The 80s Called …
and they want their condensing lenses back.
By Dan Beck, OD Leland, N.C.
BUY THE 90 and 20 (28 if you're short) diopter condensing lenses. That's what nearly every first year student hears in his first week of optometry school. Oh sure, sometimes an upper classman or hip instructor will encourage a student to buy a 78 diopter or, more recently, a Volk SuperField lens instead of a 90, but that's usually about as far as anyone deviates. It isn't questioned, it's just accepted. Later, when it's time to purchase a gonioscopy lens, nothing is mentioned beyond the same 3-mirror and 4-mirror designs that have been around for decades.
Believe it or not, condensing lens manufacturers have come out with some pretty cool products over the last 20 years. Clearly, most optometry students are clueless about this developement. It's not really their fault, however, because they haven't been made aware of the new lenses. The instructors, along with a large percentage of practicing ODs, are just as clueless. There are many old school optometrists still using — and only using — the same condensing lenses they purchased as students 20, 30 or even 40-plus years ago.
New Slit Lamp Lenses
SuperPupil XL by Volk Optical: While certainly not new (this lens has been available for about 15 years), most docs have never seen it. The SuperPupil XL lens provides an amazingly wide field of view in an undilated pupil. The company claims a field of view of 103° (compared with 74° for a 90 diopter lens). This lens is ideal for a quick view of the posterior pole on non-exam office visits and for those patients who refuse dilation. The SuperPupil XL does have a steeper learning curve than traditional lenses and practice is required to become comfortable with it.
MaxField 100 and 120 by Ocular Instruments: The company claims these lenses provide 110° and 120° fields of view respectively. The SuperField lens offers around 95° in dilated pupils by comparison. Whether that's through an undilated or dilated pupil isn't clear, but I suspect dilated. I've never used either of these lenses but if Ocular Instruments wants to send me one or both, I would be more than happy to try them out.
New Gonioscopy Lenses
G2 and G4 by Volk Optical: Many optometrists dislike, OK hate, performing gonioscopy. It's certainly a skill that requires a lot of practice. Even after the gonio lens is on the patient's eye, views can be difficult and confusing. The great advantage of the G2 and G4 lenses is the increased magnification.These lenses give 1.5X mag. All other conventional gonioscopy lenses only magnify 1.0X at the most, and many are slightly below that. Being able to see angle structures can actually make performing gonioscopy fun. Well, maybe more pleasant or less painful would be more apt descriptions.
Condensing lens companies have been pretty quiet in the binocular indirect ophthalmoscopy lens area, although most companies offer a wide variety of magnification powers including 15D, 20D, 25D, 28D, 30D, and even 40D. I've worked with all of these and still find that the 20D is the easiest to use. The 30D can work well with pediatric patients, but is hard to use without getting glare. I recommend students check out the 25D, which offers a wider field of view and is a favorite with many retina specialists.
Try Before You Buy
There are a bunch of cool and useful condensing lenses out there. Before you make a purchase, I highly recommend trying several. The 20D and 90D are still good, workhorse condensing lenses, but they may not be the best fit for your needs. nOD
|Learning about lenses, Dr. Beck is a 1993 graduate of the Pennsylvania College of Optometry. E-mail him at firstname.lastname@example.org.|
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