Changes in retinal nerve fiber layer thickness following mechanical microkeratome-assisted versus femtosecond laser-assisted LASIK

Abstract

PurposeTo study the influence of the transient elevation of intraocular pressure during suction in laser-assisted in situ keratomileusis (LASIK) on the retinal nerve fiber layer (RNFL) thickness both in microkeratome assisted and femotsecond (FS) LASIK.Patients and methodsAn interventional case series that included 40 eyes suffering from myopia who were candidates for LASIK. All underwent Wave Front Guided LASIK by the same surgeon using the VisX CustomVue platform. A corneal flap was created in 20 eyes using a mechanical microkeratome Moria M2 (MMK), while the IFS IntraLase™ was used in the remaining 20 eyes. Mean suction time was recorded from “Suction ON” to “Suction OFF” time. Optic cube and RNFL thickness analysis using Spectral Domain Optical Coherence Tomography (SD-OCT) Cirrus-HD was completed before, and 1 month after LASIK.ResultsThe study included 40 eyes of 20 patients. All were females with mean age 33.5 ± 6.4 years. Mean preoperative spherical equivalent was −3.62 ± 2.31D. Average preoperative RNFL thickness was 94.6 ± 12.1μm in MMK group while the postoperative average thickness was 95.1 ± 11.9 um with no statistically significant difference (P-value: 0.37). Average preoperative RNFL thickness was 108.28 ± 8.4 μm in FS group compared to 108.38 ± 11.2 μm in the postoperative average with no statistically significant difference (P-value: 0.94). Mean “Suction ON” to “Suction OFF” time was 22 seconds in the MMK group compared to 41 seconds in the FS group.ConclusionThe rise of intraocular pressure during application of suction ring in LASIK surgery does not affect the RNFL thickness as measured by SD-OCT, whether the flap is created by MMK or FS.

The Effect of LASIK Procedure on Peripapillary Retinal Nerve Fiber Layer and Macular Ganglion Cell-Inner Plexiform Layer Thickness in Myopic Eyes

“…In the current study, we attempted to evaluate the effect of applied suction during microkeratome-assisted LASIK on OCT-derived RNFL and macular GC-IPL thickness, in a cohort of myopic patients without any other ocular pathology. According to our findings, suction-induced IOP elevation during LASIK produces nonsignificant alterations on the OCT-derived peripapillary RNFL, which is in agreement with previous literature reports [ 4 , 5 , 16 , 19 , 20 ]. Zhang et al [ 13 ] reported nonsignificant changes in both RNFL and GCC thickness after femtosecond laser-assisted LASIK and femtosecond lenticule extraction.…”

“…This was further supported by similar reports, which using SLP with variable corneal compensator concluded that RNFL actually remained unaffected following LASIK, when compensating individually for changes in corneal birefringence [ 17 , 18 ]. In addition, more recent studies utilizing OCT analysis found no LASIK induced peripapillary RNFL alterations [ 4 , 5 , 15 , 16 , 19 , 20 ].…”

Analysis of Macular and Retinal Nerve Fiber Layer Thickness in Children with Refractory Amblyopia after Femtosecond Laser-assisted Laser In situ Keratomileusis

“…Some researchers have reported no changes in the peripapillary RNFL thickness. [ 25 26 ] and other researchers reported that the peripapillary RNFL thickness is thinner soon after LASIK. [ 22 27 ] However, a few, rare studies reported changes in the peripapillary RNFL thickness in children.…”

Effect of corneal refractive surgery on optical coherence tomography measurements

“…Данный метод обладает большей точностью, высокой повторяемостью и малой вариабельностью получаемых результатов [25][26][27]. При его использовании в работах, посвященных сравнению способов формирования роговичного клапана (микрокератомом или фемтолазером) при проведении операции ЛАЗИК, стойких изменений ПСНВС выявлено не было [7,10]. Лишь непосредственно после вмешательства (через 30 мин) обнаруживались истончение ПСНВС и утолщение фовеа, которые носили кратковременный характер и уже на следующий день после операции не определялись [10].…”

“…Хорошо известно, что характеристики оптической системы глаза, в первую очередь его длина, могут весьма существенно изменять количественные показатели ОКТ, особенно у лиц с аномалиями рефракции высокой степени [1][2][3][4][5][6]; роль других характеристик менее исследована. В ряде работ изучалось влияние кераторефракционных вмешательств на параметры ОКТ -толщину перипапиллярного слоя нервных волокон сетчатки (ПСНВС) [7][8][9][10], режедругих структур глазного дна [10]. Однако целью большинства этих работ была оценка возможного повреждающего действия кратковременного повышения уровня внутриглазного давления (ВГД) во время операции ЛАЗИК, в том числе в зависимости от способа формирования роговичного клапана (микрокератомом или фемтолазером).…”