Plateau iris syndrome: changes in angle opening associated with dark, light, and pilocarpine administration.
OBJECTIVE
To report changes in angle configuration associated with dark, light, and pilocarpine administration in plateau iris syndrome.


METHODS
In 10 eyes of 10 patients with plateau iris syndrome and persistent narrow angles after patent peripheral Nd:YAG laser iridotomy, ultrasound biomicroscopy was used to image variations in angle opening, iris thickness, and trabecular-ciliary process distance. Measurements were taken in the dark, in full room light, and after administration of pilocarpine 2%.


RESULTS
Average angle opening distance increased in the light compared with the dark (113+/-34 microm vs. 22+/-34 microm, P = .0001) and increased further after pilocarpine administration (171+/-52 microm vs. 113+/-34 microm, P = .0034). Average iris thickness decreased in the light compared with the dark (338+/-34 microm vs. 436+/-58 microm, P = .0009) and decreased further after pilocarpine administration (253+/-48 microm vs. 338+/-34 microm, P = .0002). Average trabecular meshwork-ciliary process distance measurements were smaller than normal and did not change significantly in the light compared with the dark (481+/-42 microm vs. 464+/-44 microm, P = .4001) or after pilocarpine administration compared with light (451+/-67 microm vs. 481+/-42 microm, P = .1304).


CONCLUSIONS
In plateau iris syndrome, anteriorly located ciliary processes support the peripheral iris. Changes in angle opening in dark and light are solely related to changes in iris thickness. Pilocarpine produces iris thinning and is an effective method of opening the angle. Ultrasound biomicroscopy can be used to perform a darkroom provocative test, which provides information on whether the angle anatomically closes in the dark.
Pavlin
C J
CJ
Department of Ophthalmology, Ontario Cancer Institute, Princess Margaret Hospital, University of Toronto, Canada.
Foster
F S
FS
D000869:Anterior Eye Segment / Q000000981:diagnostic imaging / Q000503:physiopathology*; D002924:Ciliary Body / Q000000981:diagnostic imaging / Q000503:physiopathology*; D003623:Dark Adaptation; D005260:Female; D006801:Humans; D007498:Iris / Q000187:drug effects / Q000503:physiopathology*; D007499:Iris Diseases / Q000000981:diagnostic imaging / Q000503:physiopathology*; D008027:Light; D008297:Male; D008875:Middle Aged; D008916:Miotics / Q000008:administration & dosage*; D010862:Pilocarpine / Q000008:administration & dosage*; D011680:Pupil / Q000187:drug effects; D013577:Syndrome; D014463:Ultrasonography
D008916:Miotics; D010862:Pilocarpine