Lens: where to get them, which ones, and when to buy?

[leverp2000]

I had a question about lenses:
When should you buy them? As a 1st year resident, as an intern, as a 4th year? It seems like the earlier you get them the more comfortable you will be with them.

What lens are the best to buy in terms of brand and type (good quality, cost effective)? I was thinking of a 90D, 78D, 20D, +/- gonio lens and 28D. Are there any others to get, or ones that are less necessary?

Where should you buy lenses? Are there any deals at ARVO/AAO? Are there good websites with deals on lenses?

Thanks in advance for the advice.

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[idoktor]

At least a slit lamp indirect lens (90, 78, super 66, digital wide), a BIO lens (usually 20 or pan retinal 2.2), and a gonio lens (we use volk 4 mirror). Personally, I use the digital wide and/or 2.2 for 95 percent of the patients. Digital wide will let you see pretty peripherally with dynamic and the optics are good enough that you could just increase the zoom for closer views of the nerve or macula. Get Volk. The ocular instruments feels like plastic. Usually the programs have some deal with lombart.

 

[OphthoApp]

Create an account with pioneer. The prices are much better than AAO prices. Start with 90, 20, and 4 mirror gonio. You will eventually buy a higher mag slit lamp lens and you'll eventually need a 28. Get Volk.

 

[orbitsurgMD]

One lens from each general group is all you need. You should wait until residency; don't bother buying in your 4th year. A BIO lens: the classic is a 20D but 2.2 PanRetinal from Volk and 22D from Ocular Instruments are great alternatives. A slit lamp lens: the classic was 90D, then came 78D and now there are a slew of alternatives (66, 81D, etc) try them out. The bigger the number, the lower the magnification but wider the field (generally.) A gonio lens: the classics were the Sussman from Ocular Instruments and the Zeiss. There are lots of newer designs now as well, some with different magnifications, some with reversing optics (Khaw). If you buy something extra, maybe a small-pupil lens like the Volk SuperPupil XL or Ocular Instruments 132D.

 

[rocketbooster]

One lens from each general group is all you need. You should wait until residency; don't bother buying in your 4th year. A BIO lens: the classic is a 20D but 2.2 PanRetinal from Volk and 22D from Ocular Instruments are great alternatives. A slit lamp lens: the classic was 90D, then came 78D and now there are a slew of alternatives (66, 81D, etc) try them out. The bigger the number, the lower the magnification but wider the field (generally.) A gonio lens: the classics were the Sussman from Ocular Instruments and the Zeiss. There are lots of newer designs now as well, some with different magnifications, some with reversing optics (Khaw). If you buy something extra, maybe a small-pupil lens like the Volk SuperPupil XL or Ocular Instruments 132D.

I think you meant the opposite? i.e. the 20D has a wider field/lower mag since it's used for the peripheral retina but also has lower "resolution", while the 90D has the narrowest field/highest mag and the highest "resolution" so is used for the disc and macula. No?

 

[orbitsurgMD]

No, I have it posted right. A 20D has higher mag than a 30D (and that is why people sometimes use a 15D, which has higher mag than the 20.) The 90D has lower mag than the 78D, and the 78D lower than the 60D. For your reference: http://www.ocularinc.com/media/pdfs/Ocular Instruments - Indirect Chart.pdf

We are referring to image mag, here. Laser spot mag for indirect BIO endolaser is the reverse.

The best way to see how this is so is to get a 20D and a 30 D and look at something through them using the BIO. With wider field comes lower mag (controlling for lens diameter.) So the 30 D is nice when you want or need to see things quickly or want to see farther into the periphery, the penalty being less magnification.

 

[rocketbooster]

No, I have it posted right. A 20D has higher mag than a 30D (and that is why people sometimes use a 15D, which has higher mag than the 20.) The 90D has lower mag than the 78D, and the 78D lower than the 60D. For your reference: http://www.ocularinc.com/media/pdfs/Ocular Instruments - Indirect Chart.pdf

We are referring to image mag, here. Laser spot mag for indirect BIO endolaser is the reverse.

The best way to see how this is so is to get a 20D and a 30 D and look at something through them using the BIO. With wider field comes lower mag (controlling for lens diameter.) So the 30 D is nice when you want or need to see things quickly or want to see farther into the periphery, the penalty being less magnification.

Oh I see. What is the indirect BIO endolaser? Is that the same laser used for treating PCO?

So for image mag, where does resolution fit in? I could have sworn hearing that the higher D gave higher resolution?

For the 20D used with the indirect and looking at the periphery, so the 20D is higher mag than the 90D used with the slit slamp but the 20D is also a wider lens diameter to make up for the narrower field that comes with higher mag? You said the wider field causes lower mag if lens diameter is controlled, but I feel every different diopter lens have different diameters so you are never really controlling for lens diameter.

 

[idoktor]

The BIO lenses (20, 2.2...) have much higher mags but have much less field for the same unit area of lens but makes up for it by being a large lens. The slit lamp indirect lens (66, 78, 90, wide field)... have much lower mag compared with BIO lenses but have much bigger field per unit area of lens surface. Their image appear larger because of the additional mag of the slit lamp.

 

[rocketbooster]

Hmm so why even use the BIO lenses (20D)? If the 90D slit lamp indirect is lower mag/wider view but compensated by the additional mag of the slit lamp, why do we even need the indirect ophthalmoscope? I get that it's binocular but the slit lamp is also binocular so we can still see stereo that way. You can have your patient look in all directions to see the periphery under the slit lamp too but it might just be a little more annoying to keep adjusting using the slit lamp.

 

[JayZBlue]

Good question. There are several benefits to the indirect retina exam: 1) Allows you to do scleral depression, 2) you get a much wider view to give you the 'big picture' (for example nevi can be missed at the slit lamp but it's usually obvious with the indirect), 3) it's a lot faster to scan the entire retina, and 4) it's easier to see through media opacities. Some people routinely do both the slit lamp and indirect exam, while some are comfortable with limited use of the indirect. In any case, the indirect retina exam is something you'll need to master during residency.

 

[idoktor]

depression and LIO...you may burn something you're not suppose to if you try doing it with a 78

 

[orbitsurgMD]

At least a slit lamp indirect lens (90, 78, super 66, digital wide), a BIO lens (usually 20 or pan retinal 2.2), and a gonio lens (we use volk 4 mirror). Personally, I use the digital wide and/or 2.2 for 95 percent of the patients. Digital wide will let you see pretty peripherally with dynamic and the optics are good enough that you could just increase the zoom for closer views of the nerve or macula. Get Volk. The ocular instruments feels like plastic. Usually the programs have some deal with lombart.

Some of the OIs are plastic--acrylic plastic--and are sold alongside their glass lenses which are also very good. The acrylic lenses are advertised as lite in their product line. The acrylic lenses are much lighter than glass. OI has long experience in lensmaking in both materials, and I wouldn't hesitate to buy any of their products. They have excellent customer service.

 

[switchwithme]

when purchasing lenses, given the choice of one big case for multiple lenses vs small cases for each lense - why pick one over the other?