Magnifier Guide For Macular Degeneration

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Dr. Randolph Kinkade
Magnification Treatment for Macular Degeneration

Why does magnification help reading with macular degeneration?

The macula is in the center of your retina in the back of the eye.  A healthy macula is needed for reading.   With advancing macular degeneration, you lose this sharp center vision that is necessary for reading and seeing details. 

Patients with macular degeneration describe their center vision as being “cloudy” or “greyed-out” or “distorted”.  They describe “letters are missing” or “letters come and go” as they read.  This loss in vision is a relative blind spot or central scotoma that usually cannot be restored.

 

Simulated Reading Scotoma

Magnification aids make what you are looking at bigger so it is it is easier to see.  The more you magnify, the smaller your blind spot becomes relative to the size of the magnified print you are looking at.  This makes reading better, not perfect, but better.   Magnification means more healthy macular cells are being stimulated.  Depending on the level of vision loss, magnification may not always make vision clearer. 

What is the power of my magnifier?

There is always confusion between magnification power (X power) and optical power (diopter power) of a magnifier.

What is a “X” power of a magnifier really mean?
Magnification power is the ratio between the image size you see through the magnifier compared to the true size of the object you are looking at.  If an object seen through magnifiers appears five times larger than its true size, the magnification power is 5 times or 5X.

Why do I see “diopter” power listed or printed on some magnifiers?

The term diopter refers to the optical power of the lens with regards to its ability to bend light and not directly to the magnification power.   The higher the dioptric power the more the lens bends light and the higher the potential magnification.  The higher the dioptric power the higher the magnification.

All “X” power is not the same, but all “diopter” power is the same.

Unfortunately manufactures use different formulas to calculate the power of their magnifiers so it can be challenging to tell whether one manufacture’s 6X magnifier is really stronger than another’s 5X magnifier.  With diopters you cannot go wrong.  A 24-diopter magnifier is stronger than a 16-diopter magnifier.

Some manufacturers divide the “diopter” power by four to get their “X” power.  Other manufacturers divide the “diopter” power by four and add one more “X” to their formula to get their “X” power.

Another challenge in comparing strengths is the manufacture may not disclose the diopter power to you and they often inflate the “X” power.

Why can I not find a really strong page magnifier to help me read?
Sorry, it is the laws of physics and optics that prevent you.  The stronger the lens (more diopters or magnification) the more curved the lens has to be.  It is the lens curvature that limits the physical size of the magnifier.  Flat page magnifiers cover a large area, but offer minimal magnification.  A chicken egg has a very steep curvature and is small in size.  An ostrich egg is relatively large because its shell is not as curved. 

 

Curvature adds power, but limits its diameter.

In the movies, Sherlock Holmes’ magnifiers were large, but also with minimal power.  Most large magnifiers are only 1-2.5X.  A medium size magnifier will be 3-4X.  Small magnifiers will be 5-7X The tiniest magnifiers, about the size of a quarter and with a very steep curve will be 10-12X.  






Dr. Randolph Kinkade 
large diameter, 4-diopter magnifier.

Some magnifiers come with an additional tiny strong button magnifier near the edge.  Noticed how powerful and curved that extra lens is. 

What is “focal length”?
Focal length is the distance behind the lens where print focuses the best.  The higher the “diopter power” or “X power” of the lens, the shorter the focal length of the lens. 

Why do I have to hold a stronger magnifier closer to the page?
Since a strong magnifier has a very short focal length it needs to be held close to the page.  A

2X magnifier needs to be held 5” from the page for best magnification.  A 5X magnifier needs be held 2” from the page and a 10X magnifier needs to be held 1” from the page.

Why should I hold a strong magnifier closer to my eye?

One of the challenges of using a strong magnifier is the small field of vision it provides (i.e., only a few letters at a time).  The closer you hold the magnifier to your eye the more letters you will see at a time before you have to move the magnifier.

How do I use a 10X (40-diopter) or 12X (48-diopter) magnifier?

This lens has a very small diameter and visual field.   You will want your best seeing eye almost against the lens to see as many letters as possible.  This lens has a very short focal length and should be held very close to the page. 

At this power, it works best to have a built in illumination source.   It is difficult to get an external reading lamp to brighten what you are reading due to the required short viewing distances.  Your head and magnifier get in the way of a reading lamp illuminating the page properly so it is best to use a magnifier with its own illumination source.



10X LED Illuminated
Eschenbach Stand Magnifier

(800) 756-0677
www.LowVisionEyeglasses.com
DrKinkade@SeeandHearAmerica.com
Cheshire - Danbury - Farmington - Litchfield - Manchester - Norwalk - Waterford