The Relationship between the Duration of IOP Elevation during LASIK and Nerve Fiber Layer Thickness Measured by GDx(R)

ABSTRACT

PURPOSE: To determine the effect of temporary intraocular pressure (IOP) elevation during laser in situ keratomileusis (LASIK) on retinal nerve fiber layer measurement by scanning laser polarimetry in a clinical trial. METHODS: The duration of IOP elevation was recorded during LASIK and scanning laser polarimetry (GDx(R) Retinal Nerve Fiber Analyzer. Laser Diagnostic Technologies, Inc, San Diego, California) measurements were performed in 60 eyes of 30 consecutive patients before and after the LASIK procedure. RESULTS: The mean duration of IOP elevation during LASIK was 27.2+/-4.5 seconds. The mean retinal nerve fiber layer (RNFL) thickness measured by scanning laser polarimetry were 73.2+/-12.8 micro meter preoperatively, 65.6+/-12.7 at postoperative 1 month and 66.0+/-9.8 micro meter at postopertive 3 months. The mean postoperative 1 month and 3 months values showed significantly reduced RNFL thickness. But, there was no relationship between the duration of IOP elevation and the amount of nerve fiber layer thickness reduction. (R2=0.064, p=0.627) Furthermore, there were no interval change between the retardation values of postoperative 1 month and 3 months (p=0.706). CONCLUSIONS: There was no relationship between the duration of IOP elevation during LASIK and the postoperative reduction of RNFL thickness measured by scanning laser polarimetry. When using scanning laser polarimetry as a helpful diagnostic and follow-up tool for glaucoma, care should be taken in the interpretation of the result after LASIK procedure. If a comparison is likely to be needed in the future, this image should be obtained after the LASIK procedure to set the postoperative baseline.