Purpose: To investigate the interocular difference of axial length (AL), mean keratometry (K), corneal astigmatism and anterior chamber depth (ACD) according to AL without history of ocular surgery.Methods: This study was performed on 16,411 patients (32,825 eyes) who were measured AL, K, corneal astigmatism and ACD by IOL Master® from April 2007 to September 2016, excluding patients with missing values and extreme values in AL. After, patients were divided into four groups based on AL; AL < 24

more »

... mm, 24 mm ≤ AL < 26 mm, 26 mm ≤ AL < 28 mm, AL ≥ 28 mm, we investigated which variables were associated according to AL. To compensate for age and sex, 1:1:1:1 random matching was performed for age and sex.Results: The longer the average AL of both eyes, the greater the difference between the AL, ACD and mean corneal K of both eyes. The longer AL group had the deeper ACD, the flatter mean corneal K, the higher corneal astigmatism. The older age group had the more shallow ACD, the steeper mean corneal K, lower corneal astigmatism.Conclusions: Ophthalmologists have to be careful in setting fellow eye as control in treating or studying patients with long AL or axial myopia. Because, the longer the average AL of both eyes, the greater the difference between the AL, the ACD and the mean corneal K of both eyes.