α1-ARAs are frequently used in treatment of Hypertension and symptomatic Benign prostatic hypertrophy (BPH) [7]. Of the three subtypes of alpha-1 receptors (a, b, and d), the alpha-1a receptor dominates in the iris dilator muscle as well as in the smooth muscles of the prostate tissue. Also, the beta Tamsulosin is subtype specific and has affinity 20 times for the alpha-1a receptor [8]. The pupillary dilatation is severely impeded by the use of α1-ARAs, however, the frequency and severity of pathological alterations in the iris morphology is most marked with use of Tamsulosin (α1A-ARA) [9] [10] [11]. Our observations regarding the reduction in pupil diameter and iris rigidity among patients receiving α1-ARAs are consistent with existing literature.
There is scientific evidence establishing the association between the use of α1-ARAs in Intraoperative floppy iris syndrome (IFIS) [12], a term, coined by Chang and Campbell in 2005 [1]. These are the possible alterations resulting in the clinical entity of IFIS. This consists of fluttering and bellowing of iris stroma, propensity for the pupil to constrict during surgery, and tendency for the iris to prolapse toward the incisions. Few studies have mentioned that IFIS has been noted even in patients who had stopped tamsulosin 2 years before cataract surgery [13] [14]. However, minimum duration of intake of tamsulosin leading to IFIS has never been suggested or remarked upon by any of the studies.
In our study the results show marked changes in the iris morphology in patients with a past or current history of α1-ARAs usage as compared to age-matched controls. There was statistically significant decrease in the DMR thickness, lower DMR/SMR ratios and smaller pupillary diameters. This is in consonance with the first report by Prata TS et al[15] which demonstrated structural alteration in the iris dilator muscle region in patients using α1-ARAs. We found no significant difference in the SMR thickness which showed no statistically significant difference between the study patients and control group. Altered iris morphology was present in 68% of treated patients compared to controls. This figure is in sync with the reported prevalence of clinical IFIS in 62.5–93.8% patients on tamsulosin or with history of tamsulosin use [16] [17] [18] [19].
These alterations in iris can lead to myriad of complications that range from poor visibility of the operative field, iris damage, posterior capsule rupture and posterior dislocation of lens material intraoperatively. The surgical challenges posed by IFIS and other complications related to α1-ARAs necessitate specific management strategies.
Strategies such as medication review, preoperative discontinuation of alpha-blockers when feasible and modification of surgical techniques can help optimize outcomes and minimize complications. Preoperative planning is crucial, including a thorough medication review and consideration of discontinuing α1-ARAs prior to surgery when feasible. However, this approach must be balanced against the potential risks of interrupting treatment for the underlying condition. Alternative medications, such as non-selective α-ARA, may also be considered in consultation with the patient’s primary care provider. A study by Chang DF (2008) suggested preoperative administration of alpha-adrenergic agonists may help improve iris tone and mitigate the risk of IFIS during surgery [20]. Similar study by Bucci Jr FA, et al (2012) found that preoperative use of topical phenylephrine and ketorolac combination was effective in reducing the severity of IFIS and improving surgical outcomes in patients on tamsulosin [21].
Intraoperative management techniques are equally important in preventing or addressing the potential complications. The use of mechanical devices such as iris hooks or rings, like the Malyugin ring, can help maintain pupil dilation and stability during surgery. Viscomydriasis, which involves the injection of a cohesive viscoelastic agent, can also aid in maintaining pupil size and preventing iris prolapse. Additionally, modifications in phacoemulsification techniques, such as adjusting fluidics settings and carefully manipulating the iris, can help manage its instability and reduce the risk of complications.
While this study provides valuable insights into the effects of α1-ARAs on iris parameters and cataract surgery outcomes, several limitations must be acknowledged. The nature of the study design introduces the potential for selection bias and limits causal inference. Future prospective studies with larger sample sizes are needed to validate our findings and elucidate the underlying mechanisms driving medication-specific differences in IFIS risk. Furthermore, our study did not assess the impact of α1-ARAs on postoperative complications or long-term visual outcomes as it primarily focused on the immediate perioperative period. To evaluate their implications on long-term ocular health and visual function, longitudinal studies with extended follow-up periods are warranted. Additionally, studies evaluating comparative effectiveness of different management strategies for IFIS, including preoperative medication review, intraoperative techniques, and postoperative care protocols, are needed to establish evidence-based guidelines to further optimize surgical outcomes.