Quantitative analysis of iris changes after physiologic and pharmacologic mydriasis in a rural Chinese population.
OBJECTIVE
To estimate and compare the change in iris cross-sectional area (IA) and iris volume (IV) following physiologic and pharmacologic pupil dilation in primary angle closure suspects (PACS) and normal subjects.


METHODS
Anterior segment-optical coherence tomography (AS-OCT) measurements in light, dark, and following pharmacologic dilation were obtained on 186 PACS and 224 normal subjects examined during the 5-year follow-up of the Handan Eye Study. Iris cross-sectional area, IV, and other biometric parameters calculated using the Zhongshan angle assessment program in the right eyes of all subjects were analyzed.


RESULTS
The mean IA and IV decreased in dark compared with light and after pharmacologic dilation in both PACS and normal eyes. This change was statistically significant in normal eyes: light versus pharmacologic dilation for IA (P = 0.038) and for IV, both light versus dark (P = 0.031) and light versus pharmacologic dilation (P = 0.012). A longer axial length (P = 0.028) and a greater change in pupil diameter (PD) (P < 0.001) were associated with a larger decrease of IA for the light to dark comparison. A diagnosis of normal eyes (P = 0.011), larger PD in dark (P = 0.001), and a larger change in PD (P = 0.001) were associated with a larger decrease of IV from light to dark.


CONCLUSIONS
The differences in iris behavior between PACS and normal rural Chinese subjects following physiologic or pharmacologic pupillary dilation may help provide insights into the pathogenesis of angle closure.
Beijing Tongren Eye Center, Beijing Tongren Hospital, Capital Medical University, Beijing Ophthalmology and Visual Science Key Lab, Beijing, People's Republic of China.
Ye
Y
Zhang
Nanjing Aier Eye Hospital, Nanjing, People's Republic of China.
Si Zhen
SZ
Li
Beijing Tongren Eye Center, Beijing Tongren Hospital, Capital Medical University, Beijing Ophthalmology and Visual Science Key Lab, Beijing, People's Republic of China.
Lei
L
Li
State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangzhou, People's Republic of China.
Ming Guang
MG
He
Queensland Eye Institute, Brisbane, Queensland, Australia University of Queensland, Brisbane, Queensland, Australia.
Ravi
R
Thomas
Beijing Tongren Eye Center, Beijing Tongren Hospital, Capital Medical University, Beijing Ophthalmology and Visual Science Key Lab, Beijing, People's Republic of China Beijing Institute of Ophthalmology, Beijing, People's Republic of China.
Ning Li
NL
Wang
D002681:China / Q000453:epidemiology; D003430:Cross-Sectional Studies; D005260:Female; D005500:Follow-Up Studies; D015812:Glaucoma, Angle-Closure / Q000453:epidemiology / Q000473:pathology* / Q000503:physiopathology; D006068:Gonioscopy; D006801:Humans; D007429:Intraocular Pressure; D007498:Iris / Q000187:drug effects / Q000473:pathology*; D008297:Male; D008875:Middle Aged; D015878:Mydriasis / Q000139:chemically induced / Q000453:epidemiology / Q000473:pathology*; D009184:Mydriatics / Q000494:pharmacology*; D015995:Prevalence; D012189:Retrospective Studies; D012424:Rural Population; D041623:Tomography, Optical Coherence
D009184:Mydriatics
anterior segment–optical coherence tomography; iris cross-sectional area change; iris volume change; mydriasis; primary angle closure suspect