Blog

20/20 Vision

Karen Griffith

During an eye examination, I always use the eyechart to measure the distance vision, usually with the most current glasses or contact lenses. This gives me a place to begin and tells me what sort of vision a person has and a quantity to compare. snellen chart
The classic example of an eye chart is the Snellen eye chart, developed by Dutch eye doctor Hermann Snellen in the 1860’s. There are many variations of the Snellen eye chart, but in general it has 11 rows of capital letters. The top row contains one letter (usually an E). the other rows contain letters that are progressively smaller.

In the United States, the standard placement of the eye chart is on a wall that’s 20 feet away from your eyes. Since most of our exam rooms are shorter than 20 feet we use mirrors to simulated the 20 foot distance. 20/20 vision is considered “normal vision”, meaning you can read at 20 feet a letter that most human beings should be able to read at 20 feet.

In the US a person is considered “legally blind” if his best-corrected visual acuity with glasses or contact lenses is 20/200 or worse. To get a driver’s license in California a person must have at least 20/40 best corrected acuity.

An eye chart is a measure of visual acuity only. It is an aid to prescribing glasses and contact lenses. But eye charts don’t measure peripheral vision, depth perception, or color perception. They also don’t determine the ocular health.

The visual acuity measurements done with the Snellen eyechart are simply a starting place for any eye examination, a method to quantify it.

Are Contact Lenses Dangerous?

Karen Griffith 1 Comment

Contact lenses are safe when you follow replacement schedules, maximum wearing time and other recommendations from Westside Optometry.
Dirty Contact LensA new report from the US Center for Disease Control and Prevention (CDC) reveals that millions of Americans who wear contact lenses do things that can significantly increase their risk of eye infections. The findings come from an online survey of contact lens wearers designed to assess the prevalence of contact lens wear and hygeine-related risk behaviors.
According to the study 99% of contact lens wearers reported at least one habit or behavior that increases their risk of eye infection. I know that none of my patients would act in a way to compromise their eye health, but just in case some of you have lapsed, here are some reminders:

Contact lens “wear” risks

  • Sleeping in contact lenses
  • using contact lenses for longer than the recommended replacement schedule

Contact lens “care” risks

  • “Topping off” disinfecting solution in the lens case and using it again
  • Using the same storage case for more than 3 months
  • Not using the prescribed disinfection solutions

Not surprisingly nearly one third of the respondents reported having experienced a red and painful eye that required a visit to the doctor.

Contact lens wear is safe when you follow recommendations and use common-sense.

Good Vision and Learning

Karen Griffith

Vision is a dominant process in the growth, development and daily performance of children. Many children with undetected vision problems struggle in the classroom. Some symptoms of learning related vision problems are:

  • Trouble finishing written assignments
  • Losing ones place when reading
  • Having a short attention span when doing close work
  • Skipping words when reading
  • Making errors when copying from a classroom board
  • Having greater potential than grades may indicate (under-performing)

Vision problems can affect comprehension performance in reading and manifest as social, eye-hand coordination, discipline, or emotional problems. From there, such vision problems can impact the rest of your child’s life and ability to succeed.

 

[heading centered=”yes” margin_bottom=”no”]What is Good Vision?[/heading]

Back to school Visual Acuity: It’s important to realize that good vision is more than 20/20 eyesight, Invented in the 1860’s, the term 20/20 indicates if you can see letters 3/8″ high at 20 feet. This does not take into account the eyes’ ability to see books or view the computer screen.

Eye Health: Eye disease can impair vision or lead to vision loss if not diagnosed and treated.

Visual Integration: The ability to process and integrate visual information, which includes and coordinates input from our other senses and previous experiences so that we can understand what we see.

Eye Teaming: The ability of the eyes to work properly together.

Eye Focusing: The ability of the eyes to focus and shift focus to near and distant points easily and effortlessly.

Eye Motility or Tracking: The ability of the eyes to move together across a page of print, to directly view an object, to move from one viewing area to another, or follow a ball.

The good news if that with early diagnosis and appropriate, comprehensive intervention, the prognosis is good in a majority of cases. Schedule your child’s eye examination to make the most of the new school year.

Back to School with Technology

Karen Griffith

Today’s gadgets and devices are placing demands on young eyes. The benefits of technology have a downside, especially when it comes to the eyes. Stress on the accommodative system (focusing) causes eye fatigue.

This can cause headaches, blurred vision and other related chronic discomforts.
Nearly 1 in 4 children are on digital devices 3 or more hours per day.
School text books are rapidly moving to tablets
40% of young adults spend at least 9 hours per day on digital devices.

Computer lab

[heading centered=”yes” margin_bottom=”no”]10 things you should know about digital eyestrain:[/heading]

  • BLURRED VISION Think about how you look at your phone, then your computer screen, back to your phone then at the TV. Like any muscle that is holding in one position for a length of time it contracts and then has a hard time relaxing. Same goes for your eye muscles. You have been looking at near objects, the muscles have contracted, then you quickly look up and the muscles have locked up and can’t relax and your vision becomes blurred.
  • TIRED EYES. Any muscle that is fatigued is going to be sore and tired.
  • HEADACHES. When your eyes are tired you will get headaches. This type of headache tends to occur around the eyes.
  • BODY FATIGUE. At the end of the day patients are finding they are just too tired and need to close their eyes. When the eyes are closed there is nothing for them to foccus on and the muscles can relax.
  • DRY EYES. Your blink rate goes down when the eye is focusing. Every time you blink the eye needs to readjust and that is work for your eye so the blink rate drops when you focus at near work. It can drop to 10 times a minute for computer work and 4 to 6 times a minute when looking at a smart phone or tablet. Not blinking allows the eyes to dry.
  • LIGHT SENSITIVITY. Eye muscles are extremely tired when working all day. When light comes into your eye it constricts the pupil which is right next to the ciliary body. the muscles that focus the eye. So when light comes into the eye it is a similar feeling to focusing. It is similar to lifting weights all day then someone comes along and punches you in the arm. That muscle is sore and tender.
  • EYE RUBBING. What tired muscle doesn’t feel good when you rub it?
  • POOR NIGHT VISION. Our eyes do not know how to focus on light. If you are staring at a light in the distance you wouldn’t be able to tell how far away it really is.
  • REDUCED CONCENTRATION. Any time a muscle is over used, such as the eye focusing on light all day, it becomes more difficult for the eye muscles to continue to hold that position.
  • DOUBLE VISION. Diplopia or double vision is caused when the eyes do not work together. Staring at near objects such as a computer, phone or tablet require persistant converging and diverging all day. The muscles become so tired they lose the ability to hold a position and we see double.

It is difficult to avoid the use of computers and tablets, but you can take steps to reduce digital eyestrain. Wearing the correct prescription and taking advantage of blue light blocking coatings are 2 ways to make your eyes more comfortable. Make an appointment.

 

Fall Trunk Show

Karen Griffith

 

Aspire2

Next month is the annual Westside Optometry Fall Event. This year we are featuring all the Clearvision eyewear collections: Ocean Pacific (OP), Cole Haan, Izod, Ellen Tracy, BCBG and 2 new lines Aspire and Dilli Dalli. Aspire is a lightweight frame design and Dilli Dalli is an incredibly durable design for small children. Dilli Dalli
In front of the office, Maui Jim is pitching a tent to display it’s collection of men and women’s sunglasses.

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Date of the show is Saturday September 12, 2015 between 10:00 and 2:00.

Refreshments will be served.

Call ahead if you need an eye examination, or come by to look at glasses.

Bring a friend.

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Contact Lens Prescriptions

Karen Griffith

Contact lens prescriptions generally expire on a yearly basis, unless otherwise specified. Seeing your eye doctor regularly for a comprehensive eye exam will not only keep your prescription updated, and evaluate your ocular health, but an eye exam will also help identify and lead to diagnosis of other health concerns such as hypertension and diabetes. At your eye exam Dr. Griffith may recommend a newer/better contact lens option for you, too.
A contact lens is a medical device and can be worn to correct vision as well as for cosmetic or therapeutic reasons. In the United States, all contact lenses, even purely cosmetic ones, require a prescription. They must be properly fitted and prescribed by an eye doctor. soft CL

An eye examination is needed to determine an individual’s suitability for contact lenses. This typically includes a refraction to determine the proper power of the lens and an assessment of the health of the eye. Dr. Griffith will also ask questions about your lifestyle, general health and contact lens wearing goal. If you haven’t worn contact lenses before, training for application and removal of the contact lens is necessary. If the lenses are to be re-used, a care and disinfecting system is required too. A follow-up appointment will determine the proper fit and lens compatibility for your eyes. Contact lenses are not a “one size fits all” device. There are many parameters to each lens. Besides the power to correct the vision, material and edge design will effect the comfort. The size: diameter and curvature are factors in the fit and ultimately the response of the cornea and eyelids to the contact lens.

Prescriptions for contact lenses and glasses may be similar, but are not interchangeable.

Westside Goes to Seattle

Karen Griffith

It’s been nearly a month since Maureen, Nannette and I came home from the American Optometric Association (AOA) meeting in Seattle.  seattle starbucksWe had amazing weather, it was in the mid-80’s! Besides enjoying the weather, the abundance of coffee and a beautiful city, we attended some excellent classes.
Nannette participated an ocular anatomy workshop where she dissected a cow’s eye to better understand the structures and function of the eye. She and Maureen also went to a lensometry workshop to learn the intricacies of measuring lens prescriptions and parameters such as power, astigmatism and axis postition.
The new buzz in eyecare is the effect of blue light that is emitted from digital devices. It is thought that exposure to the blue light can cause sleep disruption and even macular damage. It’s nearly impossible to avoid our phones, tablets, computers and even TVs so blue light filters and gaming glasses are available.
Maureen went to a contact lens course which emphasized the importance of proper care, cleaning and replacement to maintain successful wear of contact lenses.
OCT AOAAll 3 of us spent time looking at new equipment and asking the vendors questions about instruments we use in our office. We found and purchased some items to use for our dry eye treatments. I also bought a device to aid in determing spectacle prescriptions for my pediatric patients.
The courses that I learned the most at were one on glaucoma and another on cataracts. In particular the cataract course described new technology and how it compared to current surgical procedures. The educator also talked about the “premium” intra-ocular lenses (IOLs) that include multi-focal and toric designs to correct most refractive errors.

We returned to Petaluma inspired and ready to implement our new knowledge.

 

 

Heading to Seattle

Karen Griffith

Optometry's meeting 2015

Optometry’s annual meeting is in Seattle this week. Taking advantage of the proximity and a visit north, Nannette, Maureen and I will be attending. We have a list of items to purchase; equipment for the lab and a dry eye treatment. There are also some new technologies we will be checking out as well as courses and workshops. We might enjoy a cup or two of coffee as well.

Presbyopic Myths or the Truth about Aging Eyes

Karen Griffith

in need for glasses

Eye Exercises can Prevent Presbyopia
No eye exercise can prevent presbyopia. Eating bushels of carrots won’t prevent presbyopia. There is no elixer to prevent presbyopia. Presbyopia is not a disease, but an age-related condition that cannot be prevented.

 

More women than men develop presbyopia

Women are no more prone to presbyopia than men. However, you might notice that women wear reading glasses earlier than men. This is not due to differences in eye anatomy. It’s due to men having longer arms. On average, women’s arms are shorter than men’s. When it becomes increasingly difficult to read at arm’s length, women reach for reading glasses sooner.

 

Farsighted is the same as presbyopia

While both conditions relate to difficulty seeing up close, farsightedness and presbyopia are two different visual conditions with different causes and timelines.

Farsightedness (hyperopia) affects a portion of the population, but presbyopia eventually affects everyone. As you age, the lens in the eye starts to lose its elasticity and you gradually lose the ability to focus on objects up close. Farsightedness can occur at any age, where presbyopia usually occurs after age 40.

 

LASIK surgery cures presbyopia

Laser eye surgery, commonly referred to as LASIK, works very well for certain refractive errors such as astigmatism and myopia, but it will not correct presbyopia. Despite having undergone laser eye surgery, patients in their 40s will inevitable require vision correction for presbyopia.

 

If you have 20/20 vision, you can’t get presbyopia

Presbyopia is quite a surprise for someone who has always had good vision. While the age of onset varies, most people in their 40s first start to have a problem reading fine print, particularly in low light conditions. Other symptoms include needing to hold reading materials at arm’s length and headaches or fatigue from doing close-up work.

Luckily, there are visual corrections available to allow you to see up close, reading glasses, progressives and even contact lenses.

 

 

How the Eye Sees Color

Karen Griffith

Color VisionThe 6 to 7 million cones in the human retina are responsible for color vision. The cones are photoreceptors concentrated in the central zone of the retina called the macula. The center of the macula is called the fovea, and this tiny (0.3mm diameter) area contains the highest concentration of cones in the retina and is responsible for our most acute color vision.

Inherited forms of color blindness often are related to deficiencies in certain types of cones or outright absence of these cones. Color blindness is not a form of blindness at all, but a deficiency in the way we see color. With this vision problem, individuals have difficulty distinguishing certain colors, such as blue and yellow or red and green.

Color vision deficiency is an inherited condition that affects males more frequently than females. An estimated 8 percent of males and less than 1 percent of females have color vision problems.

Red-green color deficiency is the most common form of color deficiency. Red-green color blindness is caused by a common X-linked recessive gene. Your mother must be a carrier of the gene or be color deficient herself. Fathers with this inherited form of red-green color blindness pass the X-linked gene to their daughters but not their sons, because a son cannot receive X-linked genetic material from his father.

Any time a mother passes along this X-linked trait to her son, he will inherit the color vision deficiency and have trouble distinguishing reds and greens.

There is no cure for color blindness. But some coping strategies may help an individual function better in a color-oriented world. Most people are able to adapt to color vision deficiencies without too much trouble. But some professions should be avoided, such as graphic designer, ship pilots, interior decorator and other occupations that  require precise differentiation of colors and depend on accurate color perception.

If the color deficiency is identified early enough in life, the individual may be able to compensate by training for one of the many careers that are not as dependent on the ability to see in a full range of colors.

It is possible to develop color vision problems later in life. Sudden or gradual loss of color vision can indicate any number of underlying health problems, such as cataracts. Color blindness can occur when changes due to aging  damage retinal cells. An injury or damage to areas of the brain where vision processing takes place also can cause color vision changes. If you feel your perception of color is changing, schedule an eye exam.

At Westside Optometry we use a desaturated color vision test that takes a couple of minutes.