Purpose : To investigate changes of intraocular pressure (IOP) and ocular shape on ascent to high altitude from Beijing to Lhasa

Methods : 20 volunteers (17 men, 3 women) who were sent to work from Beijing to Lhasa, Tibet were enrolled. IOP, axial length (AL) and corneal curvature (K) were measured for twice at Beijing (altitude 43m) and Lhasa (altitude 3658m) respectively. They had the first examination at least 1 day before arriving Lhasa and had the second examination when stayed at Lhasa for 7 days or later. IOP was measured with applanation tonometer and the two tonometers have a consistency correction at Beijing before the study. AL was measured with two different type ultrasonic pachymeters and K was measured using two same type autofractometers. The data of highland and lowland were analyzed by paired-sample T test.

Results : The mean values for IOP of Beijing was 12.75±2.41 mmHg and Lhasa was 15.08±3.35 mmHg. The mean AL was 24.83±1.54 mm at Beijing and was 25.24±1.38 mm at Lhasa. The IOP and AL increased significantly at the altitude of Lhasa (P<0.05). The mean K was 43.54±2.17 D at Beijing and 43.52±2.21 D at Lhasa. Difference of K were not significant (P>0.05).