It is important for people with diabetes to take care of their eyes to prevent blindness. As diabetes is the number one cause of blindness in people 20-74 years of age in the United States(1) and is the single largest cause of blindness among all ages in Canada(2); we are discussing this topic in some detail in today’s article. As mentioned in Part 1 of our series What is Glaucoma and 9 facts About It, three common eye problems include glaucoma, cataracts, and retinopathy.  Part 1 focused on glaucoma.(3) Today we will focus on cataracts and answer nine questions pertaining to them. Part 3 on retinopathy will be covered in a future article. 

eye with cataracts from uncontrolled diabetesWhat are cataracts?
According to the American Academy of Ophthalmology, a cataract is a clouding of the lens in the eye. The lens should be clear but in this case becomes (or is) frosted or yellowed. Cataracts may develop differently in your two eyes.(4) The lens becomes cloudy or opaque due to a build-up of protein. When this happens, light is not able to pass adequately through the lens and vision is compromised.(5)

Question 1: Where is the lens located in the eye, and what is its function?
The lens is located in the eye behind both the iris (the colored part of the eye) and the pupil (the center of the iris where light enters the eye). A healthy lens is clear and able to change shape to focus images of objects on the retina. Muscles in the eye exert tension on the lens to change its shape. When focusing on items that are close, the lens is more rounded. When distance vision is needed, the muscles cause the lens to elongate to achieve sharp focus. As most people age, the lens becomes less flexible and loses some of its ability to focus objects that are close. This condition is called presbyopia and reading glasses become helpful to focus on objects that are close.(6,7) 

Question 2: What are the different types of cataracts that people may have?
According to The National Eye Institute (NEI) which is part of the National Institute of Health (NIH), there are five types of cataracts.(8)

1. Age Related Cataracts - This is the most common cause of cataracts.(9)  This type of cataract is the result of proteins in the eye clumping up over time. This causes a clouding of the lens which reduces the light which reaches the retina. This type of cataract may be slow to develop, and initially it may only affect a small part of your lens.  In this case, vision may decrease gradually, focus may be less sharp, and blurring and/or vision loss may occur.(10) Age related cataracts may cause the lens to change color from clear to a yellow/brown color. This tinting may cause problems with color identification. An example of this is the color purple may appear black. Tinting may also affect your ability to read.(10) Other vision problems may include a decreased ability to see items clearly without contrast and the inability to judge depths. A drop off in the pavement when walking may be more difficult to see which may result in a fall.(11) It is not unusual for people with cataracts to need four times more light to read or to do activities such as puzzles, needle work or maintenance around the home. People are often more sensitive to glare and have difficulty with driving in the evening and at night. Blurring may cause problems with enjoyment of daily activities such as watching television or movies.(11)  

The American Foundation for the Blind defines three kinds of age related cataracts. They are nuclear sclerotic, cortical, and posterior subcapscular. The subcapsular type of cataract develops in many people with diabetes or those who use steroids. It forms on the back surface of the lens. People with this type of cataract see halos and glare with lights. Visit the American Foundation for the Blind for more information.

2. Congenital and Infantile Cataracts - Congenital cataracts are present at birth and infantile cataracts form in the first six months of life. Causes of these cataracts include hereditary factors, infection and metabolic disorders. Many congenital cataracts have no known cause.(12) These types of cataracts are very rare. They are found in 1 in every 2000-5000 children. Infants should be treated for cataracts during the first six weeks of life to get the best outcomes for their sight.(13) For more information on congenital cataracts vist the Royal National Institutie for Blind People.

3. Secondary Cataracts - These may form after eye surgery or may develop in people that have health issues including diabetes or steroid use.(8) They may also develop in people who suffer from retinitis pigmentosa, hypoparathyroidism, atopic dermatitis, and uveitis.(14)

4. Traumatic Cataracts - Trauma from an eye injury can cause a cataract. These may form immediately or many years after the incident. Types of trauma can include blunt force, penetrating, chemical or electrical.(14) 

5. Radiation Cataracts - These may develop after radiation exposure (nuclear or from cancer treatments). They may also develop due to ultraviolet radiation from sunlight.(14) 

Question 3: What does it look like to see through the eyes of someone with a cataract?
The American Academy of Ophthalmology has a cataract vision simulator available on their site so you can see what vision looks like for a person as a cataract develops.

Question 4: In what age group are cataracts commonly found?
In the United States, 50 percent of people age of 80 and older have cataracts.(15) It is sad to note that they also develop in people as young as 40 years of age who were exposed to excessive radiation, cigarette smoke, some medications and in those with diabetes.(16) In fact, according to the American Diabetes Association, people with diabetes are 60 percent more likely to develop cataracts than those without diabetes. In addition, those that have diabetes are more likely to develop cataracts at a younger age and they may develop faster than those without diabetes.(17) 

Question 5: I heard that cataracts are the leading cause of vision loss in the United States.  Is this true throughout the rest of the world?
While cataracts are the leading cause of vision loss in the United States(18), according to the World Health Organization, cataracts remain the leading cause of blindness in middle- and low-income countries.(19)

Question 6: I also heard that smokers have a greater incidence of cataracts. Is this true?
Heavy smokers (15 cigarettes/day or more) have up to three times the risk of cataract as nonsmokers.(20) 

Question 7: What are they symptoms of cataracts?
Johns Hopkins Medicine lists the following as possible symptoms of a cataract:
  • vision that is cloudy or blurred
  • double vision 
  • colors that appear faded instead of bright
  • halos around lights;
  • problems with glare
  • vision distortion, objects are no longer clear(21) 
Question 8: Is there anything I can do to prevent cataracts from forming?
 According to Loma Linda University the following six steps can be taken to help delay or avoid cataracts;
  1. In people with diabetes control blood glucose levels to normal or nearly normal.(22)
  2. Stop smoking if you are a smoker.(22)
  3. Control alcohol consumption - consuming more than one alcoholic beverage per day potentially increases the risk of cataracts by four times.(22)
  4. Some medication such as steroids may increase the risk of cataracts. These medications may be the best choice for your health condition.(22) Talk to your physician about this. 
  5. Obesity is a mild risk for the development of cataracts.(22) Work with your dietitian to maintain a healthy weight.
  6. Eat your fruits and vegetables.(22) (Results from the Women’s health study showed a 10-15 percent reduce in the risk of nuclear cataract formation if they ate more than 3.4 servings of fruits and vegetables per day.(23) 
For more information on preventing cataracts visit the Loma Linda University - Opthamology page.
The Mayo Clinic also recommends wearing sunglasses in the sun to protect your eyes from ultraviolet light.(24) 

Question 9: What are the treatments I can consider if I have cataracts?
If vision is not a problem and the cataract is small, your eye doctor may prescribe different glasses. You may also try using a magnifying glass and read or work with strong lighting. Surgery is available when cataracts become worse. An artificial lens replaces the lens that has been affecting your sight.(25)  Visit the National Eye Institute for more information regarding Cataract Surgery.

Remember to take good care of your eye sight. Ask your eye doctor how often you should have a complete eye exam. Problems with eyes occur more frequently in people with diabetes. Educate yourself on potential problems you may have and what to do if you develop signs or symptoms of cataracts. Your vision may depend on it!

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