Eye Exams

So do you ever feel like you really have to concentrate during an eye exam? 

Michael Nelson, OD

Infiltrates

One of the most common complications with contacts is the lack of oxygen(hypoxia).  The cornea is a unique tissue because it is the only tissue in the body that absorbs it’s oxygen supply directly from the air and not from blood vessels.  If you reduce the oxygen supply to the cornea by wearing contacts too long the cornea will have trouble repairing itself.  This will result in some swelling of the cornea and some difficulty with the cornea repairing itself: these changes show up as microscopic  white patches known as infiltrates.  When this occurs patients will often experience redness, sensitivity to light and intolerance to contact lenses.

Hypoxia can occur slowly over time before someone develops problems.  Usually it develops from wearing contacts most of the time for years and years, then suddenly someone develops problems.  The best way to avoid the development of hypoxia and infiltrates is to not over-wear contacts and to change to some form of silicone-hydrogel lens material.

The treatment for hypoxia and infiltrates is to discontinue contact lens wear until all signs of infiltrates resolve, which can usually mean months without contact lens wear.  When the infiltrates resolve sometimes the individual can wear contacts again, but they need to be a high oxygen lens and the person must reduce their wearing time.

Websites for more information on Infiltrates:

Infiltrate Article

Review of Optometry Article

Michael Nelson, OD

Silicone Hydrogel Materials

Up until 2000 there were relatively few major advances in contact lenses.  Mostly changes were a result of lenses that would not dry out as much or changes to the shape of the lens to make them more comfortable.

In 2000 contact lens companies started introducing silicone-hydrogel lenses which were able to provide much more oxygen permeability to contacts.  We have know for the last 30-40 years that silicone is extremely permeable to oxygen, the problem is that lenses made out of silicone dry out very quickly and were very uncomfortable.  Silicone-hydrogel lenses were able to combine the oxygen permeability of silicone with the comfort of traditionally hydrogel lenses.

Before the silicone-hydrogel lenses the 2 brands with the most permeability were Acuvue2 (25units of permeability) and Proclear(34 units of permeability).  Currently there are 5 brands of silicone-hydrogel lenses on the market(In brackets are their oxygen permeability):

  • O2 Optix (138)
  • Focus Night & Day (175)
  • Acuvue Advance (85)
  • Acuvue Oasys (147)
  • Purevision (101)

As can be seen, Silicone-hydrogel lenses can provide ~5X as much oxygen as even the best hydrogel lens.  That’s a big improvement, which can significantly reduce the risk of corneal infiltrates.  It just doesn’t make sense to not wear a silicone-hydrogel lens.

Michael Nelson, OD

Price Comparisons

I was talking with some business owners the other day and they were asking me about how I compete with all the sales that the big box and chain optical stores provide. I said that the key to competing is to educate our patients about what the ‘sales’ are. The interesting thing is that when a chain optical store offers $75 off coupons, this brings their price into the normal price range of our clinic. So basically if someone is shopping at an optical store without a coupon they are paying $75-$150 more than they should.

The other aspect that we educate our patients on is that quality of frames and lenses can vary dramatically. We can offer very inexpensive frames and lenses if a patient would like, however we don’t recommend it because we can’t afford our patients to be unhappy when their coatings or frames start to fall apart within a year.

Michael Nelson, OD

Optomap

Part of an Optometrist’s responsibility is detecting eye disease or risk factors for eye disease. We use a number of tools in order to do this: microscopes, penlights, visual acuity, etc. One area that we need to look at is the retina. You can view the retina by shining a light and looking through the pupil, basically it is like looking inside a round vase. With training it is relatively easy to view the areas directly at the back of the eye, approximately a 30 degree field of view. To view more of the peripheral areas of the retina requires drops which dilate (enlarge) the pupils so you can see more area inside the retina. These drops blur the vision and are inconvenient for most patients, but until a few years ago it was the only way to view a larger area of the retina.

The Optomap is a digital imaging system that allows us to view a larger, up to a 200 degree field of view, area of the retina without using eye drops. Not only does this provide a more comprehensive view of the retina with less inconvenience for the patient, but it also gives us a permanent record that can be compared to from one visit to another. Conditions that the Optomap can screen for include retinal tears & detachments, diabetic retinopathy, macular degeneration and glaucoma.

We recommend Optomap imaging for each patient at each exam because it helps provide the most through eye exam that we can provide. While this exam is usually covered by private health care plans, it is not covered by Manitoba Health. For this reason and for the reason that each individual has different priorities we also provide this as a strongly recommended, but optional test.

Fortunately most of my patient’s eyes are healthy and we do not detect any vision threatening pathology. I am surprised that we do regularly find asymptomatic problems and risk factors that we would not find without the Optomap exam. Basically, you don’t know what is there unless you can see it.

Michael D. Nelson, OD

Common Eye Conditions

0-6 years:

Common Eye Conditions that may be noted in 6 year olds and under include the following: Myopia(nearsightedness), Hyperopia (farsightedness), Astigmatism, Amblyopia(Lazy Eye), Strabismus (turned eye) and Eye Infections.

In my opinion the most important of these is Amblyopia, which affects 5% of children and responds well to treatment under the age of 6. Unfortunately it only affects one eye so most children will often have no symptoms or complaints. Worse yet, any reduced vision that is still present after the age of 7 is usually permanent. Amblyopia is an important reason to ensure annual eye exams starting at 3 years old.

6-20 years:

Common Eye Conditions that may be noted in 6 year olds to early 20’s include the following: Myopia(nearsightedness), Hyperopia (farsightedness), Astigmatism, Amblyopia(Lazy Eye), Eye Infections, Eye Trauma and Contact Lens related problems.

The most common vision problem in this age group is refractive in nature, meaning a need for glasses. I recommend annual eye exams for this age group because I think it is important to detect any vision problems early so that blurred vision does not cause a problem in school. In Manitoba at least a portion, if not all, of the eye exam fee is paid for by Manitoba Health for those 18 and under.

 

Michael Nelson, OD

Eye Blog

Thanks for dropping by.  Now I can only assume that if you have taken the time to stumble across our blog you are almost as passionate about vision as we are.  I hope we can help inform and perhaps entertain a little.

magnifying glasses

Low Vision

Low Vision is basically when someones vision is reduced and cannot be improved with glasses or contacts.  Usually it is a result of some form of eye disease or condition.  The most common form cause of Low Vision is Macular Degeneration. 

Low Vision treatments basically involve using magnifiers or other optical devices to try to use the vision that the person still has.  Low Vision treatment does not improve vision or stop it from getting worse, this is managed by a patient’s Ophthalmologist.

Although Optometrists have by far the most amount of training and expertise in Low Vision, very few have taken the effort to add this to their services.  It was out of this lack of care available that I started Eye Canada, a sub-specialty business focusing solely on Low Vision.

magnifying glasses

Michael Nelson, OD