Figure 6.

Posterior movement of scleral spur upon ciliary muscle contraction. (A) Upon ciliary muscle contraction, the scleral spur moves from point A to point B. A horizontal distance (Δh) of at least 0.047 mm (represented by the yellow arrow) is needed to fully open up the TM and support SC to maintain adequate outflow, according to Moses and Arnzen.²⁰ (B) Estimated mean theoretical distance (Δh) of scleral spur posterior movement in normal and POAG eyes. The scleral spur in normal eyes would move a distance of 0.054 ± 0.001 mm, which is greater than the required value of 0.047 mm, whereas the scleral spur in POAG eyes would move a distance of 0.040 ± 0.002 mm, which is less than the required value and significantly shorter than the distance in normal eyes (P < 0.0001). Errors bars: SE. **P < 0.0001.