In this study, we analyzed the results of primary BDP and probing for persistent CNLDO at different age groups in order to identify the optimal age at which to use BDP as a primary treatment. This study showed that the overall success rates of both procedures were similar in simple and incomplete complex CNLDO, but the age groups evaluations revealed the primary BDP offers better success rates after 24 months of old.
The success rate of probing was decreased by 9.7% for every one-month increase in patients’ age, and the median timing for successful probing was found to be 18 months of age in simple or incomplete complex CNLDO in this study. Similarly, a large cohort study by Sathiamoorthi et al. showed that probing’s success rates decreased with increasing patient ages and reported an 89% resolution rate from primary probing in 289 eyes, while children probed at 15 months or older experienced lower resolution rates [2]. Recently, Świerczyńska et al. showed that probing success rates decreased dramatically with increasing patient age and one-third of operations ultimately failed after patients reached 24 months of age, regardless of their obstruction type [7]. In the present study, the probing success rate was significantly decreased between the age of 24-36 months (Group 1 vs. Group 2, p = 0.003). Additionally, the probing success rate fell to 27% in patients older than 36 months (Group 3). Strict complete success criteria and a small number of patients in Group 3 could explain the high failure rate in this study.
In general, nasolacrimal probing is recommended as a first-line treatment for persistent CNLDO after 12 months of age. According to different patient age groups, there are variable results for probing in the literature, making the timing of intervention controversial [2,7,4,9]. Many surgeons prefer other procedures than primary probing for patients at older months of age. In a published questionnaire survey among 119 members of the American Association for Pediatric Ophthalmology and Strabismus, 53% of physicians preferred primary BDP or silicone tubes if probing treatment was delayed until 24 months of age [20]. Furthermore, this rate increased to 68% if probing treatment was delayed until 36 months of age. In our practice, we prefer primary BDP instead of silicon tubes because of the possibility of the focal damage to the punctum and canaliculus, extrusion of the stent, and corneal damage previously reported with silicon tubes [19].
BDP is a well-known procedure; however, there are limited numbers of study comparing primary BDP and probing in the literature. We found that primary BDP was slightly more successful than probing in terms of overall success rates (81.1% vs. 76.3%, p=0.481), even though the primary BDP patients were significantly older than the probing patients (41.5±27.2 vs. 21.8±10.8 months, p<0.001). Similar to our study, Goldich et al. [18] also reported no significant differences between the overall success rates of primary BDP and probing (89.5% vs. 86.7%, p=0.548) at significantly different mean ages (55.9±113.6 vs. 18.5±6.5 months, p<0.01). Additionally, the authors reported that the patient's age had no significant effect on either surgery [18]. Gunton B. et al. conducted a study in which the mean ages of primary BDP and probing were similar (31.1±13.5 vs. 37.1±25.2 months, respectively, p=0.36) [17]. They reported no significant difference between primary BDP and probing either in overall success rates (90% vs. 86%, respectively, p=0.22) or in different age groups [17]. In contrast, we found that primary BDP yielded significantly better results than probing after 24 months of age. In Group 2 (patients aged 25–36 months), we observed a highly significant difference in success rates of primary BDP (93.3%) and probing (50%) (p=0.012). This result seems to be due to a significant decrease in probing’s success rate since no difference was observed in BDP’s success rate until patients reached 36 months (BDP, Group 1: 93.8%, Group 2: 93.3%, p = 0.963).
One of our study’s important results is that the success of primary BDP decreased significantly after patients reached 36 months of age compared to the other age groups. Group 3’s primary BDP success rate significantly reduced to 63.6% from 93.3% (p=0.041). A previous study about primary BDP reported the procedure’s success rate at 100% before patients reached 24 months (n=5), decreasing to 75.9% for children older than 24 months (n=29) (mean age: 35.6 months). Still, this result was not statistically significant (p=0.526) [12]. Another study, conducted by the Pediatric Eye Disease Investigator Group, showed that primary BDP’s failure rate was 14% for patients between 12 and 24 months old, and this rate increased to 25% for patients between 24 and 48 months old (mean age: 23 months) [15]. Although the failure rate was reported to increase with patients’ age, no statistical evaluation was reported between these two groups [15]. Interestingly, in the recent research by Gazit I. et al., it was found that the primary BDP success rate was significantly decreased after 36 months of age, quite similar to our study [16]. This success reduction in these studies, including ours, could be explained by persistent and late-intervened CNLDO’s ability to result in increased adhesions and fibrosis in the nasolacrimal duct [6]. BDP’s effectiveness may decrease when opening these tighter adhesions for older patients.
Our study contributes to filling the literature’s gap insufficient results for primary BDP versus primary probing at patients’ different ages [19]; however, it faces some limitations. Due to this study’s retrospective nature, we could not specify patients’ types of occlusions. However, only patients who had metal-to-metal contact per-operatively and whose patency was controlled by irrigation-aspiration were included in the study. These inclusion criteria resulted in a cohort that included both simple and incomplete complex CNLDO cases. Given that complete complex CNLDO is rare and mostly seen in syndromic patients [5,21], we can conclude that our study results suggest patient age’s effect on probing and primary BDP for the remaining major patient population. Future studies can prospectively divide the definition of incomplete complex occlusion into more detailed stages and investigate the effect of patient age on these stages and primary BDP’s success rate.
Secondly, the fact that endoscopy was not used in the study can be considered a limitation. Although the early study about endoscopy-assisted probing concluded that endoscopy usage is not required in most cases [22], more recent studies reported positive results using endoscopy in CNLDO [23,24]. However, a recent survey from the United Kingdom showed that while 43.9% of oculoplastic consultants were using nasoendoscopy, only 12.9% of pediatric consultants were [25]. Considering that the primary treatment of a prevalent disease such as CNLDO is also applied by general ophthalmologists, it can be predicted that the overall rate of endoscopy use is lower than these rates. Therefore, the present study has illuminating aspects about these two procedures performed conventionally without using an endoscope.
In conclusion, amid the ongoing debate about the optimal timing and more favorable surgical choices for CNLDO, this study suggests that after a cut-off point of 18 months, probing success decreases to a level that other options such as primary BDP could be discussed with the patient’s parents. However, no significant difference was found in primary BDP success for patients between 12 and 24 months with simple and incomplete complex CNLDO. Moreover, due to the decrease in BDP’s success rate after the age of 36 months, BDP may be chosen as a primary treatment with an excellent success rate, especially for children between 24 and 36 months of age.