Hypersensitive mAChRs are involved in the epiphora of transplanted glands

Salivary Gland Transplantation as a Promising Approach for Tear Film Restoration in Severe Dry Eye Disease

With increased awareness of dry eye disease (DED), a multitude of therapeutic options have become available. Nevertheless, the treatment of severe DED remains difficult. In a patient whose DED is related to the loss of lacrimal function without severe destruction of the salivary glands, autologous transplantation of the latter as functioning exocrine tissue to rebuild a stable tear film is an attractive idea. All three major and minor salivary glands have been used for such transplantation. Due to the complications associated with and unfavorable prognosis of parotid duct and sublingual gland transplantation, surgeons now prefer to use the submandibular gland (SMG) for such procedures. The transplantation of the SMG not only has a high survival rate, but also improves dry eye symptoms and signs for more than 20 years post-surgery. The regulation of the secretion of the transplanted SMG is critical because the denervated SMG changes its mechanism of secretion. Innovative procedures have been developed to stimulate secretion in order to prevent the obstruction of the Wharton's duct and to decrease secretion when postoperative "epiphora" occurs. Among the minor salivary glands, the transplantation of the labial salivary glands is the most successful in the long-term. The measurement of the flow rates of minor salivary glands and donor-site selection are critical steps before surgery.

The role and mechanism of tight junctions in the regulation of salivary gland secretion

Tight junctions (TJs) are cell-cell interactions that localize at the most apical portion of epithelial/endothelial cells. One of the predominant functions of TJs is to regulate material transport through paracellular pathway, which serves as a selective barrier. In recent years, the expression and function of TJs in salivary glands has attracted great interest. The characteristics of multiple salivary gland TJ proteins have been identified. During salivation, the activation of muscarinic acetylcholine receptor and transient receptor potential vanilloid subtype 1, as well as other stimuli, promote the opening of acinar TJs by inducing internalization of TJs, thereby contributing to increased paracellular permeability. Besides, endothelial TJs are also redistributed with leakage of blood vessels in cholinergic-stimulated submandibular glands. Furthermore, under pathological conditions, such as Sjögren's syndrome, diabetes mellitus, immunoglobulin G4-related sialadenitis, and autotransplantation, the integrity and barrier function of TJ complex are impaired and may contribute to hyposalivation. Moreover, in submandibular glands of Sjögren's syndrome mouse model and patients, the endothelial barrier is disrupted and involved in hyposecretion and lymphocytic infiltration. These findings enrich our understanding of the secretory mechanisms that link the importance of epithelial and endothelial TJ functions to salivation under both physiological and pathophysiological conditions.

SHED-derived exosomes ameliorate hyposalivation caused by Sjögren's syndrome via Akt/GSK-3β/Slug-mediated ZO-1 expression

BACKGROUND

Sjögren's syndrome (SS) is an autoimmune disorder characterized by sicca syndrome and/or systemic manifestations. The treatment is still challenging. This study aimed to explore the therapeutic role and mechanism of exosomes obtained from the supernatant of stem cells derived from human exfoliated deciduous teeth (SHED-exos) in sialadenitis caused by SS.

METHODS

SHED-exos were administered to the submandibular glands (SMGs) of 14-week-old non-obese diabetic (NOD) mice, an animal model of the clinical phase of SS, by local injection or intraductal infusion. The saliva flow rate was measured after pilocarpine intraperitoneal injection in 21-week-old NOD mice. Protein expression was examined by western blot analysis. Exosomal microRNA (miRNAs) were identified by microarray analysis. Paracellular permeability was evaluated by transepithelial electrical resistance measurement.

RESULTS

SHED-exos were injected into the SMG of NOD mice and increased saliva secretion. The injected SHED-exos were taken up by glandular epithelial cells, and further increased paracellular permeability mediated by zonula occluden-1 (ZO-1). A total of 180 exosomal miRNAs were identified from SHED-exos, and Kyoto Encyclopedia of Genes and Genomes analysis suggested that the phosphatidylinositol 3 kinase (PI3K)/protein kinase B (Akt) pathway might play an important role. SHED-exos treatment down-regulated phospho-Akt (p-Akt)/Akt, phospho-glycogen synthase kinase 3β (p-GSK-3β)/GSK-3β, and Slug expressions and up-regulated ZO-1 expression in SMGs and SMG-C6 cells. Both the increased ZO-1 expression and paracellular permeability induced by SHED-exos were abolished by insulin-like growth factor 1, a PI3K agonist. Slug bound to the ZO-1 promoter and suppressed its expression. For safer and more effective clinical application, SHED-exos were intraductally infused into the SMGs of NOD mice, and saliva secretion was increased and accompanied by decreased levels of p-Akt/Akt, p-GSK-3β/GSK-3β, and Slug and increased ZO-1 expression.

CONCLUSION

Local application of SHED-exos in SMGs can ameliorate Sjögren syndrome-induced hyposalivation by increasing the paracellular permeability of glandular epithelial cells through Akt/GSK-3β/Slug pathway-mediated ZO-1 expression.

Profiling the lncRNA-miRNA-mRNA interaction network in the submandibular gland of diabetic mice

BACKGROUND

Hyposalivation is one of the common symptoms of diabetes. Although long non-coding RNAs (lncRNAs) have recently been reported to play important roles in the pathogenesis of diabetes, the role of lncRNAs in diabetes-induced hyposalivation remains unknown.

METHODS

The present study aimed to explore the function of lncRNA-microRNA-mRNA regulatory network in the submandibular gland (SMGs) under the context of diabetes. LncRNA expression profile of the SMGs was analyzed using microarray technology. Differentially expressed lncRNAs were confirmed using real-time quantitative PCR. Bioinformatics analyses were performed, and Coding-non-coding gene co-expression (CNC) and competing endogenous RNA (ceRNA) networks were constructed to explore the potential mechanisms of diabetes-induced hyposalivation.

RESULTS

A total of 1273 differentially expressed lncRNAs (536 up-regulated and 737 downregulated) were identified in the SMGs tissues of db/db mice. CNC and ceRNA network analyses were performed based on five differentially expressed lncRNAs validated by real-time quantitative PCR. Gene Ontology analysis of target genes of CNC network revealed that "calcium ion binding" was a highly enriched molecular function. Kyoto Encyclopedia of Genes and Genomes pathway analysis of target genes of ceRNA network revealed that the "mammalian target of rapamycin signaling pathway" was significantly enriched.

CONCLUSIONS

On the whole, the findings of the present study may provide insight into the possible mechanism of diabetes-induced hyposalivation.

Corneal Penetration of Low-Dose Atropine Eye Drops

Major studies demonstrating the inhibition of myopia in children and juveniles by low-dose atropine eye drops provide little information on the manufacturing process and the exact composition of the atropine dilutions. However, corneal penetration might significantly vary depending on preservatives, such as benzalkonium chloride (BAC), and the atropine concentration. Since there is a trade-off between side effects, stability, and optimal effects of atropine on myopia, it is important to gain better knowledge about intraocular atropine concentrations. We performed an ex vivo study to determine corneal penetration for different formulations. Atropine drops (0.01%) of different formulations were obtained from pharmacies and applied to the cornea of freshly enucleated pig eyes. After 10 min, a sample of aqueous humor was taken and atropine concentrations were determined after liquid–liquid extraction followed by high-performance liquid chromatography–tandem mass spectrometry (LC-MS/MS). The variability that originated from variations in applied drop size exceeded the differences between preserved and preservative-free formulations. The atropine concentration in the anterior chamber measured after 10 min was only 3.8 × 10⁻⁸ of its concentration in the applied eye drops, corresponding to 502.4 pM. Obviously, the preservative did not facilitate corneal penetration, at least ex vivo. In the aqueous humor of children’s eyes, similar concentrations, including higher variability, may be expected in the lower therapeutic window of pharmacodynamic action.

Analysis of tear film spatial instability for pediatric myopia under treatment

In Taiwan, the prevalence of myopia in children between 6 and 18 years old is over 80%, and high myopia accounts for over 20%, which turned out to be in the leading place worldwide. Orthokeratology and low-dose atropine are proven treatments to reduce myopia progression, though the potential corneal disturbances remain an issue in young populations. The alteration of the tear film is widely discussed but there is no consensus to date, so we aim to investigate the tear film spatial instability in children with myopia control using atropine or orthokeratology. Thirty-eight treatment-naïve participants and 126 myopic children under treatments were enrolled. The ocular surface homeostasis, spatial distribution of tear break-up, and high-order aberrations (HOAs) of the corneal surface were assessed. We found out that myopic children treated with either atropine or orthokeratology showed ocular surface homeostasis similar to that in treatment-naïve children. Nevertheless, children treated with orthokeratology presented higher HOAs (p < 0.00001) and a tendency of the first tear break-up zone at the inner half of the cornea (p = 0.04). This unique spatial instability of the tear film associated with myopia treatment might provide a more focused way of monitoring the pediatric tear film instability.

[Role and mechanism of muscarinic acetylcholine receptor in the regulation of submandibular gland secretion]

Muscarinic acetylcholine receptors (mAChRs), including M1-M5 subtypes, are classic receptors in regulating water, ion, and solute transport in salivary gland. Our work focuses on the studies on the expression pattern and function of mAChR in the submandibular gland (SMG), and the underlying mechanism involved in the mAChR-regulated secretion, together with the effect of parasympathectomy on the salivary secretion. Microvascular autotransplantation of SMG into the temporal fossa provides a continuous and endogenous source of fluids, and is currently an effective method for treating severe keratoconjunctivitis sicca. By using RT-PCR, Western blotting, and immunofluorescence, our data demonstrated that the expression of M1 and M3 subtypes were decreased in latent period in rabbit SMG autotransplantation model, whereas carbachol stimulation promoted the salivary secretion, as well as M1 and M3 expressions. By contrast, mAChRs were hypersensitive in epiphora SMGs, whereas atropine gel and botulinum toxin A application significantly inhibited the hypersecretion in both animal models and patients. Furthermore, the possible intracellular signal molecules involved in the mAChR-modulated salivary secretion were explored. Activation of mAChR upregulated the expression of aquaporin 5 (AQP5), the main transporter that mediated water secretion through transcellular pathway, and led to AQP5 trafficking from lipid rafts to non-lipid microdomain. Extracellular signal-regulated kinase 1/2 (ERK1/2) was involved in the mAChR-regulated AQP5 content. mAChR activation also modulated the expression, distribution, and function of tight junction proteins, and increased paracellular permeability. ERK1/2/β-arrestin2/clathrin/ubiquitin signaling pathway was responsible for the mAChR-regulated downregulation of tight junction molecule claudin-4. Cytoskeleton filamentous actin (F-actin) was also involved in the distribution and barrier function of epithelial tight junctions. Besides, endothelial tight junctions were opened by mAChR agonist-evoked salivation in the mice. Furthermore, parasympathetic denervation increased resting salivary secretion in the long terminrats and minipigs. Taken together, our work demonstrated that mAChR regulated saliva secretion via transcellular and paracellular pathways in SMG epithelium as well as tight junction opening in SMG endothelium. Modulation of mAChR might be a promising strategy to ameliorate SMG dysfunction.

Botulinum toxin A treatment of epiphora secondary to autologous submandibular gland transplantation

The aim of this study was to explore whether botulinum toxin A (BTXA) injection treats epiphora secondary to submandibular gland (SMG) transplantation for severe keratoconjunctivitis sicca. Fifteen patients with epiphora after SMG transplantation were separated to three groups, and received 15U, 20U and 25U BTXA injection in the transplanted SMG, respectively. Secretion of transplanted SMG was assessed subjectively by visual analogue scale (VAS) regarding epiphora, and objectively by Schirmer test. There were no significant differences in the 15-U BTXA group regarding the values of the VAS on epihora before and 1 month after BTXA injection. While in 20-U group and 25-U group, the values of VAS on epihora decreased significantly after BTXA injection, and lasted for 6months. Under resting conditions, the secretion of transplanted SMG decreased 64.4%, 73.0% and 78.0% in 15-U, 20-U and 25-U groups, respectively (P<0.01), in 1month after BTXA injection; significant secretion decreasing lasted 3months only in the 25-U BTXA group. BTXA injection can decrease the secretion of transplanted SMG significantly, relieving the symptoms of epiphora; 25U BTXA is a suitable dose to treat 'opportunistic epiphora' after SMG transplantation.

Autonomic reinnervation and functional regeneration in autologous transplanted submandibular glands in patients with severe keratoconjunctivitis sicca

Autologous submandibular gland (SMG) transplantation has been proved to ameliorate the discomforts in patients with severe keratoconjunctivitis sicca. The transplanted glands underwent a hypofunctional period and then restored secretion spontaneously. This study aims to investigate whether autonomic nerves reinnervate the grafts and contribute to the functional recovery, and further determine the origin of these nerves. Parts of the transplanted SMGs were collected from the epiphora patients, and a rabbit SMG transplantation model was established to fulfill the serial observation on the transplanted glands with time. The results showed that autonomic nerves distributed in the transplanted SMGs and parasympathetic ganglionic cells were observed in the stroma of the glands. Low-dense and unevenly distributed cholinergic axons, severe acinar atrophy and fibrosis were visible in the patients’ glands 4–6 months post-transplantation, whereas the cholinergic axon density and acinar area were increased with time. The acinar area or the secretory flow rate of the transplanted glands was statistically correlated with the cholinergic axon density in the rabbit model, respectively. Meanwhile, large cholinergic nerve trunks were found to locate in the temporal fascia lower to the gland, and sympathetic plexus concomitant with the arteries was observed both in the adjacent fascia and in the stroma of the glands. In summary, the transplanted SMGs are reinnervated by autonomic nerves and the cholinergic nerves play a role in the morphological and functional restoration of the glands. Moreover, these autonomic nerves might originate from the auriculotemporal nerve and the sympathetic plexus around the supplying arteries.

Regenerated nerves play a role in restoring the function of transplanted submandibular glands (SMGs) in treating dry eye syndrome. Dry eye syndrome, or keratoconjunctivitis sicca (KCS), is a leading cause of patients visiting ophthalmologists, and one effective treatment in severe cases is transplanting SMGs (to the temporal area). Autonomic nerves have an important function in maintaining the secretory function of salivary glands, and a team headed by Yan Zhang and Guang-Yan Yu at Peking University, China investigated whether those nerves underwent reinnervation (restoration of nerve control) with transplanted SMGs in KCS patients and in a rabbit model. The authors found that in both the patients and rabbit model, the transplanted SMGs were reinnervated and the regenerated nerves played a role in restoring the glands’ function. The findings offer new insights into managing SMG transplantation.

β-adrenoceptor activation increased VAMP-2 and syntaxin-4 in secretory granules are involved in protein secretion of submandibular gland through the PKA/F-actin pathway

Autologous submandibular gland transplantation is an effective treatment for severe dry eye syndrome. However, the protein secretion in transplanted gland is altered by a mechanism that remains to be elucidated. In the present study, we found that β1-adrenoceptor (β1-AR) and β2-AR expression and the phosphorylation of the downstream molecule protein kinase A (PKA) were elevated in transplanted submandibular glands obtained from epiphora patients. Synaptobrevin/vesicle-associated membrane protein 2 (VAMP-2) interacted with syntaxin-4 and actin in human submandibular gland. The contents of syntaxin-4 and actin interacting with VAMP-2 were increased in transplanted gland. Moreover, VAMP-2 and syntaxin-4 expression in the secretory granule fraction, and VAMP-2 expression in the membrane protein fraction were increased in isoproterenol-treated and transplanted glands. Isoproterenol increased F-actin polymerization in the apical and lateral regions of the cytoplasm in both control and transplanted glands. Inhibiting PKA activity and/or F-actin formation abolished the isoproterenol-enhanced expression of VAMP-2 and syntaxin-4 in the secretory granule fraction and the isoproterenol-enhanced expression of VAMP-2 in the membrane protein fraction. Taken together, these results indicate that the activation of β-ARs induces secretory granules and cell membrane fusion via the interaction of VAMP-2 and syntaxin-4 in a PKA- and F-actin-dependent manner in human submandibular gland. Up-regulated β-ARs might participate in altering protein secretion in transplanted submandibular gland by promoting the interaction of VAMP-2 with syntaxin-4.

Ca2+-CaMKKβ pathway is required for adiponectin-induced secretion in rat submandibular gland

Adiponectin functions as a promoter of saliva secretion in rat submandibular gland via activation of adenosine monophosphate-activated protein kinase (AMPK) and increased paracellular permeability. Ca²⁺ mobilization is the primary signal for fluid secretion in salivary acinar cells. However, whether intracellular Ca²⁺ mobilization is involved in adiponectin-induced salivary secretion is unknown. Here, we found that full-length adiponectin (fAd) increased intracellular Ca²⁺ and saliva secretion in submandibular glands. Pre-perfusion with ethylene glycol-bis (2-aminoethylether)-N,N,N',N'-tetraacetic acid (EGTA) combined with thapsigargin (TG), an endoplasmic reticulum Ca²⁺-ATPase inhibitor, abolished fAd-induced salivary secretion, AMPK phosphorylation, and enlarged tight junction (TJ) width. Furthermore, in cultured SMG-C6 cells, co-pretreatment with EGTA and TG suppressed fAd-decreased transepithelial electrical resistance and increased 4-kDa FITC-dextran flux responses. Moreover, fAd increased phosphorylation of calcium/calmodulin-dependent protein kinase (CaMKKβ), a major kinase that is activated by elevated levels of intracellular Ca²⁺, but not liver kinase B1 phosphorylation. Pre-perfusion of the isolated gland with STO-609, an inhibitor of CaMKKβ, abolished fAd-induced salivary secretion, AMPK activation, and enlarged TJ width. CaMKKβ shRNA suppressed, whereas CaMKKβ re-expression rescued fAd-increased paracellular permeability. Taken together, these results indicate that adiponectin induced Ca²⁺ modulation in rat submandibular gland acinar cells. Ca²⁺-CaMKKβ pathway is required for adiponectin-induced secretion through mediating AMPK activation and increase in paracellular permeability in rat submandibular glands.

Decreased interaction between ZO-1 and occludin is involved in alteration of tight junctions in transplanted epiphora submandibular glands

Tight junctions (TJs) in salivary epithelium play an important role in regulating saliva secretion. Autologous transplantation of submandibular glands (SMGs) is an effective method to treat severe dry eye syndrome. However, epiphora occurs in some patients 6 months after transplantation. We previously found that the acinar TJs are enlarged in rabbit SMGs after long-term transplantation, but the exact TJ components involved in the epiphora are still unknown. Here, we found that the mRNA and protein expression of ZO-1 and occludin were increased in the transplanted SMGs obtained from epiphora patients, while other TJs were unchanged. The intensity of ZO-1 and occludin at the apicolateral membranes as well as occludin in the cytoplasm were increased in epiphora SMGs, but the interaction between ZO-1 and occludin was decreased as evidenced by both co-immunoprecipitation assay and co-immunofluorescence staining. Mechanically, the expression of casein kinase 2α (CK2α) and CK2β, which was reported to affect occludin modification and the interaction of occludin with ZO-1 in previous literatures, were increased in epiphora glands. Moreover, activation of muscarinic acetylcholine receptor (mAChR) by carbachol directly decreased the interaction between ZO-1 and occludin and increased the acinar TJ width in the freshly isolated human SMGs, whereas these effects were abolished by pretreatment with CK2 inhibitor. Taken together, our findings suggest that decreased interaction between ZO-1 and occludin might contribute to the epiphora occurred in the transplanted SMGs, and mAChR together with the intracellular molecule CK2 might be responsible for the alteration of TJs in epiphora glands.

Endothelial Tight Junctions Are Opened in Cholinergic-Evoked Salivation In Vivo

Blood vessels provide the original supplies for the formation of primary saliva, which is regulated by the tight junctions (TJs) between endothelial cells. Previous studies have shown that blood flow increases with vasodilatation during cholinergic-evoked salivation. However, changes in vascular paracellular permeability and the role of endothelial TJs in salivation are unknown. Here, we established an in vivo paracellular permeability detection system and observed that the endothelial TJs were permeable to 4-kDa fluorescein isothiocyanate (FITC)-dextran while impermeable to 40- and 70-kDa FITC-dextran under an unstimulated condition in mouse submandibular glands (SMGs). Pilocarpine increased the flux of 4- and 40-kDa FITC-dextran out of blood vessels but did not affect 70-kDa FITC-dextran. Claudin 5, a TJ protein specifically localized in salivary endothelial cells, was redistributed from the apicolateral membranes to the lateral and basolateral membranes and cytoplasm in cholinergic-stimulated mouse SMGs and freshly cultured human SMG tissues. In the transplanted SMGs from epiphora patients, we found that claudin 5 was present in the basolateral membranes and cytoplasm, instead of the apical region in control SMGs. Moreover, the level of phospho-myosin light chain 2 increased within the blood vessels of the pilocarpine-stimulated mouse SMGs and transplanted human SMGs, while the downstream molecule F-actin was reorganized in the endothelial cells of the transplanted human SMGs. Taken together, our findings provide direct visual evidence that the opening of endothelial TJs and the redistribution of claudin 5 are essential events contributing to cholinergic-evoked salivation, thus enriching our understanding of the secretory mechanisms that link blood flow to primary saliva formation by regulating the endothelial paracellular permeability.

Parasympathectomy increases resting salivary secretion in normal and irradiated submandibular glands of rats

Fluid and ion secretion from the submandibular gland (SMG) is mainly regulated by parasympathetic nerves. This study evaluated the effect of parasympathectomy on salivary secretion from normal and irradiated rat SMGs from 1 to 24 wk after denervation. Although stimulated salivary secretion was significantly lower in denervated SMGs compared with contralateral self-controls, the resting salivary flow rates were markedly higher in the denervated SMGs at 1, 12, and 24 wk after denervation. The levels of muscarinic acetylcholine M1 and M3 receptors, as well as of aquaporin 5, were up-regulated. Notably, although irradiated SMGs showed significantly lower resting and stimulated salivary secretion rates than non-irradiated SMGs, the resting salivary secretion rates of the irradiated and denervated SMGs were markedly higher than seen in the irradiated self-control SMGs at 1, 12, and 24 wk after parasympathectomy, and were even higher than seen in the non-irradiated sham-operated rats. The expression of M1 and M3 receptors was similarly elevated. Taken together, our results suggest that parasympathetic denervation increases resting salivary secretion of both normal and irradiated SMGs. This approach might provide a potential modality for relieving radiation-induced xerostomia, which is a common complication following treatment of head and neck cancer.

Muscarinic acetylcholine receptor-mediated tight junction opening is involved in epiphora in late phase of submandibular gland transplantation

Submandibular gland (SMG) autotransplantation is an effective therapy for treating severe dry eye syndrome. However, epiphora occurs in more than 40% of patients 6 months after operation. We previously found that muscarinic acetylcholine receptor (mAChR) plays a crucial role in regulating SMG secretion partially through the modulation on tight junction (TJ)-based paracellular pathway. Therefore, the present study aimed to investigate the possible involvement of mAChR and TJ in a rabbit long-term model of SMG transplantation. We found that SMG secretion was significantly increased on postoperative days 90 and 180, which imitated epiphora observed in the patients with SMG transplantation. Although the mRNA expression and fluorescence intensity of M1 and M3 mAChR subtypes were reversed to control levels on postoperative days 30, 90, and 180, the content of β-arrestin2, but not β-arrestin1, was gradually decreased after transplantation, which suggests that mAChR may be hypersensitive in late phase of SMG transplantation. The width of acinar TJs was enlarged and fluorescence intensity of F-actin in peri-apicolateral membranes were remarkably increased on postoperative days 90 and 180. Topical treatment with atropine gel significantly reduced SMG secretion, TJ width, as well as F-actin intensity in peri-apicolateral membranes on postoperative days 180. Moreover, in a perfused rabbit SMG, carbachol increased salivary secretion, enlarged TJ width, and induced F-actin rearrangement, whereas these responses were inhibited by atropine pretreatment. Taken together, our findings suggest that the hypersensitive mAChR may contribute to epiphora in late phase of SMG transplantation through modulating TJ-based paracellular permeability.

A new treatment for epiphora secondary to submandibular gland transplantation: transcutaneous atropine gel

PURPOSE

To explore whether topical application of atropine gel controls epiphora secondary to submandibular gland (SMG) transplantion for severe keratoconjunctivitis sicca.

METHODS

Eighteen patients with epiphora after SMG transplantation participated in a double-blind, controlled, crossover study. Patients were treated with topical smear common atropine (CA) and modified atropine (MA) gels (intervals ≥1 day). The control effect of atropine gels was observed for 5 hours. Tear flow was quantified in resting and stimulated (after exercise) states using the Schirmer I test.

RESULTS

With the CA gel, tear flow decreased significantly at 10, 30, and 120 minutes. Average epiphora reduction rates (AERRs) were 22.37%, 18.14%, and 13.27%, respectively (P<.05). With the MA gel, tear flow decreased significantly from 5 minutes to 5 hours; AERRs increased from 24.06% to 42.67% (P<.05); Maximum efficacy was maintained from 15 minutes to 3 hours (P<.01); Tear flow gradually increased from 4 to 5 hours but was still lower than that before atropine use (P<.05). According to results of the Schirmer I test and AERRs, the control efficacy of the MA gel was significantly better than that of the CA gel (P<.05).

CONCLUSIONS

Topical application of atropine gel could effectively control mild epiphora for patients with SMG transplantation for severe keratoconjunctivitis sicca. The efficacy of MA gel was much better than that of the CA gel.