Tuesday, March 29, 2011

Nobody wears hard contact lenses anymore!!!!!!!!

Nobody wears hard contact lenses anymore....right?   Whoa there horsey!  While many patients and the general public think that hard lenses are a thing of the past, this is definitely not the case.  Hard lenses in their new form, rigid gas permeable contact lenses, are still a viable alternative for many types of vision corrections.  They are terrific for those that want the sharpest vision possible, those that have astigmatism, those that have irregular corneas, post Lasik and refractive surgery patients, and those that want to actually improve their vision through corneal molding or Orthokeratology. 

It is true that it takes a little more time to adjust to rigid gas permeable contacts lenses.  When they are fitted correctly, the adjustment is very short and the lenses become very comfortable after adaptation.  There are many other advantages to rigid gas permeable contact lenses.  They last a long time.  The average life span of a rigid gas permeable lens is about two years.  In addition, if the lenses develop some scratches on the surface, these scratches can be polished out.  The lenses are less subject to prescription changes than are soft lenses.  Unlike soft lenses that correct astigmatism, the blinking of the eyes does not generally affect the clarity of the vision with "gas perms".  Gas perms are also terrific for multifocal applications.  It is also possible to adjust the fitting characteristics of "gas perms".  This is becoming a "lost art".  Doctors that are comfortable with adjusting "gas perms" can make the edges thinner, add power, loosen the lenses, make the lenses smaller, etc.  No way is this possible with soft lenses. 
It is very common in our office to modify rigid gas permeable lenses to fine turn both the vision and the fitting characteristics of the lenses.  This allows us to adjust the lenses to the finest fitting possible.

So, are rigid gas permeable contacts (gas perms) the best lenses for all patients?  I would definitely say "Maybe!".  Each case is different, but "gas perms" are  an excellent alternative for those patients that could best benefit from their unique characteristics. 

Be sure to ask your eye doctor if "gas perms" would be a good choice for you.  If you have any questions, please feel free to email me at jon@villageeyes.com

Wednesday, March 16, 2011

How To Tell If You Have Good Quality Sunglasses

It is well established that sunglasses are an important part of proper eyecare. Good quality sunglasses block out the sun's harmfull rays and provide comfort for the wearer. They can prevent eyestrain, eye irritation and can even slow down the development of cataracts and other eye aging changes. Prescription sunglasses should not only have the best possible prescription in them, but they should be treated to block the sun's harmful rays and have a degree of tint in them that is best suited to the individual patient.

In general, if you purchase non-prescription sunglasses from a quality provider you will most likely get a good product.  If you buy them from the booth on the sidewalk at the beach, all bets are off.  Good quality non-prescription sunglasses are made the same way as prescription eyeglasses.  The lenses are optically ground.  The difference is that they are ground to have zero prescription. The front and back surfaces exactly match one another.  This creates a lens that allows light to pass directly through it without bending.  Significant research goes into the determination of the tint in the lenses.  The lenses can be polarized as well which does a great job of eliminating reflected glare from horizontal surfaces.  This is helpful when on the water or skiing of after rainy days.  Lenses that have a yellow color or amber color are noted to enhance contrast.   This can be helpful of outdoor activities like shooting and skiing.

So how do you tell if the lenses are ground properly?  Turn the sunglasses over and look for a reflection from the back surface of the lens.  You can look at a reflection from a horizontal light tube or the edge of a light source.  Move the lens so you can follow the reflection.  If the reflection does not "wobble" or seem to become irregular as you move the lens, this indicates that the surface has been optically ground.  There is another way to demonstrate the optical properties of the lens.  Light can be projected through the lens at a doctor's office.  The images projected through the lens should be clear and well defined.  If not, this can indicate optical distortion.

Lenses can be treated to block UV but still may not be optically ground.  Ideally the lenses should both be treated to block UV and be optically ground.