Talk:Anisometropia

Astigmatism

Astigmatism is also a source of anisometropia. Glasses correction of anisometropia can lead to aniseikonia, or different retinal image sizes. Thalakan (talk) 04:25, 14 December 2011 (UTC)

What causes anisometropia?

[Blank contribution by Special:Contributions/2601:2C3:4201:D70:CC1A:C3C1:6DB3:367B on 28 Feb 2020.]

As a guideline: "Talk pages are for discussing the article, not for general conversation about the article's subject". Wikipedia is not a forum.

It is true that the article does not already yet fully address causes of anisometropia. I have added an empty heading on "Causes" to try to spur this (following the precedent for the "Diagnosis" section!).

If you feel that the article is incomplete or unclear, then please provide specific & constructive feedback on the Talk page, with as much detail as you are able to give. Alternatively, if you are confident about what should be added or amended, then you can be bold and make the edits yourself!

—DIV (1.129.106.159 (talk) 05:37, 27 February 2021 (UTC))

Example of the formula for iseikonic lenses

The formula for iseikonic lenses would benefit from an example.

Though I'm not an expert, I started drafting an example based partly upon general knowledge, and partly upon on default values for an online calculator.

However, I ran into trouble trying to typeset the mathematical formula. I wanted to show the working (including the size of each term in the formula), but I cannot seem to get the syntax to work.

Hence I left the following 'hidden' in the article for someone else to pick up on.

<!-- Example:<br> Consider a pair of spectacles to correct for myopia with a prescription of −1.00 m⁻¹ in one eye and −3.00 m⁻¹ in the other. Suppose that for both eyes the other parameters are identical, namely ''t'' = 1 mm = 0.001 m, ''n'' = 1.6, ''P'' = 5 m⁻¹, and ''h'' = 15 mm = 0.015 m. <br> Then for the first eye <math> \textrm{Magnification} = \frac{1}{(1-(0.001/1.6)×5)}\cdot \frac{1}{(1-0.015×−1)} </math> -->

—DIV (1.129.106.159 (talk) 06:50, 27 February 2021 (UTC))

I got the LaTeX syntax working, and have completed the example. (In fact, I extended it based upon some existing notes in the article.)

AFAIK, it is entirely consistent with the online calculator I linked to above. Nevertheless, I encourage experts to review it independently.

—DIV (1.129.106.159 (talk) 11:39, 27 February 2021 (UTC))

BTW, if you do review, then please do so carefully. For example, the online calculator has a drop-down option for a refractive index of 1.60, but in the underlying code (which I have examined in detail) the value actually used is 1.598 when that option is selected. —DIV (1.129.106.159 (talk) 11:43, 27 February 2021 (UTC))

I was tempted to say something like, "If full iseikonia cannot be achieved with practical lens dimensions, then a compromise that yields less severe aniseikonia may be deemed the best choice". Although this seems logical to me, I don't know for sure whether it's correct. If it is, I suggest it can be added to the article (preferably with citation of suitable references).

Peter Shaw distinguishes between "static" and "dynamic" mismatches. —DIV (1.129.106.159 (talk) 13:17, 27 February 2021 (UTC))

Vertex distance

This online calculator indicates that the distance used in the formula should be defined as that from the pupil to the back of the spectacle lens, rather than the cornea. It seems reasonable to me. If so, then the definition of h in the current WP article is not quite right.

It would also imply that with contact lenses the severity of aniseikonia would be much reduced, but not strictly zero.

—DIV (1.129.106.159 (talk) 11:56, 27 February 2021 (UTC))