Some interesting points here and as I am involved in the clinical work with KeraSoft3 and the new KIC lenses, I think I can answer some of the queries.
First, as Andrew so rightly says, there is NOT one contact lens answer to keratoconus. To borrow the phrase of a US colleague of mine, Keratoconus is a "designer condition" . Every cornea is unique and each wearer requires a designer approach.
Secondly, soft lenses for keratoconus have been around for some time now and some of the "problems" quoted relate to the material type. When oxygen transmission rates and infection rates are quoted for keratoconic soft lenses, this refers to hydrogel material because until this year, there were no successful Silicone Hydrogel (SiH) materials that could be lathe cut. SiH material has been available for some years now in disposable form and has now been generally accepted world wide that they offer excellent ocular health even for extended wear. The contact lens industry just needed the material to be in a form that could be lathed so that specialist lenses could be made.
This year has seen several such materials come onto the market and here you need to distinguish between companies that manufacture materials and those that manufacture lenses from those materials. So for example, you can get a RoseK RGP lens made from a variety of different materials all of which have different properties and oxygen transmission, so you can't just say Rose Ks do this or that - performance can depend on the material its made from. Similarly, the KeraSoft is available in normal hydrogels and also now, the KeraSoft3 is available in SIH high water content materiaL.
These new materials are being assessed by hospitals, including Moorfields, for use not only in KeraSoft lenses but also for bandage lenses, paediatric and other medical usages. As for trials comparing infection rates between RGP lenses and soft lenses this is actually not an easy comparison as it very much depends on what use the lenses are being put to (i.e. normal wear, ortho K, irregular cornea etc etc). A more useful comparison for this forum is a comparison between the two types as far as Keratoconus is concerned.
RGP lenses themselves have other issues. There is a some evidence now (e.g. the CLEK study) that RGP wear actually increases the likelihood of central scarring which can lead to needing a graft. More information can be found here
http://www.kerreyecare.co.uk/kerratoc_lecture.html. One of the reasons I started to become interested in soft lenses for keratoconus was from when I went to work in Trinidad, where there is a lot of KC. Many patients there simply cannot tolerate rigid lenses of any sort, partly due to the climatic conditions. It struck me immediately that central scarring was much lower in this group. Part of the problem is that often the best vision in RGPs is obtained by fitting the lenses flat on the cornea, which means the lenses rub and cause damage. I was horrified on a recent lecture visit to South Africa that ophthalmologists were actually writing notes to optometrists instructing them to "Fit flatter" in order to get better vision for their patients.
Many patients simply cannot tolerate rigid lenses - if everyone got on with them perfectly, there would be no market at all for soft lenses. The main issue with any contact lens for keratoconus is that it is comfortable and has a wearing time that is adequate for the wearer, which in KC has to be most of the day or the wearer cannot function visually. Making lenses out of SiH material is a significant breakthrough that the professionals are finding quite exciting.
To answer the point about coming out of RGPs. The KeraSoft3 lens works more consistently on eyes that have not worn RGPs. There is the issue of unmoulding to be considered for people swapping from rigids to softs and I personally recommend swapping over one eye at a time. As with ANY lens type, there is a difference between what the lens can achieve theoretically and how it is fitted by different practitioners.
New design: there are many corneas that have very odd shapes. KC obviously falls into this category but also PMD (Pellucid marginal degeneration), post graft, post refractive surgery of all types. The KIC is aimed at these types of corneas and many manufacturers have an "IC" lens in their portfolio. What is exciting is that we are looking at creating lenses that have different curvatures at different places on the lens (sector management control)- previously this has only been possible in rigid materials.
Prices: It is impossible to talk about prices because keratoconus fitting is more about chair time than actual physical costs of lenses. We sometimes discuss this on the US KC group and one optom ruefully said she didn't think she ever charged a realistic price for her KC lenses. The condition itself is often a moving target and it is not unusual for ordered lenses not to perform as promised during the trials. This applies to any KC lens and most KC fitters are dedicated people with a genuine interest in their patients - otherwise they would simply just fit disposables to the general population. I know its frustrating not to be given a straight costing but honestly, no-one can hand on heart predict exactly the costs and fitting times for KC lenses.
As ever, I just want to say again that no one lens is a cure all and what works for one person may not work for another. I know many patients who look at message boards such as this one, see an endorsement by a member for a treatment or contact lens and go "WOW!" and off they go and try it only to be disappointed if it doesn't work superbly for them. Conversely, some may complain such and such a lens or treatment did not work for them and others may be put off when in fact it may be just right for them. Please DO remember Andrew's health warning and try to look at information on these boards as a starting point for gathering more information. The only person who can advise you properly is your own eye care professional!
Lynn
I just question was that soft lenses in general or soft lenses used for the treatment of KC, is there a like for like comparison as we often have other vison complicatiosn because of the alergies we have.
