Category: Astigmatism

New Progressive Lenses

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Progressive lenses offer a range of vision as close to natural as can be obtained from prescription eyeglasses. Their hallmark is clearer vision at any distance or angle, and because there is no abrupt change of power anywhere in the lens, there are no visible dividing lines. They provide a great solution for many people who find their present lenses limit their vision for a particular distance or activity.

Continuing advances in manufacturing techniques mean more precise lenses that deliver even sharper, clearer vision; most patients consider them an improvement over their older ones. Ongoing design research has produced ways to further increase depth perception and the amount of clear vision at any angle of the newer progressives. In addition, the latest technology eliminates swimming and swaying sensations associated with typical progressive lenses.

Furthermore, if you’re like most progressive lens wearers then the exact prescription for each of your eyes is different. And the position of your nose and cheekbones affects the way you see through your lenses. So even with a correct prescription, older progressives were still limited in perfecting your vision. Increased measurements for fitting the newest progressive lenses produce a more customized, personalized set of glasses with the widest, clearest viewing zones possible, no matter how intricate the prescription. Ask us about the latest innovations in progressive lens designs and improve your vision experience. There are a variety of designs to choose from today.

Visual Stress and Technology

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A study published by the New York Times in 2009 revealed adults are exposed to screens – TV, cell phones, computers, etc. – roughly eight and a half hours on any given day.

Even the smallest uncorrected prescription can cause problems at the computer. This is especially true if you happen to be far-sighted or have astigmatism, due to the excessive focusing required to maintain a clear image.
Dry eyes and poor tear quality can cause blur and eye discomfort. We tend to blink less often when viewing the computer allowing the tears to evaporate.

Some solutions to eyestrain at the computer or with other digital devices  include a correction specific for the task. For example, a pair of computer glasses designed with optimal correction at the distance to the digital display and including appropriate coatings and tints to reduce strain and improve efficiency.

Reducing glare from overhead lights and windows will minimize squinting. Simply adjusting the screen position, closing window blinds and decreasing the wattage of a desk lamp will reduce glare. To see an earlier post with more details click here.

Wearing Contact Lenses Overnight

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Have you ever wondered what would happen if you wore your contact lenses overnight? Unexpectedly stayed the night at a friends house and didn’t have anywhere to put your lenses? Enjoying a  late night and fall asleep with your contacts on?

It happens, contact lenses get worn too long and sometimes over night. Some contact lenses are better for this than others. I prescribe and fit people with the intention of overnight use. I also warn patients about the risks they are taking with their eyes.

Depending on the contact lens type and material, oxygen is reduced to the cornea. Movement of the contact with each blink aids the transmission of oxygen. When you are sleeping with the contact lens, the eye is closed and no oxygen gets to the cornea. There is no blinking either so the lens doesn’t move. The reduction in oxygen causes the cornea to swell, if the lens allows plenty of oxygen to get to the cornea during the day, the cornea will deswell and return to normal. However, if the cornea remains swollen, and you sleep in the lens consecutive nights, blood vessels will begin to grow into the cornea. Sometimes the eye responds by becoming inflamed, red and painful.

Another risk of leaving the lenses in overnight is infection. Typically when a lens is removed it is thrown away or placed in disinfecting solution. In the morning a new lens or a clean, disinfected lens is applied to the cornea. Microbials build up on a lens that is worn continually. If your cornea is compromised by a scratch or edema, the bacteria will infect the eye.

If you have been prescribed extended wear contact lenses, stay compliant to your wear schedule, once in awhile overnight or 6 consecutive nights. Clean and replace your lenses as prescribed. If you are wearing your daily wear contacts overnight, let’s talk about a safer option. This may include a higher oxygen material or even LASIK. Sometimes the prescription can be a limiting factor. If the prescription is higher,  farsighted or is toric and corrects astigmatism, the lenses will be thicker and reduce oxygen transmissability.

Is LASIK Right for Me?

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I discuss LASIK with several patients each week and realize I have never written about it. LASIK is a refractive procedure that quickly, painlessly and permanently changes the corneal topography (shape of the front of the eye) to correct a person’s vision. Many people are candidates for the procedure, but some are “better” candidates than others. My strongest recommendation goes to people with astigmatism. This refractive condition is usually caused by the shape of the cornea and often makes contact lens use challenging or impossible. My second favorite candidate for LASIK are people with myopia or  nearsightedness. I do want to qualify this because some myopes are not great candidates. Someone who reads and works at the computer comfortably without glasses or contact lenses will require more education about future vision changes and glasses. The other end of the myopic spectrum are people who are really really nearsighted and too much corneal tissue would have to be removed to be safe. Otherwise most nearsighted people are very good candidates and enjoy the results.

Other important criteria include stable vision. LASIK will not prevent  the prescription from changing. I like to see no changes in the distance vision for at least 12 months, preferably 2 years. If the vision is going to change, it will, with or without the refractive procedure. If you have the procedure, you can expect good vision without glasses for a very longtime.

The actual laser procedure takes 2 minutes or less per eye. Many precise measurements are taken before the procedure. Proper alignment with the laser is made in all axes. A super thin flap of cornea is created with the Intralase Method which uses tiny, ultra-precise pulses of light. It is laid back while the surgeon lasers the tissue underneath it to correct the refractive error. The flap is carefully replaced and smoothed into place. And that is the extent of the actual LASIK. The rest is healing and post-operative care. Some lifestyle modifications are required initially, but most people are surprised how much they can do and see right after surgery.

If you have any questions or comments about refractive surgery, please leave a comment or call the office (707)762-8643.

Reliability of Vision Screenings

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     The department of motor vehicles, the school nurse and the pediatrician use vision screening to identify vision problems. Screening usually involves standing a given distance from a lettered chart, covering one eye and reading down the chart to the smallest letter possible.
     According to a recent study in Australia, researchers found that results for detecting myopia in 12 -13 year olds was nearly 98%. Good news for the nearsighted, but not so good for the tweens with astigmatism or hyperopia. Only half of the hyperopic children were identified by the vision screening and 25% of the kids with astigmatism were missed.
Screenings are best designed to detect problems with distance vision, and that is important for children socially and physically, but myopia represents the least risk for reading and learning. A myopic child is more likely to notice that the board is blurry and move to the front of the classroom. Hyperopia on the other hand, makes it more difficult to see things close up and astigmatism effects vision at all distances. Children with uncorrected hyperopia and astigmatism will have more difficulty reading and writing and may not even be aware that the difficulty is due to his or her vision. These are the children that may complain of headaches, avoid reading and school related tasks.
     A vision screening test identifies some vision problems, but can miss disorders that have a profound effect on a child’s ability to succeed in school.

Computer Vision

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Computer Vision

Computer technology has evolved faster than the human eyeball. Our eyes accommodate our reading needs by focusing downward and approximately 16 inches away. Most computer monitors sit about 18 to 24 inches away from our eyes and only a few degrees below eye level. This is not much of a problem if your visual system is working accurately, but if you have a little refractive error such as astigmatism, farsightedness, or a difference between the two eyes, the result may be headaches, eyestrain and frustration.

If you are 40 years of age or older, the stress of viewing a computer screen is probably compounded by presbyopia: your eyes no longer accommodate, or focus, to read. (You may have noticed that your arms seem shorter.) Bifocals are often prescribed between the ages of 40 and 50, to allow you to see a distant object and also focus downward and close-up.

For someone who spends more than a couple of hours a day in front of a computer screen, a pair of glasses designed specifically for that task is the best solution. Do you wear cleats for golf? Flip-flops at the beach? Old tennis shoes to wash the dog? Do you have special shoes for special events? One pair of shoes can not fill every need; a single pair of glasses does not either.

A lens designed especially for the computer is recommended. It may be a single vision lens or a specifically designed multifocal.

A few more tips for comfortable computer use:
• Modify the room lighting to reduce glare and reflections.
• Anti-glare coatings can also eliminate reflections from windows, overhead lights and other computer monitors
• Place reference materials close to the screen so you do not have to turn your head back and forth to read.
• Use high-index materials to keep lenses thinner and lighter in weight.
• Take breaks to rest your eyes.