Plateau iris in Asian subjects with primary angle closure glaucoma.
OBJECTIVE
To determine the prevalence of plateau iris in Asian eyes with primary angle closure glaucoma (PACG) using ultrasound biomicroscopy (UBM).


METHODS
In this cross-sectional observational study, subjects older than 40 years with PACG who had a patent laser peripheral iridotomy underwent UBM in 1 eye. Ultrasound biomicroscopy images were qualitatively analyzed using standardized criteria. Plateau iris in a quadrant was defined by anteriorly directed ciliary body, absent ciliary sulcus, steep iris root from its point of insertion followed by a downward angulation, flat iris plane, and irido-angle contact. At least 2 quadrants had to fulfill these UBM criteria for an eye to be classified as having plateau iris.


RESULTS
One hundred eleven subjects (70 from Singapore, 41 from Thailand) with PACG were recruited. The mean (SD) age was 65.6 (8.1) years, and 63.9% were female. Based on standardized UBM criteria, plateau iris was found in 36 of 111 eyes (32.4%; 95% confidence interval, 24.4%-41.6%). In these 36 eyes, quadrant-wise analysis showed 66.7% had plateau iris in 2 quadrants; 22.2%, in 3 quadrants; and 11.1%, in all quadrants.


CONCLUSIONS
About 30% of PACG eyes with a patent laser peripheral iridotomy were found to have plateau iris on UBM, highlighting the importance of non-pupil block mechanisms in Asian individuals.
Kumar
Rajesh S
RS
Singapore National Eye Centre and Singapore Eye Research Institute, Singapore.
Tantisevi
Visanee
V
Wong
Melissa H
MH
Laohapojanart
Kobkuea
K
Chansanti
Orathai
O
Quek
Desmond T
DT
Koh
Victor T
VT
MohanRam
Lakshmana S
LS
Lee
Kelvin Y
KY
Rojanapongpun
Prin
P
Aung
Tin
T
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D044466:Asian People / Q000208:ethnology*; D002924:Ciliary Body / Q000000981:diagnostic imaging; D003430:Cross-Sectional Studies; D005124:Eye Abnormalities / Q000000981:diagnostic imaging / Q000208:ethnology*; D005260:Female; D015812:Glaucoma, Angle-Closure / Q000000981:diagnostic imaging / Q000208:ethnology* / Q000601:surgery; D006068:Gonioscopy; D006801:Humans; D007429:Intraocular Pressure; D032801:Iridectomy; D007498:Iris / Q000002:abnormalities* / Q000000981:diagnostic imaging / Q000601:surgery; D053685:Laser Therapy; D008297:Male; D033401:Microscopy, Acoustic; D008875:Middle Aged; D015995:Prevalence; D011446:Prospective Studies; D012846:Singapore / Q000453:epidemiology; D013785:Thailand / Q000453:epidemiology; D014065:Tonometry, Ocular; D014129:Trabecular Meshwork / Q000000981:diagnostic imaging