LASIK creates several types of ocular mechanical stress: (a) an increase in intraocular pressure (> 65 mm Hg.) during suction, (b) an acoustic shock wave during laser ablation, and (c) a rapid lowering of intraocular pressure when the suction ring is decompressed. These types of mechanical stress have the potential to lead to a "maculopathy," from a variety of mechanisms.
Ellies P, Pietini D, Lumbroso L, Lebuisson DA. Macular hemorrhage after laser in situ keratomileusis for high myopia. J Cataract Refract Surg. 2000;26:922-4.
Mansour AM, Ojeimi GK. Premacular subhyaloid hemorrhage following laser in situ keratomileusis. J Refract Surg. 2000 May-Jun;16(3):371-2.
Luna JD, Reviglio VE, Juarez CP. Bilateral macular hemorrhage after laser in situ keratomileusis. Graefes Arch Clin Exp Ophthalmol. 1999 Jul;237(7):611-3.
In part, these studies disclose that the mechanical stress of the LASIK procedure can cause ruptures of Bruch's membrane and the choriocapillaris, resulting in "lacquer cracks," and potentially ruptures in superficial peripapillary and perifoveal retinal capillaries.
One may also speculate that the elevated intraocular pressure, and/or the sudden release of the vacuum pump pressure from over 65 mm Hg to zero, alters normal microvascular blood supply to the macula, and may lead to a "maculopathy" in select patients. Certainly, highly myopic patients have a higher tendency for macular pathology, as compared to emmetropes.
Another uncommon cause of maculopathy during operative procedures would be phototoxic maculopathy, due to prolonged exposure of the eye to light during surgery. While most procedures are sufficiently short in duration to avoid this complication, a case of photic maculopathy has been described in which the surgical procedure (i.e. radial keratotomy) lasted approximately 7 ½ minutes. In general, light induced maculopathy can be prevented by using infrared filters, low intensity microscope light, keeping the pupil small, and performing the operation quickly.
High myopes are subject to “Myopic Retinal Degeneration,” which can manifest in the macular area.
1. Menezo JL, Harto MA, Cisneros AL. Light-induced maculopathy from the operating microscope in radial keratotomy. J Refract Surg 1988;4:179-182.