Bisma Ikram, Abdul Hannan, Umar Ikram, Maha Amjad.
Comparison of Eye Axial Length Measurements in Sitting and Supine Position with Contact A-Scan Biometry.
Ophthalmol Update Jan ;12(4):278-81.

Background: Biometry i.e. the measurement of the eye axial length is performed in patients before cataract surgery and in studies on refractive errors. Purpose: To compare axial length measurements obtained in sitting and supine position by contact A-scan biometry. Materials and methods: Axial length of 55 non paired eyes was measured using contact method in both sitting and supine position, randomly as to which perform first to avoid measurement bias. Results: The mean axial length in supine position was 22.68 mm (min 21.25 mm, max 24.53 mm), compared to mean of 22.63 mm (min 21.22 mm, max 24.53 mm) obtained in sitting position, (SD <0.10). Axial length obtained in supine position was on average 0.05 longer than obtained in sitting position. A statistically significant difference was proved between making measurements in sitting and supine position (p=0.000). 50 eyes (90%) had longer axial length, 4 eyes (7.3%) had same axial length and only 1 eye (1.8%) had shorter axial length in supine position compared to axial length in sitting position. Conclusion: The axial length value obtained in supine position was longer than obtained in sitting position. Less corneal compression and better target fixation makes the supine position superior to sitting position.

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