ThisIsNotMedicine wrote:
"LASIK flaps do heal very securely and eventually contribute at least to some degree to the bio-mechanical strength of the cornea." http://www.usaeyes.org/faq/subjects/lasik_flap_heal.htmShow me where the scientific evidence supports this claim.
Here's scientific evidence to the contrary:
Ophthalmology. 2005 Jun;112(6):1009-16.
Change in intraocular pressure measurements after LASIK the effect of the refractive correction and the lamellar flap.
Chang DH, Stulting RD.
Department of Ophthalmology, Emory University School of Medicine, Atlanta, Georgia, USA.
OBJECTIVE: To study the relationship between intraocular pressure (IOP) readings after LASIK and the amount of refractive correction.
DESIGN: Retrospective noninterventional case series.
PARTICIPANTS: Patients receiving primary LASIK for myopia and myopic astigmatism.
METHODS: A database of preoperative, intraoperative, and 3-month postoperative data for 8113 consecutive eyes that underwent primary myopic and myopic astigmatic LASIK was retrospectively reviewed. Linear regression analysis of measured IOP change as a function of refractive change was then performed. Age and preoperative keratometry were also reviewed by multiple regression.
MAIN OUTCOME MEASURES: Best-fit curve relating change in measured IOP to refractive change.
RESULTS: The mean spherical equivalent of the refractive change was -4.98+/-2.64 diopters (mean +/- standard deviation). The mean decrease in measured IOP was 2.0+/-3.3 mmHg. Linear regression analysis revealed a decrease of 0.12 mmHg of measured IOP per diopter of refractive change (95% confidence interval [CI], 0.09-0.15, R(2) = 0.009, P<0.001). Extrapolation of the data to a theoretical correction of zero diopters revealed a decrease of 1.36 mmHg (95% CI, 1.20-1.51, P<0.001), suggesting a component of measured IOP change that is independent of laser ablation.
CONCLUSIONS: The reduction of IOP readings after corneal refractive surgery is a linear function of the amount of refractive correction, with an additional constant reduction that is probably related to the lamellar corneal flap.
These data suggest that the lamellar corneal flap makes no contribution to the load-bearing characteristics of the post-LASIK cornea.
Cornea
Volume 25(3), April 2006, pp 331-335
Immunohistochemical Findings After LASIK Confirm In Vitro LASIK Model
Excerpts:
"However, one aspect still in discussion is the wound-healing process in the created interface that leads to an
easily removable flap even years after treatment."
"The lack of pronounced morphologic changes in the central area of the LASIK interface, which only showed little accumulation of fibronectin, supports the hypothesis of
reduced wound-healing reactions after performing this surgical procedure. Only at the rim zone of the incision, scar tissue formation can appear and might form an incomplete fixation zone for the corneal flap.
Due to this impaired healing process, even years after the LASIK procedure, a corneal flap displacement can occur."
"In summary, our histologic findings confirm the well-known clinical phenomenon that wound-healing reactions are marginal after uncomplicated LASIK treatment."