In Contact - May 2004

Alan Saks Dip.Optom(SA), MCOptom(UK),FAAO(USA), FCLS(NZ)

New Toys?

It's always good to get new equipment!

Well once you get the hang of it that is and lose the old habits honed from years of experience with your trusty old stuff.

Some time ago, during a retinal workshop at Snowvision 2002, I used a 132D lens to view the retina. I got such a great view with it I subsequently decided to play a game of pool with the distributor of said lenses. If he won I was to cough up the four hundred odd dollars and buy it, if he lost he would give it to me.

Needless to say my motivation was high and sometime later I received the lens, gratis.

Frankly I was disappointed; the image I obtained seemed nowhere near as clear as I recalled seeing during the workshop. I blamed my obviously altered perception on too much Tequila, consumed during apr?s ski activities?

I also recall being impressed with the slit lamp we were using in the workshops. It had stepless motorised zoom and illumination, both easily controlled via a 4-way press-pad switch such as one finds on Game Boy toys. A Nice touch.

The pop-up illuminated magnification scale is less impressive. Why would one remove one?s eyes from the eye pieces to read off say ?32X? when one?s eyes had already seen the level of magnification ? give or take a few units?

One of my colleagues recently had one of these Takagi slit lamp microscopes on trial. I decided to use their room one day to see what it was like.

It seemed like d?j? vu.

I didn't think one could get a Tequila relapse so long after the fact but the image I got with the 132D was even better than I recalled almost two years earlier. Views with a 60D and 90D were also fantastically improved. The Haag-Streit-type design and superb blue white illumination, coupled with excellent zoom optics gave me a crystal clear view with very easy stereopsis, undilated.

I was sold.

Bye Bye Nikon. Well almost

Obviously there was nothing wrong with the 132D lens ? it was my old slit lamp that was limiting the image quality and stereopsis.

It was hard to part with my trusty twenty-year-old Nikon FS-2 Photo-Zoom slit lamp. I had also used the first model at Optometry School in J'oburg, from ?78-?80, where Des Fonn and I did endothelial specular microscopy and endothelial cell counts utilising the Holden-Zantos technique. We also obtained great images for lecturing and illustrating striae, neovascularisation, RGP fits and more.

Those were the days eh? Heaps of HEMA induced hypoxic signs.

I've also patiently waited for an easy way to do digital imaging with my Nikon. The FS2 slit lamp is one of few with integrated through-the-slit flash with a background illuminator and other features that make for great photography. Of course the FS3V was even better with automated exposure and video. Haag-Streit makes one too. Of course they both cost at least two to three times what other slit lamps cost. Now alas Nikon have moved out of slit lamp manufacture. An OEM manufacturer - that made some Nikon branded slit lamps - will continue to make certain models but Nikon branded slit lamps are apparently no-more.

My investigations had revealed that converting the trusty old FS2 to digital imaging was not easy, nor cost effective. Additionally eye piece mounted cameras are not for me. The other option was for a video camera, at no inconsiderable cost ? with limited resolution as far as print publication is concerned, but with the Nikon out of the slit lamp business parts and adapters are no longer available.

Since my wife purchased a second hand Nikon Coolpix 950 digital camera last year and following rave reports from patients, I've had my eye on the ?newer? 4500 Coolpix. At double the resolution, with hundreds of individual settings and features and a whole raft of Nikon lenses and accessories It's become something of a cult camera along with the likes of early Leica M-series, Olympus XAs, Polaroid SX70s and Nikon F2s. Apart from the odd Fuji and Sony there have not been many digital cameras earn this type of following.

There are now so many digital cameras, of little use to anyone, that they?ve become like the digital calculator. Once calculators sold for thousands of dollars and one would bow and scrape to owners of HP41CVs. These days a solar-powered calculator is a stocking-stuffer - or you get one free with a dozen coat-hangers at the two dollar shop.

Neway, as my teen would say, I have looked out for a Coolpix 4500 for a while now. Two years ago one would not have had much change from two thousand dollars. In November ?03 they were around $1200. February ?04 they were $899 at duty free. In March ?04, en route to the ICLC, I picked up one of the last few at duty free for $689.

SM-90

A few weeks ago we installed the Takagi SM-90 slit lamp. The beam-splitter arrived soon after. We connected it to the SM-90 and my Coolpix 4500 and I am now experimenting with the numerous settings to try maximise image quality. As expected the images will never be a patch on the Nikon FS2 shot with low ISO colour positive film and precise through-the-slit flash imaging. I am waiting for some feedback on suggested settings from Takagi but in the meantime have set white balance, best shot selector, continuous mode, contrast, manual focus and exposure enhancements.

So far so good.

I am already getting decent NaFl RGP images suitable for PPT and hopefully reproduction, after just a few attempts and am learning a few tricks in the process.

What?s great is that each image has an info file detailing every setting and exposure for each image ? a great help with setup.

The Coolpix was also great for shooting lectures at ICLC. Used in museum mode [no flash] and perched on an upside-down water glass it was a boon for note taking. My handwriting is notorious and even I can?t read it sometimes so having precise notes and PowerPoint images from a conference or lecture is well like, you know, Utopia.

that's why the digital age has been such a boon to me. With Word, PPT, digital imaging, the Net and ADSL I can now almost keep up with my ADHD brain. Well I guess that's the label they would have given me and my ilk, if they'd had that particular 4 letter-acronym back then.

In my day we were still on two and three letter acronyms.

Two I remember with fondness were: IQ - they tested me every year ?cos the score didn't match the results - and ITA ? a form or phonetic reading system. Some regard it as a flop. Others blamed it for their Dyslexia. My spelling is marvellous, so I can?t complain. Today?s educational experiment, NCEA, seems a hell of a lot more dangerous and no less useless?

Never mind. Today our kids have TXT - gr8 4 splng and grmr, not. They will apparently also become re-wired, pre-programmed, TV-induced ADHD psycho killers.

Neway, as I was saying, I am very happy with the enhanced image quality and the marvellous 3D I get with my new SM 90.

My indirect ophthalmoscopy is now way better and more pleasurable.

Maybe they?ll let me keep practising and continue to recognise my Mac Optom?

Will that be with fries, sir?

Matrix Revisited

we've had quite a few instruments on trial over the past few months. The new Zeiss-Humphrey Matrix based on Welch Allyn licensed frequency doubling technology [FDT] was one of these. Having performed over 20,000 fields on our Mark I FDT ? and knowing its pros and cons ? we were interested to trial the new Matrix FDT. The Matrix is an altogether more functional unit. The original FDT is VERY simple to operate ? all from a 5x7 LCD screen and is quick, easy and repeatable. The Matrix has a lot more functionality with a hard drive, CD R/W, TFT monitor, database and is complete with various setup and test options and harvests patient data and so on. Its multi-mode fixation monitoring is also a big step up.

Probably its best feature is the ability to spit out ?proper? field plots with dBs ala the HFA plots we all know and love. Those used to these types of field analysis and print out, including co-managing ophthalmologists, will appreciate this major advantage.

From my point of view, with an FDT for screening and a Medmont M700 for detailed fields ? and a whole host of print out and analysis options ? there was no real point in getting the Matrix. It would however be useful for a practice yet to invest in a perimeter. As FDT technology is aimed at [but not limited to] early detection and management of glaucoma, it has a strong advantage in this area but again one must consider ? if you are buying a general purpose field analyser - whether or not a full house HFA or M700 Medmont, is not the more versatile choice? The biggest advantage of FDT technology is that it is fast. With our old machine we can do both eyes from setup, intro, to end in less than three minutes.

With fuller fields we are talking units of 10 minutes - often 20-30 minutes on a regular field analyser. So is it better to screen everyone and only do fuller fields ?where indicated? or have a fancy machine standing idle, getting used a few times a week? The only downside of FDT, in my view - apart from its limited 20-30 degree test area - is that fields are negatively affected by cataracts, reduced contrast sensitivity and conditions such as epilepsy and so on.

Fortunately perimeters have evolved and the modern bunch are much easier to use, repeatable and accurate. Much easier than I recall doing fields on old B&L Autoplots, Goldman, Friedmann, Bjerrum screen, digitised LED Bjerrum?s and so on. I well remember building my own for a student project. It worked.

The basics of perimetry haven?t changed much.

It's the testing technology, sensitivity and data analysis that have.

Journal of Optics A:

No edition of In Contact would be complete without at least one reference to some serious applied science. For those of you with a desire for some high level applied optics I reckon you should take a look at this recent paper; The double superficiality of the frontal image of the Turin Shroud as it appears in the latest edition of Journal of Optics A: Pure and Applied Optics Vol: 6: 2004.

One can usually download for free, for ?own use? and research a full copy of the paper for 30 days. Simply create an account and download the full paper in pdf format.

What with Mel Gibson?s ?Passion? this paper is rather timely.

Storm Warning

We had a massive storm blow through Mount Eden the other night.

It's been a long time coming for the Stormers and I wish them well for the top of the Super Twelve. They looked like the Jaapies of old.

At last.

Or did the Blues just play badly?

 

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