Investigation Of Retinal Nerve Fiber Layer Changes In Different Stage Of Type Ⅱ Diabetes Mellitus

ObjectiveIn order to reveal the relationship between DR with different extent and thickness of RT and RNFL, retinal nerve fiber layer thickness changes of the optical nerve and the macular retinal thickness in health adults and diabetes mellitus patients were investigated and assessed by using optical coherence tomography (OCT).MethodsIn this prospective study, we selected 120 eyes of 76 cases with typeⅡdiabetes mellitus. The patients were consisted of 34 men and 42 women, ranging in age from 40-75 years, average age 60.01±10.99 years. The diabetic history, duration and treatment were recorded. The fasting blood glucose, postprandial blood sugar, blood pressure and glycosylated hemoglobin (HbAlc) were detected. All the patients underwent detailed ophthalmological examination, including the visual acuity, IOP, anterior segment, fundus examination with papillary dilation, fundus fluorescein angiography (FFA). According to the staging standard of diabetic retinopathy, the diabetes mellitus patients were divided into three groups by criterion of FFA: non-diabetic retinopathy (NDR), non-proliferative diabetic retinopathy (NPDR), proliferative diabetic retinopathy (PDR).20 age-matched normal subjects were enrolled as control group. We observed the RNFL thickness of normal subjects and diabetic patients by using OCT. The Retinal Thickness of macular (around center point with 1000μm diameter) and the RNFL thickness of optical nerve (with circle scan around optic nerve head, scan diameter of 3.46mm) were measured with the macular cube 512×128 and the optical disc cube 200×200 of the OCT, to compare the RNFL changes of the control and the patients.ResultsThere was no statistically significant difference between RNFL thickness and average retinal thickness in normal control group and NDR group (P>0.05).But it had statistically significant difference between RNFL thickness and the average retinal thickness among NPDR group, PDR group and normal control group (P< 0.05). The RNFL was thicker in superior and inferior,and thinner in temporal and nosal in normal control group and DM group. The RNFL in PDR group and NPDR group was thinner than that of the normal control group, whereas it was obviously decreased in PDR group. There was statistically significant difference in macula retinal thickness among the NDR group, NPDR group and PDR group (P<0.05). Furthermore,the main manifestation of macula in diabetic patients is diabetic macular edema, including sponge-like retinal swelling, cystoid macular edema (CME) and serous neuroepithelium detachment features.ConclusionsOCT can be used to measure quantitatively the changes of retinal nerve fiber layer of optic nerve and macular retinal thickness in typeⅡdiabetic mellitus. With the the development in the degree of diabetic retinopathy, RNFL thickness gradually decreased and retinal thickness was increased, but RNFL thickness of the patients in PDR was significantly decreased. retinal nerve fiber layer thinning is strang evidence of optic neuropathy, which should serve as an important diabetic retinopathy pathological changes, the same as for diabetic macular edema should be given adequate attention. OCT is a useful tool to observe the changes in diabetic retinopathy qualitatively and quantitatively, which provide a reliable means for guiding treatment and follow-up.