All participants underwent a standardized interview and systemic and ocular examinations, including collection of blood samples at a centralized study clinic.15 Relevant portions of the examination are presented herein. Blood pressure was measured with a digital automatic blood pressure monitor (Dinamap Pro Series DP110X-RW 100V2; GE Medical Systems Information Technologies, Inc, Milwaukee, Wisconsin) after the participants were seated for at least 5 minutes. Nonfasting venous blood samples were drawn and sent that day to the National University Hospital Reference Laboratory, Singapore, for analysis of the following levels: glucose, creatinine, glycated hemoglobin, and serum lipids (total, high-density lipoprotein cholesterol [HDL-C], and low-density lipoprotein cholesterol [LDL-C]). Total, HDL-C, and LDL-C levels were directly measured from assays. The refraction (sphere, cylinder, and axis) of each eye was measured using an autorefractor machine (Canon RK 5 Auto Ref-Keratometer; Canon Inc Ltd, Tochigiken, Japan). The CCR in the horizontal and vertical meridian was measured at the same time, and the mean of 2 CCR readings was obtained. Before pupil dilation, slitlamp biomicroscopy (model BQ-900; Haag-Streit, Köniz, Switzerland) was performed to identify abnormalities of the anterior segment, including evidence of secondary glaucoma, ischemic sequelae of previous acute primary angle closure, and signs of previous surgery. A broad beam at ×10 magnification was used to obtain an overall view of the cornea, and the presence of corneal arcus was assessed by the examining ophthalmologist (R.W., H.C.-U., and 3 nonauthors). Corneal arcus was defined as gray-white or yellow opacity located near the periphery of the cornea but separated from the limbus margin by a clear zone. Five CCT measurements were obtained from each eye using an ultrasonographic pachymeter (Advent; Mentor O & O, Norwell, Massachusetts), and the median reading was recorded. Noncontact partial coherence laser interferometry (IOLMaster version 3.01; Carl Zeiss Meditec AG, Jena, Germany) was used to measure axial length.