Posterior Vitreous Detachment (PVD) is when the clear jelly-like substance in the large globe of the eye separates from the back of the eye. PVDs occur natually and are generally considered a part of the aging process. During PVDs patients may experience arcs of light or flashes, however after PVD vision is normally not affected.
Floaters are opaque particles of the inner eye that move within the clear jell-like substance in the large glove of the eye. Floaters are occur naturally and are generally related to myopia (nearsighted, shortsighted) vision, however occur in people with no refractive error. PVD can induce floater material into the line of sight, as can many other events and maladies.
, All-Laser Lasik
, and Epi-Lasik
use a microkeratome to create a flap of corneal tissue. The microkeratome is affixed to the eye globe with suction. This suction will dramatically raise the intraocular pressure (IOP) within the eye globe.
A small study published in February 2006 by the Department of Ophthalmology, Johann Wolfgang Goethe University, Frankfurt am Main, Germany evaluated the incidence of PVD in Lasik patients with healthy vitreous and a partial PVD preop.
In the study, Ninety-five eyes (92.2%) had no PVD preoperatively. Nine eyes out of this group (seven patients, 9.5%) developed incomplete PVD as assessed 1 week postoperatively. Eight eyes (7.8%) had a partial PVD preoperatively and in only one eye was an extension of vitreous detachment observed after the surgery. This is an important distinction. Intuitively one would expect that a patient with a partial PVD would have that PVD expand, yet this happened to only one of the eight preop partial PVD patients.
The study concludes that Lasik may in rare cases lead to new occurrence of PVD or extension of a previously existing partial PVD, however None of the preoperatively measured parameters could predict the occurrence of PVD by Lasik.
Even if Lasik does not cause a PVD, the rise and drop of IOP can stir up existing floaters. Floaters often become ignored by the brain if they stay in the same location. Move them and they suddenly are "visible" again.
Whether or not floaters or PVD should be in an informed consent is an issue of law. We include an article about Lasik floaters
with this information to inform the public of a potential problem after Lasik even if it is considered very rare.
The IOP issue is of great importance regarding a compromised retina or patient with very high myopia. I have aften suggested investigating an alternative such as PRK
, or PIOLs
instead of Lasik for those with a elevated risk of retina damage, plus a full exam by a retina specialist before any
elective ocular surgery.