Clinical Research On Early Changes Of Visual Functions In Diabetic Patients

Diabetes mullitis(DM)has become a global disease.Currently there are nearly 240 million diabetic patients,a main burden in the world.As one of major complications of diabetes-diabetic retinopathy(DR) has become one of the leading causes of blindness.Pathological changes of DR includes diabetic microangiopathy and diabetic retinal nerve abnormalities.Relative to basic and clinical researches on diabetic microangiopathy home and abroad,evaluation on diabetic retinal neurological function is very weak.DR indicates the occurrence of impairment of visual functions and the retinal function will be irreversible.So early representation data of the visual functions of retinal is very critical.How to master the early changes in visual functions as well as its relation to diabetes condition will help us to take timely treatment intervention to curb the occurrence and development of DR,to rescue and protect visual functions in diabetic patients.From these we choose visual contrast sensitivity(CS),colour vision and multifocal electroretinogram(mERG) as research tools,not only to clarify their important role on assessment of visual functions,but to reveal the relationship between condition of diabetes and these indicators.We will filter out the indicators which are closely related to the impairment of visual functions to provide clinical comprehensive and accurate data.Purposes1.To study the changing characteristics and scopes of contrast sensitivity values in diabetic patients with normal visual acuity and without DR;2.To investigate the characteristics of color vision damage in the different diabetic conditions;3.To explore the change principals in mERG in early diabetic patients;4.To probe the intrinsic relations between CS,color vision,mERG changes and some biochemical indicators which closely associated with DM.Methods1.CS:CS values were measured in 72 diabetic patients(126 eyes) and 45 healthy persons(78 eyes),non-glare of five frequencies,both in far- and near-distance,with application of OPTEC 6500 tester.Compared CS values in each frequency between these two groups and disvovered the relationship between CS values changes and age,duration time of DM,application time of insulin & some biochemical parameters;2.Color Vision:Color perception was measured in 42 diabetic patients(74 eyes) and 45 healthy persons(78 eyes) with use of Farnsworth Munsell-100 hue tester respectively and analysed difference on total error score(TES),√TES as well as red,green,blue error scores and their square roots,the relationship were determined between color damage and age,duration time of DM,application time of insulin & some biochemical parameters;3.mERG:mERG was detected in 19 diabetic patients(34 eyes) and 17 healthy persons(30 eyes) with application of the Roland RETIport21 visual electrophysiology instruments,according to the same procedure and parameters. Selected the first-kernal-order(FOK) response results as analysis data.Analysed the difference on amplitude and latency of P₁ & N₁ wave between two groups,and their relation to age,duration time of DM,application time of insulin & some biochemical parameters.Results1.CS:(1) There were significant difference(P＜0.03) between diabetic group and control group on CS values in both far- and near-distance,espacially in high frequencies;(2) There were significant difference(P＜0.00)between far- and near-distance CS values in both diabetic group and normal controls;(3) Significant differences existed in different ages mainly in high-frequencies, different diabetes duration almost in full frequencies and application time of insulin within 1 month only in high-frequency section;(4) CS values closely related with many biochemical markers,especially with rapid ACR (albumin/cretinine ratio ),very significant on full range of frequencies;2.Color Vision:(1) There was significant difference(P＜0.005) between two groups on red,green,blue error scores and their square roots.The red perception damage was the most significant and the blue was most minor.No difference between the TES and√TES;(2) Color damage mainly related with age and duration time;(3) TP and FBG closely related with damage of blue and green perception respectively;3.mERG:(1) The wave amplitude reduced and the latency extended in diabetic patients,mainly in P₁ amplitude and N₁ latency;(2) These changes related with age and application time of insulin;(3) Some biochemical parameters such as FBG,glycosylated plasma protein etc.mainly associated with the latency of P₁ wave in every cycle.Conclusions1.Visual contrast sensitivity function declines early in full frequencies in diabetic patients,especially in high frequencies,and relate to many biochemical parameters,can be a sensitive marker in evaluating the functions of retina.Rapid ACR elevation can be a risk factor with impact on early CS values in high-frequencies;2.Color damage happens in red,green and blue in early diabetic patients, especially in red,green perception in nearly 50%patients and relate closely to age, duration time of DM,so can be sensitive indicators in early evalution of visual functions in diabetic patients.TP and FBG can be risk factors in leading to blue and green perception early damage in diabetic patients;3.mERG changes early in diabetic patients.P₁ wave amplitude fall and N₁ wave latency extension are main features of damage in retinal functions,can be sensitive indicators in early evalution of visual functions in diabetic patients. Elavation of FBG and glycosylated plasma protein have close relation to early P₁ wave latency extension in diabetic patients.