The rollercoaster of lens fitting

[Lia Williams]

I originally drafted this posting as a contribution to MKnight’s thread ‘Soft Lenses / Keratoconus’ but didn’t want to interrupt Lynn and Ali’s fascinating discussion.

As patient with keratoconus I just want to see clearly and comfortably! After 35 years plus of RGP contact lens wear I’ve often described a refit as ‘a nightmare’ as it never seems to be straightforward.

When a re-fit seems to be taking forever it’s often a rollercoaster of emotions. When the new lens gives great vision but falls out; or is impossible to remove or becomes uncomfortable after a few weeks’ wear it’s such as a disappointment. It can be equally disappointing if the new lens has the comfort but not the vision. One’s initial reaction is blame the optometrist and friends seeing me struggling with a new lens will suggest that I see an expert. But I AM seeing an expert who is a specialist so I know I’m in good hands. It’s at this time that I then despair with my eyesight.

Then there are the times when the optometrist says ‘that’s it’ and you just know it’s going to work. The vision that I now have with my right lens is the best I’ve had in years, the comfort level is slightly down; but to see things ‘crisply’ rather than ‘smudgy’ is brilliant. Over the years I always thought that there must be a better lens for my right eye and to see things in the distance without ghosting is fantastic.

Am I successful RGP wearer? In many senses I am because I’m getting 15 hours per day of lens wear so I’m probably not an obvious candidate to transfer to soft lenses. On the other hand the thought of being able to wear lenses all my waking hours would be great and I would no longer have to plan for a late night. I believe that when attending the clinic one has to be open and honest about how the lenses are working but sometimes that can be difficult when you have to say that you actually prefer your old worn out lens not the one that took an hour to fit last time. It seems as if one is complaining. I’ve never quite understood why a comfortable lens can be a bad fit and a good fit (although comfortable) can still leaving ghosting.

My current approach is to understand as much as I can about keratoconus and contact lenses so I can get the best outcome for myself. Although the more I read the more I realise there is a lot to know and it’s not quite as simple as balancing a saucer on the end of rugby ball. What is important to me is that the lenses aren’t making my eyes worse and when I asked the clinic how much scarring I had I was reassured that there was relatively little in KC terms and it was unchanged in the twelve years or so I have been attending the clinic.

So at the moment I’m alternating between a couple of lenses in my right eye to ensure I get the crisp vision when I need it; but at the same time ensuring that I don’t overwear the lens and get a bad eye day. I guess for me it might be a case of piggybacking the right lens to improve comfort then I might get comfort and vision.

Just a thought could piggy backing be done with multifocal lenses as my biggest problem is remembering where I put my reading glasses!

Lia

[Andrew MacLean]

Lia

I wonder, how would it work for piggy backed lenses to be multi-focal? If it could work, it would be a boon to many of us.

Andrew

[Lynn White]

Hi Lia,

Comfort vs vision with RGPs...

It is a bit like balancing a saucer on a rugby ball actually.... KC corneas are simply not symmetrical whereas RGP lenses are. In normal eyes, RGPs naturally on the highest pint of your cornea which is in the centre of your pupil and thus visual axis.

In KC, your highest point could be anywhere, usually NOT on your visual axis. So a lens that centres naturally left to its own devices will not be sitting in your line of vision. To get it to do so requires some design changes and these often tend to reduce overall comfort.

Also, a flat fitting RGP will nearly always give you good vision as it is sitting directly on the cornea, relatively speaking, but runs the risk of causing abrasions and thus scarring. A better fit where the lens has some tears underneath it can cause reduced vision precisely because of that tear pooling.

For some patients, getting this balance is relatively easy. For others, it is not. We still do not understand everything about KC eyes and why some lens designs work brilliantly for one person and not on another.

Makes it all very interesting, but as all my patients say, I'd rather not be interesting thank you very much!

Lynn

[Lia Williams]

Lynn,

I don't mind being interesting; as long as I can see!

Lia