Confused and delaying cataract surgery

im curious. how do smaller pupils lead to a better(Larger i assume) range of focus? thx

i dont know. pinhole effect?

That is correct. It is like simple box camera with a very small aperture (F16 or smaller). It increases the range of distances that are in focus.

Take a piece of aluminum foil, poke a hole with a pin, and hold the hole near your eye on a sunny day. See how well you can focus over a big range.

I sometimes form 3 finger into a pinhole, and use that in a grocery store to see the fine print ingredients.

Similarly, when your pupil gets smaller just from bright light, your depth of focus (depth of field) will get wider-- not as much as an actual pinhole.

I want to thank RonAKA for calling this study to our attention. On the one hand, it is consistent with other studies showing generally favorable results with the Barrett Universal II formula (my own surgeon's choice). See, e.g., Oleksiy V. Voytsekhivskyy, et al., Accuracy of 24 IOL Power Calculation Methods, J. Refract. Surg. 2023; 39(4):249-256 (noting, however, that "the small amount of short and long eyes did not allow us to perform a full-fledged statistical analysis in the different subgroups, so that the results were reported with informational purposes only").

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Also, in considering or using the "Optimizing Outcomes" article, one should be aware of possible limitations. For example, a Bryan Lee reviewed what appears to be the same study in "Comparison of IOL power calculations for low myopia in monovision", American Academy of Ophthalmology (Aug. 20, 2020). I say appears because the article Dr. Lee reviewed is by the same authors but entitled "Accuracy of intraocular lens power calculation methods when targeting low myopia in monovision", and was published in the Journal of Cateract and Refractive Surgery in June 2020. Although the JCRS article is not open access, what is freely available suggests that, at a minimum, it reports on the same underlying study, and is possibly the same basic article, as "Optimizing Outcomes".

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According to Dr. Lee:

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First, the Optimizing Outcomes study examined 88 patients targeted for plano in one eye and -1.25 D in the other eye. Insofar as the question is the accuracy of IOL calculation formulae for myopic targets, the study may be less reliable when the targets are, for example, -0.75 D or -1.00 D in the "distance" eye" and -2.00 D in the "near" eye (using myself as an example).

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Second, patients studied only were offered monovision if the distance eye achieved uncorrected distance vision of 20/25 or better and the second eye had similar visual potential. Among other things, this may have been a source of bias because entry criteria based on successful near vision performance may have produced different results.

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Third, this was a small retrospective study.

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Fourth, the study does not discuss biometry, so it is difficult to assess the applicability of the study's results to general practice.

Cool! Dr. Lee was my surgeon. (San Francisco bay area)

I got Vivity mini monovision and am very happy with it. One eye has some vitreous degeneration, which causes clear blobby floaters sometimes, but that is probably partly due to being 64 years old.

While endorsing everything @Lynda111 says, one point I'd add is the importance of deciding on your vision priorities in the context of the plusses and minuses of different possible approaches. Some people, for example, choose multifocal IOLs for the possibility of achieving, or of having a greater likelihood of achieving, good distance, intermediate, and near visual acuities. Others, myself included, are unwilling to risk the negative optical/visual side effect experienced by a significant number of multifocal recipients. And for many multifocal IOLs--or the LAL for that matter--simply aren't an affordable option.

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And there are choices within the monofocal category, too. Some simply prioritize seeking the best distance vision attainable. Others, @RonAKA and myself, for example, choose monovision--for us, in its "mini" form--aiming at good visual acuity at more than one focal distance. @RonAKA chose distance and intermediate, and may have lucked out and also gotten some functional near vision. I chose intermediate and near, and depending on the results from my second eye, scheduled for August, may also end up with functional distance vision.

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Given all the variables and uncertainties, however, I follow my own sympathetic surgeon in urging you not to overthink your choices.

Just to be clear, the near vision I got was quite intentional and well planned. It was not good luck. If there was any good luck involved it would be the intermediate vision I got with my distance eye. Most people with monofocals do not seem to see well down to 18" like I can with my distance eye. Some cannot even see their car dash clearly. So I lucked out in that respect. I suspect it is due to being myopic prior to surgery, and being 73 with smaller pupils, and in being very careful (thanks to my surgeon) not to go over into the plus side of plano.

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If I was to do the near eye over again there is only one thing I would change. I would get a 1.0 D cylinder AcrySof toric lens to reduce my cylinder, and go one step higher in overall sphere power to give me more residual sphere myopia. The end spherical equivalent still would have been in the -1.6 D range, but it would be more pure sphere power and less astigmatism cylinder. Astigmatism can give you some near vision but it is not the ideal way to get it. It compromises visual acuity. I get drop shadows on text especially when reading white text on a black background.

Eyeballing the Clareon monofocal defocus curve in a recently published, open access, Alcon-sponsored study shows a mean visual acuity of 0.0 logMAR, or 20/20 Snellen, at 0.0 D, and 0.30 logMAR, or 20/40 Snellen, at -1.25 D. Clayton Blehm and Brad Hall, Evaluation of Visual Outcomes and 3-Month Refractive Stability of a New Hydrophobic Acrylic Intraocular Lens, Clinical Ophthalmology (July 3, 2023).

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Moving the curve 1.5 D to the right, that is, to a refraction very slightly more myopic than your 1.40 D spherical equivalent, would indicate this same mean visual acuity at -2.75 D, or 14.31", which is very close to the distance for reading the Jaeger chart. As 0.30 logMAR corresponds to reading J5, if, as you've written, you " can read J1 in full sunlight, and J3 with indoor lighting", then I suggest you have lucked out.

You seem to take defocus curves as the "Gospel" quoting them down to the second decimal point. They have significantly large error bars with them. The second decimal point is insignificant let alone the third decimal point. It is misleading to think of those defocus curves as a single line. They should be seen as a big broad band of potential outcomes with units of feet or meters, not fractions of an inch. My outcome is well within the broad band.

I've many times noted that defocus curves report mean visual acuities--indeed, that's the phrase I used in the comment to which you've replied--and sometimes show standard deviation (not error bands, at least within 1 standard deviation). If one ends up with better than the mean result, I think good luck is involved. If you want to think it the result of something else, possibly, careful planning, intentionality, or superior moral character, you're welcome to your opinion.

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In all events, what alternatives are there to defocus curves that don't involve statistical analysis of data gathered from multiple subjects?

"Understanding the Defocus Curve Millennial Eye" Not a technical article. Written for laypersons.

An article with which I'm familiar, it having been written by my surgeon.

All of the information I have seen available indicates -1.5 D is the optimum amount of myopia for mini-monovision. That is what I have and I like it. You have to careful not to get so into the detail that you don't see the forest for the trees. For example, mixing up sphere with spherical equivalent. Spherical equivalent is what is important.

Now that is cool!

Experts disagree regarding the "optimum" degree of monovision. Further, most discussions with which I'm familiar presume that the distance eye is targeted for somewhere between plano and the first minus result shown in the patient's IOL power calculation. If one doesn't prioritize distance vision, different conclusions well may follow.

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Regarding the "optimum" degree of monovision, for example, a February 2021 article in Cataract & Refractive Surgery Today by Drs. Andrew Turnbull, Warren Hill, and Graham Barrett says that "[s]o-called modest monovision, which aims for emmetropia in the distance eye and approximately -1.25 D in the near eye, has been shown to offer the best of both worlds, with a good level of spectacle freedom for most tasks and a minimal risk of anisometropic symptoms." Optimizing Outcomes When The Target Is Low Myopia, p. 35 (citing Naeser K, Hjortdal JØ, Harris WF. Pseudophakic monovision: optimal distribution of refractions. Acta Ophthalmol. 2014;92(3):270-275). I don't present the view of these eminent authors as gospel, only as substantial evidence that matters are not as simple as some may think.

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Regarding the optimum refractive targets, at least two points are worth making here. First, they depend on one's visual priorities/goals. If excellent or very good distance vision is primary, then targeting plano or, for the more prudent among us, targeting the first minus may be optimum for the intended distance eye, which ought to be done first. Assuming the actual result hit or is very close to the targeted refraction and that it actually provides a satisfactory distance visual acuity, then one could subtract whatever degree of monovision one regards as optimum to determine the optimum target for the second, near eye. And in this case it might turn out that the targeted refraction for the near eye indeed is -1.50 D. Or, it might not.

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But if excellent or very good intermediate and near reading vision are primary, then plano or the first minus is unlikely to be the target for either eye and, as my surgeon suggested and I agreed, doing the intended near eye first makes sense. One might, for example, target somewhere between -2.00 D and -2.50 D. Assuming the result hits or comes very close to the target and that intermediate and near vision are satisfacotry, then one could add the "optimum" degree of monovision to determine the target for the second, more distant eye. Whether that differential is 1.25 D or 1.50 D, the "optimum" target won't be -1.50 D..

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Finally, the discussion so far has assumed that the surgery hits or comes very close to the targeted refraction. But this often doesn't happen, and this without any fault or incompetence of the surgeon. Because the consequences of "too great" a differential between the two eyes may be severe, a patient may avoid @ronAKA's sugeted optimum and, ideally having been able to trial mini-monovision with contact lenses either before the first surgery or between the first and second, will choose a refractive target for the second eye that allows for a degree of refractive surprise.

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If this is too much detail, and bearing in mind that refractive targets and degrees of monovision are only some of the decisions to be made for cataract surgery, then I suggest finding a highly reputable surgeon who is willing to listen patients' desires, provide objective information, and suggest possible alternatives, and then rely on his or her judgment. For me, getting into the weeds was preparation for conversations with my surgeon, on whose judgment I've ultimately relied.

The issue is much simpler than what you have talked yourself into. This will be my last response to your posts. Good luck with your second eye. As I have said before I think your double conservative approach is leaving you with compromised distance vision. If you end up wearing glasses for distance or normal near, then your mini-monovision approach has failed.

"For every complex problem there is an answer that is clear, simple, and wrong." H. L. Mencken. (Also reproduced on the web as: "There is always a well-known solution to every human problem—neat, plausible and wrong.")