Back to Journals » Clinical Ophthalmology » Volume 7

Diabetic and non-diabetic human cornea and tear γ-glutamyl transpeptidase activity

Authors Burnham J, Sakhalkar M, Langford M, Liang C, Redens T, Jain S

Received 31 August 2012

Accepted for publication 23 October 2012

Published 10 January 2013 Volume 2013:7 Pages 99—107


Checked for plagiarism Yes

Review by Single-blind

Peer reviewer comments 2

Jordan M Burnham,1 Monali Sakhalkar,1 Marlyn P Langford,1 Chanping Liang,1 Thomas B Redens,1 Sushil K Jain2

1Department of Ophthalmology, 2Department of Pediatrics, Louisiana State University Health Sciences Center, Shreveport, LA, USA

Background: Diabetes-related eye disease is due in part to oxidative stress. Gamma-glutamyl transpeptidase (GGT) is a γ-glutamyl cycle enzyme that protects against oxidative stress via glutathione recapture. This study investigates corneal and Schirmer tears GGT activity in diabetic and non-diabetic adults aged 50 to 83 years old.
Methods: GGT activity was determined by colorimetric assay on 50 corneas from 14 diabetic (without keratopathy) and 20 non-diabetic donors and on Schirmer type 1 test strips (no anesthesia) of 14 diabetic and 14 non-diabetic subjects.
Results: Type 1 (T1) diabetic cornea GGT activity was 40% lower than Type 2 (T2) diabetic cornea GGT activity (P = 0.04), but GGT activity was similar for corneas (without keratopathy) from diabetic and non-diabetic donors (P ≥ 0.44 for all). The number of endothelial cells/unit of GGT activity in diabetic corneas was 22% higher (P = 0.1) than in non-diabetic corneas. GGT activity per Schirmer strip and GGT activity per mm of tears were 36% and 50% higher (P ≤ 0.008 for all) for non-diabetic (tear volume dependent) than diabetic donors (tear volume independent), respectively. GGT activity per mm was 50% lower in T1 than T2 diabetics (P = 0.02). Higher tear GGT activity in non-diabetic than diabetic females (P ≤ 0.05) was due to higher GGT activity in the African American females.
Conclusion: GGT activity was less in T1 than T2 diabetics, but comparable to non-diabetic corneas. Schirmer tear GGT activity in diabetic eyes was tear volume independent, less in T1 than T2, lower than in tear volume dependent, non-diabetic female eyes. Low cornea and tear GGT activity suggests loss of antioxidant potential and supports ocular antioxidant therapy for diabetic patients.

Keywords: cornea, diabetes, endothelium, epithelium, eye, γ-glutamyl transpeptidase, tear, oxidative stress

Creative Commons License This work is published and licensed by Dove Medical Press Limited. The full terms of this license are available at and incorporate the Creative Commons Attribution - Non Commercial (unported, v3.0) License. By accessing the work you hereby accept the Terms. Non-commercial uses of the work are permitted without any further permission from Dove Medical Press Limited, provided the work is properly attributed. For permission for commercial use of this work, please see paragraphs 4.2 and 5 of our Terms.

Download Article [PDF]  View Full Text [HTML][Machine readable]


Other articles by this author:

Orbital sporadic Burkitt lymphoma in an adult diabetic African American female and a review of adult orbital cases

Carmody J, Misra RP, Langford MP, Byrd WA, Ditta L, Vekovius B, Texada DE

Clinical Ophthalmology 2011, 5:509-515

Published Date: 20 April 2011

Readers of this article also read:

Roles of dopamine receptors and their antagonist thioridazine in hepatoma metastasis

Lu M, Li J, Luo Z, Zhang S, Xue S, Wang K, Shi Y, Zhang C, Chen H, Li Z

OncoTargets and Therapy 2015, 8:1543-1552

Published Date: 22 June 2015

Expression and clinical significance of fibroblast growth factor 1 in gastric adenocarcinoma

Liu NQ, Zhang JG, Sun SX, Yang LG, Zhou ZJ, Sun QL, Niu J

OncoTargets and Therapy 2015, 8:615-621

Published Date: 9 March 2015

Development of a liposome-based formulation for vitamin K1 nebulization on the skin

Campani V, Marchese D, Pitaro MT, Pitaro M, Grieco P, De Rosa G

International Journal of Nanomedicine 2014, 9:1823-1832

Published Date: 10 April 2014

Bimatoprost ophthalmic solution 0.03% lowered intraocularpressure of normal-tension glaucoma with minimal adverse events [Corrigendum]

Tsumura T, Yoshikawa K, Suzumura H, Kimura T, Sasaki S, Kimura I, Takeda R

Clinical Ophthalmology 2013, 7:1363-1364

Published Date: 4 July 2013

Optic disc size and progression of visual field damage in patients with normal-tension glaucoma

Hayamizu F, Yamazaki Y, Nakagami T, Mizuki K

Clinical Ophthalmology 2013, 7:807-813

Published Date: 3 May 2013

Supramolecular micellar nanoaggregates based on a novel chitosan/vitamin E succinate copolymer for paclitaxel selective delivery

Lian H, Sun J, Yu YP, Liu YH, Cao W, Wang YJ, Sun YH, Wang SL, He ZG

International Journal of Nanomedicine 2011, 6:3323-3334

Published Date: 12 December 2011