The effects of tamsulosin and alfuzosin on iris morphology: an ultrasound biomicroscopic comparison

Context: It is well known that Alpha-1 adrenergic receptor antagonists affect the receptors in the prostate and also iris dilator muscle, leading to loss of iris muscle tone. Objective: To compare morphological alterations of iris secondary to tamsulosin and alfuzosin use. Participants: Patients included in the study were grouped as follows: 16 patients treated with tamsulosin (Group 1), 14 patients treated with alfuzosin (Group 2) and 18 untreated controls (Group 3). Materials and methods: All patients underwent ultrasound biomicroscopic and pupillometric examination. Iris thickness was measured at the dilator muscle region (DMR; measured at half of the distance between the scleral spur and the pupillary margin) and sphincter muscle region (SMR; Standardized at 0.75 mm from the pupillary margin). DMR/SMR was also calculated for each patient. Differences among groups were analysed. Main outcome measures were DMR, SMR, DMR/SMR and pupillary diameter. Results: Mean duration of treatments were 2.4 +/- 0.96 years (1-4) and 2.3 +/- 1.01 years (1-4) in Groups 1 and 2. Pupillary diameters were reduced in Groups 1-2 compared to Group 3 (p < 0.001, p < 0.001). The SMR was similar in Groups 1 and 2 (p: 0.114). These values were not significantly different from that of Group 3 (p: 0.196, p: 0.209). However, thickness in the DMR in Groups 1-2 were significantly lower than that of controls (Group 3) whereas there was no significant difference between Groups 1 and 2 (p: 0.041, p: 0.039 and 0.986, respectively). Mean DMR/SMR ratios were significantly lower in Groups 1-2 than that of Group 3 (p: 0.040 and p: 0.040, respectively). Conclusions: In patients using these medications, the iris seems to be thinner at the dilator muscle region, but preserving the sphincter muscle region.