Diabetic Retinopathy

1. Diabetic Retinopathy Management & Clinical Considerations Optometry 8370 Winter 2008

2. Diabetes – The Disease • Simulates the aging process, so that diabetics are physiologically about 10 years older than their chronological age, secondary to: • Alterations in the DNA unwinding rate • Increased collagen cross-linking • Increased free radical activity • Increased basement membrane thickening

3. Diabetes – The Disease • Increased risk of cataract and other aging related diseases • Higher incidence of atherosclerosis • Decreased general functional status Unclear whether these changes are due to increased insulin resistance or glucotoxicity…

4. Diabetes Management • Since 90% of our diabetes patients are of the Type II variety, we don’t often deal with frank proliferative disease • The optometric challenges are to: • Rule out neovascular disease by thorough expert retinal examination • Refer patients with the appropriate signs to a retinal specialist at the appropriate time • Confirm that the patient is doing all they can to manage their condition medically

5. Analyzing Risk in Diabetic Retinopathy • To adequately know the risk a patient with nonproliferative retinopathy has of moving to proliferative disease, the optometrist must first be confident of the eye signs; when any doubt exists, a prompt second opinion is warranted. Underestimation of the degree of retinopathy may have grave consequences

6. Analyzing Risk • Standards for clinical management of diabetic retinopathy are based on the results of 3 nationwide clinical trials: • The Diabetic Retinopathy Study (DRS) • The Early Treatment Diabetic Retinopathy Study (ETDRS) • The Diabetic Retinopathy Vitrectomy Study (DRVS)

7. Analyzing Risk • “These studies have definitively established the efficacy of laser surgery for PDR and ME and have provided guidelines concerning the most opportune time for intervention with laser surgery and vitrectomy.” • Care of the Patient with Diabetes Mellitus AOA Clinical Practice Guidelines

8. Analyzing Risk • The ETDRS modified and extended the Airlie House classification of DR to assess the severity and extent of the various lesions; clinical approximations of these levels provide practical guidelines for the clinical diagnosis and management of DR, and risk of progression to proliferative disease

9. Analyzing Risk • Severe nonproliferative DR (NPDR) has a 52% risk of progressing to PDR in 1 year, and a 60% risk of progression to high-risk PDR within 5 years; follow-up every 2-3 months in consultation with a retinal specialist is advisable • What constitutes severe NPDR?

10. Analyzing Risk • Severe NPDR: • One or more of the following: • Heme or MA in all 4 quadrants • Venous beading definitely present in 2 quadrants • IRMAs in 1 quadrant • Definition not met for Very Severe NPDR (2 or more lesions of severe NPDR) and PDR

11. Analyzing Risk • Appropriate referral for retinal consultation exists when the patient exhibits Severe NPDR or CSME, or when the clinician lacks the clinical skills and confidence to manage less severe classifications of disease • Patients with moderate NPDR (heme &/or MA, soft exudates, venous beading, and IRMA definitely present) should be considered for focal laser Tx of ME, whether clinically significant or not, in preparation for possible future need for PRP

12. Analyzing Risk • DRS and ETDRS conclusively proved that timely laser photocoagulation of diabetic retinopathy can reduce severe visual loss by 95% • Such treatment saves $250-500 million annually by keeping patients off disability and welfare

13. Analyzing Risk • ADA Recommends: • Type I patients: Annual screening starting 5 years after the onset of disease, then annually thereafter • Type II patients: Immediate screening, then annually thereafter

14. Analyzing Risk • Remember: • One fourth of IDDM patients and one third of NIDDM patients have never had their eyes examined • One third of DM patients who are at high risk of vision loss have never had an eye exam; when they are examined, two thirds exhibit ocular manifestation of DM • Half of all Americans with diabetes do not receive an annual dilated eye examination (especially the poor and blacks) • Half of all diabetic Americans aren’t aware of their disease

15. Analyzing Risk • These numbers are disturbing, since the DRS, ETDRS, DRVS, and numerous other studies have shown that early referral for eye care, and prompt and appropriate intervention, significantly reduce the risk and severity of eye disease • Work with primary care physicians, patients & their families, and other health care professionals you meet to urge regular eye care for diabetics • Many cases of vision loss are preventable!!!

16. Analyzing Risk • Note: The Airlie House classification of DR, and the accompanying standard photographs, are available from the AOA. The general guidelines outlined here are a good start to understanding the management of diabetic eye disease, but careful review of the Airlie House photos and guidelines is strongly recommended

17. Optometry and Medicine • Organized medicine has been slow to recognize optometry as being its ally in the fight against diabetic blindness, despite our expertise in diagnosis and management • Duane’s 2001: “Alternative methods of screening when ophthalmologists are not available include the use of primary care physicians or photography. Although primary care physicians commonly fail to detect significant retinopathy with direct ophthalmoscopy, training significantly improves their ability. If ophthalmologists are not available, photography has also shown to be an effective means of screening.” • What about the expertise of 30,000 O.D.s nationwide??

18. Diabetes Management • Patients suspected of having DM should be referred to their physician to be screened for high blood glucose levels • Fasting blood glucose analysis is the screening method of choice • Values over 126 mg/dl suggest DM • Values of 115-126 may have impaired glucose tolerance, and should be retested • Random blood glucose levels over 200 mg/dl are suspect; further work up is mandatory

19. Diabetes Management • What does the OD need to know to manage the DM patient appropriately? • Thorough medical and ocular history, with emphasis on new symptoms and complaints • Type and duration of DM (time of onset of disease is not as important at duration of disease in predicting complications) • Name, address, phone number of patient’s PCP

20. Diabetes Management (cont.) • Other required medical information: • Diet information • Oral medications and dosages • Insulin type & dosage • Presence of proteinuria • Method, frequency, and results of blood glucose self-monitoring • Date and results of last glycosylated hemoglobin (HbA1c) test • In-office measurement of blood pressure

21. Diabetes Management (cont.) • Why do we need all this information? • Insight is provided into: • Patient compliance with sometimes complicated therapeutic regimens • Control of DM, which may affect development of ocular complication • The level of care being provided by their PCP

22. Diabetes Management (cont.) • HbA1c: • Indication of average blood glucose levels and control of DM over previous 8-12 weeks • Level at baseline examination has been shown to be a strong and independent predictor of incidence and progression of any retinopathy or progression to proliferative retinopathy • (Klein R, Klein BE, Moss SE, Davis MD, et al. Glycosylated hemoglobin predicts the incidence and progression of diabetic retinopathy. JAMA 1988; 260:2864-71)

23. Diabetes Management (cont.) • HbA1c: • Laboratory values vary, but values between 5.0-7.0 % usually indicate adequate control; always check reference values from lab • Values greater than 10.0% significantly increase the risk for PDR • Educate DM patients that the results of this test are as important for them to know as other routinely performed tests in health care • Write test name on business card, and have patient ask their physician to keep them apprised of the number • When reporting to PCP regarding eye status, ask that they keep you updated on patient’s HbA1c

24. A1C and Risk of BlindnessNew England Journal of Medicine 1993; 329:977-986. • A1C Level Risk of Significant Blindness 8.0 4X 8.5 5.5X 9.0 6X 9.5 8X 10.0 10X 10.5 11.5X

25. Diabetes Management (cont.) • The Diabetes Control and Complications Trial clearly demonstrated that tight glycemic control decreases secondary complications • The Veterans Affairs cooperative trial demonstrated the feasibility of tight glucose control in middle-aged and older patients • The Wisconsin Eye Study has demonstrated that for every 1% decrease in glycosylated hemoglobin levels in Type II diabetics, there is an exponential decrease in secondary diabetic complications; this supports the idea that even modest improvement in HbA1c levels will reduce risk of vision loss

26. Stay current! • The scientific literature is there for us to learn more about new developments in basic and clinical science related to diabetes and other conditions affecting the eye • This knowledge can help us manage our patients better • Pathophysiological mechanisms of disease in diabetes are similar in the various organ systems involved • Examples….

27. New ThinkingExcerpts from ADA Scientific Sessions, June 2004 • hsCRP and the total cholesterol/HDL ratio were independent predictors of subclinical complications (eye & kidney disease and peripheral neuropathy) • “Reasonable to consider dyslipidemia and subclinical inflammation as part of the microvascular pathogenesis” of diabetes

28. New ThinkingExcerpts from ADA Scientific Sessions, June 2004 • There exists a clear relationship between diabetic retinopathy and preclinical diabetic nephropathy • In Type 2 patients, presence of retinopathy was the second best predictor (after the preexistence of CVD) of death, cardiovascular events, and end-stage renal disease • Risk of worsening of retinopathy in pregnancy is related to pre-pregnancy A1C

29. Conclusion • Our actions as optometrist can significantly improve the lives of our patients with diabetes, and lessen their risk of vision loss • Most optometrists don’t go far enough in their care of diabetics