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E. Gonzalez, M. Pekmezci, T. Porco, M. He, S. Radhakrishnan, S. Lin; Thicker Irides in Chinese versus Caucasians and the Association With Angle Closure. Invest. Ophthalmol. Vis. Sci. 2010;51(13):5527.
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© ARVO (1962-2015); The Authors (2016-present)
This study evaluates the relationship between iris thickness and narrow angles in Chinese and Caucasian populations.
In a prospective study, 243 eyes (92 Chinese and 151 Caucasian) from 157 patients seen at UCSF underwent anterior segment optical coherence tomography imaging under standardized dark conditions. Images were analyzed using the Zhongshan Angle Assessment Program. Main outcome variables were iris thickness at 750 um and 2000 um from scleral spur, as well as maximum iris thickness at middle one third of the iris. Measurements were taken nasally and temporally for a total of 6 parameters per patient. Results were analyzed as follows:• Chinese versus Caucasian controls with open angles• Chinese versus Caucasian primary angle closure suspects (PACS)• Chinese controls versus PACS• Caucasian controls versus PACSMixed effects regression analysis was used to correct for the use of both eyes in some patients. The analysis controlled for age, gender, pupil diameter, anterior chamber depth and refraction.
Within the control population (133 eyes, 38 Chinese and 95 Caucasian), Chinese had thicker irides in 4/6 parameters (p<0.05 for the 4 parameters). Among those with PACS (110 eyes, 54 Chinese and 56 Caucasian), Chinese had thicker irides in 2/6 iris parameters. Within the Chinese population (92 eyes, 38 controls and 54 PACS), PACS had thicker irides in 1/6 parameters. Within the Caucasian population (151 eyes, 65 controls and 56 PACS), PACS had thicker irides in 4/6 parameters.
Among Caucasians, thicker iris parameters are more common in those with narrow angles. Chinese had thick irides in both controls and PACS, suggesting that this feature may represent a baseline predisposition for narrow angles in this group. Iris thickness may play an important role in the development of narrow angles in both Chinese and Caucasians.
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