Efficacy Of Omega-3 In Dry Eye Induced By Topical Administration Of Benzalkonium Chloride

Background:Dry eye is a common disease in Ophthalmology and it has affected people quality of life. The prevalence of dry eye in the world is about 33.7% to 5.5%. In the United States, epidemiology shows that the incidence of dry eye in each age stage is not the same, probably from 5% to 43%, with the higher incidence of age. In the United States, over age 50 of dry eye patients are 4 million 910 thousand people, including 3 million 230 thousand female patients and 1 million 680 thousand male patients. The incidence of dry eye in China is about 30% to 21%, which is similar to other Asian countries, but higher than the United States and European countries.Dry eye has a wide range of complex pathological process.Inflammatory response, apoptosis, decreased levels of sex hormones and the influence of external factors are the main causes of the disease, and inflammation plays an important role in the pathogenesis of dry eye. No matter what type of dry eye will cause inflammation of the eye, and ocular surface inflammation will increase the dry eye. Increased tear osmolarity caused by tear composition changes or the tear film instability caused by ocular surface inflammation. Ocular surface inflammation, in turn, affect the function of lacrimal gland cells and even lead to apoptosis of lacrimal gland.Impaired lacrimal gland cells resulted in increased tear osmolarity, and lacrimal gland cells resulted in a decrease in tear secretion volume decreased, forming a vicious circle.Dry eye disease has complex pathogenesis. Artificial tears and lacrimal punctum embolization only increase the tear in symptomatic treatment. Cleaning, massage, hot compress of the meibomian gland can only improve the evaporation dry eye symptoms. Glucocorticoid in a certain extent can control inflammation, but it has a serious side effects.Cyclosporine A (CSA) although in the long-term curative effect is more suitable than glucocorticoid, but it is not for each patient. Therefore, it is urgent to find a new effective method to treat dry eye, reduce dry eye symptoms, and improve the quality of life of patients. Recently, some scholars have found that oraling omega-3 can play a role in the treatment of dry eye.Objective:Discussion on the possible mechanism of the efficacy of omega-3 in dry eye induced by topical administration of benzalkonium chloride.Method:1. Group:45 only 6 to 8 weeks old SD rats, were examined by slit lamp microscope no abnormal, tear secretion and corneal fluorescein staining revealed no abnormalities. The random number table method was divided into blank group, control group and experimental group. Blank group is 15 rats, control group is 15 rats, experimental group is 15 rats.Experimental intervention:the experimental group was given omega-3 irrigation treatment, each 1ml, one time a day, continuous in three months. The control group was given olive oil irrigation treatment, each 1ml, one time a day, continuous in three months. The blank group was given physiological saline irrigation treatment, each 1ml,1 time/a day, continuous in three months.2. Dry eye modeling:after 2 months, blank group, control group, experimental group received 15 days of dry eye induced by topical administration of benzalkonium (per SD rat randomly selected one eye dry eye model, per eye for each drop of 5 μl of a 0.2% benzalkonium chloride,2 times a day, at nine o’clock in the morning, at nine o’clock in the evening each time).3. Detection of indexes:dry eye induced on day 0,5 days,10 days,15 days of tear volume measurements, tear break-up time; corneal fluorescein staining. After the end of treatment, examination of SD rat cornea, conjunctiva and meibomian gland pathology hematoxylin eosin staining. The level of expression of tumor necrosis factor alpha and interleukin 6 was used by Western blot in the cornea, conjunctiva and meibomian gland.4. Statistical analysis using SPSS13.0 software for statistical analysis, all of the experimental data with the average±standard deviation. At 4 time points to detect the tear break-up time and corneal fluorescein staining, tear volume measurement values compared with one-way ANOVA, multiple comparisons between groups using SNK. Western Blot was used to detect the expression of the protein in the three groups were compared with one-way ANOVA, multiple comparisons between groups using SNK. P<0.05 as the difference has statistical significance.Results:1. Omega-3 group, olive oil group, normal saline group of tear secretion in dry eye after 0 day,5th day,10th day,15th day are (11.95±1.45,11.02±1.27, 10.96±1.57);(10.06±1.35,9.89±1.85,9.67±1.74); (9.98±1.27,8.01±1.43, 7.89±1.12); (9.56±1.34,5.66±1.41,5.76±1.53)。Dry eye induced on 0 day,5th day,10th day of omega-3 group and olive oil group, normal saline group pairwise between tear secretion no statistics differences, on the 15th day of the omega-3 group compared with olive oil group, normal saline group tear secretion was significantly prolonged, the difference is statistically significant (P=0.023, P= 0.027).2. Omega-3 group, olive oil group, normal saline group of tear break-up time in dry eye after 0 day,5th day,10th day,15th day are (9.72±0.82,9.21±0.69, 9.61±0.72); (9.05±0.94,7.44±0.87,7.20±0.83); (8.95±1.16,6.47±0.97, 6.38±0.72); (7.73±1.05,4.65±0.95,4.80±0.65)。Dry eye induced on 0 day,5th day of omega-3 group and olive oil group, normal saline group pairwise between tear break-up time was no difference, on the 10th day, the 15th day of omega-3 group compared with olive oil group, normal saline group break-up time was prolonged, the difference is statistically significant (P= 0.037, P= 0.032); (P= 0.024, P= 0.020)3. Omega-3 group, olive oil group, normal saline group of corneal fluorescein staining scores in dry eye after 0 day,5th day,10th day,15th day are (9.72±0.82, 9.21±0.69,9.61±0.72); (9.05±0.94,7.44±0.87,7.20±0.83); (8.95±1.16, 6.47±0.97,6.38±0.72); (7.73±1.05,4.65±0.95,4.80±0.65). Dry eye induced on 0 day,5th day,10th day of omega-3 group and olive oil group, normal saline group pairwise between corneal fluorescein staining scores no statistics differences, on the 15th day of the omega-3 group compared with olive oil group, normal saline group corneal fluorescein staining scores was significantly prolonged, the difference is statistically significant (P= 0.037, P= 0.032); (P= 0.024, P= 0.020)4. Corneal histopathological observation:on 15th day, omega-3 group showed:the corneal epithelium is stratified squamous epithelium,5-6 layer, organizational structure is normal. Shallow layer is 2 to 3 layers of squamous epithelial cells, compared to the flat, surface cells keratosis; intermediate layer 1 to 2 layers of epithelial cells, were polygonal; basal cell layer is a single layer of cuboidal cells, cells arranged neatly. The olive oil group and the normal saline group were similar: corneal epithelial cell level increased significantly, not lack of the rules of the surface cells, cells and basal cells arranged in disorder, the stromal layer a little edema.5. Conjunctival histopathological observation:on 15th day, the omega-3 group showed:conjunctival epithelial structure integrity, arrangement is regular, conjunctival epithelial cell proliferation was not obvious, the basal layer cells arranged in neat rows, and a few of inflammatory cells infiltration. The olive oil group and the normal saline group were similar:conjunctival epithelial structure is not complete, irregular arrangement,conjunctival epithelial hyperplasia, basal cells arranged irregularly, inflammatory cells infiltration.6. Meibomian gland tissue pathological observation:on 15th day, is similar to the omega-3 group, olive oil group and physiological saline group:connective tissue real depth will divided into different sizes of the lobular glandular tissue. Acinar cell nuclei are uniform, uniform size, acinar inner columnar epithelial cells, nucleus in the basal part of gland is a concentric tube wall thickness, normal.7. Western blot was used to detect the omega-3 group and olive oil group, saline group among the three groups in cornea, conjunctiva and meibomian gland expression level of TNF-a changes.The results showed that the corneal tissue TNF-a expression for the omega-3 group (0.34±0.01), olive oil group (0.913±0.04), normal saline group (0.90± 0.04), three groups of corneal tissue TNF-a expression differences, with statistical significance (P< 0.05). Omega-3 group and olive oil group between the two groups was statistically significant difference of TNF-a expression (P<0.05); Omega-3 group and olive oil group between the two groups was statistically significant difference of TNF-a expression (P<0.05).The results showed that in conjunctival tissue TNF-a expression for the omega-3 group (0.52 ±0.27), olive oil group (1.44 ± 0.14), normal saline group (143± 0.33). Among the three groups in conjunctival tissue TNF-a expression differences, with statistical significance (P< 0.05). Omega-3 group and olive oil group between the two groups was statistically significant difference of TNF-a expression (P<0.05); Omega-3 group and olive oil group between the two groups was statistically significant difference of TNF-a expression (P<0.05).The meibomian gland tissue in TNF-a expression for the omega-3 group (2.16 ± 0.66), olive oil group (2.29 ±0.57), normal saline group (2.39 ±0.41). Among the three groups of meibomian gland tissue in TNF-a expression had no significant difference, without statistical significance (P> 0.05).8. Western blot was used to detect the omega-3 group and olive oil group, saline group among the three groups in cornea, conjunctiva and meibomian gland expression level of IL-6 changes.The results showed that the corneal tissue IL-6 expression for the omega-3 group (0.38± 0.02), olive oil group (1.01 ±0.07), normal saline group (0.95±0.03), three groups of corneal tissue IL-6 expression differences, with statistical significance (P < 0.05). Omega-3 group and olive oil group between the two groups was statistically significant difference of IL-6 expression (P<0.05); Omega-3 group and olive oil group between the two groups was statistically significant difference of IL-6 expression (P<0.05).The results showed that in conjunctival tissue IL-6 expression for the omega-3 group (0.61 ± 0.32), olive oil group (135 ±0.13), normal saline group (1.06± 0.40). Among the three groups in conjunctival tissue IL-6 expression are differences, with statistical significance (P< 0.05). Omega-3 group and olive oil group between the two groups was statistically significant difference of IL-6 expression (P<0.05); Omega-3 group and olive oil group between the two groups was statistically significant difference of IL-6 expression (P<0.05).The meibomian gland tissue in IL-a expression for the omega-3 group (0.85±0.11), olive oil group (0.79 ±0.18), normal saline group (0.83±0.08). Among the three groups of meibomian gland tissue in IL-a expression had no significant difference, without statistical significance (P> 0.05).Conclusion:1. Omega-3 fatty acids can effectively in dry eye induced by topical administration of benzalkonium chloride in reducing tear secretion and enhancing the stability of tear film, protection of corneal and conjunctival tissue2. Omega-3 fatty acids can effectively in dry eye induced by topical administration of benzalkonium chloride in reducing cornea and conjunctiva inflammation of TNF-a and IL-6 levels of expression.