Iris Morphologic Changes Related to α1-Adrenergic Receptor Antagonists Implications for Intraoperative Floppy Iris Syndrome
Received 16 October 2008; received in revised form 9 December 2008; accepted 15 December 2008.
Purpose
To identify iris structural alterations associated with intraoperative floppy iris syndrome (IFIS) in patients using systemic α1-adrenergic receptor antagonists (α-1ARA).
Design
Cross-sectional study.
Participants and Controls
Twenty-nine patients with current or past treatment with any systemic α-1ARA and 22 untreated controls.
Methods
Consecutive eligible patients underwent slit-lamp–adapted optical coherence tomography in a masked fashion under standardized lighting conditions.
Main Outcome Measures
Iris thickness at the dilator muscle region (DMR; measured at half of the distance between the scleral spur and the pupillary margin) and at the sphincter muscle region (SMR; 0.75 mm from the pupillary margin), the ratio between the DMR/SMR (to compensate for possible intersubject variability), and pupillary diameter.
Results
Most treated patients were on tamsulosin (27/29). Mean age was similar in study and control groups (70.6±7.6 vs 67.1±9.1 years; P = 0.061). Photopic pupil diameter was reduced in the study group (2.06±0.5 vs 2.5±0.6 mm; P = 0.001). The SMR was similar between groups (P = 0.53). Significantly lower values were found in treated subjects for the DMR and the DMR/SMR ratio (P<0.001). These differences remained significant after adjusting for pupil diameter (P<0.001). Multiple regression analysis showed that a longer duration of α-1ARA treatment correlated to a reduced DMR/SMR ratio (P = 0.001; r = 0.47). Age and eye color were not significant in this model.
Conclusions
Patients using systemic α-1ARA have significantly lower values of DMR thickness and DMR/SMR ratio and smaller pupil diameter when compared with age-matched controls. These differences seem to be related to the duration of drug exposure and provide evidence of structural alterations to the iris dilator muscle from this class of agents in IFIS.
Financial Disclosure(s)
Proprietary or commercial disclosure may be found after the references.
1Einhorn Clinical Research Center, New York Eye and Ear Infirmary, New York, New York
3Manhattan Eye, Ear and Throat Hospital, New York, New York
4New York University School of Medicine, New York, New York
Correspondence: Tiago Prata, MD, Glaucoma Service, Department of Ophthalmology, The New York Eye and Ear Infirmary, 310 East 14th Street, New York, NY 10003
ABSTRACT