Saturday, November 10, 2012

Magnification is Key in Macular Degeneration Treatment

Magnification treatment is the best option for restoring vision with macular degeneration

Dr. Randolph Kinkade Demonstrating Magnification
in the Treatment of Macular Degeneration

Magnification is the key low vision rehabilitation treatment option
for people with macular degeneration. Magnification Power
can be determined theoretically by ratios.
Near Magnification ratio:
    Smallest Print Size the Patient Can Read Without Magnification/
Print Size the Patient Wants to be Able to Read
If a patient can read 3M print with their glasses and they would like to read 1M Print:
3M/1M = 3X magnification is the starting point (Linear Magnification)
3X Reading Telescope
Distance Acuity Magnification ratio:
Patient’s Current Distance Visual Acuity/
Patient's Goal Distance Acuity Level
For example, if a patient has 20/80 minus visual acuity and they want to see 20/40 then they will need 2.0+ magnification.
20/80-  = 2.2X Telescope  (Angular Magnification)
2.2X Bioptic Telescope
Stargardt's Macular Dystrophy
Corrected For Refractive Error

Dr. Kinkade Calculating Magnification
Based on Visual Acuity

(800) 756-0766

Call Dr. Kinkade for a free telephone consultation
Cheshire - Danbury - Farmington - Litchfield - Manchester - Norwalk - Waterford


Therapy for Macular Degeneration

High-Power Glasses and Eccentric Viewing Therapy are two key factors for regaining reading ability for people with macular degeneration.   Patient motivation and adaptability are equally important.  Prescription low vision glasses and locating the patient’s best eccentric viewing position (preferred retinal locus: PRL) are challenging.
Telescopic Reading Glasses
PRL for Reading
With advancing macular degeneration, the center straight-ahead detail vision reduces.  The clarity is no longer there due to “blurry-blind” spots (scotomas).

NEI Central Scotoma

Eccentric viewing is particularly useful when scotomas affect both eyes.  When a person no longer looks directly at the object they want to see, they are eccentrically viewing (i.e., they are using a healthier part of the retina).  If they look directly at something, they cannot see it as well as if they look to the side.
With a central blind spot, looking slightly above, below or to one side of the object it can be seen better.  The view is not perfect, but better than if they were looking straight ahead.  For example, someone’s facial features may be better seen by looking over their shoulder or at their forehead.
"I recognize the body, but not the face"

Regaining Ability to Perform Everyday Reading Tasks
When reading, patients report different symptoms.  They will say letters are “missing”, “greyed-out”, “distorted”, “do not make sense” or “they come and go”. 
Reading speed is dramatically reduced.  With advancing disease it is not uncommon to hear patients say “I read like a first grader”.  Eye fatigue and body stress are also common symptoms leading to frustration and exasperation.
Most patients have one off-center position where they can see the best.  The challenges are to find this position and to be able to hold it consistantly so it can be use most effectively.  The position can be practiced while looking at people’s faces, watching television and reading.  For reading it is some times best to practice with single words.

Ways to Find the Best Eccentric View Point:
Amsler Grid

Clock Dial

Single  Letter or Words


Steady-Eye Posture Therapy
Once the eccentric viewing position is determined high-powered glasses (prismatic, telescopic, or microscopic) are prescribed.  The patient views a word maintaining the eccentric position and the print is slowly moved to the left so that each word in turn is moved into the best area of vision.
With central scotomas, the patient must continue to view eccentrically or the glasses will only magnify a blurry image.

Monocular Reading Telescope
Binocular Reading Telescope

Experience has shown that it is best to have the patient sit back comfortably in a chair and bring the print up to the glasses (to the focal length of the prescription) keeping the back and neck straight. 
Depending on the size of the scotoma, it is often more challenging to place the reading material on the table and bend over close to it.  Using a clipboard to support and help stabilize the reading material is beneficial.

Telescope Reading With a Clipboard
Start with large print initially to establish consistency.  Patience is the key and the goal is to reduce the font size as reading speed increases.  Fluidity is one goal.  Reading one-word-at-a-time makes it difficult to get the context of the sentences. 
Returning back to the next line of print presents another challenge.  One technique is to slide the print back to the right to allow the patient to quickly scan back along the line of print that has just been read to the beginning and then move down to the beginning of the next line.
Another technique is to use a line guide across the sentence that is dropped down when the sentence is completed.
Experience has also shown that for some patients the power of the prescribed glasses (i.e., magnification) may be reduced after adapting Steady-Eye Posture strategies.  Reducing the power increases the field of view and the reading distance.

Powerful Reading Telescope
Therapy sessions are best in short duration and repeated several times throughout the day.  Length and duration depends on the level of vision loss and the print size goals.
For effective therapy, prescription glasses, eccentric viewing techniqes, and patient motivation are critical components.
(800) 756-0766

Call Dr. Kinkade for a free telephone consultation
Cheshire - Danbury - Farmington - Litchfield - Manchester - Norwalk - Waterford

Friday, November 9, 2012

Macular Degeneration Patients of the Month: November 2012

Dr. Randolph Kinkade, utilizes Spectacle Miniature Telescopes (SMTs) and Implantable Miniture Telescopes (IMTs) to help patients with macular degeneraion and other vision limiting conditions.

Condition: Macular Degeneration
V.V. has bioptic distance telescopic glasses for walking, watching television, seeing facial features, bird watching and social interaction.  She is able to raise her chin to look under the telescopes for using her normal vision and lower her chin to spot through the telescopes for enhanced distance vision. 

Wide-Angle Bioptic SMT Telescope
She was also dispensed a slip-behind glare filter for use outside with two drilled holes in the filter allowing the mounted telescopes in her glasses to fit through.  
Dr. Randolph Kinkade with V.V.
and her Wide-Angle Bioptic SMT Prescription

V. V.'s right eye monocular reading telescope allows her to read .8M at a 14” viewing distance (prescription bottles, mail, newspapers).  With practice she is looking forward to writing her Christmas cards. She has a pen pal in Iceland.

Monocular Full-Diameter Reading SMT 

Condition: Congenital Aniridia, Glaucoma, Corneal Dystrophy, Nystagmus
D.M.  is using a 10X bi-convex microscopic prescription in his right eye.  He is able to spot read 1.6M @ 2” viewing distance.  He is scheduled for glaucoma surgery and an artificial cornea in his left eye.


D.M.uses sunglasses for glare control and has a guidedog to assist with mobility.

(800) 756-0766

Call Dr. Kinkade for a Free Telephone Consultation
Cheshire - Danbury - Farmington - Litchfield - Manchester - Norwalk - Waterford

Thursday, November 8, 2012

Prismatic Eyeglasses for Macular Degeneration

Prismatic glasses use prism to improve reading for people with macular degeneration and other vision limiting conditions. They are useful for patients whose two eyes are approximately equal in vision and require relatively lower magnification. They are often beneficial for reading the newspaper and for writing checks.

Dr. Randolph Kinkade and Eileen Zitnik with
Prismatic Glasses for Macular Degeneration

Patients with macular degeneration and other vision limiting conditions need more magnification in order to read.  Regular glasses have a limit on how much magnification they can provide. With mild to moderate vision loss, prismatic magnifying glasses can offer reading improvement.

Prisms are used in higher power reading glasses for patients with equal vision in both eyes.   High magnification lenses require both eyes to turn in far enough to see a single image and to be able to read comfortably.

There are three significant challenges when trying to gain extra reading magnification when reading with both eyes is one of the goals.  The first challenge is the lens power's relationship relative to the viewing distance and depth of field.  The second challenge is the limits of binocularity (fusion of the two eyes) due to our eye anatomy.  The third challenge is our reading habits of where we hold our reading material.

Dr. Kinkade's Patient
+8-Diopter Full-Frame Prismatic
Lens Power and Viewing Distance

As a lens becomes more curved and thicker it becomes more powerful.  As the power increases, the focal length or viewing distance (i.e., where you hold the reading material from your glasses) becomes shorter. 

There is no way to get around the laws of optics.  For gaining the most magnification and clarity, and assuming there is no distance refractive error, the reading material must be held at the focal length of the lens.  Stronger lenses have shorter focal lengths, and therefore, stronger lenses require you to position the reading material closer to the lens.  That is the law.

Over-the-counter reading glasses are labeled in diopters. They come under powers of +4.00 diopters.  Diopters are a measure of focusing power.  The higher the diopter value, the quicker the lens focuses images.  For the average reader, with no distance refractive error, a pair of +2.50 diopter lenses focuses reading material best when held at 16" (i.e., a normal reading distance).

+4-Diopter Prismatic

Patients with macular degeneration and other vision limiting conditions need more magnification in order to read.  We can gain higher magnification by holding reading material closer than the normal 16".   The closer the material is held to the eyes, the more magnification is gained.  As the reading material is held closer, higher dioptric power lenses are needed to focus what is being read at the close viewing distances.

+6-Diopter One-Piece Prismatic
Designs For Vision

For someone without a distance refractive error (i.e., no farsightedness or nearsightedness) the following table is educational:
Focal Distance in Inches Based on Dioptric Lens Power
    Wearing a  +4.00 diopter lens requires the reading material must be held at 10".
 Wearing a  +5.00 diopter lens requires the reading material must be held at 8".
  Wearing a   +6.00 diopter lens requires the reading material must be held at 7".
  Wearing a   +8.00 diopter lens requires the reading material must be held at 5".
  Wearing a +10.00 diopter lens requires the reading material must be held at 4".
  Wearing a +12.00 diopter lens requires the reading material must be held at 3".


Prismatic Half Eyes:
Designs and Powers
Prismatic reading glasses come in different dioptric powers: +4.00, +5.00, +6.00, +8.00, +10.00, and +12.00.

Another challenge with stronger lenses is their shorter depth of field.  Although a lens can precisely focus at only one distance, the depth of field is the distance on either side of this point where the reading material still appears sharp enough to read. The shorter the depth of field the more critical it is that the reading material be placed and held at the precise focal distance.

Functional Reading Depth of Field Based on Dioptric Lens Power With Small Print
+2.50  diopter lens  13.00" - 20.00"
+4.00  diopter lens   9.50" - 10.50"
+8.00  diopter lens   4.75" - 5.25"
+12.00 diopter lens   2.82" - 3.12"

As you can see from the above, when viewing through a +2.50 diopter lens the reading material can be moved 3-4 inches closer or further away from the sharpest focus point of 16" before it blurs. With a +12.00 lens you only have to move the reading material an eighth of an inch away from its focal distance of 3"and it will be blurred.

Eye Convergence and Anatomy

When we look into the distance, our eyes are looking straight ahead and parallel with each other.  The closer something is to the eyes the more the eyes have to converge (turn in).  The eyes sit in the orbits in the skull and each eye has six muscles used for positioning the eyes.  At the normal 16" viewing distance the eyes can easily and comfortably converge.  For viewing distance less than 12" it becomes more difficult for us to converge enough to remain binocular (i.e., use both eyes).

A prism bends but does not focus light.  A prism creates rainbows by bending each color wavelength differently.  In glasses, prisms are used for several different things and not for making rainbows.    For prismatic reading glasses, prisms help reduce the convergence needed in order to see binocularly.

Prism Reduces
Convergence Demand

Base-in prisms (the think part of the prism is placed towards the nose), in various amounts, are used to reduce the amount of  convergence needed to remain binocular depending on the power of the prescription lenses.

The closer you hold things the more prism is needed to remain binocular.

Rule of Thumb
Prism Required Based on the Convergence Demand
4 lens diopters with 6 units of prism
 6 lens diopters with 8 units of prism
   8 lens diopters with 10 units of prism
10 lens diopters with 12 units of prism
12 lens diopters with 14 units of prism
Convention and Muscle Memory

+5-Diopter Prismatic
+6-Diopter Prismatic



The longer someone has read at 16" the more adaption time it takes to learn to read at closer distances.  You have to learn to bend your elbows and allow the print to get closer to the eyes.  The muscles in your arms (proprioceptors) will feel funny at first.  The more magnification needed requires more time learning and more practice.

Start reading with large print so the power and depth of field are not so critical.

The Take Home Messages
1.  The more magnification required, the stronger the lens has to be.

2.  The stronger the lens has to be, the closer you need to have the reading material to your eyes and 
     at the focal length.

3.  To read binocularly you need relatively equal vision in both eyes.

4.  To read binocularly at close distances you need prism to help with the convergence of the eyes.

6.  It takes practice and motivation to learn new ways of seeing.

(800) 756-0766

Call Dr. Kinkade for a free telephone interview
Cheshire - Danbury - Farmington - Litchfield - Manchester - Norwalk - Waterford

Tuesday, November 6, 2012

Guide to Macular Degeneration: Short Answers to Complex Questions

Questions and Answers Concerning Vision and Macular Degeneration.

What is the miracle of sight?

Sight is something we use almost every waking minute, and take for granted until it is diminished.  Of our five major senses (taste, touch, sight, smell, hearing), vision is primary as it best connects us to our world.    Vision lets us be productive.  Vision helps to protect us from danger.  Vision brings us joy. 

How does the eye work?

First, the eye focuses light and images of our world onto the retina in the back of the eye.  In “technical geek language” the eye is a transducer.  The retina cone and rod photoreceptors instantly help convert the light energy all around us by a biochemical reaction into electrical energy the brain can use.   The electrical signal from each eye is transmitted to the brain by its own optic nerve.

What are cone and rod cells?

Cones and rods are light-sensing cells. 

There are 120 million rod cells and they are more sensitive to light than cone cells.  Rods are located more in the peripheral retina and are helpful for side and night vision.  A rare condition, called retinitis pigmentosa, affects these cells creating “tunnel vision”. 

The 6-7 million cone cells are critical for providing central detail vision.  There are three types of cone cells, each most sensitive to a different color:  blue, green or blue.
Rod and Cone Cell

What are the similarities between the eye and a digital camera?

The cornea and the eye's lens, at the front of the eye, are used to focus light similarly to a camera lens.  Like a camera, the eye must capture and process this light energy.  This is done by the retina in the back of the eye.

Instead of a retina, digital cameras record images electronically on fingernail-sized silicon chips that are image sensors having millions of photosensitive diodes.  Each captures a single pixel in the photograph.

Each optic nerve is a bundle of over 1 million nerve fibers “cabling” the eye to the visual cortex at the back of the brain.  On route from the retinal photoreceptors to the brain, the signal is starting to be processed.  The brain further processes these signals. 

What are the differences between the eye and a camera?

The eye is easily one thousand times more complex than most advanced camera.  The eye is essentially an extension of the brain.  Before birth, during embryological development the eye, and brain develop from the same neural tube.  That is why it is said “the eye is part of the brain”.

You can easily replace your camera, its components and batteries.  There are no whole eye transplants.  Only the cornea and lens can be replaced.  There are no retina (macula) or optic nerve transplants.  There certainly are no brain transplants.

What is the Retina?

The retina consists of ten layers which make up the inside layer of the eyeball.  It can be described as having the thickness and consistency of a single sheet of wet tissue paper.  The retina's rod and cone photoreptors change light energy into electrical energy.

What is the difference between central and peripheral vision?

It is helpful to use the analogy of two, but interrelated, bull’s eye targets to describe the relationship between central and peripheral vision.

Clarity drops off dramatically as one moves out from the center rings.  By the fourth ring, acuity (sharpness) approaches the level of legal blindness (20/200)

The center red dot represents the macula.
Each consecutive ring from the center to the periphery represents another drop in acuity level.
What is the Peripheral Retina?

Side vision, or peripheral vision, is not affected by macular degeneration.  Peripheral vision is very useful for walking and general vision, but it provides low resolution (i.e., details are not clear) vision.

With the use of magnification and eccentric viewing techniques, the peripheral vision becomes very beneficial for macular degeneration patients.

Where and what is the Macula?

The macula is a highly pigmented spot near the center of the retina about 5 mm or ¼th inch in diameter.  It is about the size of the capital letter “O”   Due to the density of cone photoreceptors, the macula is responsible detail and color vision.

What is the Fovea?

The tiny fovea is the sweet spot in the center of the macula where the highest resolution vision is located.  This is the “HD-high definition” part of the macula and is only 1mm or less than 1/16th of an inch in diameter.  It contains over 100,000 densely packed cone cells and no rod cells. 

The fovea comprises less than 1% of the retina size or two degrees of visual field (twice the width of your thumbnail arm’s length), but is vital for seeing fine detail and color.

Why is the Fovea so important to vision?

It is responsible for providing the clearest and most distinct 20/20 vision.  It is needed for reading, writing, driving and any activity where visual detail is necessary.

Despite its small size, approximately 50% of the nerve fibers in the optic nerve carry information from the fovea, and information from the fovea takes up over 50% of the visual cortex in the brain. 

What is Macular Degeneration?

Macular degeneration is the physical breakdown of the macula that causes problems with vision.  Anything that affects the macula affects one’s central high-resolution vision.  Anything that affects one’s central detail vision greatly affects one’s quality of life.  

Macular degeneration progresses to a certain stage and then stabilizes. 

What are the different types of macular degeneration?

Based on the age when the condition manifests itself, there are early, middle, and late-onset macular degenerations.  The early and middle-onset macular degenerations are hereditary and classified as a group of macular dystrophies (juvenile macular degeneration).  The late-onset macular degeneration is usually age related, but may also have some hereditary influences. 

What is Stargardt’s Disease?

Although rare, this early-onset MD is the most common of the hereditary macular diseases
Stargardt’s is transmitted recessively, meaning the gene had to come from both parents.

Other hereditary macular diseases are:  
1. Juvenile Best’s disease
2. Adult vitelliform degeneration
3. Cone dystrophies  (affects one of three classes of cones)
4. Leber’s congenital amaurosis

What is Age-Related Macular Degeneration (AMD)?

For varied and not fully understood reasons, the macula begins to break down.  AMD is disease associated with the aging process of the macula.  AMD initially advances slowly with little change in vision.  As the condition advances some vision-related activities become more difficult than others (i.e., reading).   Vision loss becomes debilitating when the fovea in the better seeing eye is affected.   

Thirty percent of adults over age 75 have early signs of macular degeneration and over fifty percent by age 80.

What are RPE cells?

The Retinal Pigmented Epithelial cells (RPE) help support, nourish and maintain the health of the photoreceptors.  It is believed that it is the loss of the RPE cells that causes the loss of the photoreceptors needed to see with. 

What is Drusen?

Drusen are small yellow or white deposits under the retina in the macula seen in the early stages of MD.  They can be classified as “hard” or “soft”.  Soft drusen is more medically significant.  Drusen causes the RPE to separate from the retina.

What are the levels of vision loss due to MD?

The severity of vision loss depends on the stage of the disease.  In the early stages, only the doctor may notice changes in the macula during an examination.  In the intermediate stages, optical aids are needed to help with reading and other visual activities.  At the advanced stages of MD, low vision rehabilitation is required to help restore some visual functioning.

How many people have Age-Related Macular Degeneration?

It is believed that about 10 million Americans or 3% of the population suffer from some degree of macular degeneration.  Based on current demographics, approximately 200,000 people in Massachusetts, 100,000 people in Connecticut, and 30,000 people in Rhode Island have this condition.

What is Dry Macular Degeneration?

Eighty-five to ninety percent of people with macular degeneration have the dry form, which involves thinning of macular tissue and disturbances in its pigmentation.  It is usually the milder and more slowly advancing form of the disease, but it still can lead to significant vision loss (geographic atrophy).

What is Geographic Atrophy?

End-stage macular degeneration due to loss of pigment
Vision Level: legal blindness

What is Wet Macular Degeneration?

Whereas Dry MD comes on slowly over many years, the onset of Wet MD tends to appear suddenly (overnight) and gets worse rapidly.  In reality, Wet MD also takes years to develop, but shows up quickly by its sudden reduction in vision.  There are treatments to curtail the damage, but there is no cure.

 What is Discaform Scarring?

End-stage macular degeneration due to scar formation
Vision level: legal blindness

Are there symptoms of MD?
a.      The most common symptom is blurred vision
b.      A blind spot in the center of vision  
c.       Straight lines may become distorted or crooked
d.      Reading mail or newspapers becomes challenging
e.      Seeing road signs and traffic lights become difficult
f.        Faces become more difficult to recognize
g.      Considerable more light is needed to read
h.      Side or peripheral vision remains unaffected
i.        Glare sensitivity increases
j.        Adjusting to changes in lighting environments becomes problematic

What are the treatments for MD?

Presently there is no cure for any form of macular degeneration.  There is only treatment for the wet from of age-related macular degeneration and treatments are aimed at stabilizing and preventing severe vision loss.  Current treatment consists of a series of injections with the drugs Lucentis and Avastin (anti-angiogenesis drug) that block the development of new blood vessels and damaging leakage. 

Good nutrition, including ocular vitamin supplements, appears to slow the progression of AMD. 
For vitamin and nutritional therapy consult your doctor.

 What is on the horizon for treatment of MD?

1.      Stem Cells: growing replacement RPE cells for injection into the eye
2.      New drugs: in clinical trials
3.      Gene Therapy: altering hereditary factors
4.      Retinal Chips: artificial retinas

What are the risk factors for AMD?

The risk for AMD increase with age and age is the number one risk factor. 

a.      Age  (the number one risk factor, prevalence increase with age)
b.      Smoking (increased risk 2-5 times)
c.       Race (blue eyed Caucasians)
d.      Family history (25%-40% AMD patients have a family history)
e.      High fat diet or one low in nutrients and antioxidants
f.       Obesity
g.      High exposure to ultraviolet light (UVA & UVB)

What is an Amsler Grid?

Self-monitoring of the Amsler Grid can assist in monitoring the progression of the disease.
Any additional squiggly lines or distortions require immediate medical attention.

Can you go totally blind with MD?

It is exceedingly rare to go totally dark-blind with macular degeneration because peripheral vision remains intact.  Seeing well enough to safely walk can become more challenging, but certainly not impossible.

Is there rehabilitation for macular degeneration?

Absolutely! Low Vision Rehabilitation restores useful vision by eccentric view training and employing magnification and lighting techniques.  Low vision rehabilitation serves a vital and necessary role in the treatment of macular degeneration.

Dr. Randolph Kinkade
Low Vision
Magnification Demonstration
Dr. Randolph Kinkade
Low Vision
Lighting Demonstration

Dr. Randolph Kinkade's Macular Dengeneration
Treatment Television Interview

(800) 756-0677

Call Dr. Kinkade for a free telephone interview
Cheshire - Danbury - Farmington - Litchfield - Manchester - Norwalk - Waterford