Preventing and/or Minimizing Diabetic Eye Disease: Clinical Pearls

Paul Chous, M.A., O.D. Doctor of Optometry
Type 1 diabetic since 1968

In my previous monographs on “diabetic eye disease,” we have considered different ophthalmic conditions more prevalent in diabetic patients. While diabetic retinopathy is a quintessential example of both microvascular diabetes complications and diabetic eye disease, we have seen that it is only one of several distinct eye conditions commonly affecting this population of patients. In addition to retinopathy, diabetes also causes, or is highly associated with, glaucoma, corneal disease, cataract, and eye muscle dysfunction.

And this list is by no means exhaustive, as patients with diabetes also experience acute retinal vascular occlusive disease (both retinal artery and retinal vein occlusion) and ischemic optic neuropathy (essentially a “stroke” of the optic nerve) at much higher rates than the general population (for a thorough and accessible discussion of each of these entities and the points that follow, the interested reader may wish to consult my book on diabetic eye disease.) Taken collectively, this constellation of eye diseases accounts for many times the number of cases of ocular morbidity and vision loss than does diabetic retinopathy as an isolated entity. Moreover, as many of these conditions occur concomitantly with diabetic nerve, kidney, and macrovascular disease, the importance of prevention, detection and coordinated management becomes even clearer.

Keys To Preventing Diabetic Eye Disease

(1) Optimize blood glucose control.
Chronic hyperglycemia plays a clear and direct role in the pathophysiology of four of seven diabetic eye diseases (retinopathy, cataract, keratopathy, and cranial neuropathy). Moreover, because hyperglycemia negatively affects lipid status and hemodynamics (including increased adhesiveness of platelets), it plays at least an indirect role in glaucoma, retinal vascular occlusion, and ischemic optic neuropathy.

The DCCT showed that intensive blood glucose control lowered the risk of developing diabetic retinopathy by 76%; secondary (meta-) analysis further showed that each 10% reduction in HbA1c reduced the risk of retinopathy progression by 43%, and this linear reduction in risk held until glycohemoglobin was well under 6%. The UKPDS demonstrated a 25% overall reduction in microvascular complications amongst intensively managed Type 2 patients, the majority of which benefit derived from reduction in the incidence of retinopathy. Evidence suggests equally encouraging reduction in risk for premature development of cataract; at this time, insufficient data exist regarding glycemic status and risk of other diabetic eye disease (i.e. the question has not been studied rigorously vis a vis these other entities), though the epidemiologic link between diabetes and each of these conditions is indisputable. .

(2) Optimize blood pressure control
The UKPDS clearly showed that, for Type 2 patients at least, tight control of any hypertension lowers the risk of diabetic retinopathy even more than does tight glycemic control, yielding a 34% reduced risk of substantial worsening of DRT. Moreover, reducing blood pressure lowers the risk of retinal vein occlusion, the second most common retinal vascular disease seen in eye care practice (after DRT), and improves overall ocular blood flow to cranial nerves, including the optic nerve (although lowering systolic blood pressure acutely may worsen pre-existing glaucoma by disrupting vascular autoregulation at the optic nerve). There is certainly no doubt about the macrovascular benefits of strict blood pressure control in patients with diabetes.

(3) Optimize blood lipids
Dyslipidemia increases the risk of vascular occlusion, and this raises the risk of diabetic eye disease. Diabetic macular edema, in particular, often is worse in patients with lipid abnormalities. Epidemiological studies also show an association with retinal vascular occlusion, cataract, glaucoma and other cranial neuropathies. In addition to its macrovascular benefits, aspirin therapy may lower the risk of diabetic eye disease, and the Early Treatment of Diabetic Retinopathy Study (ETDRS) showed that aspirin does not worsen pre-existing retinopathy (though in cases of active vitreous hemorrhage, it may be prudent to delay therapy.)

(4) Dilated Eye Examinations
Ensure your patients receive a dilated eye examination per ADA guidelines. Most cases of serious vision loss from diabetes are preventable with early diagnosis and timely therapy. Dilated examinations enhance detection of virtually all eye disease by facilitating better, stereoscopic views of all ocular structures. Make certain your patients understand that good vision on an eye chart does not mean they don’t have serious, vision threatening diabetic eye disease, as many patients with severe retinopathy and glaucoma have 20/20 vision at the time of diagnosis (including myself, circa 1985).

(5) Educate and Communicate
Patient education is perhaps the single most important tool for preventing diabetes complications, including eye complications. We are all well aware of the rationalizations offered by poorly informed and non-compliant patients, and I have given them myself. My experience has been, not surprisingly, that the more informed patients are about all aspects of diabetes, the more motivated they will be to accept our guidance, the less likely they are to experience complications and the better able they are to cope with complications if/when they do occur. Of course, patients can be overwhelmed by details, but then again, so too can health care professionals; yet this fact does not and should not deter us from knowing and mastering the details that allow us to give better patient care. As my fellow diabetic and patient advocate extraordinaire, Steven Edelman, M.D. says “People with diabetes must work with their caregivers and not merely trust and wait for the proper care to be delivered…the educated patient is the best patient because they help you do your job and, in the long run, save you time and money.”

Effective communication also means that members of a patient’s health care team communicate well with each other. This not only facilitates coordinated care, but allows practitioners from various disciplines to present mutually reinforcing messages about good diabetes management. This will, indeed, make all of our jobs easier and, most importantly, give our diabetic patients the best possible chance for good outcomes. Patients must live with diabetes every minute of every day, and it makes absolute sense that they and their health care providers be empowered to control diabetes through excellent communication, education, understanding, and encouragement.
Next time, we will consider “remedies” for irreversible vision loss, including a “crash course” of sorts into the field of low vision.

About the Author

Dr. Paul Chous received his undergraduate education at Brown University and the University of California at Irvine, where he was elected to Phi Beta Kappa in 1985. He received his Masters Degree in 1986 and his Doctorate of Optometry in 1991, both with highest honors from the University of California at Berkeley. Dr. Chous was selected as the Outstanding Graduating Optometrist in 1991. He has practiced in Renton, Kent, Auburn and Tacoma, Washington for the last 12 years, emphasizing diabetic eye disease and diabetes education. Dr. Chous has been a Type 1 diabetic since 1968. He lives in Maple Valley, Washington with his wife and son.

About the Author Dr. Paul Chous is the recent author of a critically acclaimed book for patients and health care providers on diabetes and the eye, Diabetic Eye Disease: Lessons From A Diabetic Eye Doctor – How To Avoid Blindness and Get Great Eye Care (Fairwood Press). He may be reached via his web site at http://www.diabeticeyes.com.