Ostium Characteristics and Its Relevance in Successful Outcome Following Endoscopic Dacryocystorhinostomy

Abstract

Study aims to assess the postoperative ostium shrinkage pattern and also attempted to evaluate various ostium parameters and their impact on surgical outcome by using DOS scoring system. Prospective study comprising 44 patients of NLD obstruction with 52 procedures performed during October 2016 to November 2018. Various dimensions of bony neo-ostium were recorded intraoperatively and during 1st, 3rd and 6th month follow up. Degree of ostium shrinkage and its correlation with anatomical and functional success was studied. DCR ostium (DOS) scoring system, comprised of ten various ostium parameters, was used to evaluate postoperative ostium. Intraoperative mean ostium height and width were 13.67 ± 2.76 mm and 7.0 ± 1.94 mm and surface area was 98.33 ± 38.46 mm². Maximum ostium shrinkage (by 66.93%) occurred at 1 month and after which, average size of ostium was quite stable with little change. The anatomical and functional success rate was 94.23% and failure rate was 5.77%. DOS score was “excellent” in 40(75.92%), “good” in 9(17.31%) and “poor” in 3(5.77%) cases. Meticulous evaluation at regular intervals is important for surgeon to understand the characters of ostium during healing and also helps in early detection of pathologies and may facilitate early corrective intervention. We believe that DOS system provides an effective protocol to standardize the ostium evaluation. The ostium parameters with favourable surgical outcome are ostium location anterior to axilla of MT, circular/ oval shape with shallow base, size > 8 × 5 mm, clearly visualized and dynamic ICO, absence of ostium cicatrization, granulomas, synechiae and other pathologies.

Introduction

Since decades, Dacryocystorhinostomy (DCR) is the gold standard surgical procedure for Nasolacrimal duct (NLD) obstruction. External and endoscopic approaches were described in literature with variable success rates, their advantages and surgical limitations. The reported success rates of endonasal DCR vary between 63% and 93.5%, whereas external DCR has success rates of 70% to 95.8% [1–5]. Despite numerous surgical modifications failure rates for endonasal DCR ranges from 4 to 13% [4–6]. Ostium scarring and cicatrization of ostium site were listed as the most important causes of failure in endonasal DCR [7–10]. The other causes of ostium-related failures include, inadequate sac exposure, small opening of the sac, cicatrization of sac prior to surgery, inappropriate location of ostium, unopened agger cells, removal of sac wall with poor approximation of\lacrimal sac and nasal mucosal membranes over internal common opening (ICO), granulomas and sump syndrome [8, 10, 11].

The majority of studies published till now, have focused on measurements of ostium dimensions or patency testing for assessing postsurgical outcomes [12–20]. There has been little or no discussion of other ostium parameters like location, shape, base, ICO dynamicity and ostium pathologies. These finer physical and functional details of the ostium need to be evaluated postoperatively in an orderly manner to appreciate pathological behaviours and institute corrective measures. MJ Ali [21] proposed a DCR ostium protocol for a detailed evaluation of ostium and also the DCR ostium or the DOS scoring to standardize the evaluation.

In present study, we tried to determine how the size of the surgically created lacrimal ostium changes over time. We also attempted to evaluate various ostium parameters and their impact on surgical outcome by using systematic approach (DOS scoring).

Material and Methods

This prospective, nonrandomized, interventional study included 44 patients of epiphora due to NLD obstruction and conducted during October 2016 to November 2018 in Government Medical College and Hospital, Nagpur, India. The research protocol was approved by the institutional ethics committee. All patients were subjected to detailed history, clinical (ENT and ophthalmological), hematological and radiological examination. All patients underwent complete lacrimal system examination. Patients having recurrence of epiphora after endonasal/external DCR were also included. However, those having canalicular or punctum block, orbital or sino-nasal malignancy, noticeable lower lid laxity, ectropion/entropion were excluded. Dacryocystography was done to rule out canalicular obstruction in revision cases and for selective primary cases. Nasal endoscopy was done to look for any associated sino-nasal pathology. With proper counseling and consent, all patients were subjected for Endoscopic Endonasal DCR under necessary anaesthesia.

Surgical Steps

Curvilinear mucosal incision anterior to axilla of middle turbinate was made and posteriorly based mucoperiosteal flap elevated. Adequate bone removal was done to expose the whole medial wall of lacrimal sac. Condition of the sac was noted whether bulged, normal or cicatrized. The lacrimal sac was opened to create anterior and posterior flaps and its contents were assessed (mucoid/clear/mucopurulent). Condition of sac wall was noted (normal/ inflamed/edematous). Careful inspection of ICO was done to evaluate any obstructions. The vertical and horizontal dimensions of the neo-ostium were measured using Castroviejo calipers and Schirmer strips (Fig. 1) and surface area was calculated. Adequate mucosal preservation with flap refashioning and nasal to lacrimal mucosal approximation was done. Bare bone of osteotomy was covered with nasal flap. Silicone stenting was done in selected cases.

Fig. 1.

a Curvilinear incision over mucosa of lateral wall of nose anterior to middle meatus. b Measurement of Bony window. c Measurement of Vertical dimension of lacrimal sac window. d Measurement of Horizontal dimension of lacrimal sac window

Follow up

Major time points in evaluation were 1st, 3rd and 6th months post DCR. During follow-up visits, patients’ symptoms were assessed; lacrimal syringing and nasal endoscopy were done. On nasal endoscopy, neo-ostium was examined for its anatomical patency and its horizontal, vertical dimensions and surface area were measured (Fig. 2). Any associated pathologies like synechiae/ granulations/ cicatrisation were noted and addressed (Fig. 3). At 6th month, Functional endoscopic dye test (FEDT) was done with 2% fluorescein drops. Various ostium parameters mentioned in DOS scoring system were evaluated at the 6th month follow-up.The DOS scoring assesses ten major parameters. Each parameter is subdivided into four subparameters with a specific score in a descending order. Normal subparameter gets the highest score of 4 points and the worst subparameter gets the lowest score of 1. The maximum points are 40 and minimum are 10. (Tables 1, 2).

Fig. 2.

a1 and a2 Measurement of ostium at 1st month follow up. b1 and b2 Measurement of ostium at 3rd month follow up. c1 and c2 Measurement of ostium at 6th month follow up

Fig. 3.

Showing pathologies of ostium—a Granulomas; b Complete cicatrisation; c Synechiae; d Incomplete cicatrisation

Table 1.

The DCR ostium (DOS) scoring system [21]

Parameters	Characteristics	Score	Parameters	Characteristics	Score
1. Location of ostium	In front and above axilla of MT	4	6. ICO	Uncovered by edge	4
	Behind axilla of MT	3		Overhanging edge	3
	Any other location	2		Partially obstructed/ membrane	2
	Not recognizable	1		Non-traceable with FEDT/ irrigation	1
2. Shape of the ostium	Circular/oval with shallow base	4	7. FEDT	Spontaneous and in < 1 min	4
	Circular/oval with deep base	3		Spontaneous and in > 1 min	3
	Crescenteric/ vertical slit/ others	2		Not spontaneous but positive with irrigation	2
	Not recognizable	1		Negative with irrigation	1
3. Size of the ostium (length × breadth)	> 8 × 5 mm	4	8. Silicone stents	Course traced, moved with blink/ unintubated	4
	5–8 × 3–5 mm	3		Intubated but lost/ removed before 4 weeks	3
	1–4 × 1–3 mm	2		Associated contact granuloma	2
	Obliterated	1		Entrapped in ostial tissue	1
4. Ostium cicatrisation	None	4	9. Ostium granuloma	None	4
	Pseudo cicatrix	3		On one or more edges	3
	Incomplete cicatricial closure	2		Peri-ICO/ threatening ICO	2
	Complete cicatricial Closure	1		Covering/ obstructing ICO	1
5. Synechiae	None	4	10. other Ostium pathologies	None	4
	Nonostial/ noninterfering	3		1 minor	3
	Interfering ostial	2		> 1 minor	2
	Complete synechial closure	1		Major	1

Maximum Possible Score: 40, Minimum possible score: 10

Table 2.

Ostium grading score

Score	Grade
36–40	Excellent
30–35	Good
21–29	Fair
10 to 20	Poor

Surgical success was characterized by anatomic and functional success. Anatomical success was defined as endoscopic evidence of patent neoostium and free flow of dye from conjunctival cul-de-sac into ostium and functional success as resolution of symptoms.

Statistical Analysis

Intra operative height, width and area were compared at different follow-up by performing one-way repeated measure ANOVA. Paired t-test was used for comparison of outcome of 2 consecutive follow-up. p < 0.05 was considered as statistically significant. Statistical software Open Epi 3.03(2014) was used for data analysis.

Results

We performed 52 Endonasal Endoscopic DCR in 44 patients where 36(81.82%) cases were unilateral and 8(18.18%) were bilateral. The age group ranged from 6 to 67 years with mean age of 36.86 years. Our study was female preponderant with male to female ratio of 1:2.6. The cause of NLD obstruction was idiopathic in 49(94.23%) cases, and congenital in 3(5.77%) cases. Out of 5 cases of anatomically failed DCR, primary surgery was external DCR in 2 and endonasal DCR in 3 cases. Epiphora was present in all 100% cases with 7(13.46%) cases had associated discharge, 9(17.31%) had swelling or mucocele and 3(5.77%) had lacrimal fistula. Intraoperatively, lacrimal sac was bulged in 43(82.69%) cases, cicatrized in 7(13.46%) and normal in 2(3.85%) cases. The content was mucoid in 5(9.62%), mucopurulent in 39(75%) and clear in 8(15.38%) cases. Lacrimal sac wall was edemaotus in 33(63.46%) cases whereas inflamed in 9(17.31%), fibrosed in 2(3.85%) and normal in 8(15.38%) cases.

Evaluation of Ostium

Measurements of Dimensions; Intraoperatively and at Follow Up

Intraoperative mean ostium height was 13.67 ± 2.76 mm, width was 7.0 ± 1.94 mm and surface area was 98.33 ± 38.46 mm². The mean ostium surface area was reduced to 32.52 mm² (66.93%) at 1st month, and 19.81 mm² (79.85%) at end of 6th month. At 6th month, total reduction in mean ostium surface area was 79.85% whereas for height and width, the reduction was 78.28% and 54.14% respectively. The mean ostium dimensions at specified time points and degree of shrinkage are summarized in Table 3. All mean ostium dimensions (height, width and surface area) showed statistically significant reduction during 1st month when compared to intraoperative dimensions (p < 0.0001) but the dimensions were not significantly different when dimensions at 1st month were compared with 3rd and 6th month (one way ANOVA with Bonferroni correction).

Table 3.

Mean Ostium dimensions and Degree of Shrinkage—intraoperatively and at 1st month, 3rd month and 6th month follow-up

Parameter	Intraoperative	1st month	p value	3rd month	p value	6th month	p value	Degree of shrinkage %
Height (mm)	13.67 ± 2.76	6.13 ± 3.27	p < 0.001 (HS)	5.25 ± 3.14	p = 0.16 (NS)	4.79 ± 2.86	p = 0.43 (NS)	78.28
Width (mm)	7.0 ± 1.94	4.35 ± 2.37	p < 0.001 (HS)	3.71 ± 2.37	p = 0.17 (NS)	3.21 ± 2.02	p = 0.2 (NS)	54.14
Surface area (mm2)	98.33 ± 38.46	32.52 ± 28.54	p < 0.001 (HS)	25.23 ± 25.11	p = 0.17 (NS)	19.81 ± 19.26	p = 0.22 (NS)	79.85

Various Ostium Parameters and DCR Ostium Scoring System (Table 4)

Table 4.

The DCR ostium (DOS) scoring in present study at the 6th month follow up

Parameters	Characteristics	Score	No. of cases (%)	Parameters	Characteristics	Score	No of cases
1. Location of ostium	In front and above axilla of MT	4	52 (100%)	6. ICO	Uncovered by edge, dynamic	4	32 (61.54%)
	Behind axilla of MT	3	0 (0%)		Overhanging edge, dynamic	3	17 (32.69%)
	Any other location	2	0 (0%)		Partially obstructed/ membrane	2	0 (0%)
	Not recognizable	1	0 (0%)		Nontraceable with FEDT/ irrigation	1	3 (5.77%)
2. Shape of the ostium	Circular/oval with shallow base	4	30 (57.69%)	7. FEDT	Spontaneous and in < 1 min	4	49 (94.23%)
	Circular/oval with deep base	3	16 (30.77%)		Spontaneous and in > 1 min	3	0 (0%)
	Crescentric/ vertical slit/ others	2	3 (5.77%)		Not spontaneous but positive with irrigation	2	0 (0%)
	Not recognizable	1	3 (5.77%)		Negative with irrigation	1	3 (5.77%)
3. Size of the ostium (length × breadth)	> 8 × 5 mm	4	5 (9.62%)	8. Silicone stents	Course traced, moved with blink/unintubated	4	51 (98.08%)
	5–8 × 3–5 mm	3	24 (46.15%)		Intubated but lost/ removed before 4 weeks	3	1 (1.92%)
	1–4 × 1–2 mm	2	20 (38.46%)		Associated contact granuloma	2	0 (0%)
	Obliterated	1	3 (5.77%)		Entrapped in ostial tissue	1	0 (0%)
4. Ostium cicatrisation	None	3	43 (82.69%)	9. Ostium granuloma	None	4	51 (98.08%)
	Pseudo cicatrix	3	0(0%)		On one or more edges	3	1 (1.92%)
	Incomplete cicatricial closure	2	6 (11.54%)		Peri-ICO/ threatening ICO	2	0 (0%)
	Complete cicatricial closure	1	3 (5.77%)		Covering/ obstructing ICO	1	0 (0%)
5. Synechiae	None	4	50 (96.15%)	10. Other ostium pathologies	None	4	52 (100%)
	Nonostial/ noninterfering	3	2 (3.85%)		1 minor	3	0 (0%)
	Interfering ostial	2	0 (0%)		> 1 minor	2	0 (0%)
	Complete synechial closure	1	0 (0%)		Major	1	0 (0%)

1. Location of ostium In all 52 cases, ostium was observed anterior and above the axilla of middle turbinate (MT).

2. Shape of ostium 30(57.69%) ostia were circular to oval in shape with shallow base, 16 (30.77%) were circular to oval with deep base and 3 (5.77%) ostia were cresentric or vertical slit shaped.

3. Size of ostium (Height x Width) Ostium size was in the range of 5–8 × 3–5 mm in 24 (46.15%) cases, 1–4 × 1–2 mm in 20 (38.46%) cases whereas ostium was obliterated in 3 (5.77%) cases.

4. Ostium cicatrisation We noticed incomplete cicatrization in 6 (11.54%) cases (Fig. 3) and complete cicatrization in 3(5.77%) cases. We didn’t have any case of pseudocicatrix.

5. Synechiae Synechiae was observed between inferior turbinate and septum in 2(3.85%) cases which was non-ostial, noninterfering type.

6. Internal Common Opening (ICO) ICO can be traced by simple visualization of an opening, its movements, by using a dye test or by silicone tube. Location and dynamicity of ICO during blinking of eyes were noted. Any obstructing tissues like membrane or granuloma were noted. ICO was centrally located and dynamic in 32 (61.54%) cases, behind overhanging edges in 17 (32.69%) whereas it was nontraceable in 3 (5.77%) cases.

7. Functional Endoscopic Dye Test (FEDT) We performed FEDT at 6th month follow up. Spontaneous flow of dye was present in 94.23% cases and we didn’t have any case of lacrimal pump failure or obstruction at the level of ICO.

8. Silicon Stents We used stents in 3 cases of revision DCR. In 1 case stent was removed due to granuloma formations by 1st follow up and patient developed complete cicatrization of ostium. In rest 2 cases, stent was removed at 3rd month and they had patent ostium.

9. Ostium granuloma Granuloma was encountered in 1(1.92%) case over anterior edge of ostium (Fig. 3) and responded well to topical steroids.

10. Ostium related pathologies We had not noticed any ostium related pathologies.

Outcome

At 6th month, 49 (94.23%) cases had complete resolution of symptoms with wide, patent ostium. 3 (5.77%) patients returned with epiphora (functional failure) whose lacrimal sac syringing showed complete block with regurgitation from opposite punctum and complete closure of neo-ostium on nasal endoscopy (anatomical failure). The overall anatomical and functional success rate was 94.23% each and the failure rate was 5.77% (Fig. 4). The DCR ostium scoring (DOS) was “excellent” in 40 (75.92%), “good” in 9 (17.31%) and “poor” in 3(5.77%) cases (Table 5).

Fig. 4.

Demonstrating the surgical outcome

Table 5.

DOS score of present study

Grade	No of patients (%)
Excellent	40 (75.92)
Good	9 (17.31)
Fair	–
Poor	3 (5.77)

Discussion

Present study investigated the pattern of ostium shrinkage and various parameters related to ostium evolution in postoperative period and their role in surgical outcome. Regular monitoring, knowledge of the typical sequence and temporal nature of events in the healing process helps surgeon understand the response to operative technique, to identify aberrations early and institute corrective measures.

We had 52 cases of DCR performed in 44 patients presenting with epiphora. Similar to previous studies, we also had idiopathic or primary acquired obstruction as most common cause of NLD obstruction [22–24]. According to Beigi et al. [25] lacrimal syringing alone has a high false positive rate for NLD obstruction and many cases with NLD obstruction also had concomitant canalicular obstruction. DCG visualizes the exact location of obstruction and the size of lacrimal sac. We performed DCG in primary cases with suspicion of canalicular block and in all revision cases to locate the site of obstruction and to rule out canalicular block. In our opinion DCG is not mandatory in all cases. This helped us in low cost examination, accurate case selection and consequently improving the surgical outcome.

Ostium dimensions were recorded during each follow up and noteworthy was that maximum ostium shrinkage (by 66.93%) occurred at 1 month postoperatively. However, after this point time, average size of ostium was quite stable with little change seen thereafter till 6 month which was statistically not significant (Table 5). This ostium shrinkage pattern was supported by previous published literature [13, 17, 18, 20, 21]. The degree of ostium shrinkage is variable, with wide reported ranges of 20–98%. This variability may be influenced by various surgical techniques and patient factors. Contracture of ostium occurs during proliferative and remodeling stage of wound healing. Majority of healing and scar formation occurs during first 4 weeks, although ostium remodeling continues beyond this time. Granulation tissue when heal by secondary intention, result in subsequent cicatrix formation. Thus by restricting development of granulation tissue and facilitating healing by primary intention, ostium shrinkage can be reduced. In addition, Shin et al. [26] observed that fibrosis with lager degree of ostium shrinkage led to poor rhinostomy movement and functional failure. We believe that instead of making efforts to achieve a standard size in all cases, the primary aim should be proper identification of lacrimal sac site, adequate osteotomy exposing sac from fundus till proximal NLD, adequate marsupialization to meet the nasal mucosal apposition and creating mucosal flap to cover all exposed bone. This fact was supported by various authors in their respective studies on surgical outcomes of endonasal DCR [17, 26–30].

Similar to Chan [18] and Ben Simon et al. [14], we observed strong positive correlation between initial and final ostium size. We had complete cicatrization of ostium in 3 (5.77%) cases and pin-point ostium (< 1 × 1 mm) in 5 cases. These cases remarkably had smaller intraoperative ostium dimensions. It was observed that in cases where intraoperative dimensions of ostium were higher, the corresponding post-operative dimensions were also higher and statistically significant (p < 0.0001). We had anatomical and functional failure in cases having complete closure of ostium site. Though in 5 cases there was pin point ostium, the patients were symptom free and were considered as surgical success. Thus our findings suggest that intraoperative and postoperative ostium size is not predictive of a successful surgical outcome [18].

MJ Ali et al. [21] proposed DOS scoring with the purpose to standardize the evaluation of ostium. They defined ostium as a surgically created opening in lacrimal drainage system located on lateral nasal wall with mucosal lined base and exposure of ICO[21]. We will discuss various ostium parameters in sequential manner;

1. Location of ostium PJ Wormald [31] described intranasal surface anatomy of sac to be located largely anterior to free edge of MT. The major portion of sac (10 mm) was found to be situated above axilla of MT, whereas only 1–2 mm was below this landmark. Most of the post-DCR ostia are located in this location. However, some ostia occasionally found behind the axilla of MT owing to a forward-protuberant MT, which makes lacrimal sac appear to be positioned more posteriorly. In our series, ostium was anteriorly located in all cases. MJ Ali [21] documented anteriorly located ostium in 85.8% cases.

2. Shape of Ostium MJ Ali [21] described various ostium shapes depending upon the healing procedure, bone removal, sac exposure and mucosal approximation which include; circular to oval with shallow base, circular to oval with deep base, cresentric or vertical slit. Precision of osteotomy site, circumferential mucosal apposition and radial healing achieve circular to oval shape with shallow base and it is favourable ostium shape for surgical success. Deep bases typically result from inadequately large osteotomy with poor saucerization of edges. Although have favourable outcome, they are associated with incomplete visualization of canalicular system on postoperative endoscopy, early crusting and granulomas from excessive bone exposure. Crescentric and vertical slits, less favourable shapes, reflect suboptimal irregular healing and inconsistent patchy cicatrization. Some authors have reported that ostium shape is associated with functional failure[32, 33]. Shin et al.[26] demonstrated that intraoperative lacrimal sac findings (sac size, wall thickness, mobility), ostial shrinkage and ostium movement are associated with postoperative rhinostomy shape which in term is a predictor of functional surgical success. We concur that patients with larger, thinner and more mobile lacrimal sacs have favourable ostium shape and better outcome.

3. Size of Ostium MJ Ali [21] propose that at 4th postoperative week, ostium measuring > 8 × 5 mm should be considered as good, large size and an ostium < 4 × 3 mm be considered as small. They had 78.3% patients with ostium size > 8 × 5 mm. On contrary we had only 9.62% patients with ostium size of > 8 × 5 mm.

4. Ostium Cicatrization Cicatrization can be complete or incomplete. Complete cicatrization is a leading cause of surgical failure and in our series, it’s the only cause of failure in 5.77% cases. Sometimes ostium is covered by a thin layer of scar tissue, much medially towards septum with normal patent ostium behind it, is termed as pseudocicatrix. In pseudocicatrix, patient is asymptomatic and FEDT and irrigation are patent.

5. Synechiae Synechiae, between lateral wall of nose and MT or septum, are cause of surgical failure in 2–20% cases [34–37]. Early detection and management prevents consolidation of synechiae. Synechiae obstructing visualization of ostium or threatening lacrimal drainage need synechiolysis. Certain steps should be followed deliberately to prevent synechiea formation like adequate bone removal, creation of mucosal flaps to cover exposed bone, avoid unnecessary removal or injury of surrounding tissue, correction of associated nasal pathologies. Depending upon the anatomical location and threat to lacrimal drainage, synechiae can be divided into noninterfering (Fig. 3), interfering or likely to interfere with ostium functions. We had 2 cases of non-ostial noninterfering synechiae.

6. Internal Common Opening ICO represents the opening of distal end of common canaliculus into the lacrimal sac. The most common location of ICO in ideal ostium is on central or paracentral area of the base and same was encountered in 61.54% cases in our series. Movement of ICO is one of the key factors in lacrimal drainage. Kakizaki et al. [38] conducted a study on movement of ICO and concluded that ICO is incompletely closed with eyelid opening, but this orifice opened during eyelid closing, with gradual inflow of lacrimal fluid, helped by gravity. Shin et al. [26] established the association of poor rhinostomy and ICO movement with poor functional surgical outcome. We demonstrated ICO movement in 49(94.23%) cases. MJ Ali et al. [39] reported peri ICO granulomas in 6.3% cases and bang on ICO granulomas in 4.2% cases which resolved with topical steroid spray. We didn’t encountered ICO granulomas in any case.

7. Functional Endoscopic Dye Test Lacrimal syringing and probing are invasive methods that do not easily diagnose functional failure. FEDT is noninvasive method and a reliable tool to predict the functional failure [40]. In addition, inferences regarding lacrimal pump function and obstruction at the level of ICO or in proximal location to ICO can be concluded from FEDT. In presence of normal functioning lacrimal pump and patent passages, dye flows spontaneously and is visualized in ostium within few seconds. Irrigation is indicated only if patient is symptomatic and FEDT is delayed or negative [21]. If no spontaneous flow of dye is noted into ostium, irrigation can occasionally show a dye into ostium, reflecting lacrimal pump failure. No dye in ostium on irrigation and reflux indicates a physical obstruction at ICO or proximal to it.

8. Silicon Stents We reserved use of stents in revision cases only. Complications associated with stents are contact granulomas, discomfort, punctal laceration, stent extrusion or prolapse, and difficulty in stent removal. The presence of stents and ostium’s response to their presence should be carefully assessed. Stent should be traceable from its distal cut end right up to the ICO. Any developing contact granulomas or stent entrapment within healing tissues should be addressed. Peri tubal granulomas respond well to stent removal and topical steroids[39]. We observed granuloma formation in 1 case which didn’t resolve after stent removal and eventually lead to complete cicatrization.

9. Ostium granulomas Granulomas formation could be due to operative trauma, bare bone without mucosal coverage, silicone tubes and inherent aggressive healing. A good mucosal approximation is the key to avoid granuloma formation. Though less frequent, ostium granuloma could contribute to surgical failure. Elmorsy and Fayk [41] found 6 patients to have contact granuloma that contributed to failure. MJ Ali [39] classified granulomas into 8 subtypes with most common location being edge granulomas. Most of the granulomas respond well to topical steroids. Injection triamcinolone and excision are recommended for refractory cases [39]. We had 1 case of edge granuloma that resolved with topical steroids and 1 case of refractory peritubal granuloma.

10. Ostium related pathologies—Ostium pathologies are arbitrarily classified as major and minor. Major pathologies include soft tissue infection, orbital breach with fat prolapse toward ostium and obstructive tissues threatening the ICO. Minor pathologies can be diffuse ostium edema, organizing discharge and unwarranted ethmoid entry. MJ Ali [21] noted diffuse edema in 2 cases and one case each of soft tissue infections and unwarranted ethmoid entry. We have not encountered any ostium related pathology.

We believe that, DOS system includes all ostial parameters those have potential influence on lacrimal system and its ultimate outcome. We found it elaborative, time efficient, highly comfortable and simple tool to apply in all our cases. In our experience, it is a uniform systematic approach for ostium evaluation and precise documentation for medical records. To our best knowledge, very few reports are available in literature using DOS scoring for ostium evaluation. It would definitely help future studies in standardizing the ostium evaluation. Further studies need to be carried out to validate and modify this system so that it can provide standardized objective way for assessment and comparison of outcomes between different approaches and techniques. We achieved functional and anatomical success of 94.23% with failure rate of 5.77%. Our results were comparable with other studies in literature [2, 22, 42, 43]. Complete cicatrization of ostium site was the cause of surgical failure in all cases. Cicatrization was secondary to refractory granuloma in 1 case and in 2 cases complete closure of ostium site could be attributed to smaller intraoperative ostium size.

Conclusion

Meticulous evaluation of DCR ostium at regular intervals is important for surgeon to understand the characters of ostium during the course of healing and to identify pitfalls of surgical techniques affecting ostium healing. It also helps in early detection of pathologies and may facilitate early corrective intervention. The maximum shrinkage of ostium occurs within first month after surgery, remaining relatively stable thereafter. To date, we believe that DOS system provides an effective protocol for ostium evaluation. The ostium parameters with favourable surgical outcome are ostium location anterior to axilla of MT, circular/ oval shape with shallow base, size > 8 × 5 mm, clearly visualized and dynamic ICO, absence of ostium cicatrization, granulomas, synechiae and other pathologies. Precision of osteotomy, adequate sac marsupialization, mucosal preservation with good approximation to cover bare bone and minimum trauma to surrounding tissue are the keys to success.

Funding

No funding sources.

Compliance with Ethical Standards

Conflict of interest

None of the Author has any conflict of interest.

Ethical Approval

The study was approved by the Institutional Ethics Committee.

Informed Consent

Informed consent was obtained from all individual participants included in the study.