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Diabetes: A Deep Dive

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Diabetes: A Deep Dive

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The eye is the only place in the body where we can non-invasively view blood vessels and how healthy they are. So viewing the retinal blood vessels tells us a lot about your overall health and wellness. By having an annual comprehensive checkup, diabetic complications (as well as other conditions) can be caught early and addressed. If complications are seen in the eye, chances are there could be issues in other parts of the body as well, including nerve damage (neuropathy), kidney damage (nephropathy), cardiovascular disease, and foot damage. As eye care providers, we are able to communicate our findings to your primary care provider, endocrinologist, and other specialists as needed allowing everyone to work together to care for you. We love being a part of your health care team!

You may hear about newer technology available that allows a doctor to see the back of the eye without dilating the pupil, sometimes called Optos or Optomap.  This is a excellent tool for providers to put together a complete picture of the retina, when we see it in pieces during examination.  It also is a wonderful way to educate patients about any form of ocular disease because they can see a representation of what we are examining.  It is a great option for young, healthy patients with no family history of eye disease to have at some visits, rather than having their pupil dilated.  However, when doctors are looking for signs of diabetes mellitus in the eye, nothing can substitute for a dilating the pupil and examining the retina with a slit-lamp biomicroscope or a binocular indirect ophthalmoscope (BIO).  Dilation is not optional for the diabetic patient, so be prepared to have this done during your visit by bringing your favorite suns (or we will give you a really fashionable disposable pair, haha) and a driver if you feel uncomfortable driving afterward.  With your normal distance correction, most patients are not bothered enough by the dilating drops to not want to drive, but its always good to have company and a second set of ears to listen to the doctor’s findings and recommendations. 


When blood glucose levels are chronically elevated, damage can occur to the tiny blood vessels in the eye leading to diabetic retinopathy.  The vessel wall is weakened, which allows blood and other fluid to leak out onto the retina. If this leaking is severe enough, it can cause permanent loss of vision. The retina has a high metabolic requirement, meaning it needs a lot of oxygen and nutrients to function well.  If the tissue is not getting the required amount of oxygen (called ischemia) the cells will release signals such as vascular endothelial growth factor (VEGF).   This will stimulate new blood vessel growth in an attempt to bypass damaged arteries.  This new abnormal blood vessel growth can occur on the surface of the retina, the iris, and the optic nerve, which can lead to scarring and cell loss.  Sometimes swelling in an area of the eye called the macula causes diabetic macular edema. In addition, fluctuation in glucose levels can cause the lens in the eye to swell. We will discuss a little more of each of these complications.

Diabetic retinopathy is progressive damage to the back wall of the eye, the retina, and is a serious potentially sight-threatening complication from diabetes mellitus.  Over time, high glucose levels in the bloodstream will damage the tiny blood vessels that supply blood to the retina.  This allows blood and other material to leak and tissue to swell.  The severity of the condition will determine appropriate treatment. 

Diagnosis and severity of:  Non-Proliferative Diabetic Retinopathy (NPDR)

-  Mild - at least one microaneurysm or hemorrhage found anywhere in the retina 

-  Moderate - multiple retinal hemorrhages, cotton wool spots, or venous beading

-  Severe - multiple retinal hemorrhages, cotton wool spots, or venous beading and severe intraretinal vascular abnormalities (IRMA), a combination of each usually in multiple quadrants of the retina.

Diagnosis and severity of:  Proliferative Diabetic Retinopathy (PDR)

-  Involves neovascularization anywhere in the eye, including the iris, retina, angle, and optic nerve.  These new blood vessels are leaky and fragile and sometimes even grow off the retina protruding into the internal space of the eye and the vitreous. Natural changes that occur in the vitreous over time can cause friction and pulling on these fragile vessel and can tear them off resulting in blood in the vitreous (vitreal hemorrhage) and can even progresss into a tractional retinal detachment.

Ever notice that the glasses that worked really well one day this week, are not working so well anymore?This results in the lens changing shape and can change your refractive error or glasses prescription.  Elevated blood glucose levels will increase sorbital concentration.  Sorbital cannot easily pass through the walls of the lens fiber cells.  But water can.  And so to try to correct this imbalance, water moves into the cells of lens causing the lens to swell.  A swollen lens will bend light rays differently that one that is more normal in shape, therefore you prescription is very different at times if your blood glucose levels are swinging.  Therefore, stable blood glucose levels are important to get an accurate glasses prescription.  Your optometrist may recommend waiting to update your glasses prescription if your blood glucose is poorly controlled.

Neovascularization of the iris in diabetes in referred to as rubeosis iridis and appears as tiny blood vessels crossing over the surface of the iris.  It occurs in response to ischemia in the eye.  The body is responding to low levels of oxygen in some tissues by creating new tiny blood vessels in an attempt to get those cells oxygen.  Rubeosis iridis is a form of proliferative diabetic retinopathy and if this is observed, we become concerned about neovascularization in the angle of the eye, where the cornea and the iris meet.  This can lead to a difficult condition to control - neovascular glaucoma.  Diabetic patients that do develop proliferative diabetic retinopathy will often first develop it the back of the eye, with retinal complications.  Then as the eye becomes progressively ischemic, the new blood vessel growth will happen more toward the front of the eye, involving the iris and angle.


Insulin is produced by the pancreas, which helps glucose to enter the cells of the all the organs and tissues throughout the body. We want glucose to enter our cells to be used as an energy source.  In a healthy person, this process takes place without any problems.  However, complications arise in people diagnosed with diabetes.

In type I diabetes, the pancreas is unable to produce insulin, which causes glucose to remain in the bloodstream (hence the elevated blood sugar readings) and unable to enter cells. Injecting insulin is literally lifesaving therapy to these patients.

In type II diabetes, insulin is produced and actually binds to the insulin receptor of the cell, but the cell does not get the correct signal to open the glucose channel and allow glucose to penetrate. Again, the glucose will remain in the bloodstream, unable to be used for energy production in the body and high blood sugar readings will result.


The body wants blood glucose maintained in a very narrow range and insulin is one of the hormones that help regulate this. Insulin is a molecule produced by the pancreas, specifically beta cells and it is the signal for muscle, fat, and liver cells in the body to absorb glucose from the bloodstream to be used for energy. Insulin is so important in the body because we cannot survive without glucose and it acts like a key that unlocks the cells to let glucose enter them.

Did you just eat an amazingly, tasty meal and maybe over eat a little? We’ve all been there.  Insulin will help the body to store any excess glucose lingering in the bloodstream inside the liver to be used later.  When there has been enough glucose released from the liver, insulin will signal it to stop.  Additionally,  amino acids and fatty acids are also helped into cells by insulin.

Type I diabetes is an autoimmune disease where the body actually attacks and destroys the beta cells in the pancreas, therefore annihilating the body’s ability to produce insulin.  But, that doesn’t mean that the patient’s body won’t have glucose in the blood.  It comes from the food we eat being broken down into smaller molecules.  So a patient will have glucose in there bloodstream, but no insulin to help it into cells.  Therefore, levels of glucose in a type I diabetic patient can actually be dangerously high, to the point that develop a serious and potentially fatal condition called diabetic ketoacidosis.  An injection of insulin or insulin pump is actually life-saving for some patients.

In type II diabetes, insulin is actually being produced by the body, but remember the cells receptors are not responding to it properly.   The body will essentially need even more insulin to get that glucose across the cell membrane to be used in cellular respiration.  The beta cells in the pancreas go into overdrive and wear themselves out.  Eventually, they will not be able to keep up with the demand and glucose levels will rise to abnormal levels. 


Laser treatment can be performed in an office setting and involves highly focused intense beams of light applied to the damaged leaky retinal vessels to seal them off.  The most common laser used is Argon Green, with a wavelength of 530nm.  Each bright flash of light lasts about 0.02 seconds on an individual point on the retina.  This helps prevent further progression of the disease but it does destroy retina tissue that will no longer be usable for vision.  A patient will experience a visual field defect or scotoma in there field of view where treatment occurred.  A more extensive form of laser treatment is pan retinal laser photocoagulation, where laser is applied to a large portion of the entire peripheral retina.

In extremely advanced diabetic eye disease, medications and laser is not sufficient.  Vitreal hemorrhages must be removed from inside the eye by a vitrectomy, which will be performed in an operating room, not an office setting.  If a retinal detachment develops, a vitrectomy will also be necessary.


Ocular complications from diabetes mellitus can be a potentially serious and sight-threatening condition.  Our goal is to provide you with the best care to ensure your vision remains as normal as possible.  With the newest in technology here at the office, including optical coherence tomography (OCT) and retinal photography, we can provide superior care and love spending time with our patients to ensure they understanding everything about their ocular health. We would love to be part of your healthcare team.  Come see us today!