One of the most important things you can do for yourself when you have diabetes is having a thorough dilated eye exam every year. Vision loss that occurs from diabetes is often asymptomatic and preventable if caught at the right time.
Usually, we do not have ample time to explain every little thing that we are looking for. So, if you are curious, I will be going through what I look for and think about while examining patients with diabetes.
When it comes to diabetes, numbers matter.
A few of those numbers are:
- How many years you have had diabetes. Around years 10-15 is when I see issues pop up regardless of how tight your blood sugar control has been.
- How high are your fasting blood sugar levels? Higher is likely to affect your eyes more quickly than if you are able to keep them lower.
- How much do your numbers fluctuate? Going from 70 to 300 in one day is much harder on your eyes than being at 100-190.
- Your A1C. It gives me an overall idea of your average over 3 months. If you have large fluctuations, your A1C can appear normal but in fact still have trouble with stable blood sugar levels. This is why your A1C is often paired with regular blood sugar checks (follow your doctor’s advice on this one).
As an eye doctor, what am I looking for?
- Blood spots (hemorrhages) and microaneurysms. These are the first signs that the blood sugar levels have caused microscopic damage to the blood vessel walls, which can cause leaking/hemorrhages or microaneurysms. Usually, these signs only need to be followed once a year unless they are many in number or are close to the macula/optic nerve head.
- Cotton Wool Spots and Exudates. These sound fluffy and cute but their presence indicates that there is now inflammation present in and on the retina. Inflammation means swelling of structures which can lead to vision changes that cannot be corrected with glasses or contact lenses. Depending on location, size, and amount seen, follow-up can be 1-6 months if I think it may be a threat to your vision.
- Swelling of the retinal tissue. If caught early and responding well to treatment, the swelling may not cause any permanent vision loss/changes. This would very likely be a referral to a retinal specialist for treatment or close monitoring.
- New blood vessel growth. The retina is not receiving enough blood and oxygen, so the retina creates new blood vessels. Unfortunately, these new blood vessels are sticky and end up deforming the tissue. These changes can permanently alter your vision or even pull your retina out of place. If the blood vessel growth extends to the iris, can cause an aggressive form of glaucoma.
- Tractional retinal detachment. These are rare and occur in patients who are non-compliant with diabetic treatment or who have a particularly difficult time with blood sugar control. This sort of detachment is devastating to the retinal tissue and will pull it out of place. Treatment is difficult because the tissue is so delicate and damaged.
Usually, patients only have #1 and #2 on this list. I share the information with the doctor that manages your diabetes, and they are able to more aggressively treat you if they need to. Usually #3-#5 are patients who have a very difficult time controlling their blood sugars, are non-compliant with treatment, or neglect their yearly dilated eye exam to screen for changes.
Other considerations:
If you have blood sugars that fluctuate, this can cause mild swelling in the lens of the eye. This swelling can slightly change your refractive error (glasses prescription) and even change throughout the course of the day. I may have you come back to repeat the refraction if I believe your blood sugars are affecting the results of the testing.
Just like your feet, the front surface of your eye is susceptible to bacterial infection. Even mild neuropathy (loss of sensation) can make it difficult for patients who wear contact lenses to know if they have an ulcer. Your doctor will take extra time to make sure that your cornea is safe from ulceration. This is why it is not recommended to sleep in contact lenses if you are diabetic. Sleeping in contact lenses dramatically increases your risk for ulceration and bacterial infection.
I also want to add that I have caught diabetes with routine eye exams many, many times in my career. These people are asymptomatic except for a few blood spots. A quick visit to their primary care provider revealed diabetes before they even have any symptoms of increased thirst, increased urination, increased hunger, or unexplained weight loss. This is yet another reason why I believe in routine eye exams before symptoms of vision change occur.