ObjectiveTo observe the features of temporal macular thinning and its value for the diagnosis of Alport syndrome (AS) in young patients.MethodsEighty-one young patients with AS (81 eyes) from Peking University First Hospital during January 2016 and July 2017 were included in this study. There were 67 males (67 eyes) and 14 females (14 eyes),the aged from 3 to 17 years, with the mean age of 9.6 years. Among 81 patients (81 eyes), there were 64 patients with X-linked AS (XLAS, including 53 males and 11 females), 17 patients with autosomal recessive AS (ARAS, including 14 males and 3 females). One hundred healthy subjects aged 4 to 17 years were included as controls. Clinical data were retrospectively evaluated, including visual acuity, slit-lamp microscopy, dilated fundus photography, and OCT. Retinal thickness was measured with an OCT scan and the temporal thinning index (TTI) was calculated as stated in a previous study. The TTI values of each group was compared by One-way ANOVA or independent sample t test. The receiver operating characteristic (ROC) curve was used to evaluate the diagnostic effectiveness for AS.ResultsThe TTI of the control group, XLAS and ARAS patients were 6.46±1.58, 10.93±3.77, 12.14±4.05, respectively. Compared with the control group, the TTI value of males were larger in the XLAS and ARAS group (F=45.056, P＜0.001), the TTI value of females were larger in the ARAS group (F=26.541, P＜0.001). The difference of TTI value in females was significant between the XLAS and ARAS groups (F=26.541, P＜0.001). In males, the area under the ROC curve was 0.896 (95%CI 0.837−0.955, P＜0.001). The optimal cutoff value of the TTI was determined as 9.47, with a sensitivity of 73.1% and a specificity of 100%.ConclusionsTTI is a common ocular finding in young patients with AS. In males, a TTI ＞ 9.47 may differentiate AS from normal males.