Problem with Optician

[Tracey rssll]

Hi I am looking to see if anyone has issues with eye tests at the opticians? I feel my last two prescriptions have been to strong in one eye which is my worst eye however the keep telling me no it is fine. They are now encouraging me to more to contact lenses as they say with glasses my sight is very poor and close to the driving standard however I do not feel this is the case and I wonder if anyone else has had this issue? Thanks

[Lia Williams]

Hi Tracey,

Getting an optimised glasses prescription for keratoconus does take longer than a more normal one. This is because our answers to the "better or worse" questions aren't consistent due to the irregular astigmatism we have.

The optician I go to allows 45 minutes for my appointment rather than the standard half hour but I did speak to one person at the conference last month who said that it usually takes two hours to optimise hers.

I feel my last two prescriptions have been to strong in one eye

What makes you think that the prescription is too strong? If like most of us you are short sighted, with a -ve prescription, you could easily check this with a pair of simple, low powered, reading glasses from a pound shop. If the image is clearer when you hold them in front of your glasses then your glasses may indeed be too strong. If you are in your late 40s or older it could be that presbyopia is the problem and you do need a weaker pair of glasses to read.

They are now encouraging me to more to contact lenses as they say with glasses my sight is very poor and close to the driving standard however I do not feel this is the case

Most people with keratoconus do see a lot better with contact lenses as they are able to better correct the irregular astigmatism. Although you may not feel that your eyesight is poor with glasses it may be much better with contact lenses. I can still remember "the wow moment" when I got my first pair of lenses. Do try contact lenses you may be surprised how much better your eyesight is with them.

Lia

[FERNANDO]

Hi everyone:

As an optometrist who has devoted a large part of his career taking care of patients with keratoconus, before in Spain and now in the UK, I have to say that making a refraction for spectacles on patients with KCN is very demanding and tricky at the same time.
First, as it was told before, it not a feasible way to translate ocular aberrations values into a standard prescription only with the sphere (myopia) and astigmatism. Even the total power of the eye can change dramatically with light because of the pupil (as with a larger pupil more cornea is visually used). For that reason, some patient with KCN can cope with daylight driving but at night vision is worse and different.
Second, as the corneas became thinner and softer, vision can be modified during the day. If you sleep on your eyes on the pillow, you could experience mild corneal flattening which can affect refraction afterwards. There is at least one study that tries to link keratoconus and its progression and position of the head during nighttime.
Third and no last, most of the patients with KCN need to wear contact lenses, and these devices are going to affect the shape of the cornea and the power.
The advice to my patients is they need to have updated spectacles but...
1) A balanced prescription for both eyes: In most of the cases, KCN is more severe in one eye than another, so it is worthy to seek the best visual performance from the best eye.
2) Try to avoid one-time decision: Before I made a final prescription I need 2-3 checks, so I dont jump into a -5.75 @ 37º in the first moment, but I tend to average several measurements (as everyone is going to be slight or blatant difeferent), as well as significant changes in the prescriptions without an excellent reason.
3) I need to know the purpose of the new spectacle before prescribing: Is going to be for watching tv at night after taking out contact lenses? If so, I recommend to visit me at pm with the lenses on, and make the refraction at that moment. The goal is to measure in the same conditions spectacles are to be worn. Sometimes in patients who wear RGP lenses, there is a significant shift in vision from the morning before wearing lenses, and late at night son probably two different spectacles could do better than just one.

Hope my English is not too bad after all and could help in some way with this answer
regards
Fernando J Fernandez-Velazquez

[Lia Williams]

Hi Fernando,

Thank you for your explanation.

I tend to wear my glasses in the morning before I put my lenses in - so I have my refraction appointment in the morning. When I wear my glasses in the evening the vision is slightly different but I don't think I would have a second pair. The vision I get with my glasses is good enough to use around the house and for watching TV but not for doing detailed things. However I wouldn't be without my glasses as I can see very little unaided.

Lia

[FERNANDO]

Hi Lia
Sorry I could not answer you before. What kind of lenses are you wearing?

[Lia Williams]

Hi Fernando,

I wear piggy backs - corneal RGPs with disposable soft lenses underneath. I love them. I wear them for 15 hours a day, seven days a week, so I do need glasses first thing in the morning and last thing at night as I can see very little unaided.

Hopefully Tracey, the original poster in this thread, will also have seen your explanation about the difficulties in prescribing glasses for some one with keratoconus.

Lia

[FERNANDO]

Piggy-backs was something great in the past and helped to solve many issues in patients with keratoconus. At this moment, personally, I don't see them as a first choice as the contact lens industry has evolved a great deal with new lenses and designs. But it is still worthy in many cases like yours.

Thanks for your reply

[Lia Williams]

I don't see them as a first choice as the contact lens industry has evolved a great deal with new lenses and designs. But it is still worthy in many cases like yours.

Piggy-backs weren't the first choice for me. Originally I hard lenses and moved to RGPs in the early nineties.

About eight or nine years ago when I needed new lenses semi-scleral were tried but the optician wasn't happy with the fit. I also had a trial fitting with a specialist soft lens and that was really comfortable but the vision wasn't great.

The RGPs I now have give me excellent vision and comfort when piggy-backed. Without the piggy-back the right lens becomes intolerable (like having soap in my eyes) after a couple of weeks and the left lens gets a bubble underneath which turns into froth after an hour or two blurring my vision.

More recently I had a trial fitting of a hybrid lens. In theory this would save the hassle of dealing with two lenses. But I was very aware of the lenses in my eyes.

So yes, you are correct, in my case piggy-backs are the solution.

Lia

[CrippsCorner]

Hi everyone:

As an optometrist who has devoted a large part of his career taking care of patients with keratoconus, before in Spain and now in the UK, I have to say that making a refraction for spectacles on patients with KCN is very demanding and tricky at the same time.
First, as it was told before, it not a feasible way to translate ocular aberrations values into a standard prescription only with the sphere (myopia) and astigmatism. Even the total power of the eye can change dramatically with light because of the pupil (as with a larger pupil more cornea is visually used). For that reason, some patient with KCN can cope with daylight driving but at night vision is worse and different.
Second, as the corneas became thinner and softer, vision can be modified during the day. If you sleep on your eyes on the pillow, you could experience mild corneal flattening which can affect refraction afterwards. There is at least one study that tries to link keratoconus and its progression and position of the head during nighttime.
Third and no last, most of the patients with KCN need to wear contact lenses, and these devices are going to affect the shape of the cornea and the power.
The advice to my patients is they need to have updated spectacles but...
1) A balanced prescription for both eyes: In most of the cases, KCN is more severe in one eye than another, so it is worthy to seek the best visual performance from the best eye.
2) Try to avoid one-time decision: Before I made a final prescription I need 2-3 checks, so I dont jump into a -5.75 @ 37º in the first moment, but I tend to average several measurements (as everyone is going to be slight or blatant difeferent), as well as significant changes in the prescriptions without an excellent reason.
3) I need to know the purpose of the new spectacle before prescribing: Is going to be for watching tv at night after taking out contact lenses? If so, I recommend to visit me at pm with the lenses on, and make the refraction at that moment. The goal is to measure in the same conditions spectacles are to be worn. Sometimes in patients who wear RGP lenses, there is a significant shift in vision from the morning before wearing lenses, and late at night son probably two different spectacles could do better than just one.

Hope my English is not too bad after all and could help in some way with this answer
regards
Fernando J Fernandez-Velazquez

Hi Farnando... you sound, amazing!

Visiting at the time you would normally wear the glasses sounds like a great idea, and in fact your example is exactly my situation. Wear my contacts all day then pop them out and replace with glasses for my evenings in.

Also, would you happen to be able to link to that study regarding sleeping!? Sounds really interesting, as I always lay face down or to the side.

One more question I have had for a long time but as yet have never had an answer to: Can rubbing your eyes etc. further damage or adjust prescription requirements to your keratoconic eyes post-CXL?

Thanks.