In Contact - June 2009

Safe as Houses?

Over the years I've commented on contact lens materials and which ones I find to be the best. At times I report on favourable initial results with new materials with the caveat that ?time will tell? if they are all they are cracked up to be. A site specific search of In Contact provides references, going back ten years, to XO, my all time favourite. Day after day I see Boston XO RGP lenses that remain within strict manufacturing tolerances after two, three, five, eight and even ten years. Remarkable.
The lenses generally wet well and are well tolerated. The lenses also remain in remarkably good condition and withstand polishing and repowering. Although any RGP may buckle in time, XO is only rarely plagued by such problems. I reckon buckling is more a patient specific problem than material specific. Buckling seems to occur with specific patients and lens designs no matter what material one tries.
Paragon HDS 50 also performs well as does Optimum Extra and when all else fails [due to wetting and allergy issues] then trusty Fluoroperm 30 is usually a winner, albeit a lower Dk option. There are of course a number of other good materials.
You may also recall that I had been wary of some variable and in some cases downright poor results, with the more recent Boston XO2. Thus I was impressed when I recently saw an extended wear RGP wearer for aftercare. Her two year old custom tetracurve XO2 lenses were dead stable and within 0.02mm of ordered base curve.
Maybe XO2 is best used for extended wear and XO for regular daily wear?

The patient concerned began self prescribed extended wear a decade or two ago while wearing 12 Dk Paragon O2 lenses [also known as XL40]. My predecessors had read her the riot act over many years and the file is full of notes to that effect. After discussing the issues when she first consulted me I realised she was not about to change her habits. I therefore upgraded her to Quantum II in 1997 and to its successor, Boston XO, in 2001. In 2007 I refitted her into 141Dk, XO2. At her recent aftercare she reported having not removed the lenses for ?some months?. Her corneas were crystal clear and showed zero staining on one eye and a few small punctate stains on the other! Less than you would see on many of your average daily wear, disposable soft lens wearers. Her tarsal conjunctivae were also pretty normal.
Now she may be atypical with bullet proof leather-like corneas but I've also seen others with similarly positive results over the years.
We also know that MK risk in RGPs is extremely rare, at worst around 1/10,000 thus making them the safest of all modalities.
If considering EW then RGPs should be our number one choice.
Why aren?t they?

 

CONTACT LENSES: THE STORY

Those with an interest in contact lens history need look no further than the recently released book, Contact Lenses: The Story by Timothy J. Bowden.
Tim does a great job of covering, in quite some depth, the five hundred year history of these remarkable devices which have made such a great difference to the lives of so many. Apart from the usual prefaces, the first dozen or two pages include definitions of some terminology used as well as some great quotes relevant to the topic. I felt I should share two of these with you. One ascribed to Brien Holden in 1974 - before the advent of silicone hydrogels - is arguably as pertinent today as it was back then and reads as follows; ?Extended wear lenses have now reached the point where they are the safest daily wear lenses on the market?
The other more tongue in cheek comment from Malcolm Rogan in 1987, goes like this: ?Modern contact lenses are so easy to fit that even a one-armed gorilla can do it?.

The first few hundred years of CL history are given a ?brief? forty page overview with a further one twenty devoted to sclerals.
Hard and soft lenses are covered in two more sixty-page chapters chock full of information. The creation of spin casting by the late Czechoslovakian contact lens legend Otto Wichterle is given great coverage. It describes how spin casting went from Otto?s legendary home-based Heath Robinson contraption in Czechoslovakia to America.
Bob Morrison?s involvement and the various shenanigans, legal wrangles and patents that finally led to B&L acquiring and commercialising the technology is also well covered and worth a read. It includes some amazing insights.
Interestingly enough I interviewed Bob a decade ago after the passing of Otto. My Dad had met Bob and stayed with him in the US years before and thus knew some of the background. Bob told me our interview was the first time he?d told the full story to anyone. Although the versions differ a little, depending on who is telling it, the basics are fairly similar.
You can read my version here.
Another Czech mentioned is the late Eugene Hirst, who played a significant role in the development of contact lenses in NZ. Apparently when asked why he chose NZ he reported that it was the furthest he could get from Czechoslovakia! Other Kiwi?s and Aussies are also mentioned. In fact the remarkable number of people mentioned and interviewed is fantastic. It gives credit and recognition to the hundreds of behind the scenes people who helped develop these breakthroughs. They may otherwise have never been mentioned or given the recognition they deserve.
Growing up in a pioneering contact lens family I've been lucky to meet and hear about many of the contact lens greats. I continue to be fortunate in this way but there were many people in the book that I'd never heard of.
Great stuff.

The development of the now ubiquitous disposables and silicone-hydrogels, takes up another one hundred pages, over the next two chapters. There are some tremendous stories in this section too and some fantastic technological achievements.

I feel that more extensive coverage should have been given to the amazing CNC lathe and milling technology that is responsible for the making of the moulds from which the final disposable lens is derived. This technology is also responsible for the amazingly complex RGPs we have these days of which reverse geometry and asymmetric peripheries are but two examples. In addition there was a dearth of information on contact lens pioneers in Africa. This region was blessed with a number of great people in this field. Significant hard lens developments came from practitioners in Southern Africa. Some of the first scientific reports of corneal topographic changes, in the mid 1960s, were reported from altitude in South Africa as were the earliest scientific reports of hypoxia induced soft lens myopic ?creep?, seen with early soft lenses in the 1970s. These reports triggered much research that made a number of international people famous.
Des Fonn was one, if not the only South African mentioned in the interesting research chapter. This followed an equally interesting section that detailed the history of the major lens manufacturers. The closing chapters cover the chronology of landmark developments, a bibliography and appendices. David Westerhout of Zimbabwe is for example credited with piggybacking the first soft and hard lens, as early as 1964.

The minor oversights mentioned do not detract from the work as It's an amazing reference that will have pride of place in my reference library. It is impossible for one person to attempt to know about and cover every event or person in contact lens history.

Full credit Tim for this significant seven hundred page story.

 

RUGGER ETC.

My Pretoria boys managed to finish top of the Super 14 log, much to the chagrin of most of my Aussie and Kiwi mates. Here?s hoping the Blou Bulle deal to the Crusaders at altitude at Loftus. The party faithful will be well oiled on their traditional Naartjies, injected with liberal doses of Brandy that seems to confound gate security who confiscate all other booze. They will also be well fed on adrenaline and steroids from the biltong and huge 1kg Blue Bull steaks they will consume at the pavement Braai?s that surround the stadium.
It could be that we see a Bulls versus Chiefs final at the very same venue.

Here?s hoping?

Formula 1 continues to languish in disarray with Ferrari threatening to pull out of a sport that has been synonymous with their name. It's time F1 rids itself of the dictatorial Mosley and Ecclestone. They helped build the billion dollar F1 into something pretty remarkable but politics and greed got in the way. F1 has massive problems that almost seem unresolvable.

The economic crisis has merely fuelled the fire

 

For more information or any comments email Alan at incontact@optom.co.nz.