JRS September/October 2005 21:5 p502.
Lin and Tsai.
Retinal Plebitis After LASIK



"An IOP of at least 65mmHg is necessary to create a corneal flap with the microkeratome. During this time, the shape of the anterior segment may change rapidly and structures posterior to the suction ring are also compressed in sequence. When the suction stops and the suction ring is released, ocular decompression leads to dynamic equatorial elongation and anterior-posterior contraction. This barotrauma is analagous to what happens in closed eye injury, and can alter delicate retinal structures, especially small vessels, and induce vitreoretinal traction at the vitreous base and posterior pole. Sudden elevation of IOP also disturbs the retinal circulation and increases venous pressure, which results in retinal ischemia. All of these conditions may aggravate the original impaired blood-retinal barrier in highly myopic eyes and increase vascular permeability, leading to the loss of integrity of tight junctions of endothelial cells. Laser in-situ keratomilieusis-induced shock waves can generate up to 100atm. Although the pressure decreases steadily to values below 10 bars toward the retina, we believe it may still cause mechanical stress to the retina, resulting in structural damage and intraocular inflammation.

In addition, total energy and duration increase with higher refractive error and the effect of mechanical stress may be more severe in higher myopia, which has more liquification of the posterior vitreous gel."