7 votes
Accepted

What are the different eyesight measures and how are they related to each other?

First of all, one has to distinguish between visual acuity (VA), which is a measure for the maximal possible resolution your eye-brain-system can achieve, and the refractive error, which measures the ...
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  • 781
6 votes
Accepted

What is this dot on the iris?

It is difficult to tell from that photograph what the pigmented area represents; a good photograph of the iris is hard to get without a slit-lamp (an instrument for close examination of the eyes.) ...
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5 votes
Accepted

How to reduce the side effects of wearing contact lens?

Questions 1-2 Unfortunately, the answer to these depend on the exact brand and line of contacts used. For example, here is a long list of silicon hydrogel lenses, and how long they last. Here is ...
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5 votes
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Is eye patching effective for older children with amblyopia?

Some studies have shown that eye patching has been effective in adults. One study1 tested teenagers ages 13-17 and found that, combined with glasses and near vision activity, patching was effective in ...
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  • 7,717
3 votes

What are the different eyesight measures and how are they related to each other?

The 0 to 1 scale is simply a decimal expression of the 20/20 (Imperial) or 6/6 (metric) measure of visual acuity. It's related to the smallest gap size someone can see on the Landolt C chart. ...
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  • 1,970
3 votes
Accepted

How is the eye score interpreted?

The information you provided Right lens Sph -0,50 Cyl -0,50 axis 10 Left Lens Sph -0,50 Cyl -0,50 axis 170 Type CR39 SN ARC is a little bit clearer than you can sometimes see. When you look ...
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  • 5,852
3 votes

What effects would aspheric contact lenses have on eyes without astigmatism?

A toric lens is the type that is used to treat astigmatism, not an aspheric lens. An aspheric lens is primarily designed to correct for the spherical aberration of the contact lens itself, the ...
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  • 237
3 votes
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Why are there different perscriptions for glasses and contacts? Help me see eye to eye on this

Partly the additional sizing information required for contacts (Diameter and curvature of the cornea are needed for contact lenses but not for glasses) and the power also changes because the physical ...
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  • 1,252
3 votes
Accepted

Based on the metrics of two glasses prescriptions, can I deduce values of an intermediary prescription

You should not try to self diagnose an eye prescription. That being said, I'm going to partly disagree with the previous answer based on some technicalities. First, the process you describe is ...
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2 votes

Based on the metrics of two glasses prescriptions, can I deduce values of an intermediary prescription

I have a magic number X. Take a guess what it could be? Is it 15? No, 15 is too high. Is it 12? No, 12 is too low. This leaves you with the mathematical average of 13.5, but that doesn’t help you ...
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  • 6,480
2 votes
Accepted

How do blue light filtering lenses work? Is it possible that they could they negatively impact your vision?

There are many different ways (proprietary methods) that these blue light coating are manufactured, but one general principle is called anti-reflection coatings. *I say "one general method" because ...
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  • 411
2 votes

Using farsighted glasses to counter nearsightedness?

Note This answer is not a substitute for medical advice and medical advice questions are off-topic here. If you have concerns about your eyesight you must speak to your optometrist (or ...
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  • 5,852
2 votes

Contiuously wearing the same contact lens - ok?

Generally, wearing the same pair of contact lenses longer then 6-12 months can cause increased risk of infection, as your biggest concern. Sleeping with contact lenses in has a similar risk, as ...
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  • 121
2 votes

Why do optometrists recommend dilation when the power of a lens can be measured even by a ruler?

The value of dilation of the pupil far outweighs the inconvenience.In fact, I'd offer that if an exam is done without it, you potentially lose the following: --full access to all the structure of the ...
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1 vote

"SPH" Written in Cylinder section of prescription, along with no axis?

I found the answer: "CYL" in Spherical section, means no correction needed "SPH" in Cylindrical section, means no correction needed If AXIS is zero, that is shorthand way some O....
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  • 111
1 vote

Why do optometrists "measure" your prescription with lenses orthogonal to the floor?

Although the tops of your ears maybe below the centre(s) of your eye(s) - you can have one ear lower than the other too - everyone is different. Some may find their ears are above the eye centres. ...
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  • 5,852
1 vote

Contiuously wearing the same contact lens - ok?

In optometry, "Continuous Wear" of contact lenses is a term used to refer to FDA approval of a contact lenses for wear continuously up to 30 days, then removing them for at least a full night of rest. ...
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  • 147
1 vote
Accepted

Light Sensitivity as a result of Caffeine Intake

From "Значение ретино-эпифизарной системы для психофармакологического эффекта" by Karen Ovanesov, who is co-author of one of those Russian articles on Pubmed to which you refer: (...) the ...
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1 vote

What is a "contact lens fitting"?

A contact lenses fitting is more expensive than a standard vision examination for glasses. There are several reasons. The doctor (Optometrist or Ophthalmologist) must measure more perimeters of the ...
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  • 147

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