Plus Cyls?

[futurist]

Anyone know what percentage of OMD's use plus cyls?

Isn't it generally accepted and proven that minus is the way to go?

i've always wondered about that...

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[Andrew_Doan]

Anyone know what percentage of OMD's use plus cyls?

Isn't it generally accepted and proven that minus is the way to go?

i've always wondered about that...

mRX written in either plus or minus cyls will give you the same correction. What do you mean when you say "minus is the way to go?" 😕

 

[Richard_Hom]

Anyone know what percentage of OMD's use plus cyls?

Isn't it generally accepted and proven that minus is the way to go?

i've always wondered about that...

Dear futurist,

The refractive equipment world is "split" between plus cylinder and minus cylinder phoropters. In my earlier training, ophthalmologists tended to favor plus cylinders beause they could use the plus cylinder axis as "guide" to making their ECCE incisions. As IOL's became more prevalent, this advantage isn't as obvious.

In addition, the "battle" between ophthalmology and optometry had already started in the earliest years of the 30's when the AO 590 "double banker" were being manufactured. During this formative time period, the ophthalmologic community united behind plus cylinder phoropters and thus was borne the equipment dichotomy.

Most optometrists prefer minus cylinders because soon after the advent minus cylinder ophthalmic lenses, it was much easier to refract in that manner. Minus cylinder stock or finished lenses only had to be finished on the ocular side while the plus cylinder stock lenses had to be finished on the object space side.

There aren't any practical differences between. When your Rx lands in the hand of the lens dispenser, it is transposed to whatever the dispenser likes. In most circumstances it will be minus cylinder.

One advantage of the plus cylinder, th ough, is the ability to see the markings on the phoropter if the examiner refractis in a darker room. It is much easeir to "chase the white" rather than 'chase the red".

 

[Mirror Form]

Anyone know what percentage of OMD's use plus cyls?

Isn't it generally accepted and proven that minus is the way to go?

i've always wondered about that...

I think the vast majority of US ophthalmologists use +, whereas in europe they use minus.

 

[shredhog65]

every ophthalmologist i have ever worked with used "plus cylinders".

i think this is just more of a gerenal convention used by ophthalmologists in order to make it so everyone is on the same page. they all understood that plus and minus cylinder are easily converted back and forth.

from what i understand, it makes no difference if you use "plus" or "minus" cylinder as long as everyone understands which one you are using.

 

[JennyW]

every ophthalmologist i have ever worked with used "plus cylinders".

i think this is just more of a gerenal convention used by ophthalmologists in order to make it so everyone is on the same page. they all understood that plus and minus cylinder are easily converted back and forth.

from what i understand, it makes no difference if you use "plus" or "minus" cylinder as long as everyone understands which one you are using.

Refracting in minus cylinder form allows for much better control of accommodation, particularly when refracting hyperopes.

Using minus cylinder, the back focal line is placed on the retina first, with the circle of least confusion, and front focal line in front of the retina. Minus cylinder is then used to move the front focal line onto the retina.

In plus cylinder, the front focal line is placed on the retina first, leaving the circle of least confusion, and the back focal line behind the retina. Patients can still accommodate to place the circle of least confusion on the retina in this case, and I have found that this leads to many many more inaccurate Rxs.

Jen

 

[Richard_Hom]

Refracting in minus cylinder form allows for much better control of accommodation, particularly when refracting hyperopes.

Using minus cylinder, the back focal line is placed on the retina first, with the circle of least confusion, and front focal line in front of the retina. Minus cylinder is then used to move the front focal line onto the retina.

In plus cylinder, the front focal line is placed on the retina first, leaving the circle of least confusion, and the back focal line behind the retina. Patients can still accommodate to place the circle of least confusion on the retina in this case, and I have found that this leads to many many more inaccurate Rxs.

Jen

Quite true. Unless you refract under peripheral fusion only and central fusion is reduced. My favorite binocular balance technique is the Humphriss. Quick!

Richard_Hom

 

[cpw]

I've worked with both now... it took me awhile to get used to plus cyl (which is what the VA uses)... But like everyone is saying, you get used to what you have.