Influence of tamsulosin on the iris and its implications for cataract surgery.
OBJECTIVE
To study iris-related complications during cataract surgery in patients on tamsulosin medication.


METHODS
Twenty-one consecutive cataract patients administered tamsulosin and 21 control patients were studied. Characteristics of the iris during surgery were recorded. Pupillary diameters of 16 patients were measured before and after iris dilatation. Tamsulosin concentrations in the aqueous humor and serum were analyzed. In five patients, surgery on the second eye was carried out after a 7- to 28-day pause in tamsulosin medication.


RESULTS
Each patient administered tamsulosin had a sluggish hypotonic iris, along with a tendency toward miosis and a tendency for prolapse of the iris into the phaco tunnel or into the side port during cataract surgery. Sluggish irises also often adhered to the phaco tip or to the irrigation-aspiration tip. Despite a pause of 7 to 28 days in the use of tamsulosin, the adverse effects persisted. Tamsulosin concentrations varied between 0.1 and 1.0 ng/mL in the anterior chamber fluid. In three of five cases, tamsulosin remained in detectable amounts the aqueous humor after the 7- to 28-day pause. Preoperative pupillary diameter was smaller in the patients using tamsulosin than in the controls.


CONCLUSIONS
Tamsulosin has selective alpha1A-adrenoreceptor antagonistic properties and obviously binds for a long period to the postsynaptic nerve endings of the iris dilator muscle, thus affecting iris dilatation and leading to complications in cataract surgery. The iris remained floppy after 7- to 28-day interruption of the tamsulosin regimen.
Pärssinen
Olavi
O
Ophthalmic Department, Central Hospital of Central Finland, Jyväskylä. olavi.parssinen@top.fimnet.fi
Leppänen
Esa
E
Keski-Rahkonen
Pekka
P
Mauriala
Timo
T
Dugué
Benoit
B
Lehtonen
Marko
M
D058668:Adrenergic alpha-1 Receptor Antagonists; D000317:Adrenergic alpha-Antagonists / Q000009:adverse effects / Q000493:pharmacokinetics; D000368:Aged; D000369:Aged, 80 and over; D000970:Antineoplastic Agents / Q000009:adverse effects* / Q000493:pharmacokinetics; D001082:Aqueous Humor / Q000378:metabolism; D002387:Cataract Extraction; D006801:Humans; D007498:Iris / Q000187:drug effects*; D007499:Iris Diseases / Q000139:chemically induced*; D008297:Male; D008875:Middle Aged; D015877:Miosis / Q000139:chemically induced; D011391:Prolapse; D011470:Prostatic Hyperplasia / Q000188:drug therapy; D011680:Pupil / Q000187:drug effects; D013449:Sulfonamides / Q000009:adverse effects* / Q000493:pharmacokinetics; D000077409:Tamsulosin
D058668:Adrenergic alpha-1 Receptor Antagonists; D000317:Adrenergic alpha-Antagonists; D000970:Antineoplastic Agents; D013449:Sulfonamides; D000077409:Tamsulosin