Talk on RxLAL plus lens, with EDOF

Thanks.

Do you think this might be good for a "near" eye, and if so, what target would you aim at.... I am thinking about -1D below the "far" eye, instead of about -1.5D.

This is asking for a guess before actual data is out. But I wonder if data will be out? I have not seen a defocus curve for RxLAL, even tho that has been out since 2017, and was in testing for a good while before.

Without data it is just a bit of a guess as to what would work. I guess the up side is that you have the ability to adjust up or down from the -1.0 D starting point based on what you can see. -1.0 D would be good for a Vivity lens in the near eye, so if it is similar to Vivity, you should be in the ballpark.

FWIW, Dr Wong says he generally uses -0.75 D or -1.00 D for the near eye using the regular LAL. He has posted videos showing impressive-seeming results.

trilemma,

Can a defocus curve be done for the LAL if every lens has different adjustments?

My suspicion is that the depth of focus addition, if it really exists, would occur in both the LAL and LAL+ lens, as it seems to be simply a side effect of the light adjustment process. If that is true then the LAL+ would ultimately have more depth of focus for the same adjustment step.

If we assume asphericity that just broadens the defocus curve, that would not seem to imply that a peak focus -1D would be chosen vs a -1.5D for a non EDOF lens.

Positive asphericity tends to flatten the defocus curve. At a cost in peak visual acuity it extends good vision to closer distances. For that reason one my get good enough near vision at -1.0 D comparable to a standard monofocal at -1.5 D. But stretching the focus point by 0.5 D is quite a lot. 0.5 D is the minimum required to call the lens an EDOF. It will be interesting to see if they will claim EDOF status.

I don't see that that flattening should make you chose a less negative target for the near eye.

What you need to look at is the defocus curve and where it intersects the horizontal 20/32 visual acuity limit. Normally the flattened curve will let you see 20/32 at closer distances than a standard monofocal. For that reason you can pick a less myopic offset from plano to get the same near reading vision.

To get a good feel for the EDOF factor have a look at the P930014 Vivity Package Insert PDF. Figure 5 on page 13 compares the standard monofocal defocus curve to the EDOF Vivity curve. The logMAR equivalent of 20/32 is 0.2. So if you follow along the 0.2 horizontal line you can see the Vivity extends the defocus at that visual quality from 1.0 D to 1.5 D. That would be the logic for offsetting the Vivity by 0.5 D less than a standard monofocal to get the same reading vision. And at the 0.0 D peak vision point you can see the visual acuity price that is paid for that extension. And further back you can see the MTF contrast sensitivity curve where a much higher price is paid for the EDOF effect. That is the other technical information that is missing from the LAL+ product, the impact on contrast sensitivity.

What you need to look at is the defocus curve and where it intersects the horizontal 20/32 visual acuity limit. Normally the flattened curve will let you see 20/32 at closer distances than a standard monofocal. For that reason you can pick a less myopic offset from plano to get the same near reading vision.

The usually reason for not targeting -2.5D is so that your two eyes share enough info to give you some depth of field. With a broadened curve, you could still get more depth perception. It seems to me that this works both ways.

It is not an objective to not be able to read 6-point type. [intentional double negative] Product packages sometimes have 7 point font. Targeting -1.5D, vs -1.0D, with an EDOF would seem to make 7-point font more readable, with out giving up depth perception and stereo.

So I guess I am skeptical of the doctors that suggest moving the mini-monovision closer to plano because an EDOF lens is being used.

Yes, it depends on your priority and view about anisometropia. Some want to minimize the differential between the eyes, and want more overlap between the eyes. But, yes if you are not worried about that, it is possible to use the EDOF to get better near vision.

"To get a good feel for the EDOF factor have a look at the P930014 Vivity Package Insert PDF."

.

Those figures and tables are highly informative. I think a good plan would be to target:

• Substantial EDOF for the near eye, using LAL or LAL+ to nail the desired myopia
• No EDOF for the far eye, using regular LAL to nail plano sphere and cylinder.

The near eye would provide good-though-not-perfect acuity over a relatively broad range of near/intermediate distances. If contrast sensitivity is ever a problem, you can just shine a flashlight or cellphone on something that close.

.

The far eye would provide best attainable acuity and contrast sensitivity for nighttime driving, and could also be used (with glasses) for seeing tiny print or objects.

Eyeglasses can correct refractive errors, but they cannot correct the smearing of the focus point caused by the EDOF. So, I am not so sure they can help one recover the lost contrast sensitivity. The distance non EDOF eye may save the day for nigh time driving.

I would guess you are right, that glasses would not correct for loss of contrast sensitivity in the near eye. That's where I would expect to rely on either good lighting or the non-EDOF distance eye with strong reading glasses.

o get a good feel for the EDOF factor have a look at the P930014 Vivity Package Insert PDF. Figure 5 on page 13 compares the standard monofocal defocus curve to the EDOF Vivity curve. The logMAR equivalent of 20/32 is 0.2.

I was not expecting that degree of asymmetry about zero. Your point make sense. Thanks.

The fact that that graph shows inferior focus for the EDOF at 0D makes that graph much more credible.