Clinical Research On Changes Of Visual Function In Patients With Non-proliferative Diabetic Retinopathy

Diabetes mellitus (DM) has become a global disease. Currently there are nearly 240 million diabetic patients in the world. A recent investigation indicated that 92.4 million people suffer from DM, about 9.7% in people older than 20 in China. One of the major complications of diabetes-diabetic retinopathy (DR) has become the leading cause of blindness. Relative to basic and clinical researches on diabetic microangiopathy home and abroad, evaluation on visual function of diabetic patients is very weak. DR indicates the occurrence of impairment of visual functions and the retinal function will be irreversible. Early representation data of the visual functions of retina 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 visual functional impairment in diabetic patients.From these we choose visual contrast sensitivity (CS), colour vision and visual field as research tools to study visual functions in non-proliferative retinopathy(NPDR), to reveal the ordinary principles of visual function changes in different DR stages,to provide clinical comprehensive and accurate data.Purposes1. To study the changing characteristics and scopes of contrast sensitivity values in patients with non-proliferative retinopathy(DR gradeⅠ, DR gradeⅡand DR gradeⅢ);2. To investigate the characteristics of color vision damage in patients with non-proliferative retinopathy;3. To explore the change principals in central visual field in patients with non-proliferative retinopathy.Methods 1. Contrast Sensitivity:CS values were measured in patients with NPDR(group DRⅠ, group DRⅡand group DRⅢ) and diabetic patients without retinopathy (group DR0), non-glare of five frequencies, both in far-and near-distance, with application of OPTEC 6500 tester. Compared CS values in each frequency between group DRⅠ～DRⅢand group DR0 respectively.To reveal the relationship between CS value changes and ages.2. Color Vision:Color perception was measured in patients with NPDR (group DRⅠ, group DRⅡand group DRⅢ) and diabetic persons without DR(group DR0) using of Farnsworth Munsell-100 hue tester respectively. Difference on total error score (TES), square of total error score(√TES) as well as red, green, blue error scores and their square roots, were compaired between group DRⅠand DR0, group DRⅡand DR0, group DRⅢand DR0 respectively.The relationship were determined between color damages and ages also.3. visual field:Central visual field were tested in diabetic patients (group DRⅠ, group DRⅡand group DRⅢ) and diabetic patients without DR(group DR0) with application of the Humphrey HFAⅡperimetry on strategy SITA-standard. Selected the mean defect(MD), pattern standard deviation(PSD) and point number of defect as analysis data. Analyzed the data difference between group DRⅠand DR0, group DRⅡand DR0, group DRⅢand DR0 respectively. The characterstics of visual field defects were analyzed.Results1. Contrast Sensitivity:(1) There were significant difference (P<0.05) between each group of NPDR and group DRO on CS values in both far-and near-distance, espacially in high frequencies; (2) There were difference between different groups in NPDR on CS values, the more serious the retinopathy,the more significant the CS decrease, and significant differences existed in different ages mainly in high-frequencies; (3) With the increase of NPDR grade,the apex of CSF moved left,transferring from 6 cpd to 3 cpd gradually.The CSF of DRⅢgroup was like inverse letter "L".;2. Color Vision:(1) There was significant difference (P<0.05) between each NPDR group and group DR0 on TES and VTES. (2) There was significant difference (P<0.05) between each NPDR group and group DR0 on green, blue error scores and their square roots. The green and blue perception damage were more significant and the red was minor. (3) Color damage was related to grade of NPDR,the more serious the retinopathy,the more significant the color damage.3. Visual Field:(1) The point number of defect in group DRⅠwas larger than that in group DR0.The MD,PSD and point number of defect were larger both in group DRⅠand group DRⅡthan in group DR0. (2)The ratio of abnomal visual field in group DR0 was 33.4%, the ratio both in group DRⅠand group DRⅡwere about 50%,and 71.4% in group DRⅢ. (3) The shape of defects in group DRⅠwere often dots or pieces, situated not along nerve fibers. The shape of defects in group DRⅡand group DRⅢwere often pieces or balls, situated not along nerve fibers,but often situated in the mid-surround zone of visual field,that was in 20°～30°visual field.Conclusions1. Visual contrast sensitivity function declines in full frequencies in patients with NPDR, especially in high frequencies, and relate to ages, can be one of the sensitive markers in evaluating the visual functions of patients with NPDR.2. Color damage happens in red, green and blue in patients with NPDR, especially in green and blue perception, increases with the serious of DR,and relate to age.CS can be a sensitive indicator in evalution of visual functions in patients with NPDR.3. With the increase of DR grade,the damage of central visual field in patients with NPDR become serious gradually.The characteristics of the visual field defects are dots, pieces, or balls, often situate in 20°～30°area.