Comparison of tear secretion and tear film function between patients with type 2 diabetes mellitus and normal people

Ling YU; Hanping XIE; Gang QIN; Xibo ZHANG

ABSTRACT

BACKGROUND:

There are various reports on studies of tear secretion and tear film function in patients with diabetes mellitus over the past. In recent years, tear proteins have drawn more and more attentions on evaluation of tear film function.

OBJECTIVE:

To observe the contents of main tear proteins and basal tear secretion of patients with type 2 diabetes mellitus and normal persons so as to probe into tear secretion and tear film function of patients with diabetes mellitus.

DESIGN:

Case-control observation was designed.

SETTING:

Department of Ophthalmology, Southwest Hospital, Third Military Medical University of Chinese PLA.

PARTICIPANTS:

Totally 50 cases (100 eyes) of type 2 diabetes mellitus were employed, which were diagnosed in Department of Ophthalmology and Department of Endocrinology, Southwest Hospital of Third Military Medical University of Chinese PLA from December 2001 to December 2002. They were free from ocular surgical and laser treatment, local medication in recent period and contact lens. Of those, there were 25 cases (50 eyes) in proliferating diabetic retinopathy group and 25 cases (50 eyes) in nonproliferating diabetic retinopathy group. In addition, 25 cases (50 eyes) of normal persons with matched age and sex were taken as the control group.There was no significant difference in age and sex among 3 groups (x2=0.024,0.321 ;P ＞ 0.05). All of the participants were in the know before the experiment.

METHODS:

[1] Tear collection 10 cases (20 eyes) were randomized from two diabetic groups and the control successively. Capillary pipette method was used to collect non-irritative tear 10 μL from lower lacrimal punctum that was preserved in refrigerator at -20 ℃ (＜ 1 month). [2] Determination of total tear protein amount Lorry method was used to determine the concentration of total tear protein, in which, calf serum albumin was taken as the criteria. [3] Determination of contents of main tear proteins SDS-PAGE (sod.dodecyl sulfate-polyacrylamide gel electrophoresis) was used and Coomassie brilliant blue staining and Bio-Rad imaging analyzing system were applied for the analysis of isolated protein strips in quality and quantity. [4] Determination of rupture time of tear film glass rod was used to get 20 g/L fluorescein sodium and drop in conjunctival sac. The examined person was required to blink gently for several times and open the eyes naturally and stare forward. That the first ruptured "black hole" was discovered on the complete tear film was taken as the rupture time of tear film. [5] Experiment of basal tear secretion No.41 Whatmann filtering paper was used, folded in 5 mm, and placed at 1/3 of conjunctiva in the lower eyelid. Five minutes later, the paper was removed and length of it after wetting was measured. [6]Experiment with rose Bengal staining glass rod was used to get 10 g/L rose Bengal and drop in conjunctival sac. After eyes blinking for several minutes, the observation was performed with green light filter under slit lamp (evaluation criteria corneal conjunctiva of palpebral fissure stained+, stained to the inferior bulbar conjunctiva++,stained to the superior bulbar conjunctiva). Dry eye disease was diagnosed indirectly with red-stained epithelial cells and mucin.MAIN OUTCOME

MEASURES:

[1] Concentration of total tear protein. [2]Concentrations of various main tear proteins. [3] Rupture time of tear film. [4]Value of basal tear secretion. [5] Positive rate of rose Bengal staining.

RESULTS:

Totally 50 cases (100 eyes) in diabetes groups and 25 cases(50 eyes) in the control group all entered result analysis. [1] Concentration of total tear protein there was no significant difference among 3 groups (P＞ 0.05). [2] Concentrations of various main tear proteins the results of lysozyme, lactoferritin and tear specific prealbumin in proliferating diabetic retinopathy group were lower remarkably compared with the control[ (0.94±0.21)vs ( 1.33±0.31 )g/L , ( 1.10±0.24)vs ( 1.67±0.43 )g/L, (0.98±0.22) vs (1.49±0.32)g/L, P ＜ 0.01]. Compared with non-proliferating diabetic retinopathy group, the results of lactoferritin and tear specific prealbumin were lower (P ＜ 0.05). There was no significant difference in human serum albumin among 3 groups (P ＞ 0.05). [3] Rupture time of tear filmcompared with non-proliferating diabetic retinopathy group and the control, the rupture time of tear film in proliferating diabetic retinopathy group was reduced significantly [(7.68±2.21)s vs (9.92±2.37)s and(10.80±2.23)s,(P ＜ 0.01 )]. [4] Value of basal tear secretion the value in proliferating diabetic retinopathy group was less significantly than that in non-proliferating diabetic retinopathy group and the control [ (8.00±2.10)vs( 11.02± 1.97 )mm and ( 12.17±2.08 )mm, P ＜ 0.05]. [5] Positive rate of rose Bengal staining the positive rate in proliferating.diabetic retinopathy group was higher significantly than non-proliferating diabetic retinopathy group and the control (48% vs 24% and 14%, P ＜ 0.05, P ＜ 0.01).

CONCLUSION:

It is suggested in the results of this paper that abnormal tear secretion and tear film function are apt to present in patients with type 2 diabetes mellitus and the declined tear film function is more remarkably in the patients with proliferating diabetic retinopathy specially. SDS-PAGE benefits the discovery of changes in tear proteins in diabetic patients.