is impor-tant. We must be continually willingto discover ourselves wrong, especially ifwe are completely confident in our firstimpression.

Aviation is not different. We mustalways seek confirmatory evidence ofwhat seems to be true, lest we be de-ceived by illusion.

Floaters obscure detail of the scenebefore us. This degrades the accuracy ofpattern-recognition, and increases errorrates. Will a distant fast-moving aircraftbe obscured by the shadow of a floater?The aircraft with which we will collidedoes not move on our retina, so our mo-tion-detecting system fails. The floaterfails the flyspeck-detecting system.

Floaters also degrade reading of texton displays and charts (if you're oldenough to remember what those are),and in the federal regs and club rules.(Perhaps this is a reason that so fewairplane pilots over 60 who see me forflight physicals actually have read any ofthe rules.)

We are like the ducks in a shootinggallery: the more time we spend cross-ing the target zone, the more likely weare to get hit. Aging is pure time andchance as much as it is senescence.

What Are Floaters Made of?It's my sad duty to tell you that these

annoying spots are part of you. No

maleficent force has inserted interstellardust into your eyeball while you sleep.

A few floaters are lifelong, a result ofslight imperfections at birth. For ex-ample, the eye forms as an extension ofthe fetal brain, at the front of which isthe cornea and lens. During the first 10weeks of fetal life, the ophthalmic arteryto the eye has an extension through thecenter of the eyeball, the hyaloid artery.This then regresses, normally leavinga clear canal through the center of thevitreous humor.

Sometimes this regression is incom-plete, leaving (usually tiny) free rem-nants, which are seen as floaters (mostlyin bright light).

Anytime during life, infection or in-flammation may affect an eye. Thereare many diseases that may be involved.Floaters can be tiny clumps of protein,white blood cells, or tiny hemorrhages.

In general, new floaters are a signalto urgently visit the ophthalmologist iflight is painful or the eye itself is red orpainful, if vision is blurred, or there seemto be flashes of lightning in your periph-eral vision.

Having said that, acquiring floatersis also a natural aging change. If you'reover 60, you've noticed that resilienceand elasticity have been replaced bystiffness and sagging. As part of thisgeneral process, without your havingnoticed, the gel of the vitreous humor(glassy fluid) shrinks a little and maydetach from the retina. This is called a

"vitreous detachment."Normally, this simply creates some

loose debris - new spots of interstellardust in our vision. Rarely, the retina willtear. This is noticed as lightning flashes,and if it detaches, a grey curtain will bedrawn across part of the visual field.

Sudden loss of vision is always anemergency, for much can be saved if theproblem is not neglected.

Clues to hurry to an ophthalmologist,to summarize, are newly blurred vision,lightning flashes, light hurting the eye,redness around the rim of the cornea,and eye pain. The feeling of somethingin the eye should go away in a few min-utes (a lash) or a few hours (a slightscratch).

Having said that, I'm continuallyamazed at how some people fail to no-tice severe vision changes. "I went to myeye doctor," the middle-aged collegedean said to me recently, "And he foundthat I'd gone blind in my right eye. Hetook a cataract out, and my vision ismuch better."

Or, "I can't read street signs, but Ican read road signs - so my wife navi-gates." He chuckles, adding, "If it getsany worse, maybe I'll talk to my eyedoctor." I ask who that is, and he says,"Wal-Mart."

At the other end of the pendulumis the perfectionist who notices everyspeck, and may try hard to persuade theophthalmologist to vacuum out the vit-reous and replace it with clean fluid. «-

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Do Floaters Ever Go Away?Fortunately, gravity helps. As the

months flow by, floaters tend to sink,migrate away from the fovea, and be-come less bothersome.

In addition, floaters are seldom obvi-ous in dim light. The reason is optical:in dim light, the pupil is dilated (4-9millimeters in diameter, varying withindividuals) and every part contributesrays of light to every rod and cone. Thiscauses the floater to become a small areathat's slightly foggy.

Contrariwise, in bright light, the pupilis small (2-4 millimeters, across individ-uals), so that the floater is more likely tocast a sharp shadow. This is why float-ers are most obvious when the light isbright and the background is featureless.We elders start seeing "insects" and dis-tant "birds" against the bright sky thatmove with our eyes, not with the breeze.

So time and dim light are nature'sremedies.

Are Floaters Disqualifying?No. Floaters rarely decrease best visual

acuity. The FAA standard is, frankly,pretty low for the 3rd class medical. Therequired best vision of 20/40 doesn'tsatisfy me with I'm in the airport trafficpattern with such "best" vision. Thequestion is, "How far away can you seethat collision coming?" At 20/40, we'relucky if the glider or small GA aircraftis visible from the far end of the down-wind leg. (See this column, July, 2011,at tinyurl.com/see-and-avoid.)

A pilot who saw me for regular flightphysicals for several years told me thatthe reason he stopped flying was that hehad so many floaters he didn't trust him-self to see distant traffic. He's a carefuland wise man, who shifted his time tograndchildren, performing folk music,and remodeling projects.

For the person in his shoes who feelsunsafe with their floater flock, there aretwo remedies.

Can Floaters Be Blasted or VacuumedAway?

Yes. When these are merely annoying,it's not worth risking even rare majorsurgical accidents to attempt a fix. Butbecause floaters are visually disabling,

they are clearly worth a careful evalua-tion by an ophthalmologist.

Laser Ablation of FloatersA very few surgeons are using lasers

to fry floaters. Only three ophthalmol-ogists in the US have extensive experi-ence with this technique. So this is notsomething you can ask your friendlyneighborhood ophthalmologist to dofor you.

Nevertheless, in these experiencedpractices, there is a very favorable risk.Reduction of floaters is excellent, thoughnot always totally cleared, and seriousadverse effects are almost non-existent.

It is attractive because laser surgerydoes not require the surgeon to poke asharp needle into the eyeball (no risk ofbleeding, retinal tears, or infection), norisk of cataract, and it's fast (two to foursessions lasting less than 30 minuteseach, on successive days).

Laser ablation is aimed at destroyingthe most bothersome floaters, especiallythose located on the visual axis, not atcompletely cleaning out the eyeball.

Cross section of laser treated eye: (a) Treatment contact lens, (b)two red diode focusing beams, (c) converging YAG laser energy cone,(d} vitreous condensation (floater), (e) apex of energy cone. This isthe only point in space where the energy is delivered, (f) diverging,dissipating laser energy

Courtesy of Dr. James H. Johnson.

And there are potential troubles. Themost significant is the chance of injuringa spot in the retina. This is not what wecame to buy, so would be a disappoint-ment. It is avoided by not treating float-ers within about 2mm of the retina. Thisalso means that such floaters cannot beremoved by laser.

Another troublesome effect is that iftoo much floater material is zapped inone session, the residue can plug up theeye's drain like oatmeal in the kitchensink. This would lead to glaucoma. It isprevented by treating the floaters in two

to four brief daily sessions to let the eyeclear itself out overnight.

Sometimes the procedure just doesn'tmeet our hopes - the floaters are toolarge or numerous, and disappointmentmay lead to derogatory or defamatoryweb comments about the surgeon.

If you consider having this procedure,which is effective and safe (it has fewerpoor outcomes than LASIK), first seeyour local ophthalmologist or optom-etrist for an internal examination ofyour eye to determine if your floaters arevisible, and to make sure that you don'thave any other important eye condition.

You can expect the procedure to costin the range of $1,500-2,000 per eye andany insurance reimbursement not worththe hassle.

Irv Arons has written an excellentsummary of this procedure at tinyurl.com/irvarons-floaters that includes ref-erences. He describes European practiceat tinyurl.com/EU-floaters. This sum-mary is about five years old. An Inter-net search for "laser treatment of ocularfloaters" reveals that this treatment isbecoming more widespread, perhapsbecause Dr. John Karickhoff has writ-ten a textbook and designed a bespokecontact lens for surgeons.

VitrectomyAs mentioned above, the vitreous can

be vacuumed away and replaced withnice, clean salt water.

This does involve poking a sharp stickinto your eye - actually three - and sothe risks are greater.

It was developed, and is the rightchoice, for people who have really majorclouding of vision from serious internaleye conditions.

For the person whose sight is in dan-ger, this is very welcome. It goes well90% of the time, more or less. However,removing the vitreous disrupts the nu-trition of the lens, so most people geta cataract of the eye sooner than theywould otherwise. The retina may be torn(< 1.5%) or the eye may bleed internally(< 2%). These are complications that canbe very troublesome, and generally causemore floaters.

It's not fair to the eye surgeon toblandly compare this to vacuuming your

floors, for vitrectomy is a precise andfairly complex procedure in which tinyinaccuracies can cause trouble.

Essentially, a fine needle, in which isnested a minuscule blender, is insertedinto the eye. The gel is liquefied by thecutter, then vacuumed out, replaced bygas and then salt water.

This was first developed in 1970, andmany technical refinements have fol-lowed. 20-gauge instruments have beenreplaced by 23-, 25-, and now 27-gaugeinstruments. The smaller instrumentsare more comfortable for the patientand cause fewer complications. As thesecomplex needles become smaller, theybecome more flexible and more chal-lenging to guide.

Vitrectomy is used mainly to treat ca-tastrophes such as retinal detachment,eyeball internal infection, penetratingforeign bodies, hemorrhage within theeye, and so on. In these conditions, thepotential adverse outcomes are clearlyacceptable, usually being less severe thanthe condition treated.

Complications are less acceptable when

treating a condition that is predominant-ly annoying. We really hate to lose an eyethat was functioning, even though sub-optimally. The most common complica-tion of vitrectomy is cataract (25-50%within 2 years). This and retinal detach-ment (5-10%) occur significantly lessoften with smaller-gauge instruments.

What to DoHere's my free advice, for what it's

worth.1. If you have floaters, take the advice

you shouted to the umpire, and haveyour eyes examined thoroughly by anoptometrist or ophthalmologist.

2. If the floaters are visible, and youdon't otherwise need eye treatment thatis more important, read Irv Aron's on-line essay and schedule a consultationwith one of the experts he names tofind out whether your own floaters arebest treated with laser, how much visualimprovement is likely, and whether thisholds any significant risks for you.

3. Waiting, after you've had your eyeschecked out, is almost always perfectly

safe. It's hard to make a good eye bet-ter, and that one on the other side is nota spare.

ReferencesArons, I. Using Lasers to Treat Float-

ers. 2010 http://www.tinyurl.com/irvarons-floaters

Chirag C Patel, MD, et al. ParsPlana Vitrectomy. 2015. http:// e m e d i c i n e . m e d s c a p e . c o m /article/1844160-overview#a7

Merriam-Webster Dictionary (An-droid app) www.m-w.com

Sommerville DN, Vitrectomy forvitreous floaters: analysis of the ben-efits and risks. Curr Opin Ophthal-mol 2015, 26:173-176 DOL10.1097/ICU.0000000000000150

AcknowledgmentsThanks to Dr. John Karickhoff, Dr.

Scott Geller, and Dr. James Johnson,for discussing laser treatment of floaterswith me by phone and email.

Illustration courtesy of Dr. James H.Johnson.

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