Lacrimal passage obstruction is a common and treatable disease that causes visual dysfunction and decreased QOL. In this study, we performed SG-BCI for lacrimal passage obstruction and obtained good surgical success and postoperative patency. AS-OCT analysis quantitatively assessed the tear meniscus and showed significant postoperative decreases in height and area. Furthermore, there was a significant postoperative decrease in HOAs, indicating a correlation between the decrease in the tear meniscus dimensions and the decrease in HOAs. These results indicate that SG-BCI for lacrimal passage obstruction leads to improvement of HOAs with a decrease in the overall tear meniscus.
Lacrimal tube intubation for lacrimal passage obstruction is a less invasive treatment than DCR as it does not require bone resection. However, because of individual variations in the morphology of the lacrimal passage [22], the surgical success rates of silicon tube intubation, which requires blind manipulation, had been reported at 50–80% [8, 9, 23]. Recently, however, silicon tube intubation using a dacryoendoscope has become widespread, especially in Japan, and the success rate has improved to about 89% because the obstructed area of the lacrimal duct can be directly observed, and the tube can be inserted more safely [10, 12, 13]. Sheath-guided BCI has also been developed. Because the sheath can push past the obstructed area and a lacrimal tube can be inserted into the sheath, the risk of lacrimal duct injury and false lacrimal passage is low, and it is considered a minimally invasive lacrimal surgery. It has been reported that lacrimal mucosal trauma associated with lacrimal tube insertion is a risk factor for surgical failure [12, 24]. In this study, SG-BCI resulted in 97.1% surgical success and 89.8% postoperative patency, which was comparable to results from previous reports [14].
As shown in Table 2, we were able to obtain relatively high surgical success and patency regardless of the occlusion site. The postoperative patency of nasolacrimal duct obstruction cases was 85.7%, and that of common canalicular obstruction combined with nasolacrimal duct obstruction was 100%. In the past, nasolacrimal duct obstruction with dacryocystitis has been reported to have poor outcomes with lacrimal duct intubation, with approximately 50% of patients experiencing reobstruction at 12 months [12]. In our hospital, DCR is often chosen for cases with a large amount of pus drainage or after acute dacryocystitis; this may explain our relatively good results for nasolacrimal duct obstruction. In the future, it will be necessary to examine the results of treatment according to the presence or absence of dacryocystitis.
Recently, AS-OCT has been used for tear meniscus assessment [15–17, 21]. Using AS-OCT, the height of the lower meniscus and the cross-sectional area of the lower meniscus can be measured objectively and non-invasively. Its efficacy in postoperative tear meniscus evaluation of DCR and lacrimal tube intubation has been reported [15, 17]. In this study, we found a significant decrease in TMH and TMA after SG-BCI using AS-OCT, which may be a useful method for pre- and postoperative evaluation. Excessive tear fluid has been shown to affect various visual functions. Lacrimal passage obstruction is associated with decreased vision-related QOL, and lacrimal tube intubation has been reported to improve national eye institute visual function questionnaire (NEIVFQ-25) scores and Glasgow Benefit Inventory scores [6, 10, 14]. There are also reports of improved contrast sensitivity [21] and functional visual acuity [20] with lacrimal tube intubation. Associations between tear meniscus dimensions and HOAs have also been noted. HOA measurements are suitable to assess ocular surface conditions due to tear fluid, and it has been reported that epiphora is involved in the deterioration of HOAs [19, 20]. Koh et al. reported a significant decrease in HOAs after lacrimal passage intubation, and our results were similar [20]. Furthermore, we have shown for the first time that there is a positive correlation between tear meniscus reduction and HOA reduction. By contrast, excessive tear fluid, tear film, and delayed tear clearance due to lacrimal passage obstruction may worsen HOAs.
The limitations of this study are that it is a single-center retrospective study of a relatively small number of patients, all Japanese, with a short postoperative follow-up period. There was also a lack of evaluation of the ocular surfaces affecting the HOAs, such as conjunctival chalasis, tear break-up time, and the Schirmer test. Further research is needed in the future.
In summary, SG-BCI for lacrimal passage obstruction showed good surgical success and lacrimal patency. Using AS-OCT we were able to non-invasively quantify postoperative tear meniscus reduction. Furthermore, we found a positive correlation between the decreases in tear meniscus dimensions and HOAs. Therefore, SG-BCI can result in improved HOAs, and the deterioration of HOAs in lacrimal passage obstruction could be a parameter indicating surgical intervention.