Changes in Pupil Area During Low-energy Femtosecond Laser Assisted Cataract Surgery

Abstract

PurposeTo study the potential changes in pupil area within low-energy femtosecond-laser assisted cataract surgery (FLACS).MethodsA retrospective assessment of the pupil size was performed in the eyes undergoing FLACS using the Ziemer LDV Z8. We measured the pupil diameters as part of the images taken preoperatively and at the completion of laser pretreatment (after releasing the suction). We calculated the pupil area in 40 eyes of 40 patients (14 right and 26 left eyes). The mean ± standard deviation (SD) of age of the patients was 74 ± 7.4 years (range: 51-87). Paired t-test was used for statistical analyses. Subgroups were built with reference to age and preoperative pupil area (smaller than or equal to the median versus larger than the median).ResultsThe mean ± SD axial length, anterior chamber depth, white-to-white distance and lens thickness were 24.01 ± 1.47, 3.23 ± 0.4, 11.97 ± 0.49, and 4.59 ± 0.41 mm, respectively. The mean ± SD pupil area was 39.33 ± 7.1 mm2 preoperatively and 39.3 ± 6.75 mm2 after laser pretreatment. The mean ± SD change in pupil area was -0.03 ± 2.12 mm2. There were no statistically significant changes between preoperative and post-laser pupil areas (P = 0.93, 95% CI: -0.71 to 0.65). Comparisons within subgroups also did not detect pupil area reduction.Conclusion This study did not detect statistically significant changes in pupil area after laser pretreatment using low-energy FLACS. This observation is in contrast to previous studies using other laser platforms.

Surgical outcomes with high and low pulse energy femtosecond laser systems for cataract surgery

“…Apparently, the low energy Z8 laser would induce minimal collateral damage to surrounding tissue, thus ensuing lower amounts of prostaglandin release, thereby reducing the risk of pupillary miosis during the surgery 32 , compared with high energy laser systems 31 , 33 , 35 , 36 . In agreement with these findings, a recent study reported no significant changes in pre- and post-laser treated pupil area with low energy Z8 FLACS system 37 . Conversely, Diakonis et al revealed significant pupillary miosis with 3 different high energy femtosecond laser platforms 38 .…”

“…Given the lower incidence of intraoperative miosis in the Z8 group, patients with documented NSAID allergy may benefit from the use of the low energy Z8 laser. The hypothesis is supported by the findings of Mirshahi et al, that did not detect statistically significant changes in the pupil area after laser pre-treatment with the low energy FEMTO LDV Z8 37 .…”

<p>Cystoid Macular Edema Following Cataract Surgery with Low-Energy Femtosecond Laser versus Conventional Phacoemulsification</p>

“…19,27 Intraoperative miosis of the pupil observed in some studies following pretreatment with the FL has also been attributed to increased prostaglandin levels after laser treatment. 28,32 Constricted pupils may increase surgical manipulation during phacoemulsification. Correspondingly, some studies have found a trend of higher risk of PCME development following FLACS compared with manual phacoemulsification.…”

“…38 Correspondingly, less pupil constriction with the use of low-energy FLs has been attributed to less release of prostaglandins. 28,33 Therefore, it can be postulated that low-energy laser platforms may induce low inflammation due to laser pretreatment.…”

“…2,26,27 In contrast, low-energy FLs that emit energy in the nanojoule range and have a high pulserepetition rate (above 1 MHz) have been associated with less collateral damage to the surrounding ocular tissue and low release of prostaglandins. 28 In this study, we investigated the risk of postoperative PCME development following FLACS with a low-energy FL compared with CPCS.…”