In this study, we evaluated the correlation between silodosin intake and IFIS development. We managed to quantify this correlation by estimating an odds ratio while adjusting for covariates reported as factors predisposing to IFIS development. Notably, the control group was homogenous to the exposed group regarding demographics, systematic comorbidities, and ocular comorbidities. Our study demonstrated silodosin as a factor strongly predisposing to IFIS development.
The studies thas have already investigated the correlation between silodosin intake and IFIS are limited. Specifically, some case reports have identified silodosin as the predisposing factor of IFIS, with the most recent one reporting a bilateral IFIS occurrence 20–22. In addition, a recent retrospective cohort study, with 19 patients exposed to silodosin, reported an IFIS occurrence rate in this sub-group of patients of 79% (15/19), which was higher than the rate of IFIS reported in their tamsulosin sub-group of patients (63%, 10/16) 23. In our study, the rate of IFIS development in the silodosin sub-group was also found higher than the rate of IFIS in the tamsulosin sub-group (37.2% vs. 21.5%).
To this day, tamsulosin remains the predisposing factor that is most strongly correlated to IFIS occurrence. Univariate analyses and multiple regression models report unadjusted odds ratios for IFIS occurrence when exposed to tamsulosin between 10.67 and 206.5 6,26,27 and adjusted odds ratios between 5.78 and 4058 4,6,26,28. For this reason, a joint statement by the American Society of Cataract and Refractive Surgery and the American Academy of Ophthalmology advocates either to initiate tamsulosin following cataract surgery or to use a non-selective a1-ARA for BPHs treatment in phakic patients 29.
Silodosin is prescribed for the treatment of symptomatic BPH and lower urinary tract symptoms (LUTS). When compared to tamsulosin, in a recent meta-analysis, based on 13 studies including 2129 randomized participants, both drugs were found equally effective in the management of symptomatic BPH and LUTS 30. Along with the prolongation of life expectancy, a larger population of patients on these a1-ARAs will unevitably require cataract surgery in the near future. When silodosin is prescribed to phacik patients, it is highly recommended that the patient’s ophthalmologist should be accordingly informed.
IFIS, especially unanticipated, is correlated with significant intraoperative complications 1,8,31,32. Fortunately, when patients are appropriately assessed preoperatively to adequately stratify the surgical risk, and the necessary prophylactic measures are employed for high-risk patients, complication rates return to their baseline 33. Therefore, we recommend that all physicians and medical personel being involved in the preoperative evaluation of cataract patients should record the intake of a1-ARAs, and particularly the intake of tamsulosin, and silodosin.
The surgical risk is not linear. This statement is implemented particularly in IFIS. The vast majority of IFIS cases are correlated with a handful of already identified risk factors. Therefore, the cornerstone in addressing IFIS is first to be familiar with these predisposing factors, then assess them properly preoperatively, and finally, employ the necessary prophylactic measures to ameliorate their impact on the surgical outcome 34.
Our study has several limitations. First, its retrospective nature could have introduced information bias in our study. In addition, several patients who were identified as high-risk patients due to their exposure to one or more predisposing factors received intracameral epinephrine preoperatively. Therefore, our analysis probably has underestimated the actual risk associated with exposure to predisposing factors. Finally, despite our best efforts to adjust for covariates, unknown cause/effect relations could have impacted our results.
On the other hand the large sample size and the utilization of propensity scores case-matching significantly strengthens our results. To the best of our knowledge, our study is the first in the literature that has linked silodosin with IFIS, managing to quantify the power of the correlation between silodosin and IFIS, by estimating an odds ratio, while adjusting for other risk factors by using two homogenous groups of patiens achieved by propensity scores case-matching.
In conclusion, silodosin, a uroselective a1-ARA, has been demonstrated in this study as a predisposing factor, strongly correlated with IFIS development. These results should increase awareness to cataract surgeons, to carefully assess their patients preoperatively for exposure to silodosin, and employ the appropriate prophylactic measures to ameliorate the impact of silodosin intake to the surgical outcome.