Intraocular pressure changes before and after a femtosecond laser procedure for cataract surgery

This study aimed to evaluate the changes in intraocular pressure (IOP) before and after femtosecond laser capsulorhexis and lens fragmentation for cataract surgery. We measured the IOP before, immediately, 30 min, and 1 h after the laser procedure in 47 eyes of 47 patients who underwent the femtosecond laser procedure. The mean IOP was 17.51 ± 3.28 mmHg, 30.23 ± 6.70 mmHg, 17.96 ± 3.75 mmHg, and 21.77 ± 5.88 mmHg before, immediately after, 30 min after, and 1 h after the laser procedure, respectively. The mean IOP significantly increased immediately (adjusted P < 0.001) and 1 h (adjusted P = 0.001) after the laser procedure compared with the pre-laser IOP. The mean IOP at 30 min after the laser procedure was significantly lower than that immediately after the procedure (adjusted P < 0.001). However, the IOP 1 h after the laser procedure became higher than that 30 min after the laser procedure. Additionally, the IOP 1 h after the laser procedure was positively correlated with the baseline IOP and negatively correlated with the axial length. In conclusion, this study demonstrated that cataract surgery should be commenced within 30 min after the femtosecond laser procedure to ensure a safe cataract surgery that reduces the risk of increased intraocular pressure.

Pupil Status with Low-Energy Femtosecond Laser-Assisted Cataract Surgery versus Conventional Phacoemulsification: An Intraindividual Comparative Study

Purpose

To compare the pupil changes in low-energy femtosecond laser-assisted cataract surgery (FLACS) with conventional phacoemulsification (CP) intraindividually.

Patients and Methods

A retrospective review of registered surgical data from patients that undergone uncomplicated cataract surgery in a single centre, with randomly assigned femtosecond laser-assisted cataract surgery (FLACS) to one eye and conventional phacoemulsification (CP) to the other, was performed. The recorded pupil images were evaluated at pre and post laser treatment (after suction release) and at several surgical timepoints for both techniques (FLACS and CP). Pupil areas were calculated and compared in the same eye undergone FLACS (pre vs post laser treatment), between eyes (CP vs FLACS) in the same patient and between groups. Subgroups were built regarding age and ocular comorbidity.

Results

This study involved a total of 164 eyes of 82 patients (55 female, 27 male). No statistical differences regarding the total duration of surgery (p=0.805) between FLACS and CP. Pupil measurements between pre and post laser treatment in the FLACS group showed no statistically significant differences (p=0.107). The mean change in pupil area from the beginning until the end of surgery (total variation) was 6.59±2.08 mm² in the FLACS group and 6.67±2.13 mm² in the CP group, associated to less narrowing of pupil area with FLACS, although not statistically significant (p=0.080). Comorbidity group analysis revealed less, but not significant, pupil narrowing with the FLACS technique (p=0.071). No statistically significant differences between FLACS and CP concerning age subgroups were registered.

Conclusion

This study shows no significant pupil changes, namely myosis, after low-energy FLACS pre-treatment. Comparison between techniques showed less pupil variation in FLACS as compared to CP, more markedly in eyes with comorbidities (particularly with shallow anterior chamber), although non-statistically significant.

Randomized Controlled Trial Comparing 1-Year Outcomes of Low-Energy Femtosecond Laser-Assisted Cataract Surgery versus Conventional Phacoemulsification

Purpose: To compare 1-year clinical outcomes, phacoemulsification energy, aqueous profiles, and patient-reported outcomes of low-energy femtosecond laser-assisted cataract surgery (FLACS) vs. conventional phacoemulsification.

Methods: The study is a randomized controlled trial (RCT) with paired-eye design. Eighty-five patients were randomized to receive FLACS (Ziemer LDV Z8) in one eye and conventional phacoemulsification in the fellow eye. Clinical data including phacoemulsification energy parameters (cumulative dissipated energy, phacoemulsification power, and phacoemulsification time), uncorrected and corrected distance visual acuities (UCDVA and BCDVA), manifest refraction spherical equivalent (MRSE), central corneal thickness (CCT), endothelial cell count (ECC), anterior chamber flare, and post-operative complications were obtained for 1 year. Aqueous humor was collected for the analysis of prostaglandin (PGE)₂, cytokines and chemokines concentrations. Patients' reported-outcomes on surgical experiences were evaluated using an in-house questionnaire.

Results: Compared to conventional phacoemulsification, the low-energy assisted FLACS group had significantly less ECC reduction at 3 months (1.5 ± 0.3% vs. 7.0 ± 2.4%; P < 0.01) and 1 year (8.2 ± 2.8% vs. 11.2 ± 3.6%; P = 0.03). There were no significant differences in the phacoemulsification energy parameters, UCDVA, BCDVA, MRSE, CCT, occurrence of post-operative complications between the 2 groups throughout post-operative 1 year. Patients' subjective surgical experiences, including the surgical duration and perceived inconvenience, were comparable between the 2 groups. FLACS resulted in significantly higher aqueous PGE₂ (P < 0.01), interleukin (IL)-6 (P = 0.03), IL-8 (P = 0.03), and interferon (IFN)-γ (P = 0.04) concentrations and greater anterior chamber flare at 1 day (P = 0.02).

Conclusions: Our RCT presented 1-year longitudinal clinical and laboratory data. The long-term ECC result was more favorable in low-energy FLACS. The rest of the intraoperative and post-operative outcomes, as well as patient-reported outcomes, were comparable between these two procedures.

Perioperative pupil size in low-energy femtosecond laser-assisted cataract surgery

PURPOSE

To assess potential changes in pupil size during femtosecond laser-assisted cataract surgery (FLACS) using a low-energy laser system.

METHODS

The pupil sizes of eyes undergoing FLACS were measured using the Ziemer LDV Z8 by extracting images from the laser software after each of the following steps: application of suction, lens fragmentation, and capsulotomy. Furthermore, the pupil diameters were measured based on preoperative surgical microscope images and after releasing the suction. Paired t-test and the two one-sided tests (TOST) procedure were used for statistical analyses. The horizontal and vertical pupil diameters were compared in each of the steps with preoperative values.

RESULTS

Data were available for 52 eyes (52 patients, mean age 73.4 years, range 51-87 years). The equivalence between mean preoperative pupil size and status immediately after femtosecond laser treatment was confirmed (p<0.001; 95% confidence interval [-0.0637, 0.0287] for horizontal and p<0.001; 95% CI [-0.0158, 0.0859] for vertical diameter). There was statistically significant horizontal and vertical enlargement of pupil diameters between 0.15 and 0.24 mm during the laser treatment steps as compared with preoperative values (all p values <0.001).

CONCLUSIONS

No progressive pupil narrowing was observed using low-energy FLACS. Although a suction-induced, slight increase in pupil area became apparent, this effect was completely reversible after removing the laser interface.

Current Challenges in the Postoperative Management of Cataract Surgery

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[Prevention of intraoperative miosis in femtosecond laser-assisted phaco surgery]

INTRODUCTION

Prevention of intraoperative miosis in hybrid (femtosecond laser-assisted) phacoemulsification is a relevant problem of cataract surgery.

PURPOSE

Development and clinical study of an effective method for preventing intraoperative miosis in hybrid (femtosecond laser-assisted) phacoemulsification.

MATERIAL AND METHODS

Hybrid phacoemulsification was performed in 300 patients (300 eyes). The first group (100 eyes) 3 days prior to the surgery was prescribed instillations of 0.1% indomethacin 3 times a day and 3 times in 2 hours before surgery at 30 minute intervals. The second group (100 eyes) 3 days prior to the surgery was prescribed instillations of 0.1% indomethacin 3 times a day, 3 times in 2 hours before the surgery at 30 minute intervals, and 1 hour before the surgery an additional intramuscular injection of diclofenac. The third group (control, 100 eyes) 2 hours before the operation was prescribed instillations of 0.1% indomethacin, 3 times at 30 minute intervals. The diameter of the pupil was evaluated before the beginning of femtosecond laser stage and before the opening of anterior chamber during the second stage of the operation.

RESULTS

When the interval between the femtosecond laser stage and emulsification of the nucleus fragments was maintained at less than 15 minutes, pronounced decrease of the pupil (more than 2 mm) was noted in 8.2% of cases in the first group, 6.7% in the second group and 14.1% in third (control) group; mean values of pupil narrowing were 0.68±0.27 mm in the 1st group, 0.63±0.25 mm in the 2nd group, and 0.93±0.39 mm (p<0.05) in the third group.

CONCLUSION

The clinical study showed high efficiency of the proposed methods for prevention of intraoperative miosis in hybrid (femtosecond laser-assisted) phaco surgery. An important factor affecting intraoperative narrowing of the pupil is the time interval between the femtolaser stage of the operation and emulsification of the nucleus fragments, which should not exceed 15 minutes.

Changes in Pupil Area during Low-energy Femtosecond Laser-assisted Cataract Surgery

Purpose

To study the potential changes in pupil area within low-energy femtosecond-laser assisted cataract surgery (FLACS).

Methods

A 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).

Results

The 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 mm 2 preoperatively and 39.3 ± 6.75 mm 2 after laser pretreatment. The mean ± SD change in pupil area was -0.03 ± 2.12 mm 2 . 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.

Risk-Adjusted CUSUM Analysis of the Learning Curve of Femtosecond Laser Assisted Cataract Surgery

Objectives: To determine the length of the learning curve of femtosecond laser-assisted cataract surgery (FLACS) by a risk-adjusted cumulative sum method. Materials and Methods: This was a retrospective review of the first 288 FLACS performed by three surgeons over a 12-month period. The learning curves were analyzed separately for each surgeon and as pooled data via risk-adjusted cumulative sum methods. Change-point analysis was performed to estimate the length of the learning curve. Results: Rates of complications were as follows: anterior capsular tear (ACT) (3.4%), posterior capsular rupture (PCR) (0.7%), vitreous loss (0.3%), iris trauma (0.7%), Descemet's membrane tear (0.3%). There was a strong confidence level (96%) that there was a stable performance in terms of PCR after case 16 for the pooled data. Surgeon 1 did not have any cases of PCR, surgeons 2 and 3 exhibited change points at case 5 and 16, respectively (confidence levels = 99%, 98%). There was a strong confidence level (99.8%) that there was stable performance in terms of ACT after case 14 for the pooled data, however the individual surgeons demonstrated individual change points at case 1 (surgeon 1, confidence 99%), case 14 (surgeon 2, confidence 99%), and case 49 (surgeon 3, confidence 96%). Conclusions: The results suggest that there is an increased risk of ACT and PCR in FLACS within a surgeon's first 14 and 16 operations, respectively. Measures should be adopted to minimize harm to patients during this phase. However, overall rates of complications were safe.

Efficacy of 0.015% intracameral epinephrine for significant miosis induced by photodisruption during femtosecond laser-assisted cataract surgery

Despite the various advantages of femtosecond laser-assisted cataract surgery (FLACS), pupillary constriction during laser photodisruption is considered one of the most unfavorable events. This study aimed to investigate the efficacy of intracameral 0.015% epinephrine injection for miosis after laser pretreatment during FLACS.A total of 82 patients who underwent FLACS for age-related cataracts were investigated in this retrospective study. The epinephrine group included patients who received intracameral epinephrine injection for miosis after femtosecond laser pretreatment, while the no-epinephrine group included the patients who underwent FLACS without intracameral epinephrine due to minimal miosis. Quantitative pupil area measurements were performed through the analysis of captured images extracted from surgical videos of both femtosecond laser pretreatment and phacoemulsification.Laser photodisruption induced miosis in both groups, although the degree of miosis was greater in the epinephrine group (4.65 ± 0.87 mm) than in the no-epinephrine group (6.30 ± 0.65 mm; P < .001). The intracameral epinephrine injection significantly increased the pupil diameter from 4.65 ± 0.87 to 5.49 ± 0.76 mm (21.61 ± 22.68%; P < .001) and the pupil area from 70.28 ± 24.46 to 96.49 ± 25.24 mm (52.89 ± 63.54%; P < .001). After additional viscomydriasis, there was no difference between groups in pupil diameter (epinephrine vs no-epinephrine group; 6.10 ± 0.77 vs 6.39 ± 0.65 mm; P = .073).A single intracameral injection of 0.015% epinephrine provided immediate and appropriate redilation of pupil in patients with significant miosis after femtosecond laser photodisruption. Intracameral epinephrine is a simple and practical option for pupil redilation in case of miosis during FLACS.

The Effect of NSAID Pretreatment on Aqueous Humor Prostaglandin E2 Concentration in Eyes Undergoing Femtosecond Laser-Assisted Capsulotomy

PURPOSE

To assess aqueous humor concentration of prostaglandin E2 (PGE2) after capsulotomy creation using a femtosecond laser (FLAC) in patients pretreated with short-term topical ketorolac versus patients without pretreatment.

METHODS

This prospective study comprised consecutive patients scheduled to undergo cataract surgery using a femtosecond laser platform to perform only capsulotomies. An identical protocol for preoperative mydriasis was used for all the eyes included in the study, while aqueous humor was extracted from the anterior chamber of all patients immediately after the initial side port incision. ELISA was performed to quantify aqueous humor PGE2. The patients were divided into 2 groups; in group 1, the patients received short-term topical ketorolac preoperatively, while the patients in group 2 did not receive NSAID pretreatment.

RESULTS

Twenty eyes of 20 patients were included in the study (10 eyes in each group). Mean concentration of aqueous humor PGE2 after FLAC was 392.16 ± 162.00 pg/ml and 622.63 ± 331.84 pg/ml for groups 1 and 2, respectively. A statistically significant difference in aqueous humor PGE2 concentration between the two groups (p < 0.05) was demonstrated, with the eyes that received ketorolac pretreatment demonstrating a lower concentration of PGE2.

CONCLUSION

Short-term topical use of ketorolac prior to FLAC seems to prevent excessive release of PGE2 in the anterior chamber of the eyes that received NSAID pretreatment when compared to the eyes that did not receive NSAIDs preoperatively.

Impact of topical nonsteroidal anti-inflammatory drugs in prevention of macular edema following cataract surgery in diabetic patients

AIM

To evaluate the efficacy of prophylactic administration of topical non-steroidal anti-inflammatory drugs (NSAIDs) on macular edema following cataract surgery in diabetic patients, and to compare between types of NSAIDs (ketorolac tromethamine 0.4% and nepafenac 0.1%).

METHODS

Group 1 (control) received artificial tears substitute as a placebo group, group 2 (nepafenac) received topical nepafenac 0.1%, and group 3 (ketorolac) received topical ketorolac tromethamine 0.4%. Patients were examined postoperatively after completing one week, one month, two months and three months' intervals for evaluating cystoid macular edema (CME) development. The main study outcomes were achieving the best corrected visual acuity (BCVA) and change in the central macular thickness (CMT) measured with optical coherence topography (OCT).

RESULTS

Eighty eyes of 76 patients were included in this study. BCVA showed a statistically significant difference at the third month postoperative follow up between the control group and the NSAIDs groups (P=0.04). There was an increase in the CMT in all cases starting from postoperative first week until third month. CMT showed a statistically significant difference between control group and NSAIDs groups from postoperative first month until third month (P=0.008, 0.027, 0.004). There was no statistically significant difference between nepafenac and ketorolac groups in BCVA and OCT CMT.

CONCLUSION

Prophylactic preoperative and postoperative NSAIDs may have a role in reducing the frequency and severity of CME in diabetic eyes following cataract surgery.

Femtosecond laser-assisted cataract surgery in a public teaching hospital setting

Background

To evaluate the efficiency and practicality of femtosecond laser assisted cataract surgery (FLACS) in a public teaching hospital setting using a mobile FLACS system compared to conventional phacoemulsification cataract surgery (CPCS).

Methods

Ninety eyes from 90 patients underwent either FLACS or CPCS (45 in each group). Cataracts were graded using the Lens Opacities Classification System III system. Outcome measures included total surgery duration, femtosecond laser treatment time, vacuum time (VT), total phacoemulsification time (TPT) and total phacoemulsification power (TPP).

Results

No differences were observed in the preoperative mean cataract grades and co-morbidities. FLACS took longer than CPCS with a mean difference of 5.2 ± 4.5 min (range: 0–18.8 min). The average femtosecond laser treatment time was 4.3 ± 3.4 min (range: 1–15.5 min). The VT was 2.51 ± 0.45 min (range: 1.59–4.10 min). Although not significant, TPT in FLACS showed a trend towards improvement (mean 1.0 ± 0.6 s; range: 0.1–2.4 s) compared to CPCS (mean 1.2 ± 0.6 min; range: 0.5–2.5 min). Whereas, TPP was significantly less in FLACS (mean 17.9 ± 5.0%; range: 5–27%) compared to CPCS (mean 20.3 ± 4.1%; range: 12.0–28.7%)(p = 0.031).

Conclusions

The mobile FLACS system housed in the same operating room increased the surgical duration by 5.2 min. The average VT was 2.51 min, which was lower in comparison to published experience using non-mobile FLACS systems.