12th November 2018, Dr Chee L Khoo
Intraoperative floppy iris syndrome (IFIS) was first described by Chang and Campbell. It is characterised by floppiness of the iris, miosis and ultimately, iris prolapse through the surgical wounds. It can occur during surgery for cataract and if not anticipated, it increases the risk of posterior capsule rupture, vitreous loss, retained nuclear fragments, post op intraocular pressure spikes, irido-dialysis, hyphema and corneal endothelial loss. It can lead to permanent pupil deformity, and vision loss secondary to endophthalmitis, macular edema, or retinal detachment. Risk factors are increasingly recognised and appropriate preventative measures can be taken to minimise the complication rates.
In the US, IFIS occurs in 2% of cataract surgeries. In large scale prospective and retrospective studies, a number of alpha-1 antagonists have been implicated. The most common of the alpha blockers is Tamsulosin but other alpha blockers implicated include terazosin and prazosin.
Alpha blockers work by relaxing the muscles in the bladder neck, urethra and prostate. Some alpha blockers selectively block alpha 1 A adrenergic receptor (α1AaR) in the urinary tract. However, in mice, rats and rabbits α1AaR is the dominant adrenergic receptor in the iris. Tamsulosin is one of the most frequently prescribed alpha blocker and has high affinity and selectivity for α1AaR. As a consequence, IFIS is extremely common in patients taking tamsulosin, occurring in 60–89% of those undergoing cataract surgeries in a number of studies (1-3).
Other drugs implicated include typical and atypical anti-psychotics (chlorpromazine and quetiapine), neuromodulators (benzodiazepines, duloxetine, donepezil (Aricept)) and finasteride (propecia).
Hypertension appears to be an independent risk factor for IFIS although it is unclear whether the risk is associated with anti-hypertensive used or the direct effect on the vasculature of the iris.
Pathophysiology
IFIS has been reported in patients even the use was months or years prior. It is thought that alpha blockers may have a long lasting effect on the iris musculature. It is thought that alpha blockers may thin the dilator muscle of the iris. As α1AaR are also present in the iris arterioles, alpha blockers can also affect the vasculature of the iris.
Management
Apart from modification of surgical approach (e.g. different incision location), use of intracameral (into the eye) injection of adrenergic agonists and the use of iris retractors, the most important aspect of prevention is risk assessment. Patients need to be specifically asked about the use of Tamsulosin or any anti-psychotics.
In 2014, the American Society of Cataract and Refractive Surgery (ASCRS) and the American Academy of Ophthalmology (AAO) recommends that patients with symptomatic cataracts should either be referred for surgery prior to starting Tamsulosin or should be started on alfuzosin (Xatral) instead of Tamsulosin.
Being aware of the syndrome and the risk factors associated with the incidence is key to reduce this complication. Communication between the GP and the ophthalmologist is vital.
Reference
- Altan-Yaycioglu R, Gedik S, Pelit A, et al. Clinical factors associated with floppy iris signs: a prospective study from two centers. Ophthalmic Surg Lasers Imaging 2009; 40:232–238.
- Blouin MC, Blouin J, Perreault S, et al. Intraoperative floppy-iris syndrome associated with alpha1-adrenoreceptors: comparison of tamsulosin and alfuzosin. J Cataract Refract Surg 2007; 33:1227–1234.
- Chang DF, Campbell JR, Colin J, et al. Prospective masked comparison of intraoperative floppy iris syndrome severity with tamsulosin versus alfuzosin. Ophthalmology 2014; 121:829–834.
- Jennifer M. Enright, Humeyra Karacal, and Linda M. Tsai. Floppy iris syndrome and cataract surgery. Curr Opin Ophthalmol 2017, 28:29–34