方法：收集40例40眼2型糖尿病患者，经散瞳眼底检查未发现糖尿病视网膜病变，均接受光学相干断层扫描(OCT)检查和活体角膜共聚焦显微镜(IVCM)检查。另收集年龄匹配的80例80眼健康正常眼为对照，分为40例40眼只行OCT检查的RNFL对照组和40例40眼只行IVCM检查的CNF对照组。利用OCT观察视乳头上方、下方、颞侧、鼻侧和平均RNFL厚度，用IVCM观察角膜上皮下角膜神经纤维长度和角膜神经密度。

结果：糖尿病组的视乳头上方、颞侧、鼻侧及平均RNFL与对照组比较，差异无统计学意义(P>0.05)，但视乳头下方RNFL糖尿病组比RNFL对照组减少，差异有统计学意义(P=0.003)。糖尿病组的角膜神经纤维长度、角膜神经密度均比CNF对照组减少(P<0.01)。糖尿病组中，平均RNFL与角膜神经纤维长度和角膜神经密度呈正相关(r=0.518，P<0.01； r=0.484，P=0.002)，下方RNFL与角膜神经纤维长度和角膜神经密度呈正相关(r=0.607，P<0.01； r=0.573，P<0.01)。

结论：糖尿病患者在未发现糖尿病视网膜病变前同时存在视网膜神经纤维层和角膜神经的丢失，视网膜神经纤维层变薄主要表现在下方象限，视网膜神经纤维层的变薄与角膜神经的减少呈正相关。

METHODS:Forty eyes of 40 patients with type 2 diabetes mellitus, who were found no diabetic retinopathy, were examined by optical coherence tomography(OCT)and in vivo confocal microscope(IVCM). Forty eyes of 40 healthy participants were only scanned using OCT served as RNFL control group, and another forty eyes of 40 healthy participants were only scanned using IVCM served as CNF control group. The thickness of superior, inferior, nasal, temporal and average RNFL to optic disc were measured using OCT. Corneal nerve fibers length(CNFL)and corneal nerve fibers density(CNFD)were measured using IVCM.

RESULTS: The diabetic patients showed decreased thickness of inferior RNFL when compared to controls(P=0.003).No significant differences were found in the thickness of superior, nasal, temporal and average RNFL(P>0.05). The diabetic patients were also found to have lower CNFL and CNFD(P<0.01). What's more, in diabetes patients, the average RNFL were positively correlated with CNFL and CNFD(r=0.518, P<0.01; r=0.484, P=0.002),and the inferior RNFL were also positively correlated with CNFL and CNFD(r=0.607, P<0.01; r=0.573, P<0.01).

CONCLUSION: RNFL and CNF are early damaged in diabetic patients without DR. RNFL decreases in the inferior quadrant of retina. The loss of RNFL positively correlates with that of CNF significantly.