【摘要】 评估马来亚大学医学中心眼科门诊的糖尿病性视网膜病变的发病率和它在糖尿病患者中的危险因素。
方法：该横向研究包括100例近期被诊断为糖尿病患者的200眼。采集有关的眼部和全身病史并对所有的眼进行彻底散瞳眼底检查。视网膜病变的状况根据早期糖尿病性视网膜病变治疗研究（ETDRS）的结果进行分类。造成视网膜病变的危险因素是通过卡方检验进行分析的，P< 0.05被认为有意义。
结果：在我们的研究中，近期被诊断为糖尿病人群中糖尿病性视网膜病变的发病率为28%，Ⅱ型糖尿病患者中非增殖性视网膜病变的发病率（36%）比Ⅰ型糖尿病患者高（24%）。在两种类型的糖尿病患者中，视网膜病变的发病率与性别、年龄、种族、社会经济状况、糖尿病类型和体重指数无关。糖尿病病史较长并控制不良的患者，高血压者，伴有神经病变者，高脂血症以及有吸烟史者，视网膜病变的发病率明显高。
结论：对糖尿病患者进行视网膜病变的基线筛查是可取的，因为早期发现，规律随访，合理的推荐给眼科医生并进行有效的治疗将减少以及避免患者严重的视力丧失。
【关键词】 糖尿病 糖尿病性视网膜病变 殖性视网膜病变 筛查
INTRODUCTION
Diabetes is a chronic disease that has no cure; the cause of this disease is a mystery, although both genetics and environment appear to play roles. It is the leading cause of blindness in people aged 2574 years. Today nearly 1.2 million people in Malaysia have diabetes. Unfortunately, more than half are not aware that they have the disease[1]. The prevalence of diabetic retinopathy in Malaysia has been reported to range from 44.1% in a 1983 study [2] to 48.6% in a 1996 study [3] while the same has been reported to be 22.2% [4] in patients at initial presentation.
The prevalence of diabetic retinopathy has been linked to the duration of the disease [57] . Retinopathy has been reported in 60%80% of longterm diabetics; and 5%10% of diabetics surviving 20 years from the time of diagnosis will become blind due to retinopathy [8].
Information regarding the prevalence of retinopathy among outpatients referred to eye clinic is not available in the published literature from Malaysia. Therefore, we planned to evaluate the prevalence of retinopathy among this group of patients and correlate with risk factors so that they can be followed up by other treating doctors such as family physicians and internal medicine specialists, and referred to the ophthalmologists whenever needed.
PATIENTS AND METHODS
Selection of Patients The study included 100 consecutive diabetic patients who were referred to the eye clinic, University of Malaya Medical Centre (UMMC), from family medicine clinic and general medicine clinic for their first diabetic retinopathy screening from March 2005 to May 2005.
Inclusion criteria All the patients referred first time for screening of diabetic retinopathy from family medicine clinic and general medicine clinic, irrespective of duration of diabetes, were included in this study.
Exclusion criteria 1)Diabetics with history of any concurrent ocular disease or ocular surgery such as glaucoma, retinal vein or artery occlusion, ocular ischemic syndrome, retinopathy of hemoglobinopathy, uveitis, radiation retinopathy, pseudophakia and vitreoretinal surgery;2)Eyes treated with any form of laser therapy;3)Patients with concurrent disease like anemia, leukemia, lymphoma, hyperviscosity syndromes, and malignancy; 4)Pregnancy.
Historytaking and Baseline Examination Each patient had their data collected on age, gender, race, socioeconomic status, family history, and smoking habits. A detailed medical history was noted from the case notes of each patient including type of diabetes, duration of diabetes, history of hypertension, hypercholesterolemia, and presence of any systemic complications of diabetes.
A complete ocular examination was then carried out in each patient. After recording the visual acuity, the anterior segment of the eye was examined with the slitlamp microscope and intraocular pressure was measured by applanation tonometer. Then the pupils were dilated using tropicamide 10g/L and phenylephrine 25g/L eyedrops, and a detailed fundus examination was done using 90D lens and slitlamp biomicroscope. Two ophthalmologists examined each patient separately and jointly documented the degree of retinopathy changes.
Retinopathy status was based on the definition used by Diabetic Retinopathy Study (DRS) and Early Treatment Diabetic Retinopathy Study (ETDRS) [9]. 1)Nonproliferative diabetic retinopathy(NPDR): mild ( one or more microaneurysm), moderate(microaneurysm,dot and blot hemorrhage, cotton wool spot, venous beading, arteriolar narrowing, intraretinal microvascular abnormalities) and severe (all of the moderate stage plus any one of the following three findings: blot hemorrhage in 4 quadrants, venous beading in 2 quadrants, intraretinal microvascular abnormality(IRMA) in 1 quadrant); 2)Proliferative diabetic retinopathy(PDR): early [neovascularization of disc (NVD) or neovascularization of retina elsewhere (NVE)]; and high risk (NVD>1/4 disc diameter/ NVD<1/4 disc diameter plus vitreous hemorrhage/ NVE>1/2 disc diameter plus vitreous hemorrhage); 3)Macular edema: early ( retinal thickening / hard exudates within 1 disc diameter from the fovea) or clinically significant macular edema (CSME) (retinal thickening or edema less than 500 microns from the fovea, hard exudates less than 500 microns from the fovea with retinal thickening or retinal thickening greater than 1500 microns with any part of it lying within 1500 microns from the fovea); 4)Maculopathy: exudative or ischemic.
The patients were then subjected to the following examinations: blood pressure measurements, body mass index (BMI) and laboratory investigations for fasting blood glucose, HbA1c, blood urea, serum creatinine, serum triglyceride, total cholesterol, highdensitylipoprotein (HDL), lowdensitylipoprotein (LDL), urine protein and urine microalbuminuria.
Blood pressure was measured through a mercury sphygmomanometer in sitting position after 5 minutes rest (<130/85mmHg—good control, >130/85mmHg—high)[10]. Height in meters and weight in kilograms were measured. Body mass index ( BMI) was calculated using the formula weight in kilograms over height in meters square. Obesity was graded based on the BMI reading and classified according to World Health Organization(WHO) 1997 criteria [11].
The data collected were tabulated in the descriptive analysis using Statistical Products and Services Solution (SPSS) programme. Nonparametric chisquare test was used to analyze various data and P value of <0.05 was taken as significant. This study was approved by the ethics committee of UMMC and informed consents were taken from all the patients.
Ocular Outcome
Based on the diabetic retinopathy staging, the patients were given appropriate treatment and followup appointment (mild to moderate NPDR6 months, severe NPDR3 months). Those with PDR were scheduled for panretinal photocoagulation and those with macular edema and CSME for focal or grid laser treatment.
RESULTS
Demographic Characteristics Out of 100 patients examined, 10 were insulin dependent diabetics (IDDM) and 90 noninsulin dependent diabetics (NIDDM). Retinopathy was not significantly associated with age, gender, ethnicity, socioeconomic status, BMI, alcohol consumption and type of diabetes as shown in Table 1. There was no significant difference in the prevalence of retinopathy between IDDM and NIDDM. Even though some patients had longer duration of diabetes, they never came to eye clinic for screening of diabetic retinopathy earlier. The prevalence of retinopathy was highest (55.6%) in diabetics with duration of longer than 10 years(P<0.05) and smokers were found to have 55.6% incidence of retinopathy (P<0.05). Patients with diabetes less than 2 years had 16.7% and 11.8% of retinopathy in IDDM and NIDDM groups respectively (Table 2).Table 1 Association between sociodemographic parameters and retinopathy in diabetes mellitus (略)Table 2 Prevalence of retinopathy in relation to the duration of the disease (略)
Frequency Distribution and Association of Retinopathy with Medical Conditions There was no significant association between presence of hypertension, hyperlipidemia and ischemic heart disease and prevalence of retinopathy. Peripheral neuropathy (75%) and nephropathy (90%) were significantly associated with retinopathy ( Table 3).Table 3 Association between other medical conditions and concurrent retinopathy in diabetic patients (略)
Association between Biochemical Parameters and Retinopathy Retinopathy was significantly associated with poor glycemic control—high fasting glucose( 49.7%) and high HbA1c(53.2%) (P<0.05), poor blood pressure control among hypertension patients, high blood urea and serum creatinine (Table 4). High fasting lipid profile (Triglycerides and HDL) also showed significantly higher prevalence of retinopathy (P<0.05).
Presence of urine protein (82.6%) and microalbuminuria (85.7%) demonstrated a higher incidence of retinopathy (P<0.05).
Frequency Distribution of Retinopathy The overall prevalence of diabetic retinopathy was 28% with NPDR being the most common (24%). Seventytwo patients did not show any retinopathy changes. Noninsulin dependent diabetic patients had the highest number of retinopathy (28%); PDR and maculopathy were only noted in NIDDM group (Table 5).Table 4Association between blood pressure control and biochemical parameters with retinopathy in diabetic patients (略)Table 5Frequency distribution of retinopathy in diabetic patients (略)
The prevalence of NPDR was higher in IDDM than NIDDM (Table 6). The PDR (Table 7) and maculopathy (Table 8) were seen in NIDDM only.Table 6 Frequency distribution of grades of nonproliferative diabetic retinopathy (NPDR) in 200 eyes Table 7 Frequency distribution of grades of proliferative diabetic retinopathy (PDR) in 200 eyes (略)Table 8 Frequency distribution of maculopathy in 200 eyes (略)
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