Efficacy and Safety of Modified Seamless Endoscopic Dacryocystorhinostomy in Patients with Chronic Dacryocystitis

Objective To evaluate the efficacy and safety of a modified seamless endoscopic dacryocystorhinostomy (EN-DCR) with chronic dacryocystitis. Methods This study included 54 patients (54 eyes) with chronic dacryocystitis treated in our hospital from 2019 to 2021, including 32 patients (32 eyes) who underwent modified and 22 patients (22 eyes) who underwent routine EN-DCR. In the modified EN-DCR, the nasal cavity was filled 30 min before the operation by injection of 1 mg/ml adrenaline hydrochloride and application of ephedrine hydrochloride and nitrofurazone nasal drops. Before the operation, the lacrimal passages were rinsed with a 1 : 2 mixture of dilute methylene blue and normal saline. The “I”-shaped incision was replaced by a “C“-shaped incision near the lateral bone window. In place of suturing, a gelatin sponge was applied at the confluence of the lacrimal sac and nasal mucosa. After the end of the operation, the lacrimal sac was filled with tapered expansion sponge for 1 week. In routine EN-DCR, the nasal cavity was filled with 1 mg/ml epinephrine hydrochloride, and nitrofurazone nasal drops were provided for 5 minutes after the beginning of the operation; and a “I”-shaped incision was made in the nasal mucosa, with one stitch for each anterior and posterior flap. Operation time, intraoperative bleeding, and postoperative lacrimal duct irrigation were compared, with the curative effect evaluated after a follow-up of 6 months. Results Operation time was significantly shorter (41.3 ± 12.1 min vs. 65.4 ± 11.6 min; χ2 = 7.312, P < 0.05) and intraoperative bleeding was significantly lower (12.5 ± 5.2 ml vs. 60.3 ± 8.9 ml; χ2 = 24.883, P < 0.05) in the modified group than in the routine EN-DCR group. After follow-up for 6 months, the effective cure rate was significantly higher in the modified group than in the routine group (96.9% vs. 68.2%; χ2 = 6.383, P < 0.05). Conclusion Compared with routine EN-DCR, modified seamless EN-DCR can achieve better surgical outcomes, shorten operation time, and reduce intraoperative bleeding.


Introduction
Chronic dacryocystitis is a common disease of the lacrimal passages that is usually caused by stenosis or obstruction of the nasolacrimal ducts. Te accumulation of internal secretions in the lacrimal sac leads to overfowing tears and mucous secretion in patients' eyes, with a large number of purulent secretions appearing after secondary infection. Because drug treatment is often inefective or can only temporarily relieve symptoms, surgical treatment is often required [1]. External dacryocystorhinostomy not only afects a patient's appearance but can also lead to scar hyperplasia, making postoperative efects unsatisfactory. Nasal endoscopy can be used in the diagnosis and treatment of chronic dacryocystitis, with endoscopic dacryocystorhinostomy being a minimally invasive method of reconstructing the lacrimal passages.
Te average success rate of endoscopic dacryocystorhinostomy was reported to be 85%. However, there are still some patients who fail the operation. Many factors afect the results of the operation [2], including inappropriate location of the lacrimal sac, inadequate osteotomy, insufcient size of the ostium, inadequate marsupialization, more bleeding during the operation, cicatricial closure of the ostium, potential intranasal pathology, and abnormal anatomical structure. In order to better solve the symptoms of lacrimal overfow, reduce postoperative recurrence, and improve the quality of life of patients, we have further improved the routine of endoscopic dacryocystorhinostomy according to some related factors and achieved good clinical results. Te following article describes these improvements and their clinical outcomes.

Objectives and Methods
Tis retrospective analysis included 54 eyes of 54 patients with chronic dacryocystitis who were treated in our hospital from June 2019 to December 2021. Tirty-two eyes of 32 patients underwent modifed seamless endoscopic dacryocystorhinostomy, whereas 22 eyes of 22 patients underwent routine endoscopic dacryocystorhinostomy. Patients were included if: (1) they had a long-term history of lacrimal discharge with purulent secretion; (2) they showed purulent or mucous refux on lacrimal duct irrigation; and (3) previous conservative treatment, such as with anti-infammatory agents, lacrimal duct irrigation, or probing of the lacrimal passage, was inefective. Patients were excluded if they: (1) had a severe deviation of the nasal septum, as shown by CT dacryocystorhinography; (2) had experienced a traumatic fracture of the nasolacrimal duct, fracture of the orbital bone, rupture of the lacrimal sac, a space-occupying lesion of the nasal cavity, or dacryocystitis; (3) had previously undergone a nasal operation; or (4) were intolerant to operation. Tis study was approved by the ethics committee of our hospital, and all patients and their families provided written informed consent before operation.

2.1.1.
Routine Endoscopic Dacryocystorhinostomy. Dacryocystography was routinely performed before the operation to roughly determine the location, size, and nasal structure of the lacrimal sac. Operations were performed under general anesthesia. Te nasal cavity was flled with cotton that was wetted with 1 mg/ml epinephrine hydrochloride, ephedrine hydrochloride, and nitrofurazone nasal drops 5 minutes after the general anesthesia. Starting from the middle turbinates, the nasal mucosa of the lateral wall of the nasal cavity was cut with a crescent surgical knife. Ten the mucosa of the nasal cavity was cut of to form a roughly 8 mm × 10 mm mucoperiosteal fap, exposing the lacrimal bone. An 8 mm × 10 mm bony window was opened with a rongeur to expose the lacrimal sac adequately. Ten a crescent-shaped surgical knife was used to make a fullthickness"I"-shaped incision of the lacrimal sac. Te anterior and posterior valves of the lacrimal sac were sutured to the corresponding nasal mucosa. Te nasal cavity was subsequently flled with cotton balls after coating with tobramycin dexamethasone eye ointment in the lacrimal sac.

Modifed Endoscopic Dacryocystorhinostomy.
Te procedure used for modifed endoscopic dacryocystorhinostomy was similar to that for routine endoscopic dacryocystorhinostomy, except that: (1) the nasal cavity was flled with a cotton which is wet with 1 mg/ml epinephrine hydrochloride, ephedrine hydrochloride, and nitrofurazone nasal drops 30 minutes before the operation; (2) the lacrimal passages were fushed with doubly diluted methylene blue solution before the operation; (3) the traditional "I"-shaped incision was replaced by a "C"-shaped incision near the lateral bone window; (4) applying the gelatin sponge to the confuence of the lacrimal sac and nasal mucosa without the suture; and (5) the lacrimal sac was flled with a conical expansion sponge, which was maintained for 1 week. Te expansion sponge was still coated with tobramycin and dexamethasone eye ointment. Te results of this procedure are illustrated in Figure 1.

Postoperative Treatment.
Postoperatively, patients were instructed to apply 0.5% levofoxacin eye drops four times per day, 0.1% fuorometholone eye drops three times per day, and triamcinolone acetonide nasal spray twice per day. One week after the operation, the expansion sponge was removed from the lacrimal sac, and the lacrimal passage was washed with saline. Te lacrimal passage was subsequently washed with a mixture of 5 ml saline and vitamin E (1 tablet) once per week for 1 month, every 2 weeks for the next 2 months, and once per month until 6 months after the operation.

Evaluation Standard of Curative Efect.
Cure was defned as the absence of symptoms of lacrimal discharge along with unobstructed irrigation of the lacrimal passage. Improvement was defned as the ability to irrigate the lacrimal passage, partial refux, partial fow into the nasal cavity, and the absence of secretions. Treatment was defned as inefective if irrigation of the lacrimal passage was obstructed. Te rate of efectiveness was defned as the sum of the cure and improvement rates.
Continuous data were compared by independent sample t-tests and categorical data by chi-square tests. All statistical analyses were performed using SPSS20.0 statistical software, with p values <0.05 considered statistically signifcant.

Results
A comparison of patients who underwent routine and modifed endoscopic dacryocystorhinostomy showed no signifcant diferences in age, sex, duration of disease, or lacrimal sac volume (P > 0.05 each; Table 1).
A comparison of clinical outcomes in patients who underwent routine and modifed endoscopic dacryocystorhinostomy showed that the postoperative efectiveness rate was signifcantly higher in patients who underwent modifed than routine endoscopic dacryocystorhinostomy (96.88% vs. 68.18%; χ 2 � 6.383 P < 0.05; Table 2).
Comparisons of operation time and bleeding volume in patients who underwent modifed and routine endoscopic dacryocystorhinostomy showed that operation time was signifcantly shorter (41.3 ± 12.1 min vs. 65.4 ± 11.6 min; χ 2 � 7.312 min, P < 0.05) and bleeding volume during the 2 Journal of Ophthalmology operation signifcantly lower (12.5 ± 5.2 ml vs. 60.3 ± 8.9 ml; χ 2 � 24.883, P < 0.05) in patients who underwent modifed endoscopic dacryocystorhinostomy (Table 2). A comparison of complications in the two groups showed excess bleeding in 11 eyes in the routine endoscopic dacryocystorhinostomy group and in two eyes in the improved endoscopic dacryocystorhinostomy group, with all bleeding efectively controlled by compression and hemostasis. In addition, several patients in both groups experienced headache, fatigue and nasal pain after the operation,

Discussion
Although dacryocystorhinostomy using a nasal endoscope for patients with chronic dacryocystitis was frst reported in 1989 and the frst clinical study of endoscopic dacryocystorhinostomy was published in 1994, the success rates of early nasal endoscopic operations were not high. Improvements in endoscopic equipment and techniques [3] and further knowledge of lacrimal duct anatomy have increased the usefulness of nasal endoscope technology in ophthalmology [4], with endoscopic dacryocystorhinostomy becoming routine in lacrimal duct operations [5]. Improvements have maximized the success rate of endoscopic dacryocystorhinostomy [6]. Tese improvements have included nasolacrimal valve suturing; the use of stents [7], mitomycin C, and 5-fuorouracil; and laser-assisted, power terminal [8], radio frequency-assisted, and balloon dacryocystorhinostomy. Comparisons have shown that the time required for balloon dacryocystorhinostomy was the shortest, and its success rates at 3 and 6 months after operation were the highest. In contrast, the success rates of intraoperative use of mitomycin C or 5-fuorouracil and laser-assisted dacryocystorhinostomy were found to be lower than those of standard dacryocystorhinostomy, although there were no signifcant diferences among these methods in the incidence of complications [9].
Despite its success rates, routine endoscopic dacryocystorhinostomy has drawbacks [10]. Many factors afect the results of endoscopic dacryocystorhinostomy [11], including inappropriate location of the lacrimal sac, inadequate osteotomy, insufcient size of the ostium, inadequate marsupialization, more bleeding during the operation, cicatricial closure of the ostium, potential intranasal pathology, and abnormal anatomical structure [12]. In anatomical structure, about 2/3 of the lacrimal sac is located above the attachment point of the middle turbinate. Considering the position of the lacrimal sac and the thickness of the nasal bone, it is very important to locate the lacrimal sac correctly and remove the bone covering the lacrimal sac completely. Improper positioning of the lacrimal sac and incomplete removal of the bone will limit the exposure of the lacrimal sac and increase the chance of subsequent failure [13]. Te insufcient size of the ostium is characterized by the failure to cut along the full-thickness lacrimal sac wall of the whole length, thus limiting the sac marsupialization [14]. If there is more bleeding during the operation, it will increase unnecessary time waste. And the stimulation of blood clots will also lead to the formation of granulation tissue. In addition, as already stated by others, contracture of the size of the ostium is known to occur during the healing process and ranges between 50% and 92% of the original diameter; hence, the bigger the size of the ostium is, the better the outcome should be. However, no direct correlation has been demonstrated between the neorhinostomy diameter and the fnal functional success rate [15]. Even so, according to our clinical experience, we think that the size of the ostium should be adequate.
In view of the factors contributing to the failure of endoscopic dacryocystorhinostomy [16], we summarized the clinical experience and improved the operation from the aspects of preoperative preparation, intraoperative bleeding control, the exposure of the lacrimal sac, incision selection, and postoperative follow-up. We perform dacryocystography before the operation to make a preliminary evaluation of the anatomical structure of the nose and the size of the lacrimal sac. Tis can provide some valuable information that can help predict the problems that may be encountered during the operation, adjust our psychological expectations, and deal with these problems more carefully during the operation.
We use a cotton ball that is wet with the 1 mg/ml epinephrine hydrochloride, ephedrine hydrochloride, and nitrofurazone nasal drops to fll the nasal cavity 30 minutes before the operation. Te main components of furoma liquid are ephedrine hydrochloride and furacilin [17]. Ephedrine hydrochloride can directly activate vascular smooth muscle receptors and contract the blood vessels in the nasal mucosa, whereas furacilin has inhibitory efects on both Grampositive and Gram-negative bacteria. Tis mixture has both anti-infammatory and sterilization activities [18], as well as relieving congestion and edema in the nasal mucosa and reducing intraoperative bleeding. Tis improves surgical vision and shortens operation time, as well as provides a faster postoperative recovery.
Methylene blue is an absorbable, strongly alkaline dye [19]. After contact with healthy tissue, it enters the blood circulation, is fltered through the kidneys, and is excreted in urine. It has a relatively reduced ability to induce allergic reactions, making it a relatively safe and efective tracer. Methylene blue stains the lacrimal sac. It can not only show the boundaries between the lacrimal sac and the surrounding mucosal tissue but also make the lacrimal sac more adequately exposed and ready for marsupialization. Tus, preoperative fushing of the lacrimal duct with a diluted methylene blue solution can improve the accuracy of the operation by better determining the site of the surgical incision [20], thereby simplifying the operation and reducing surgical trauma.
A "C"-shaped incision near the lateral bone window can avoid the collapse of the anterior fap of the "I"-shaped incision and block the anastomosis of the lacrimal sac, resulting in maximal opening of the anastomosis. In addition, a gelatin sponge was applied to the junction of the lacrimal sac fap and the nasal mucosa. Te expanded sponge flled the dacryocystorhinostomy, thus avoiding the curl displacement of the lacrimal sac fap and blocking the stoma. Te outer edge of the nasal mucosal fap healed spontaneously with reduced adhesion to the surrounding tissue, thus efectively preventing the proliferation of granulation tissue and the formation of scar tissue in the stoma [21].
Gelatin, a product of the partial hydrolysis of natural collagen, is recognized as generally safe by the U. S. Food and Drug Administration [22]. A gelatin sponge is a type of absorbable packing material that has hemostatic and ventilatory activities as well as strong wound adsorption capacity, good histocompatibility, slow liquefaction, and absorption. Gelatin has no obvious side efects on the human body [23], is neither antigenic nor allergenic, and can meet the needs of various physiological structures within the nasal cavity. Moreover, the pressure it applies during the flling period is relatively uniform, with the degree of acceptance by patients being relatively high.
Postoperatively, the conical expansion sponge was inserted into the lacrimal sac for 1 week, efectively preventing mucosal injury and rebleeding [24]. Te expansion sponge is a type of polymer expansion material that is aseptic, nontoxic, and extremely hydrophilic. It can be trimmed to a suitable size and inserted into the nasal lacrimal sac area. Tis sponge expands and softens rapidly after contact with water or blood, increasing local tension and applying pressure to the mucous membrane around the incision. Tis, in turn, reduces the proliferation of scar tissue, adhesion, and atresia of the wound and postoperative bleeding. Te expanded sponge is coated with tobramycin and dexamethasone eye ointment [25], which not only has anti-infammatory and hemostatic efects but also reduces wound edema.
Te present study found that modifed endoscopic dacryocystorhinostomy had a signifcantly higher efectiveness rate, a signifcantly shorter operation time, and a signifcantly lower intraoperative bleeding volume than routine endoscopic dacryocystorhinostomy. Tere were no serious complications in either group. A few patients experienced greater epistaxis during the operation and a slight headache after the operation, which improved after symptomatic support treatment.
Te present study had several limitations, including its retrospective design, its selection of relatively few patients from a single institution, and its short-termfollow-up period. Randomized clinical studies with larger numbers of patients and longer follow-up times are needed to confrm these fndings.
In conclusion, endoscopic dacryocystorhinostomy is currently considered the gold standard for the treatment of chronic dacryocystitis. It is reported that the success rate of this method varies. In view of the increasing correlation of this type of operation, the various types of techniques proposed rarely show their respective advantages over each other. Tis retrospective case study confrmed that modifed seamless endoscopic dacryocystorhinostomy is one of the more successful operational types for the treatment of chronic dacryocystitis. It can signifcantly reduce operation time, bleeding, cicatricial closure of the ostium, and postoperative recurrence rate, while signifcantly improving the success rate and the postoperative lacrimal symptoms. Our report also points out that the success rate of the operation can be increased by controlling bleeding, obtaining an accurate location of the lacrimal sac, performing an adequate osteotomy, completing exposure of the lacrimal sac, and creating a sufcient size of the ostium. Last but not least, it should be emphasized that adequate preoperative preparation, meticulous endoscopic operation, and accurate postoperative follow-up are also key factors for the long-term anatomic and functional patency of the nasal ostium.

Data Availability
Te data used to support the fndings of this study are available from the corresponding author upon request.

Ethical Approval
Te authors are accountable for all aspects of the work and must ensure that questions related to the accuracy or integrity of any part of the work are appropriately investigated and resolved. All research methods were approved by the Medical Ethics Committee of the First Afliated Hospital of Gannan Medical University and conducted in accordance with the Declaration of Helsinki (as revised in 2013). Tis was a retrospective study, and the requirement for informed consent to participate was waived by the Medical Ethics Committee of the First Afliated Hospital of Gannan Medical University.