Serum and tear levels of nerve growth factor in diabetic retinopathy patients.
OBJECTIVE
To measure serum and tear nerve growth factor (NGF) concentrations in diabetic retinopathy (DR) patients to determine whether the NGF correlated with parameters associated with DR.


METHODS
Cross-sectional comparative study.


METHODS
The study enrolled 254 DR patients and 71 nondiabetic controls. Patient demographic characteristics and diabetic parameters, including blood sugar levels, HbA1c, liver and renal function, were evaluated in two separate university hospitals. Serum and tear NGF concentrations and the ratio of NGF to total protein (TP) in serum and tear fluid were determined.


RESULTS
Serum and tear NGF levels were found to be higher in proliferative diabetic retinopathy (PDR) patients (98.7+/-12.1 ng/ml in serum, 45.6+/-6.3 ng/ml in tear) than in nondiabetic controls (18.5+/-6.1 ng/ml in serum and 8.3+/-4.7 ng/ml in tear) and nonproliferative diabetic retinopathy (NPDR) patients (26.6+/-5.1 ng/ml in serum and 8.6+/-4.2 ng/ml in tear; p<.001 for both serum and tear differences). Similarly, NGF levels were higher in PDR patients than in controls and NPDR patients after adjusting for possible confounding factors such as age, gender, serum blood urea nitrogen, creatinine, and diabetic parameters. In addition, the NGF-to-TP ratio for both serum and tear fluid was higher in the PDR group compared with the control and NPDR groups. NGF levels correlated well with diabetes duration, HbA1c, and blood sugar levels and diabetic nephropathy.


CONCLUSIONS
NGF concentration may be a good parameter for evaluating DR status. In addition, serum and tear NGF concentrations correlated strongly, indicating that tear fluid assays may offer an effective, accurate, and noninvasive option for NGF measurement.
Park
Kyoung Soo
KS
Institute of Vision Research, Department of Ophthalmology, Yonsei University College of Medicine, Seoul, Korea.
Kim
Sung Soo
SS
Kim
Jae Chan
JC
Kim
Hyeon Chang
HC
Im
Yong Sun
YS
Ahn
Chul Woo
CW
Lee
Hyung Keun
HK
D001786:Blood Glucose / Q000032:analysis; D003430:Cross-Sectional Studies; D003924:Diabetes Mellitus, Type 2 / Q000097:blood; D003930:Diabetic Retinopathy / Q000097:blood* / Q000145:classification; D004797:Enzyme-Linked Immunosorbent Assay; D005136:Eye Proteins / Q000378:metabolism*; D005260:Female; D006442:Glycated Hemoglobin / Q000378:metabolism; D006801:Humans; D008297:Male; D008875:Middle Aged; D020932:Nerve Growth Factor / Q000097:blood*; D013666:Tears / Q000378:metabolism*
D001786:Blood Glucose; D005136:Eye Proteins; D006442:Glycated Hemoglobin; D020932:Nerve Growth Factor; C517652:hemoglobin A1c protein, human; C042434:tear proteins