Caitlin wrote:
I wear contacts 95% of the time and I recently had my yearly check up. I found my vision less clear lately with my contacts, but my prescription hadn’t changed (-1.50 in both eyes). However, now when wearing my contacts, the left one is clearly not as sharp as the right. I’ve tried putting a new contact in, switching the contact, but nothing seems to help. It’s so annoying that I eventually give up after an hour and have to put my glasses on. What could be causing this? The obvious answer is that my left eye needs a stronger prescription, but my check up was only a month ago, and there was no change.

ANSWER

Caitlin,
Is your vision perfect with your glasses?  I would recommend returning to your optometrist to have them check this problem. Of course I haven’t examined your eyes, so it’s extremely hard to give you an answer, but I’ll give you some possibilities.  It’s possible if your glasses are perfect that you may have a small amount of astigmatism that your contact lenses are not correcting for and your glasses are.  A lot of times if there is a small amount of astigmatism it can be compensated for with regular contacts.  However if the astigmatism gets to a certain point, it will affect the vision and then a contact lens to correct astigmatism, called a toric contact lens may be required.  Astigmatism happens when the very front of your eye, the cornea is not perfectly spherical like a ball, but shaped more like a football. There are two different curvatures that need to be corrected, instead of only one.  Otherwise there could be an issue with your cornea or eyelid causing the problem.  Sometimes inflammation can develop in the cornea or eyelid, which will affect the quality of vision.  The main thing is to go back to your optometrist to make sure there is not an eye health issue which is causing your symptoms.

Dr. Doman

Melanie wrote:
I recently began swimming and want to wear corrective swimming goggles. My prescription is R (-2.75) L (-1.75/-1.50/77). In my city, I have not been able to find a retailer that sells swimming goggles corrected for astigmatism, nor are there any that sell individualized lenses.
My right eye is my dominant eye and a salesperson suggested to me that I just wear goggles that correct for my right eye and forget about the astigmatism in my left. I am thinking of purchasing a pair that is -2.50 (both eyes) because they only sell them in .50 increments. My questions are: 1) Will lack of correction for astigmatism have any adverse effects on my vision in my left eye? 2) Will the stronger correction for myopia in my left eye have any adverse effects?
I tried the goggles on, and I did notice the floor looking clear but slightly distorted and I thought that since the water will be moving anyway, it might not be a problem - I just want to be able to see the clock and not crash into the bulkhead without causing vision problems later.
Thank you.

ANSWER

Melanie,
To the best of my knowledge swimming goggles are not available with astigmatism correction.  The correction you are considering buying would work fine.  To answer your questions, neither the lack of astigmatism correction or stronger correction for myopia will have any adverse effects on your vision.  If you were wearing them for hours you may develop eyestrain or headaches, but there will be no long-term problems.  Of course you will not get perfect vision out of your left eye, but as you said it will give you sufficient vision while swimming.  The vision through the goggles may seem a little funny at first because you are accustomed to having your astigmatism corrected, but this should improve with time.  Happy swimming!

Dr. Doman

Kate wrote:
Hello,
I went to an optometrist yesterday. He was not very talkative; I was asking a lot of questions as he was doing exams and just writing stuff down. He would answer me with one word answers. Then, without explaining why, he put drops in my eyes, I didn’t even have time to ask “why”. Only after he had already put them in he said it was to measure pressure. Also, I know from previous exams that I have astigmatism. To him, however, this was irrelevant as it is not in my prescription! He said my problem was focusing of the eyes, on my prescription there is a number 6 in column “prisme” and it looks like it’s a fraction, but I cannot read it. Should I get another exam? If I bring my prescription from 2 years ago and this one (as my eye sight did not change at all), will I be able to get lenses?

ANSWER

Kate,
I would recommend calling your optometrist’s office.  Optometric assistants are very knowledgeable and would be able to answer your questions about your prescription.  Astigmatism can change throughout your life and it is possible it may have improved.  You will be able to get new glasses with your new prescription.

Dr. Doman

Joyce wrote:
I have always been slightly near sighted, but not enough to wear glasses all the time. As I have aged I have started to use prescription reading glasses, and one optometrist said I had Astigmatism.
My problem is that after watching TV, reading (with glasses) or working on the computer, my vision seems blurry and I can’t seem to refocus my eyes. If I do none of the above, I am fine. Any recommendations?

ANSWER

Dear Joyce:
If you are not wearing your glasses full time, it is not uncommon to experience blur when your glasses are removed. If you are wearing accurately prescribed and well fitted glasses full time (and based on your description of your eye condition these glasses would have to be multi-focal) it is not normal to experience the blur that you describe.
It is also possible that your symptoms are caused by ocular surface dryness, or “dry eye syndrome”. Symptoms of dry eyes are often more pronounced after periods of watching TV,  reading or using a computer. If this is the case, then you may find that using artificial tear supplements will be beneficial. You may need to see your optometrist to determine what might be the underlying cause of your current symptoms.

Dr. Smit

Regan wrote:
My prescription is -4.5 and -5 with a small degree of astigmatism). As I enter my mid-40s I also find my close vision is slowly getting worse, especially in poor light but it’s only starting to be inconvenient, mostly when I wear my contact lenses. I found the disorientation of bifocals too much for the moment, and they aren’t quite necessary since I can peek over the top of my glasses for the most part.

I tried on pinhole glasses at the store and they corrected my vision quite effectively (while standing there and testing my ability to read fine print at the counter and see the back of the store too - I don’t know how well it would work at my computer or daily life). I’d like to know more about their uses. Having used cameras, I understand how they work in terms of changing the aperture of the eye, but I’d like to know if there are developmental risks or benefits involved, and how they can best be used. I’m not looking for a miracle to replace my glasses and contacts, but I do feel that my lifelong dependence on glasses has worsened my vision, and I can also foresee situation where using pinhole glasses would be less of a strain (like cooking while also reading from a recipe). If they would also slow down or prevent further deterioration that would be an added bonus. Thanks.

ANSWER

Regan,

It is very normal for you, in your mid 40s, to be having problems with close (near) vision, and this is always more evident with contact lenses.  Speak to your Optometrist about a change to your contacts so that you can read.    We often use bifocal contact lenses or a technique called Monovision where one eye sees close up and the other far away.

I would not recommend pinhole glasses for any sustained activity.  The strain of trying to find the little holes would negate any benefits, as well as having to change to your regular glasses in order to walk or move around your office or kitchen.  I am not aware of any scientific studies which purport the use of pinhole glasses. Most often they are used as a novelty, party trick, item.  We have not found a way to stop the changes in near vision, since they are linked to aging.

Dr. Joan Hansen - Optometrist, for CAO

Dominique wrote:
How important is the precision of  the “axe” values in the prescription? These values change each time I go to a different optometrist and the latter do not all provide the same precision for their measurements. Specifically, 7 years ago I got the values R/L 175/170, 1 year ago, 165/178 and this year 170/180. I would like to purchase bi-aspherical lenses, but those are expensive, so I would like to be sure that my prescription is good enough.

ANSWER

Dominique,

The axis value (or axe in French) is an important part of a glasses prescription.  However, this value can vary from visit to visit.  The axis represents the orientation of the power of your astigmatism.  The power of your astigmatism is the second number on your glasses prescription.  If you have a small amount of astigmatism (I would say less than -1.50), it is possible for the axis to vary from visit to visit sometimes by approximately 10-20 degrees.  On the other hand if you have a large amount of astigmatism, this number would likely only vary within 5 degrees.  From looking at your numbers, especially from last year to this year the change in axis is very small.  When you purchase new lenses if you have any problems all optometrists and opticians will work with you to solve the problem.  I would go ahead and get the new prescription filled.

Dr. Carol Doman

Sarah wrote:
I have what I have been told is extreme astigmatism. I am now 32, and have been wearing glasses since I was 8; they get stronger pretty much every visit. My current prescription is (R) -2.00/-6.00/110 and (L) -2.25/-4.75/063. The glasses are working alright for distance, but I am having some difficulty reading, both on paper and the screen. It is almost as if parts of the letters are fading in and out. I had some problem with my old glasses, but not as much. If it doesn’t get better I plan on going back to be rechecked, but new glasses always take me a while to get used to, so I’m going to wait a couple more weeks. My previous prescription was (R) -2.50/-4.75/115 and (L) -2.00/-4.50/059. If the astigmatism correction is so strong, could the difference in axis be causing my problem? Thanks

ANSWER

Dear Sarah:
Yes, you do have a lot of astigmatism, and adapting to a change in prescription, even if it is minor, can be a little difficult. However, in my experience, a new correction is not likely to cause parts of letters to fade in and out as you have described. That symptom is more likely to be caused by changes occurring inside your eye, possibly changes in the macular portion of your retina. I would strongly recommend that you revisit your optometrist, describe your symptoms in detail, and ask to have your retina reassessed.
Best of luck
Dr. Henry Smit

Peter wrote:
I have mild myopia in both eyes (-1.00) and “mild” astigmatism in my left eye. I am trialling soft, disposable contact lenses and find that middle-to-near objects are often blurry (with both -1.00 or -0.75 lenses, but with my astigmatism uncorrected as I’m told it is very mild).

My optician says there is nothing he can do as this is due to my myopia being mild combined with having the contact lens “on the eye” (unlike with glasses), and suggests I wear glasses for “near vision” work and contacts for outdoor sports, etc.

Is it really impossible for me to have contact lenses that give me good near AND far vision? I’d quite like to wear them every day for both near and far vision.

Thanks

ANSWER

Dear Peter

This is an interesting question. As a contact lens expert, I am shocked to withness in my everyday practice how eye care professionnals handle astigmatism in contact lenses. In my book, this is a major mistake to not fully compensate for astigmatism, with appropriate toric lenses. In fact these professionals should be convinced of misleading the public and of malpratice. Astigmatism distorts the vision even if the amount of astigmatism is low. To compensate for it, what your optician did (wrongly) is to increase the amount of myopia. This is called fitting with a spherical equivalent technique. THis is not helping your vision at computer distance or at near because an increase in myopic correction triggers an increased accommodation effort that  can end up with ocular fatigue and a blurred vision. This is exactly what you have experienced.

In the past, astigmatism was undercorrected or spherically compensated because of the bad quality of soft toric contact lenses. They were not accurate, not stable in the eye and did not provide better vision compared with spherical lenses. This is not true anymore. Modern design of contact lenses are available and they are really stable, even for small amount of astigmatism. I strongly recommend Oasys Acuvue for Astigmatism, Air Optix Torics or Cooper’s Biofinity Toric as very good products. There is no rational to not use them on a day-to-day basis. At least, every eyecare practitionner should at least propose trying toric contact lenses and let the patient to decide if this is a better option than a spherical lens. I had patients with major myopic correction and small astigmatism who said WOW when i fitted them in toric contact lenses (for the first time) but I had also some patients who were low myopes with higher astigmatism who did not find any difference in their vision comparing spherical and toric contact lenses. Since there is no way to know in advance what the outcome will be, the only rational approach is to try it (toric vs spherical) and to let the patient experience the difference.

If your optician is not familiar with toric contact lens correction, or denies the value of it, consider consulting an optometrist that is skilled in contact lens fitting and ask to try toric lenses. There is no reason to not see clearly at near and intermediate distance with these lenses except if you are 45 years old and over where presbyopia can come in play. Even then, astigmatism should be considered to correct your vision in contact lenses. We can use monovision strategy or to use multifocal toric contact lenses as well.

Good luck,
Langis Michaud, OD, MSc, FAAO
Associate Professor, U de Montréal

Junior wrote:
I just got glasses for the first time 2 weeks ago and I was told to wear the full time even though my prescription is week in my right eye is -0.50 myopia then my astigmatism is -0.75 and the same for my left eye. I have been wearing them all the time and since then every time I take them off I find it hard to see at all distances is that normal? Should I be wearing my glasses full time? The doctor even said I should wear them even when I’m on the computer, my lenses are single vision

ANSWER

Dear Junior.

Thanks for your interest. Your have a low level of visual correction. What disturbs the most in your case is the presence of astigmatism that can distort the image at far and at near. An astigmatic eye sees skewed what is plane and planed what is skewed. Not efficient in a real-world situation. Once corrected, it takes a few days for the brain to “reinterpret” that a plane surface is plane and a skewed object is really skewed. If you withdraw the correction, the brain can not interpret what you see anymore. This is why the objects remain blurred.

I agree with the recommendation of your optometrist to wear your prescription on a full time basis. This will alleviate vision distorsion and eliminates the risk to develop ocular fatigue, migraine or other asthenopic problems. Consider contact lenses as another way to correct your vision. More convenient, they can make your vision even better.

Good luck,
Langis Michaud, OD, MSc, FAAO
Associate Professor, U de Montréal

Thornton  wrote:
I have astigmatism in both eyes. I can see clearly with my glasses, but rectangles, such as my computer monitor, look skewed (longer on the right side). With enough adjustments to PD, optical center, and lens/frame position, I was able to get the skewing to a minimum that I don’t notice (most of the time).

I recently tried rigid gas perms, which my optometrist said should correct the astigmatism better than the glasses, but there was more skewing. It was different, though; the bottoms of rectangles are narrower than the top.

My prescription is:

OD: -2.25, -2.90, 35
OS: -3.75, -1.75, 140

First, what causes the skewing? Second, are there tests that can be done to determine a prescription for me that give clear vision without rectangular objects being skewed?

ANSWER

Dear Thornton

This is an interesting question. In order to answer it properly we have first to explain what astigmatism is. It comes from an oval-shaped eye - either on the cornea (transparent surface in front of the color of the eye) or on the internal lens (crystalline) that helps to focus at far and at near. One of these structures, or both, are oval-shaped meaning that one of their curve is more prononced (steeper) than the other one. In lay terms, we describe it as a “football” eye instead of a “volleyball” eye. Once the light hits such an oval structure it is distorted. Through an astigmatic eye, if you look at a cross, it will be skewed (depending on the axis) and one arm will be clearer than the other one. In your case, your axis is 35 and 140. This is called oblique astigmatism. The skew from your astigmatism distorts the image at angles. On a clock position, the cross you would see would be skewed with one arm at 2 o’clock and the other one at 10.

In glasses, astigmatism could be well corrected but as soon as you look through the peripheries of the glasses (outside of the center) you add to your astigmatism what is called optical aberrations. This is due to the shape and the optical properties of the glasses. The more prononced the astigmatism is, the more you will get distortion outside ofthe center of the glasses. High myopes patients share the same problem.

This is why contact lenses are preferred to correct astigmatism. When they are fitted properly, the lens follows the eye and eliminated the peripheral distortion. THe vision is sharper and clearer.

In your case, modern soft contact lenses (in silicone hydrogels - to preserve ocular health) are able to correct properly the astigmatism. Problems in the past with soft lenses include bad vision and discomfort mainly due to the fact that the lenses were not stable on the eye. Modern toric contact lenses can correct vision and they are really stable. I would recommend you Acuvue Oasys for astigmatism or Cooper’s Biofinity Toric. THese are the most comfortable and stable Si-Hy lenses in the market.

For gas perm lenses, your optometrist is partly right. In the past, they were considered a better option based on the fact that soft lenses were not stable. With Oasys and Biofinity this is not true anymore. However, for some patients, especially hyperopes astigmat patients (this is not your case) gas perm rigid lenses are preferable due to higher oxygen transmission.

I don’t know if you got spherical contact lenses or toric contact lenses. Unfortunately, some practitioners tend to prescribe spherical lenses on toric corneas. This is not appropriate in soft lenses and acceptable in rigid lenses just for small amount of astigmatism, which is not the case. Another way to prescribe rigid lenses is to design a back toric lens- This is a popular method but, considering your right eye, probably not the good one. This design is not stable and can induce secondary astigmatism on highly toric cornea (like yours). THis secondary astigmatism can cause the distorsion you see through your contact lenses.

In your case, I would strongly recommend the use of a bi-toric gas permeable rigid contact lens. This is easy to design through the Mandell-Moore formula and available everywhere. This design matches the internal curves of the lens to the ones of your eye, like a mold, and the vision is fully compensated with the proprer addition of a toric correction in front of the lens. COnsequently, both surfaces are toric and the lens is named a bi-toric lens. This is the most stable on the eye and provides sharp vision. The only other thing to determine is the diameter of the lens. Based on your corneal diameter and your pupil size, your optometrist will determine the appropriate contact lens size to alleviate  glare, halos and other aberrations possible with a smaller lens.

In summary, contact lenses are a great option for you but I feel that you did not have the proper ones prescribed for you. Consult your optometrist again and explain your problems. He/she will be able to help you. Anytime he can contact me with the details of your prescription in order to discuss it over the phone or by email. It should not be difficult to achieve a favorable outcome with all the options that we have in hand nowadays.

Good Luck,
Langis Michaud, OD, MSc, FAAO
Associate Professor, U de Montréal