The application of EN-DCR has increased in recent years with a general development of endoscopic operations particularly sinus operations. EN-DCR is now considered by ophthalmologists and otolaryngologists as the modern gold standard for naso-lacrimal duct obstruction management8,9. Earlier reports showed that EN-DCR had a comparable success rates to those of EX-DCR5,10−12, but with limitations of a comparatively small sample size and short-term follow-up. There were some reports about long-term outcomes for EN-DCR5,13,14, however, measures for recurrent dacryocystitis after EN-DCR have not been established.
The most common reason for recurrent dacryocystitis after EN-DCR was the formation of a membranous scar15,16.The causes of a membranous scar were mainly related to a small lacrimal sac, excessive injury of the nasal mucosa, excessive bone exposure, septal deviation, allergic rhinitis, sinusitis or nasal polyps, the scar physique, and systemic diseases, such as sarcoidosis or Wegener’s granuloma. In recurrent dacryocystitis after EN-DCR, the anatomical changes in the lacrimal sac were seen with endoscopy during surgery; that is, the cicatricial scar and shrinkage of lacrimal sac.
In this study, at the third month, review of post-operation, all of the EN-DCR patients obtained good results with unobstructed lacrimal irrigation after removal of the silicone stents. However, at the twelfth month, ten EN-DCR patients had obstructed lacrimal passage again and only two patients that remained patency in the lacrimal duct, achieving a (success rate of 16.7% which was lower than that in) previous reports6,7,17. The possible explanations are as follows. First, the previous endoscopic surgery left a cicatricial scar filling the center of the ostium. Although the scar mucosa was removed, thus new scars easily formed in the part of the ostium when revision surgery was performed. Second, duo to the obvious shrinkage of lacrimal sac after primary EN-DCR, it was difficult to make a larger ostium through revised EN-DCR. Therefore, the new ostium was very small and was easily closed again with time.
Although stenting is controversial because of the possible induction of granulation18–20, it can help avoid obliteration and restenosis of the ostium, especially in patients requiring re-surgery. The patients in this study had a silicon stent for three months and exhibited no tube-related complications or granulomas in the ostium sites.
In this study, among eighteen EX-DCR patients, fifteen patients got success with a smooth irrigation of the lacrimal passage, achieving a (success rate of 83.3%). There was a statistically significant difference regarding success rate for the longer review period between the two groups. No major intra- or post treatment complications occurred. Thus EX-DCR is an effective and safe procedure with a higher success rate as a remedy for a failed primary EN-DCR and might be considered a preferred surgical method.
As illustrated in Fig. 1, the lacrimal opening of EX-DCR is different from that of EN-DCR. The lacrimal opening of EN-DCR is located in the middle and lower part of the lacrimal sac, while the lacrimal opening of EX-DCR is located in the middle and upper part of the lacrimal sac (as indicated by the arrow). For recurrent dacryocystitis after EN-DCR, the inner inferior part of the lacrimal sac was a cicatricial scar, therefore it was not suitable for another EN-DCR procedure. On the contrary, because the inner and upper part of the lacrimal sac was intact, it was suitable for EX-DCR. This explains why there was a higher success rate in the EX-DCR group compared with the EN-DCR group in remedy for a failed primary EN-DCR.
EX-DCR is considered the classic technology and is not out of date. It is very important to master EX-DCR. The advantages of an EX-DCR operation include a wide field of vision, full exposure of the operation area, and a large bone window, making the ostium between lacrimal sac and nasal mucosa more accurately and stably. EX-DCR does not rely on advanced equipment and instrumentation, with a high long-term success rate, a stable operation effect and a high cost-effectiveness ratio. The main disadvantage is that skin scar affected appearance and the tear pump. The potential complications of EX-DCR included bleeding, infection, and lacrimal punctum valgus. However, for experienced doctors, the incidence of these complications was very low.
To sum up, as compared with EN-DCR, EX-DCR has a higher success rate in treating recurrent dacryocystitis after a first EN-DCR, which is worthy of recommendation. However, a multicenter, randomized, controlled study with a large sample is still needed.