What is 20/20?

Optometrists love to toss around the term 20/20:  “You have 20/20 vison.” or “Gosh, you’re seeing better than 20/20.”  Perhaps, you use it at home:  “How does this dress look?”  “Sorry honey – I don’t see 20/20.”  The news program “20/20″ was actually named after the visual measurement.  Everyone knows 20/20 is ideal, but few actually know what it means.

To know how well someone sees, we must use a standardized system.  This affords doctors the ability to know if someone needs more or less correction and to compare the vision between members of a population.  For example, it’s means very little to accurately check the vision of an eight month old girl and then record it as “pretty good” or “seems normal.”  It’s far superior to be able to record her vision as 20/60 or 20/80.  Then visual changes may be tracked with tighter accuracy, her visual acuity may be compared against what’s normal for 8 month olds, and her vision may be corrected or observed against a quantifiable system.

The 20/xx system is also known as the Snellen visual acuity system.  The top number refers to the testing distance in feet.  Twenty feet is considered to be “optical infinity” due to how our eyes focus and the behavior of light waves at this distance.  However, most offices do not have patients sit 20 feet from a chart due to space constraints.  Through the use of mirrors and chart calibrations, the shorter distance is compensated for remarkably well.

The bottom number is a bit more complex.  It’s the distance at which each element of a letter has an angular height of 1 minute of arc (or 1/60th of a degree).  The letter “E” on an eye chart has 5 elements.  There is the top bar, a space, the middle bar, another space, and the bottom bar.   When one stands 400 feet from the big E at the top of the chart, each of these elements subtends 1 minute of arc.  Therefore the size of the letter is called 20/400.  For a letter on the 20/20 line, one must stand 20 feet away for each element to subtend 1 minute of arc.

The neurological processing in the human eye and key areas of the brain allows people to easily discriminate between letters with 1 minute of arc (or smaller) features.  With a (compensated or actual) testing distance of 20 feet, optometrists therefore embrace the 20/20 line as a perfect endpoint.  Please don’t fret if you can’t see 20/20 without glasses or contacts.  That will be the subject of a blog post in the near future.  Seeing 20/20 with or without visual correction means that at 20 feet away, your eyes see as well as they are expected see.  If you can’t read 20/20, please schedule an appointment, and I’d love to help boost your vision.

Spencer Ritenour, O.D.

dr.ritenour@parkslopeeye.com

That dang air puff

A lot of people are scared to visit the eye doctor because of the air puff test.  What is it?  Is it absolutely necessary?  Can you avoid it?

The air puff test is what people commonly call the non-contact tonometry (NCT) test.  It is used to determine the pressure inside the eye, also known as the intraocular pressure (IOP).  Knowing a patient’s IOP is the most important tool that optometrists have to screen for glaucoma.  An IOP that’s elevated to an unsafe rage feels very similar to most types of high blood pressure – that is you feel just fine.  By the time you begin to notice symptoms it is too late.  Consequently it’s important for your doctor to check your IOP at least annually.

I can hear you saying, “Come on doc.  That test is horrible!”  I totally agree with you.  The NCT machine blows a measured amount of air at the eye which deflects the cornea a bit.  Infrared sensors measure the corneal deflection and correlate it to the pressure inside the eye.  When one puts it that way it doesn’t sound too bad.  In fact it works extremely well on a research lab bench.  In the real world…well…not so much.  Our eyes have a great natural reflex that protects them when something comes close or contacts the eyelashes.  That’s why people blink and get nervous about the air puff.  In fact, patients typically blink and clench their eyes so much during NCT that the IOP reading frequently is nowhere near the true value.  I’m the worst at this.  Do NCT on me, and I become as fussy as a toddler without his nap and snack.  I dislike doing NCT on patients and having it done on me so much that we don’t even have this machine at Park Slope Eye.  It’s a really dated technology.

Fortunately there are alternatives.  A very common and extremely accurate way to measure the IOP is Goldmann tonometry (aka the blue light test).  With this test, patients get a yellow eye drop that makes the eye glow when exposed to a blue light.  The doctor steers an illuminated prism very close to the eye.  When the doctor looks in his microscope, the IOP is correlated to the degree that the prism bends the light.  This method is considered the gold standard of IOP measurement.  It is painless but still scares many patients.

At Park Slope Eye we have an even better way to determine patients’ IOP.  We have a special device from Helsinki, Finland that gives just as accurate IOP readings as Goldmann tonometry.  A very tiny wand bounces off the tears and the device measures the force at which it returns.  It’s very fast, painless, and requires no drops.  A few seconds after I explain it to patients, the machine has already measured the IOP three times in each eye!  We are one of the few offices in New York that actually has this technology.  Ask a friend who comes to Park Slope Eye what they think about it.  Stop by the office if you don’t know anyone who is a patient here.  I’d love to demo it for you (and make you some coffee)!

Spencer Ritenour, O.D.

dr.ritenour@parkslopeeye.com

…but my vision isn’t blurry.

How often do you visit your eye doctor?  Annually?  Every 5 years?  Still haven’t been checked?  Perhaps a better question is how often should you visit your eye doctor.  For the general population, optometrists recommend a visit at least every 12 months.  Still it’s common for people to wait until their vision gets blurry.  On the surface that seems sensible, but it overlooks some very important elements of good eye health.

Every eye exam does include a determination of one’s glasses and/or contact lens prescription.  While this is important for good vision, it’s just a small component of the examination.  When light enters the eye, it gets refocused no less than 12 times before being converted to an electrical signal behind the eye.  In most people, the summation of these focusing steps is not quite perfect – leading to a prescription that compensates for the difference.  This would be the end of the story if the eyes were simply glass and electronics like a camera lens.  Obviously they are living tissue that have special needs and interacts with the rest of the body.

There are disorders that can affect all of the elements that comprise the eye (e.g. the eyelid, tears, lens, retina).  Eye specific diseases include glaucoma, cataracts, macular degeneration, and many more.  Many systemic conditions such diabetes, hypertension, and high cholesterol may cause ocular complications as well.  In fact in certain instances, an optometrist is the first doctor to see these signs in a patient.  During a eye doctor’s examination he observes the external eye structures under high magnification.  Also he will look inside the eye at the all internal structures.  Any abnormalities are treated or aggressively monitored as warranted.  In addition to examining the physical structure of the eye, the physiology or functioning of the eye is equally important to check.  He will ensure that they eyes are moving properly, working well together and independently, communicating with the brain, and being supplied with blood as they should.

Some people are fortunate enough to not need glasses until about age 40 or maybe never need them.  Other people notice that their prescription stops changing in their late teens or early twenties.   Regardless of how blurry or clear a person’s vision is, it’s very important to ensure that her eyes are structurally sound and functioning to the max.  If a problem is ever detected, it is far superior to catch it in the early stages than to catch it much later.  Don’t let “good enough” vision rob you of a lifetime of stellar vision and healthy eyes.

Spencer Ritenour, O.D.

dr.ritenour@parkslopeeye.com

Spooky Eyes

Halloween is just around the corner.  Now is the time to decorate the house, buy the candy (KitKats please), dial in your party plans, and figure out your costume.  It’s very fun to visit a Halloween store to check out what they have.  There are always the great masks, funky ‘staches, and goofy clothes.  Many stores also carry a selection of spooky contact lenses.  These are painted to make your eyes look reptilian, cat like, or just plain creepy.  However, these lenses are not just spooky in their appearance.  They are spooky deep down to their guts.  Let me explain.

All contact lenses allow a certain amount of water and oxygen through to the eye.  Engineers and chemists work aggressively to design lenses that are safe, comfortable, stable, free from bacteria, and allow for good vision.  Then they go through a many year process of research and clinical trials to become approved by the FDA.  Finally, the contact lens companies rely upon certified optometrists to skillfully fit the lenses on patients and then to regularly check the lenses and eyes for problems.  This is how a contact lens goes from being a brilliant idea in a researcher’s head to performing beautifully on your eye.  The problem with cosmetic Halloween contacts is that nearly all of them are not approved by the FDA.  It’s also illegal to sell contacts without an explicit prescription from a licensed eye doctor.  When a company wantonly ignores these regulations, it’s pretty easy to guess how interested they are in the health of your eye.

What happens when a contact doesn’t perform safely on the eye?  At the low end of the spectrum, the eyes may become red and irritated.  They can also become painfully inflamed and sensitive to light – a condition called uveitis.  Sometimes they can develop a bacterial infection or activate a latent herpes virus.  In some very severe cases, the cornea may develop an ulcer and leave a serious scar.  Nearly all of these conditions can potentially lead to permanent vision loss or other complications.  It’s not worth having “spooky” eyes one night and have “SPOOKY!” eyes for a long time afterwards.

Have a happy Halloween that’s full of candy and not eye infections!

Spencer Ritenour, O.D.

dr.ritenour@parkslopeeye.com

Reading. Electrified.

I read 70-80 books a year.  And a couple blogs.  And a couple journals.  And the Times every morning.  Lately I’ve been very curious about the booming e-reader market.  It’s grown past early adopting techies and has moved into the territory of casual and serious readers.  Despite all the advantages of e-readers, many book lovers (including me) have many hesitations toward anything that could disrupt their reading rituals.  As the holiday shopping season approaches, one can be sure that there will be a major marketing blitz for these new devices.  Here is some information regarding how we read and what changes e-readers cause.

Let’s start with a small history lesson.  Up through the 5th century BCE, oral speeches were the most common modality for delivering information.  Around this time early adopters began to write down the speeches on scrolls in order to continually ponder on them.  For a long period this caused great uproar from governmental, religious, and cultural authorities.  2000 years ago written essays and lectures began to enjoy wide cultural appeal due to their superior distribution, time-shifting, and reproducibility characteristics.  Then in 1450 Gutenberg developed the printing press and set in motion a dominant reading paradigm that’s lasted over 500 years.  Today this is beginning to change with the onset of new digital devices.

How does the eye read?  It does not scroll along a line of text smoothly like a rolling ball.  Instead it moves in a coordinated series of movements known as saccades, fixations, and regressions.  The eye jumps to a small block of text (a saccadic movement), fixates for a given amount of time, and then jumps to the next small block of text (another saccade).  Sometimes, the eye errantly jumps backwards instead of forwards.  This is known as a regression, and even expert readers make regressive movements up to 15% of the time.  The additive effect of these 3 movements is processed by the brain as smoothly reading a line of text.  One Swiss study revealed that the number of regressive eye movement was equal between e-readers and paper book on a per person level.  Also, the mean fixation time decreased when a reader moved from paper books to e-readers.  This means that people read slightly (albeit negligibly) faster and with the same accuracy when they use an e-reader.  People certainly do not “read worse” with an electronic reader as compared to traditional books.

The eye also has a couple of reflexes that change the optics of the visual system while we read.  When we look at near objects, the lens swells to add more magnification to the optical system.  Deficiencies in this area are experienced as eye strain.  Every reader’s eye strain will be the same regardless if they read from paper books or e-readers.  If eye strain is a problem for you, be sure to visit your doctor for relief.

E-ink readers (like the Kindle) have a slightly lower contrast ratio compared to paper books.  This means to read at the same efficiency, those reading with these devices need more light than when they read with paper.  E-readers with a LCD screen (like the iPad) work well in dark and normal lighting conditions.  They are harder to use in bright light and 100% impossible to use with polarized sunglasses.

Several marketing studies have shown that people actually read more when they use an e-reader.  By more, I mean 40-55% more depending on the study!  That is an awesome benefit.  They have especially boosted the interest and number of books read by the 6 to 17 year old demographic – an age group where reading is dangerously low.  Personally, I just bought my first e-reader and really love my experience with it.  My news consumption is certainly higher, and I’m reading approximately 1 extra book a week.  I have no idea why, but subjectively reading is a bit more fun too.  Send me an email if you’d like to talk about e-readers (or books!!), how they impact the eye, or are just curious about getting one.

Spencer Ritenour, O.D.

dr.ritenour@parkslopeeye.com

Computer problems

For a lot of jobs, 99% of one’s workday is spent at the computer.  Many people come in to our office complaining of headaches, strain, blurry vision, or general discomfort while staring at their screen.  What’s going on is something known as an accomodative spasm.  That simply is a nifty term for “your eyes are tired, pal.”  It’s very common among lawyers, engineers, college students, accountants, etc.  I live to read books, and this problem begins to effect my eyes after a few minutes.  Let me explain what’s happening.

Inside the eye is a flexible disc-shaped lens that is surrounded by a circular muscle known as the ciliary body.  The ciliary body behaves somewhat differently than most muscles that people think about.  A typical skeletal muscle, such as a bicep, moves a bone around a joint similar to an actuator.  When a bicep contracts it moves the forearm up.  When a tricep contracts it moves the forearm back down.  Since the ciliary body is circular, it makes a smaller diameter circle when it contracts and a larger diameter one when it relaxes.  During contraction of the muscle, tension is relieved from the lens causing it to bulge.  It’s like squeezing your fingers around the center of a balloon so that it bulges outwards at the ends.  When the ciliary body relaxes, it adds tension to the lens causing it to flatten.  The bulging of the lens helps us to focus at the computer while the flattening action helps us to focus far away.

A person’s nervous system stimulates these dynamic lens changes very quickly and beautifully.  In most cases it responds perfectly to wherever we want our eyes to focus.  However, when we stare at the computer or a book for extended periods of time, the muscle can become “locked up”.  In this state it does not move as quickly or as seamlessly as when it’s fresh.  I like to give the analogy of hold a 2 lb. weight with your arm.  It’s very easy for nearly everyone, but after holding it for 8 hours one’s bicep is going to be screaming (or at least my tiny biceps would).

What does one do to get past this?  My first recommendation is to quit your job and spend your days at the beach.  That usually doesn’t go over too well.  Aside from that, one simple exercise you can do is take eye breaks.  About every 20 minutes, look 20 ft away, for about 20 seconds (20/20/20).  Very quickly you’ll feel your eyes and some facial muscles relax.  Other strategies are special contact lens or glasses prescriptions or in certain cases reading glasses from the drugstore.  I find a solution that is as easy as possible for every particular patient’s needs.  No treatment modality will weaken the eyes or make you reliant upon glasses.  They simply take the demand that you place on your visual system and transfer it elsewhere.  Shoot me an email if you need help or have questions.  I’ll be happy to see you.

Spencer Ritenour, O.D.

dr.ritenour@parkslopeeye.com

Stay shaded

Sunglasses do a lot of things.  They always make a fashion statement (good or bad).  They significantly cut glare.  They hide your eyes as you check out your fellow patio diners.  They protect the eyes during outside sports.  However, good sunglasses have benefits that are more than cosmetic or convenient.

The most important function of sunglasses is to block UV light.  This type of light is not visible to the human eye and comes in three forms:  UVA, UVB, and UVC.  UVC is the most damaging form, but all that is emitted from the sun is filtered by the atmosphere.  It’s main application is in industrial sterilization processes.  UVA from the sun does reach the Earth’s surface, but it’s effects are generally limited to accelerating aging.  A black light emits UVA.  UVB from the sun reaches the Earth’s surface in great amounts.  It can cause cancer, free radical damage, and disruptions in one’s DNA.

Sun damage to the eye can occur in a variety of areas.  A very common location for basal cell carcinoma and squamous cell carcinoma is the eyelid.  In fact, the bony ridge above the eye and the eyebrow help to minimize UV exposure to this area of sensitive skin.  However, they cannot protect it completely.  Being outside on the beach or ski slope with no eye protection frequently leads to photokeratitis, a painful inflamed cornea, due to the intense amounts of sunlight and glare.  By far the most prevalent eye effect of the sun is cataracts.  Cataracts are an opacity or yellowing of the lens that largely occurs due to accumulated UV damage.  The reason they typically occur later in life is that while we are younger, we  simply haven’t had enough lifetime UV exposure.  Getting in the habit of wearing sunglasses faithfully helps to delay the development and severity of cataracts.  Finally, a less common but very severe sun/eye complication is called solar retinopathy.  This is effectively a sunburn in the back part of the eye that can lead to temporary or permanent vision loss.

Sunglasses are of little value if they do not block 100% of UVA and UVB radiation.  The ophthalmic quality sun lenses that we use at Park Slope Eye always block these wavelengths.  Additionally, our optometric stylist and doctors will ensure that they fit your face properly to offer the maximum amount of protection.  If you don’t wear contacts, we can even add your prescription to them.  Lower quality department store or drug store shades may or may not block all UV light, and they cannot receive prescription lenses.  The manufacturers of knockoff sunglasses typically thumb their nose at copyright law and frequently put the same little value on UV protection.  They are the one type of sunglasses that you are best to avoid in all cases.  Getting in the habit of regularly wearing your shades when you go outside will help keep your eyes healthy throughout your life.  Wearing the right kind of shades may even get you a few second glaces from the other folks on the sidewalk.

Acuvue TruEye contacts

Recently there has been a press release announcing a recall of the popular 1-Day Acuvue TruEye contact lenses.  It’s very important to note that this recall solely affects lenses manufactured in Japan and a few other European and Asian countries.  The TruEye lenses manufactured and distributed in the US are completely unaffected.  The problem occurred on one manufacturing line that produces contacts for Asian distribution.  It was remedied immediately.

At Park Slope Eye we have had remarkably high patient satisfaction rates with all of the Acuvue contacts that we fit – especially the TruEye lens.  In addition to having an amazing safety profile and being extremely comfortable, the TruEye lens was recently certified as being in the highest class of UV blocking contacts.  I have personally visited Acuvue’s world headquarters, their North American R&D division, and their North American manufacturing plant.  Their industrial processes at every stage of contact lens development are state of the art.

If you are interested in trying TruEyes, I would be more than happy to fit you with a pair.  Of course if another lens is more appropriate for your needs and eye health, we can try those instead.

Happy 40th Birthday!

Blurry vision due to presbyopia

Many people find that they don’t need glasses for much of their early life.  Then around age 40, suddenly their near vision begins to progressively worsen.  At first they may have to strain to read the paper.  Perhaps, they have to hold their phone or watch further away.  Many years later, everything within arms reach may be very blurry.  What gives?

These visual changes are due to something called presbyopia.  It effects the structure and function of some of the internal elements of the eye.  It’s a normal part of aging that occurs around 40 years of age.  During the Iron Age the average lifespan was about 35 years, and nobody had to worry about presbyopia.  Now that average lifespan is close to 80, presbyopic changes impact us for approximately half our lives.

Inside our eye is a lens that allows light to focus on our retinas.  Overall it’s responsible for about 25% of the focusing power in the eye.  It also allows for small dynamic changes that occur as one looks far away, up close, and at all distances in between.  This is very similar to the autofocusing system in a camera.  Surrounding the lens is a circular muscle that causes the lens to stretch out or bunch up – creating this focusing ability.  Presbyopia is the sum of two natural phenomena with this system.  As one ages cellular deposits begin to reduce the natural flexibility of the lens.  I often liken this to flexing one’s bicep with a shirt sleeve over it – very easy to do.  However, if one wears 20 shirts it becomes much more difficult.  If one wears 40 shirts it becomes practically impossible.  The second change that occurs is a progressive loss of elasticity in the focusing muscle.  So with these changes added together the lens is naturally less flexible and the eye’s ability to drive this flexion is reduced.

What this means for one’s vision is that a little extra help is needed for near visual work.  This can come in the form of over-the-counter readers, prescription bifocals, or special bifocal contact lenses.  It’s important to clarify that using these devices will not make one’s eyes weaker or more reliant upon them.  As mentioned above, presbyopic changes typically begin around age 40, but they continue to increase in magnitude until about age 65.  This corresponds to an increase in the strength of the near prescription.  One’s eyes will follow the presbyopic progression that they are destined to follow regardless if reading glasses are used or not.

Even if you are lucky enough to not need glasses and haven’t experienced these presbyopic changes there is still great value in getting an annual eye exam.  Beyond checking for a glasses prescription, an annual examination includes checking the health of the internal and external eye structures, ensuring that the eyes function well together and independently, and confirming that the neural pathways between the eye and brain are working properly.  With a regular exam, presbyopia and any other prescription or health complications can addressed so that one’s eyes and vision may live up to their maximum potential.

Be beautiful. Be safe.

One’s eye can tell a beautiful story.  They can hold a mystery.  They can relay what’s on one’s mind.  There is something very wonderful about decorating them with makeup, but it’s important to ensure that one uses eye makeup in a safe and cautious manner.  When used properly, eye makeup can be an excellent complement to one’s face.  When used improperly, it can lead to infections, severe irritation, or worse.  The 3 major concerns with eye makeup are inhibiting bacterial growth, avoiding toxic ingredients, and removing it safely.

Most people are aware that food and things like handrails or doorknobs are susceptible to bacterial colonization.  Makeup is just as susceptible.  It regularly contacts the human body; often gets stored in dark, warm, moist areas; and has certain chemical properties that make it a favorite playground for many types of bacteria.  Manufactures add preservatives and other chemicals with antibacterial properties to help stem this risk.  However, there are things that women may do at home to dramatically reduce their chance of developing an infection:

-Never share makeup. Using another woman’s eye makeup is a great way to pass pathogens back and forth.  At the very least, trading eye germs is gross.  At the very worst, said germs could transmit serious eye infections.

-Store makeup properly. The bathroom drawer is one of the worst places in the home for one’s eye makeup.  The warm humid air from the shower and darkness of the drawer are prime breeding conditions for bacterial colonies.  Similar conditions often occur in the car.  It should be stored in a dry room with temperatures no higher than 85 degrees.

-Be aware of contamination: Makeup used during an eye infection can be a reservoir for the infectious organism.  Using it during or after an infection may cause a need for prolonged treatment and/or a secondary reinfection.  Using the same liner pencil on your lips and eyes may lead to greater sensitivity to normal body flora.  Using saliva or water to reconstitute dried mascara is far from sterile and is a quick way to introduce new pathogens to the eye.

Makeup for the eye contains many ingredients that help make them the products that women know.  There are chemicals used for pigmentation, retarding bacterial growth, creating a given consistency, and many other features that one may or may not consider.  The challenge for manufactures is to balance the desired effect with price and safety.  Unfortunately, safety is often compromised in the name of making the product cheaper or more desirable.  For example, lead, kohl, and neurotoxins are frequently found in many cosmetics.  To help detract attention from this, companies may use language like “natural” or “from the Earth” or incorporate packaging that encourages consumer trust.  It’s very wise to research all cosmetic products (eye and otherwise) before using them.

Sleeping with eye makeup on opens the door to some complications that can otherwise be avoided.  It’s possible for it to enter the tear film which can lead to mild to very severe irritation.  I’ve even seen patients with compromised corneas have glittery eye shadow become embedded in the problem area.  In other cases, eyeliner and mascara left on overnight commonly leads to clogged eyelid glands.  It’s very important for women to effectively remove all their eye makeup before bed.  Yet, eye makeup remover can pose similar concerns as the actual makeup does.  Be sure to thoroughly research your remover as well.

The eyes and surrounding skin contain intricate networks of blood vessels and nerves.  Additionally the eye contains unique structures like the cornea that must be well protected and preserved.  With proper usage and a bit of research, makeup can safely beautify a woman’s eyes and pose little threat to long term health.