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Question:

From St. Paul, Minnesota, USA:

I am a 37-year-old person who's had type 1 diabetes for about 19 years. I'm generally healthy, with A1c's in the 6.7 to 7.1% range. Recently, an ophthalmologist told me that I have a type of cataract called a posterior subcapsular cataract in both eyes. This is a relatively new development after I've had very early and small cortical cataracts in both eyes as well. It's my understanding that the posterior subcapsular type is known to grow much faster than many other types of cataracts. I was wondering if there is an average or expected rate at which these grow, or how long it might take before this type of cataract affects vision enough that it interferes with daily functioning, driving at night, etc. Also, are the results of cataract surgery for people with diabetes generally favorable in the absence of diabetic retinopathy?

Answer:

If we all live long enough, we will most probably all develop a cataract(s)! There are many types of cataracts; nuclear sclerotic, cortical, posterior subscapular, traumatic, senile, sugar cataract… we often hear many questions including why and how fast will it progress. Are cataract surgery and intra-ocular lens implants safe for someone with diabetes and diabetic retinopathy? Do the environment and social habits affect when a cataract will form?

What we know/questions related to cataracts:

  1. Cataracts are usually age related (38.8% of men and 45.9% of women older than 74 have cataracts)
  2. Can be hereditary or congenital
  3. Excessive sun (UVA and UVB) exposure will produce cataracts (closer you live to the equator) or living in an area with loss of the ozone layer
  4. Long duration of high blood sugar levels (Glucose)
  5. Cigarette smoking or second hand smoke (20 per day have twice the risk of non-smokers)
  6. People on long term use of prednisone
  7. Poor nutrition, lack of vitamin A, C, E as well as selenium
  8. Systemic diseases; duration of diabetes and diabetic retinopathy (more advanced form of diabetes)
  9. Is vitrectomy safe in type 1 diabetes?
  10. Is surgery for cataracts safe for people with type 1 diabetes? (cortical cataracts, posterior subcapsular cataracts and “sugar cataracts”)

Can we avoid cataracts? Most agree that the answer is probably no, however, we can slow the process down with better nutrition, always wearing sun-glasses when outside, especially when it is cloudy since ultraviolet rays are still present - but since there is less light (dimmer) the pupils of the eye open wider and allows more light exposing the intra-ocular lens and retina in each eye.

Winter sports such as skiing, snow-boarding (high altitude) and summer activities at the beach or over water can all affect the health of the eye unless protected by wearing sun-glasses. Use of UV tanning booths is not only dangerous for skin cancer but also for early formation of cataracts. Avoid smoking cigarettes as well as exposure to second hand smoke.

During our screening process at Friends for Life, we always promote the use of sunglasses – as early as two years old (or earlier, if possible). This recommendation is for two main reasons: slowing down the early formation of cataracts as well as for protecting the retinal structure against sun damage. The cells (epithelium) that form the retina (the back of the eye that allows for vision) are the same as the ones that form our largest organ, the skin. If you go outside on a warm sunny day without applying sunblock you will probably end up with a sunburn. So, we wear sunblock to reduce the risk of sunburn and skin cancer. However, the same types of cells are found in the back of our eyes (the retina) have no sunblock. Wearing sunglasses is analogous to the sunblock we wear on our skin. Wearing a cap also helps to block scatter light.

High glucose levels have the effect of damaging the cell membrane (allowing calcium and sodium to enter the lens) and reduces the antioxidative defenses of the lens needed to protect itself from forming a cataract. Our early studies indicate that a critical period time is during the puberty phase when good or tight control of blood glucose level is difficult to maintain.

Advanced form of diabetic retinopathy is called proliferative diabetic retinopathy and may often require surgical intervention to save vision. This procedure is called vitrectomy where we remove the vitreous body from the eye (resting against the retina). This procedure has been linked to higher rates of cataracts (>63%) as opposed to non vitrectomized eyes (4%).

What is a sugar cataract? It is found mostly in type 1 diabetes (young adults 20 to 35 years old) with very poor control of blood glucose (over time). Along with traumatic cataracts, sugar cataracts are the fastest growing types of cataracts (in as little as three days) where glucose is converted to sorbitol. This substance breaks down very slowly in the body, however, sorbitol does accumulate in the physiological lens of the eye and attracts large volumes of “water” in the lens that consequently creates a cataract that can block 100% of the light to the back of the eye in as little as 72 hours. Having a cataract usually translates to some level of vision loss. In some cases, total loss of vision (usually reversible with IOL implants (intra-ocular implants) during cataract surgery) may be experienced. Prior to undergoing cataract surgery, it is important to know the health of the retina as well as the macula (macular edema). Pre-existing maculopathy is strongly associated with poor visual outcome in cataract surgery. Prior to considering cataract surgery, good control of your blood sugar as well as your blood pressure is important. Use of phacoemulsification usually translates to better visual acuity and less need for capsulotomy than extracapsular cataract surgery in patients with diabetes. Larger IOLs are useful in cases with patients affected with diabetes this to allow for better peripheral visualization as well as panretinal photocoagulation treatment if needed in the future. If the IOL is 6.5 mm (as opposed to conventional 5.5 mm) in size, then it provides a 39.7% better visualization of the peripheral retina. A silicone IOL should be avoided in patients requiring pan-retinal exam/laser treatment. The best IOL (for post cataract surgery) in patients with type 1 diabetes is, by far, a hydrophilic acrylic lens. Although practical for daily life use, multi-focal IOL lenses remain controversial and for now, it is not in the best interest in long term IOL user that have type 1 diabetes (the difference is people with type 1 will live with this lens for >60 years (in these years, the eye will undergo changes) versus the person with type 2 may live with this IOL 30 years).

Along with selecting the right procedure for cataract surgery, the right IOL, having your blood sugar, blood pressure under a reasonable control, having the retina and macula “healthy" - it remains critical to select a surgeon that understands well type 1 diabetes and that the surgeon has worked with the patient and or treating physicians for the best possible outcome. We all can play a role in the positive outcome of the cataract surgery and one of those positive outcomes must be “asking many questions” and asking perhaps the most important question of them all to your proposed surgeon: “How many of these exact procedures have you performed in patients with type 1 diabetes?”

There is some suggested online reading: Cataract Surgery in Patients With Diabetes and Age-Related Macular Degeneration; Are there different types of cataracts? and Cataracts.

BZ

DTQ-20170114080019
Original posting 14 Mar 2017
Posted to Other and Complications

  
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Last Updated: Wednesday March 22, 2017 15:55:36
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