Objective To investigate the feasibility and clinical significance of monitoring diabetic macular edema by Heidelberg retina tomograph Ⅱ (HRT). Methods The diabetic macular edema (DME) was diagnosed by slit-lamp microscopy combined with three-mirror contact lens examination and fundus fluorescein angiography (FFA). The exponential of macular edema (e value) of healthy people and patients with DME or without DME (NDME) (the total number is 77 individuals and 120 eyes) were detected by HRT Ⅱ. All of the 77 people were divided into three groups. In DME group, there were 23 patients (40 eyes), including 13 males (23 eyes) and 10 females (17 eyes), at the age of 44-68 (average of 55.17plusmn;8.26). In NDME group, there were 32 patients (40 eyes), including 18 males (22 eyes) and 14 females (18 eyes), at the age of 44-68 (average of 55.17plusmn;6.5). In normal control group, there were 22 patients (40 eyes), including 10 males (19 eyes) and 12 females (21 eyes), at the age of 42-65 (average of 53.32plusmn;6.04). According to the results of FFA, the 40 eyes in DME group were divided into: grade 1 of FFA in 9 eyes, with macular suspicious leakage or the area of leakage of lt;25%; grade 2 of FFA in 10 eyes, with the area of leakage between 25% and 66%; grade 3 of FFA in 21 eyes, with the area of leakage of gt;66%. The differences of sex and age among the 3 groups were not significant (Pgt;0.05). The relationship among e value, leakage area, and visual acuity was observed. Results There was a significant difference of e value (the macular diameter was 1, 2, and 3 mm) among the 3 groups(Plt;0.05). The e value in normal control group didnrsquo;t differ much from which in NDME group (Pgt;0.05), but was statistically different from which in DME group (Plt;0.05). Significant difference of e value was also found between NDME group and DME group (Plt;0.05). There was a correlation between visual acuity and e value in DME group (Plt;0.05). In DME group, the difference of e value among FFA grade 1, 2, and 3 groups was found according to the variance analysis; the macular leakage area in FFA grade 3 group differed much from which in grade 1 (Plt;0.05) and grade 2 group (Plt;0.05), while no significant difference was found between grade 1 and grade 2 group. The result was not correlated with the macular diameter. Conclusion E value in the macular module of HRT Ⅱ can detect and evaluate the degree of DME. (Chin J Ocul Fundus Dis,2007,23:252-255)