Femtosecond laser–assisted cataract surgery

Ophthalmic surgeries on post mortem porcine eyes with picosecond ultrashort laser pulses

Purpose

This work demonstrates significant advantages in ophthalmic surgeries through the use of picosecond ultrashort laser pulses instead of state-of-the-art nanosecond laser pulses. These ultrashort lasers shall serve as universal tools more effectively combining advantages of high precision, low impact and economic advantages compared to existing instruments.

Methods

As samples, we used post-mortem porcine eyes on which we performed the experiments with both picosecond and nanosecond lasers. Performed surgeries were laser iridotomy, (post-) cataract treatment/capsulotomy and selective laser-trabeculoplasty. Pulse widths were between 12 ps and 220 ns with pulse energies between 30 μJ and 10 mJ at 532 nm and 1,064 nm. Additionally, we investigated accompanying shock waves, cavitation bubbles, and heat effects during the ablation processes.

Results

For all surgeries, significant differences were observed between picosecond and nanosecond pulses: It was possible to scale the pulse energy down to 10 of microjoules rather than requiring millijoules, and resulting tissue ablations are much more precise, more deterministic and less frayed. The shock wave and cavitation bubble investigation revealed major differences in pressure between picosecond pulses (0.25 MPa, 50 μJ) and nanosecond pulses (37 MPa, 5 mJ). The heat input during ablation could be lowered by two orders of magnitude.

Conclusion

Picosecond ultrashort laser pulses show substantial benefits for several ophthalmic surgeries, with regard to ablation precision, shock wave generation and heat input. They are better than state-of-the-art ophthalmic nanosecond lasers in all aspects tested.

X-ray generation by fs-laser processing of biological material

The use of ultrashort pulse lasers in medical treatments is increasing and is already an essential tool, particularly in the treatment of eyes, bones and skin. One of the main advantages of laser treatment is that it is fast and minimally invasive. Due to the interaction of ultrashort laser pulses with matter, X-rays can be generated during the laser ablation process. This is important not only for the safety of the patient, but also for the practitioner to ensure that the legally permissible dose is not exceeded. Although our results do not raise safety concerns for existing clinical applications, they might impact future developments at higher peak powers. In order to provide guidance to laser users in the medical field, this paper examines the X-ray emission spectra and dose of several biological materials and describes their dependence on the laser pulse energy.

Microsurgery Robots: Applications, Design, and Development

Microsurgical techniques have been widely utilized in various surgical specialties, such as ophthalmology, neurosurgery, and otolaryngology, which require intricate and precise surgical tool manipulation on a small scale. In microsurgery, operations on delicate vessels or tissues require high standards in surgeons' skills. This exceptionally high requirement in skills leads to a steep learning curve and lengthy training before the surgeons can perform microsurgical procedures with quality outcomes. The microsurgery robot (MSR), which can improve surgeons' operation skills through various functions, has received extensive research attention in the past three decades. There have been many review papers summarizing the research on MSR for specific surgical specialties. However, an in-depth review of the relevant technologies used in MSR systems is limited in the literature. This review details the technical challenges in microsurgery, and systematically summarizes the key technologies in MSR with a developmental perspective from the basic structural mechanism design, to the perception and human-machine interaction methods, and further to the ability in achieving a certain level of autonomy. By presenting and comparing the methods and technologies in this cutting-edge research, this paper aims to provide readers with a comprehensive understanding of the current state of MSR research and identify potential directions for future development in MSR.

Comparison of clinical outcomes between cystotome-assisted prechop phacoemulsification surgery and femtosecond laser-assisted cataract surgery for hard nucleus cataracts

BACKGROUND/OBJECTIVES

To compare the safety and efficacy of cystotome-assisted prechop phacoemulsification surgery (CAPPS) and femtosecond laser-assisted cataract surgery (FLACS) in patients with hard nucleus cataract.

SUBJECTS/METHODS

Ninety-six eyes of 64 patients with grade IV hard nucleus cataract were assigned to 1 of the 2 groups (49 CAPPS and 47 FLACS). Follow-up visits were performed at 1 day, 1 week, 1 month, 3 months, 6 months, and 1 year, and the outcome measures comprised ultrasound power, effective phacoemulsification time (EPT), corrected distance visual acuity (CDVA), endothelial cell density (ECD), corneal endothelium cell loss rate (ECL), central corneal thickness (CCT), and intraoperative and postoperative complications.

RESULTS

The ultrasound power and EPT were lower in the CAPPS group (p = 0.03 and <0.0001, respectively). Patients in both groups gained better CDVA postoperatively. The ECD value decreased at each follow-up visit and did not return to the preoperative level; FLACS resulted in greater endothelial cell loss compared to CAPPS. CCT increased immediately after the surgery and decreased thereafter. The mean CCT value returned to the preoperative level 3 months postoperatively in the CAPPS group, while in the FLACS group, CCT value took 6 months to return to the preoperative level. Miosis was more likely to occur in the FLACS group.

CONCLUSIONS

Due to its efficacy and cost-effectiveness, CAPPS is worth promoting and applying to clinical work in the future.

Optical Quality Variation of Different Intraocular Lens Designs in a Model Eye: Lens Placed Correctly and in an Upside-Down Position

INTRODUCTION

Intraocular lenses (IOLs) may lose their optical quality if they are not correctly placed inside the capsular bag once implanted. One possible malpositioning of the IOL could be the implantation in an upside-down position. In this work, three aspheric IOLs with different spherical aberration (SA) have been designed and numerically tested to analyse the optical quality variation with the IOL flip, and misalignments, using a theoretical model eye.

METHODS

Using the commercial optical design software OSLO, the effect of decentration and tilt was evaluated by numerical ray tracing in two conditions: in their designed position and flipped with respect to the planned position (IOL is implanted upside down). The theoretical model eye used was the Atchison model eye. Seven IOL designs of +27.00 diopters were used: a lens with negative SA to correct the corneal SA, a lens to partially correct the corneal SA, and a lens to not add any SA to the cornea (aberration-free IOL). These lenses were designed with the aspherical surface located on the anterior and posterior IOL surface. A lens with no aspherical surfaces was also included. For the optical quality analysis, the modulation transfer function (MTF) was used, together with the Zernike wavefront aberration coefficients of defocus, astigmatism, and primary coma.

RESULTS

Off-centring and tilting the IOL reduced overall MTF values and increased wavefront aberration errors. With the IOL correctly positioned within the capsular bag, an aberration-free IOL is the best choice for maintaining optical quality. When the IOL is flipped inside the capsular bag, the optical quality changes, with the aberration-free IOL and the IOL without aspheric surfaces providing the worst results. With the lens in an upside-down position, an IOL design to partially correct corneal SA shows the best optical quality results in decentration and tilt, in terms of MTF and wavefront aberrations.

CONCLUSION

The aberration-free IOL is the best choice when minimal postoperative errors of decentration or tilt are predicted. With IOL flip, the negative SA lens design is the best choice, regarding the root mean square wavefront aberrations. However, in a proper IOL implantation, the IOL designed to partially compensate the corneal SA including asphericity on its posterior surface is the better possible option, even in the presence of decentration or tilt.

Femtosecond Laser-Assisted Cataract Surgery: Analysis of Surgical Phases and Comparison with Standard Phacoemulsification in Uncomplicated Cataracts

The aim of this work is to compare the time of surgical phases and the cumulative dissipated energy (CDE) of the phacoemulsification phase in femtosecond laser-assisted cataract surgery (FLACS) and in standard surgical procedures of phacoemulsification (PCS). This prospective, non-randomized study analyzed the data of 100 cataract surgeries, 66 using FLACS and 34 with standard PCS. The time of surgical phases was recorded by a digital chronometer; an additional parameter recorded was the CDE of the phacoemulsification phase. The mean time of femtosecond laser phase was 121.7 ± 27.3 s with minimal fluctuations in duration; the mean opening time of the corneal tunnel and the service incisions was 60.5 ± 20.4 s in the PCS, and 48.8 ± 17.4 s in FLACS (p = 0.04); the mean time of capsulorhexis was 39.6 ± 12.9 s in the PCS and 7.0 ± 5.2 s in FLACS (p < 0.0001); the mean time of phacoemulsification was 180.1 ± 45.6 s in the PCS and 163.0 ± 38.2 s in FLACS (p = 0.12); the mean aspiration time of the residual cortical was 66.3 ± 27.5 s in the PCS and 91.5 ± 35.7 s in FLACS (p = 0.02). Overall, the total surgical time of the cataract surgery was 742.3 ± 185.8 s in PCS and 985.1 ± 118.6 s in FLACS (p = 0.03). The mean CDE was 11.35 in the PCS and 8.3 in FLACS (p = 0.01). In conclusion, the greatest advantage obtained from the use of the femtosecond laser was the reduction of the duration of the phacoemulsification time and of the CDE parameter.

The creation of a corneal incision with a femtosecond laser

BACKGROUND: The cutting action of a femtosecond laser (FS-laser) on the corneal tissue is performed using a photodestructive effect. FS-laser technology is used in many different areas of corneal surgery, and studying this effect is an actual issue. AIM: To evaluate the surface of the corneal incision created by a FS-laser (experimental study). MATERIALS AND METHODS: 20 porcine eyes were divided into two groups (FS-laser and keratome). The corneal tissue surface in the area of contact between two lips of the incision was visualized by electron microscopy. RESULTS: In all cases, we received a full-thickness incisions through the cornea. Images obtained by electron microscopy showed regular surface, no signs of thermal or mechanical damage to the corneal structure. CONCLUSIONS: The FS-laser is used as a microscopic scalpel in surgery. The precision cutting process is performed by mechanical forces generated by photodestruction by expanding cavitation bubbles.

Visual and refractive outcomes of new intraocular lens implantation after cataract surgery

To report the visual and refractive outcomes of new aspheric hydrophobic acrylic monofocal intraocular lens (IOL). Retrospective case series. This study included eyes of patients who underwent routine cataract surgery for uncomplicated age-related cataract with implantation of a Aktis SP (NS-60YG; Nidek Co. Ltd., Japan) IOL and attended regular follow ups at 1 week, 1 month, 3 months, and 12 months. At each post-operative visit, ophthalmological evaluation included measurement Uncorrected (UCVA) and Best corrected visual acuity (BCVA), contrast sensitivity, posterior capsular opacification (PCO), optical aberrations, analysis of point spread function (PSF) and modulation transfer function (MTF). The study included 2102 eyes of 1358 patients aged 45 to 75 years (mean age 62.6 years ± 5.6 SD). The mean preoperative BCVA was 0.56 ± 0.26 logMAR. At 1 year follow up, the mean postoperative UCVA and BCVA were 0.11 ± 0.09 and 0.02 ± 0.03 logMAR, respectively. At the end of 6 months, around 1487 (93%) eyes had BCVA of 20/20 and better than 20/30 in 100% of the eyes. Mild posterior capsule opacification (PCO) was observed in 56 patients, but none required Nd YAG laser capsulotomy. There was reduction in ocular spherical aberration and Higher order aberrations (HOAs) as compared to pre operative. This explains better contrast sensitivity obtained by MTF and PSF values. The study shows that the Aktis SP IOL is safe, effective, and stable lens that could be inserted through 2.2 mm incision with satisfactory visual and refractive outcomes, even in late post-operative period.

Femtosecond Laser-assisted Cataract Surgery in Patients With Prior Glaucoma Surgery

PRCIS

Femtosecond laser-assisted cataract surgery (FLACS) is a safe procedure in glaucomatous eyes with prior glaucoma surgery, evidenced by stable intraocular pressure (IOP) and medication use, acceptable success rate, disease stability, and low complication rates at 1-year postoperative.

PURPOSE

The purpose of this study was to assess the 1-year efficacy and safety of FLACS in glaucomatous eyes with prior glaucoma surgery.

MATERIALS AND METHODS

Retrospective case series of all consecutive glaucomatous eyes with previous glaucoma surgery that underwent FLACS using the Catalys Precision Laser System with or without concomitant glaucoma surgery at a single ophthalmology center, between 2014 and 2020. Efficacy included change in IOP, glaucoma medication use, best-corrected visual acuity, and surgical success at 12 months postoperatively (POM12). Safety included structural and functional measures of disease stability and postoperative adverse events.

RESULTS

A total of 57 eyes with an average age of 62.6±8.1 years were included. At POM12, IOP decreased from 14.5±6.6 mmHg to 13.5±3.7 mm Hg (P=0.22) and glaucoma medication use decreased from 2.1±1.5 to 1.8±1.4 with a marginal significance (P=0.089). Best-corrected visual acuity improved significantly in both groups (P<0.001) and surgical success ranged between 74% and 90% according to the study's success criteria. Safety was favorable with disease stability evidenced by lack of deterioration in cup-to-disc ratio, visual field mean deviation, retinal nerve fiber layer thickness, and ganglion cell-inner plexiform layer thickness. One eye with prior history of trabeculectomy experienced transient bleb leak. Other adverse events were minor without sight-threatening sequelae.

CONCLUSIONS

The results of this study suggest that FLACS with or without concomitant glaucoma surgery could be a safe procedure in glaucomatous eyes-a population for which FLACS has been relatively contraindicated. Nonetheless, in those with preexisting filtering bleb, extra attention should be paid to the bleb area.

Corneal perforation following arcuate keratotomy in femtosecond laser assisted cataract surgery-a case series

Purpose

Identification and management of corneal perforation during arcuate keratotomy in femtosecond laser assisted cataract cases (FLACS).

Observation

Low astigmatism correction in patients undergoing FLACS can be done by arcuate keratotomy incision made by femto-laser. Corneal perforation following arcuate keratotomy is commonly noted with manual incision but very few cases have been reported with femtolaser arcuate keratotomy (FSAK). In this case series, we have reported cases with corneal perforation following FSAK in patients undergoing FLACS. All the cases were managed by placing suture at the keratotomy site followed by phacoemulsification.

Conclusion and importance

Perforation can be expected in cases with FSAK though rare. Vigilant monitoring of the depth of laser passage and early detections of such perforations is required, for further prevention of complication. Astigmatic arcuate keratotomy is associated with a risk of perforation even if it is performed with femto laser, but risk of perforation is low and undoubtedly the benefit to risk ratio is high.

Measurement of Phacoemulsification Vacuum Pressure in the Oertli CataRhex3

Purpose

To determine the actual vacuum pressure generated by the Oertli CataRhex 3^® (Oertli), using an external measuring system.

Methods

The effective vacuum pressure created by the Oertli was measured with a pressure device that was continuous with the vacuum tubing system while closed to the external environment. Measurements were taken with the machine set to 300 and 500 mmHg at flow rates of 20, 35, and 50 mL/min and at bottle heights of 60, 80, and 100 cm. Pressures were recorded after the foot pedal was depressed to vacuum setting (second position), and the pressure was allowed to stabilize. Subsequently, it was compared to the pressure value displayed by the machine.

Results

Externally measured vacuum pressure was on average 13.02% greater (39.05 mmHg) than displayed vacuum pressure at 300 mmHg (P < 0.005) and 8.60% greater (42.98 mmHg) than displayed vacuum at 500 mmHg (P < 0.005). The average difference between displayed and measured pressure increased with increasing bottle heights.

Conclusion

On average, the vacuum pressure generated in the Oertli was found to be significantly higher than the machine’s reading when the machine was set at 300 mmHg and 500 mmHg. Adjusting vacuum had variable effects on the measured versus displayed pressure readings.

Evaluation of the Optical Aspects of the Ophthalmic Viscosurgical Device During Femtosecond Laser-Assisted Cataract Surgery

Purpose

In femtosecond laser-assisted cataract surgery (FLACS), capsulorhexis can be performed with an ophthalmic viscosurgical device (OVD) filled in the anterior chamber. We aimed to investigate changes in the laser properties in various optical aspects, such as focal shifting, reflection, and absorption associated with OVD.

Methods

Simulation was achieved by calculating the laser power attenuation due to reflection and spot size change using the Gullstrand eye model. Additionally, we calculated the absorption coefficient by measuring the laser power passing through the OVD with a laser meter and evaluated the effect of absorption by the OVD.

Results

In our simulation, power attenuation due to reflection was a maximum of 0.07%, and power attenuation was 0.08% even when considering the change according to the incident angle. Power attenuation due to the change of the spot size at the focus was 0.005%. Owing to the absorption of the OVD, a power increase of up to 13.5% was required for an anterior chamber depth of 3.0 mm to obtain the same effect as the aqueous humor.

Conclusions

The main reason for laser power attenuation associated with OVD was laser absorption through the OVD, and could also be caused by laser cavitation bubbles. To complete a safe capsulotomy during FLACS, the laser power should be increased appropriately, considering the absorption by the OVD in the anterior chamber.

Translational Relevance

The study results can be applied to calculate the optimal femtosecond laser energy to achieve complete capsulotomy during FLACS in the presence of anterior chamber OVD.

Preclinical Safety and Efficacy Assessments for Novel Femtosecond Lasers in Corneal Refractive Surgery

Preclinical safety requirements and test methods have been standardized over time to guide medical device developers in the path needed to manufacture safe devices and achieve regulatory approval. Today, femtosecond lasers are commonly used in cataract and refractive surgeries. Currently, an industry standard to guide developers in preclinical testing of ophthalmic lasers does not exist. Consequently, the data presented in regulatory submissions may vary between manufacturers, making the regulatory review process more ambiguous. Here, the authors present a comprehensive discussion of preclinical test methods applied to the evaluation of an ophthalmic laser. We include in vitro and ex vivo models, as well as an in vivo rabbit model subject to corneal refractive treatments, for consideration in a preclinical safety evaluation plan. Scientific rationale to support the ocular endpoints of evaluation in the rabbit model to demonstrate safety is also presented and discussed.

[Historical development of energetic cataract surgery]

This article reviews scientific literature analyzing the history of ultrasound and laser phaco surgery of combined or isolated designs: erbium YAG laser, 1.064 μm Nd:YAG laser for dissection of the lens capsule and nucleus, exclusively-laser technique of lens destruction with 1.44 µm Nd:YAG laser without manual, vacuum or ultrasonic action, femtosecond laser assistance with automated transcorneal delivery of radiation into the eye cavity.

Complex use of energetic surgery in treatment of patients with primary open-angle glaucoma and cataract on the background of pseudoexfoliative syndrome

BACKGROUND: Glaucoma remains one of the current problems of modern ophthalmology. The combination of glaucoma and cataract is observed in 1738.6% of cases, and glaucoma with pseudoexfoliative syndrome in 2050% of primary open-angle glaucoma cases. AIM: The aim of this work is to develop an effective and safe technology of complex energetic surgical treatment of the incipient primary open-angle glaucoma stage and cataract on the background of pseudoexfoliation syndrome on the basis of modified laser, hydrodynamic and ultrasound methods use. MATERIALS AND METHODS: 187 patients (187 eyes) with the incipient stage of primary open-angle glaucoma, cataract and pseudoexfoliation syndrome were examined. In the main group (111 eyes), selective laser trabeculoplasty followed by femtosecond laser-assisted cataract surgery with hydrodynamic trabeculocleaning was performed. Patients in the control group (76 eyes), after selective laser trabeculoplasty, underwent phacoemulsification according to the standard technique. RESULTS: The developed technology allowed to reach the hypotensive effect in 35.2% (t=23.0; р 0.001) of baseline intraocular pressure values, of individual intraocular pressure level without adding IOP-lowering medications in 27% of cases, stabilization of visual functions and morphometric indices of the optic disc during 2 years of follow-up in 97.3% of cases unlike the selective laser trabeculoplasty with subsequent phacoemulsification (21.2, 5.3 and 81.6% respectively). The patients of the main group had significantly lower energy expenditure during the stage of phacoemulsification, a lower percentage of postoperative inflammatory reaction was noted, and a persistent hypotensive effect with stabilization of visual functions was achieved based on the results of a two-year follow-up. CONCLUSIONS: Femtosecond laser-assisted phacoemulsification, performed as part of complex treatment in patients with cataract and incipient stage of primary open-angle glaucoma, is a sparing method that minimizes surgical trauma and achieves a persistent hypotensive effect, reduces intraocular pressure to an individual level and stabilizes visual functions in 97.3% of cases.

Independent contribution of optical attenuation length in ultrafast laser-induced structural change

Although laser irradiation with femtosecond pulses is known to generate crystallization and morphological changes, the contribution of optical parameters to material changes is still in discussion. Here, we compare two structures irradiated near Si-L2,3 edges by an extreme ultraviolet femtosecond pulse. Our result implies that, despite the femtosecond irradiation regime, these values of the optical attenuation length between the wavelengths of 10.3-nm and 13.5-nm differ by one order of magnitude. From the structural comparison, the original crystalline state was maintained upon irradiation at 13.5-nm, on the other hand, transition to an amorphous state occurred at 10.3-nm. The difference in optical attenuation length directly influence to the decision of material crystallization or morphological changes, even if the irradiation condition is under the femtosecond regime and same pulse duration. Our result reveals the contribution of optical attenuation length in ultrafast laser-induced structural change.

Repeatability of Anterior Eye Surface Topography Parameters from an Anterior Eye Surface Profilometer

SIGNIFICANCE

Anterior eye shape measurements are important for clinical contact lens fitting. The detailed assessment of measurement repeatability using the Eye Surface Profiler (ESP; Eaglet Eye B.V., AP Houten, the Netherlands) allows for more reliable interpretation of eye surface topography measurements.

PURPOSE

This study aimed to determine the repeatability of the ESP for anterior central corneal power and anterior eye surface height measurements.

METHODS

A Badal optometer was mounted on the ESP to provide an external fixation target with appropriate accommodation control and refractive correction. Forty-five healthy young adults underwent two sessions of anterior eye measurements, separated by 20 minutes, using the ESP. In each session, three consecutive scans were captured. Sagittal height data were obtained from 8-mm central cornea and from 8- to 14-mm diameter (encompassing the corneal periphery and anterior sclera). Anterior corneal powers were determined from the central cornea. Intersessional and intrasessional repeatability values were determined as coefficients of repeatability and root mean square error differences.

RESULTS

Sagittal height intersessional coefficients of repeatability for central nasal (5 μm) and central temporal (7 μm) were better than peripheral nasal (24 μm) and peripheral temporal (21 μm) regions. Sagittal height intrasessional coefficients of repeatability were 9, 8, 28, and 31 μm for central nasal, central temporal, peripheral nasal, and peripheral temporal regions, respectively. Intersessional coefficients of repeatability of mean sphere, 90/180° (J0) astigmatism, and oblique (J45) astigmatism were 0.67, 0.22, and 0.13 D, respectively, with corresponding intrasessional coefficients of repeatability of 1.27, 0.21, and 0.27 D.

CONCLUSIONS

The modified measuring procedure for the ESP used in this study provides highly repeatable sagittal height measurements in the central cornea but is less repeatable in the corneal periphery and scleral region. Results of the current study can be considered when using ESP in the interpretation of anterior eye surface shape measurements and in contact lens fitting and design.

Thermal Profile of Pulse Precision Capsulotomy: In vivo and in vitro Infrared Thermography Study

Purpose

This study aimed to elucidate the thermal safety of precision pulse capsulotomy (PPC) via in vivo and in vitro evaluation of the thermal profile using infrared thermography.

Methods

This prospective observational study enrolled 15 eyes from 15 participants who underwent cataract surgery using the Zepto PPC. All patients underwent temperature measurements of the incision site and the entire cornea using an infrared thermographer during the capsulotomy procedure. To accurately analyze the temperature change of the Zepto PPC, infrared thermography was performed with the Zepto handpiece while exposed to air and then in porcine eyes. Moreover, in each case, the difference in temperature change according to the use of an ophthalmic viscosurgical device (OVD) was also checked to determine the temperature buffering effect.

Results

In the clinical evaluations, the mean temperature elevation around the corneal incision and time duration from baseline to peak temperature during the Zepto capsulotomy were 4.0 ± 1.9℃ and 4.43 ± 1.26 s, respectively, with a mean peak temperature of 32.6 ± 2.0℃. The mean peak temperature and rise time of the naïve Zepto nitinol ring, as measured from the bottom side, were 109.0 ± 22.9℃ and 43.40 ± 11.06 s in the experimental procedures, respectively. In the porcine eyes, the mean elevation of temperature and rise time of the Zepto nitinol ring were 6.2 ± 1.6℃ and 11.67 ± 2.08 s with the use of OVDs, and 10.5 ± 3.3℃ and 14.00 ± 3.61 s without OVDs, respectively.

Conclusions

Zepto PPC has the potential to generate extremely high thermal energy, according to an in vitro study. However, the temperature rise of the Zepto capsulotomy can be minimized by using OVDs.

A Novel Tissue Identification Framework in Cataract Surgery using an Integrated Bioimpedance-Based Probe and Machine Learning Algorithms

OBJECTIVE

The objective of this work was to develop and experimentally validate a bioimpedance-based framework to identify tissues in contact with the surgical instrument during cataract surgery.

METHODS

This work introduces an integrated hardware and software solution based on the unique bioimpedance of different intraocular tissues. The developed hardware can be readily integrated with commonly used surgical instruments. The proposed software framework, which encompasses data acquisition and a machine-learning classifier, is fast enough to be deployed in real-time surgical interventions. The experimental protocol included bioimpedance data collected from 31 ex vivo pig eyes targeting four intraocular tissues: Iris, Cornea, Lens, and Vitreous.

RESULTS

A classifier based on a support vector machine exhibited an overall accuracy of 91% across all trials. The algorithm provided substantial performance in detecting the intraocular tissues with 100% reliability and 95% sensitivity for the lens, along with 88% reliability and 94% sensitivity for the vitreous.

CONCLUSION

The developed impedance-based framework demonstrated successful intraocular tissue identification.

SIGNIFICANCE

Clinical implications include the ability to ensure safe operations by detecting posterior capsule rapture with 94% probability and improving surgical efficacy through lens detection with 100% reliability.

Precision Pulse Capsulotomy During Combined Penetrating Keratoplasty With Cataract Surgery and Intraocular Lens in Small Nondilating Pupil

OBJECTIVE

To demonstrate precision pulse capsulotomy (PPC) in an open-sky procedure and to evaluate its use during triple procedure keratoplasty in small nondilating pupils.

METHODS

This single-center retrospective case series study included 10 eyes (from 10 patients) with corneal opacity and poorly dilated pupils who were scheduled to undergo triple procedure keratoplasty. The main outcome measures were capsulotomy performance of the PPC device and intraoperative complications. Secondary outcome measures included postoperative best-corrected visual acuity, intraocular pressure, and other postoperative complications.

RESULTS

Complete free-floating capsulotomy was achieved in all 10 eyes. There were no cases of anterior capsule tears or tags. There were no postoperative complications that occurred in association with the PPC device.

CONCLUSIONS

The PPC device facilitates creation of a smooth, round, and appropriately sized anterior capsulotomy in open-sky surgeries, particularly in presence of small nondilating pupils.

Inspection of the lens thickness with preoperative biometric measurements prevents an erroneous interpretation of posterior capsule during FLACS

Optical opacity reduces quality of biometry images, making it potentially difficult to find the correct location for irradiation during femtosecond laser-assisted cataract surgery (FLACS). After experiencing a case of posterior capsule (PC) rupture because of optical opacity, we started lens thickness (LT) inspection, which indicates comparison of between intra- and pre-operatively measured LT. We retrospectively investigated the effectiveness of the LT inspection. One observer reviewed all FLACS treatment summaries for 3 years by CATALYS in the Jikei University Hospital, Tokyo. Based on the lines defining the PC on intraoperative OCT images, all cases were classified into three groups: undescribed, appropriate and inappropriate PC. Among the 1070 cases, 1047 cases had appropriate PC. In 19 cases, the PC line was undescribed because of dense cataract. Among 474 cases with no inspection, 4 cases had an inappropriate PC. Whereas, in 596 cases with the LT inspection, there was no case of an inappropriate PC. LT inspection significantly reduced the cases with inappropriate PC. The safety margins normally work to prevent severe complications. However, rare outlier cases had a high risk of severe complications. We propose LT inspection could be the most practical and convenient way for safety surgery.

Argentinian Flag Sign and Its Management during Femtosecond Laser-Assisted Cataract Surgery in a Case with Intumescent Cataracts

We describe a case of radial extension and its management during femtosecond laser-assisted cataract surgery (FLACS) in a patient with intumescent cataracts. Radial extension was observed after injection of trypan blue into the anterior chamber. Management of the extension was achieved by separation of adhesions between the incomplete capsulotomy, along with manual completion at the areas of extensions. Careful observation during FLACS capsulotomy is advised in cases of intumescent cataracts due to the release of cortex into the anterior chamber which may interfere with the delivery of the laser treatment resulting in incomplete capsulotomy patterns. Furthermore, trypan blue staining is essential to identify possible incomplete capsulotomy patterns and extensions. The Argentinian flag sign may occur after femtosecond laser-assisted capsulotomy in cases of intumescent cataracts. Proper identification of incomplete capsulotomy patterns and radial extensions should be managed with careful manual completion of the capsulotomy.

An innovative alternative for spherophakia

Objective: The aim of this case report is to report a new aphakic intraocular lens (IOL) that can be used for spherophakia. Methods: This is a single case report wherein the authors elaborate the technique of inserting the new IOL design in patients with spherophakia. Results: This new IOL design is very stable and is very promising in our follow-up of 6 months. Conclusion: The CM T-flex IOL can be a simple and alternate option for correcting aphakia.

Evaluation of the Cataract Surgery 2018 Survey in Terms of Achieving Refractive Cataract Surgery Targets

Objectives

The aim of this study was to show at what rate the technological equipment used in cataract surgery by Turkish ophthalmologists and their knowledge are reflected in practice and how up to date they are.

Materials and Methods

A questionnaire conducted using SurveyMonkey was used to evaluate the answers to 17 questions from 823 members of the Turkish Ophthalmological Association. Results were evaluated in subgroups according to the participants' age, occupational status, institutions, and whether they conducted relevant academic activities, and the data were compared as inadequate, standard, and contemporary approaches according to the determined criteria.

Results

Optical biometry devices were used at rates of 77.7% and 67.3% for intraocular lens (IOL) power calculations and keratometric measurements in preparation for cataract surgery, respectively. For IOL power calculation, third-generation formulas, especially the SRK-T, were used most commonly (46.2%), followed by second-generation formulas (21.9%), and fourth/fifth-generation formulas and multiple evaluations for different axial lengths (31.9%). The most common incision size was 2.8 mm (51.6%), while the percentage of 2.2 mm and shorter incisions considered to be neutral in terms of surgically induced astigmatism was 18.8%. When selecting incision location, approaches to reduce corneal astigmatism were reported by 28.9%, neutral approaches by 26.2%, and insensitive approaches by 44.9%. Additionally, 55.6% of participants never implanted toric IOLs and 50.7% did not use presbyopia-correcting IOLs. The proportion of surgeons who have experience with femtosecond laser-assisted cataract surgery was 10.3% and the rate of intracameral antibiotic injection at the end of the operation was 89.4%.

Conclusion

It was seen that Turkish cataract surgeons were able to use high technology for surgical preparation and surgery at high rates, but this was not reflected in practice at same rate in terms of achieving contemporary standards of refractive cataract surgery.

Comparison of Femtosecond Laser-Assisted and Ultrasound-Assisted Cataract Surgery with Focus on Endothelial Analysis

Femtosecond laser-assisted cataract surgery has the potential to make critical steps of cataract surgery easier and safer, and reduce endothelial cell loss, thus, improving postoperative outcomes. This study compared FLACS with the conventional method in terms of endothelial cells behavior, clinical outcomes, and capsulotomy precision.

METHODS

In a single-center, randomized controlled study, 130 patients with cataracta senilis received FLACS or conventional cataract surgery.

RESULTS

A significant endothelial cell loss was observed postoperatively, compared to the preoperative values in both groups. The endothelial cell counts was significantly better in the FLACS group in cataract grade 2 (p = 0.048) patients, compared to conventionally at 4 weeks. The effective phaco time was notably shorter in grade 2 of the FLACS group (p = 0.007) compared to the conventional. However, no statistically significant differences were found for the whole sample, including all cataract grades, due to the overall cataract density in the FLACS group being significantly higher (2.60 ± 0.58, p < 0.001) as compared to conventional methods (2.23 ± 0.42).

CONCLUSIONS

Low energy FLACS provides a better result compared to endothelial cell loss, size, and shape variations, as well as in effective phaco time within certain cataract grade subgroups. A complete comparison between two groups was not possible because of the higher cataract grade in the FLACS. FLACS displayed a positive effect on endothelial cell preservation and was proven to be much more precise.

Evaluation of femtosecond laser-assisted anterior capsulotomy in the presence of ophthalmic viscoelastic devices (OVDs)

The introduction of femtosecond laser-assisted cataract surgery is an alternative approach to conventional cataract surgery. Our study aimed to determine the effectiveness of femtosecond laser-assisted capsulotomy in the presence of different ophthalmic viscoelastic devices (OVDs) in the anterior chamber. Fresh porcine eyes (n = 96) underwent LDV Z8-assisted anterior capsulotomy, either in the presence of an OVD (Viscoat, Provisc, Healon, Healon GV or HPMC) or without, using 90% and 150% energies respectively. Following that, the capsule circularity, tag’s arc-length, tag-length, tag-area and rupture strength (mN) of the residual capsular bag were evaluated. We found that increasing energy from 90 to 150% across the OVD sub-groups improved the studied capsulotomy parameters. Amongst the 90% energy sub-groups, the circularity and tag-parameters were worse with Viscoat and Healon GV, which have higher refractive index and viscosity compared to the aqueous humour. Using 150% energy, Healon GV showed a significantly worse total arc-length (p = 0.01), total tag-length (p = 0.03) and total tag-area (p = 0.05) compared to the control group. We concluded that; an OVD with a refractive index similar to aqueous humour and lower viscosity, such as Healon or Provisc, as well as a higher energy setting, are recommended, to enhance the efficacy of laser capsulotomy.

Real-Time Surgical Problem Detection and Instrument Tracking in Cataract Surgery

Surgical skill levels of young ophthalmologists tend to be instinctively judged by ophthalmologists in practice, and hence a stable evaluation is not always made for a single ophthalmologist. Although it has been said that standardizing skill levels presents difficulty as surgical methods vary greatly, approaches based on machine learning seem to be promising for this objective. In this study, we propose a method for displaying the information necessary to quantify the surgical techniques of cataract surgery in real-time. The proposed method consists of two steps. First, we use InceptionV3, an image classification network, to extract important surgical phases and to detect surgical problems. Next, one of the segmentation networks, scSE-FC-DenseNet, is used to detect the cornea and the tip of the surgical instrument and the incisional site in the continuous curvilinear capsulorrhexis, a particularly important phase in cataract surgery. The first and second steps are evaluated in terms of the area under curve (i.e., AUC) of the figure of the true positive rate versus (1-false positive rate) and the intersection over union (i.e., IoU) obtained by the ground truth and prediction associated with the region of interest. As a result, in the first step, the network was able to detect surgical problems with an AUC of 0.97. In the second step, the detection rate of the cornea was 99.7% when the IoU was 0.8 or more, and the detection rates of the tips of the forceps and the incisional site were 86.9% and 94.9% when the IoU was 0.1 or more, respectively. It was thus expected that the proposed method is one of the basic techniques to achieve the standardization of surgical skill levels.

Semiautomated optical coherence tomography-guided robotic surgery for porcine lens removal

PURPOSE

To evaluate semiautomated surgical lens extraction procedures using the optical coherence tomography (OCT)-integrated Intraocular Robotic Interventional Surgical System.

SETTING

Stein Eye Institute and Department of Mechanical and Aerospace Engineering, University of California, Los Angeles, USA.

DESIGN

Experimental study.

METHODS

Semiautomated lens extraction was performed on postmortem pig eyes using a robotic platform integrated with an OCT imaging system. Lens extraction was performed using a series of automated steps including robot-to-eye alignment, irrigation/aspiration (I/A) handpiece insertion, anatomic modeling, surgical path planning, and I/A handpiece navigation. Intraoperative surgical supervision and human intervention were enabled by real-time OCT image feedback to the surgeon via a graphical user interface. Manual preparation of the pig-eye models, including the corneal incision and capsulorhexis, was performed by a trained cataract surgeon before the semiautomated lens extraction procedures. A scoring system was used to assess surgical complications in a postoperative evaluation.

RESULTS

Complete lens extraction was achieved in 25 of 30 eyes. In the remaining 5 eyes, small lens pieces (≤1.0 mm³) were detected near the lens equator, where transpupillary OCT could not image. No posterior capsule rupture or corneal leakage occurred. The mean surgical duration was 277 seconds ± 42 (SD). Based on a 3-point scale (0 = no damage), damage to the iris was 0.33 ± 0.20, damage to the cornea was 1.47 ± 0.20 (due to tissue dehydration), and stress at the incision was 0.97 ± 0.11.

CONCLUSIONS

No posterior capsule rupture was reported. Complete lens removal was achieved in 25 trials without significant surgical complications. Refinements to the procedures are required before fully automated lens extraction can be realized.

Outcomes of resident-performed laser-assisted vs traditional phacoemulsification

PURPOSE

To compare the effectiveness of femtosecond laser-assisted cataract surgery (FLACS) and conventional phacoemulsification cataract surgery (CPS) by resident surgeons.

SETTING

Parkland Memorial Health and Hospital System, Dallas, Texas, USA.

DESIGN

Prospective randomized study.

METHODS

All surgeries to be performed by postgraduate year 3 and year 4 residents from October 2015 through June 2017 were eligible for inclusion. Patients were required to complete postoperative day 1, week 1, month 1, and month 3 visits. Specular microscopy was performed preoperatively and postoperatively. Surgeries were filmed, and each step was timed and compared. Surgeon and patient surveys were filled out postoperatively.

RESULTS

Of the 135 eyes of 96 subjects enrolled in the study, 64 eyes received FLACS and 71 eyes received CPS. There was no significant difference in corrected distance visual acuity (CDVA), either preoperatively or at the postoperative day 1, week 1, month 1, or month 3 visits (P = .469, .539, .701, .777, and .777, respectively). Cumulated dissipated energy and irrigation fluid usage were not different between FLACS and CPS (P = .521 and .368, respectively), nor was there a difference in the reduction of endothelial cell counts postoperatively (P = .881). Wound creation (P = .014), cortical cleanup (P = .009), and IOL implantation (P = .031) were faster in the CPS group. Survey results indicated that the overall patient experience was similar for FLACS and CPS.

CONCLUSIONS

This first prospective randomized trial evaluating resident-performed FLACS shows that, in resident hands, FLACS provides similar results to CPS regarding visual acuity, endothelial cell loss, operative time, patient satisfaction, and surgical complication rate.

Outcomes of toric intraocular lens implantation after femtosecond laser and traditional cataract surgery

CLINICAL RELEVANCE

Having an understanding of the refractive outcomes of different forms of cataract surgery will assist optometrists in explaining the implication of such procedures to patients being referred for such procedures.

BACKGROUND

The purpose of this study was to compare the refractive outcomes after toric intraocular lens implantation between femtosecond laser-assisted cataract surgery and traditional phacoemulsification.

METHODS

This retrospective non-randomised case series included 114 eyes of 92 consecutive patients (59 male and 55 female) aged 71.65 ± 10.46-years (range 57 to 92-years), who underwent either femtosecond laser-assisted cataract surgery (using two laser platforms) (group 1) or traditional phacoemulsification (group 2) between August 2013 and September 2015. Pre-operative keratometric values, the attempted refraction from the biometry platform and the toric intraocular lens web-based calculator, and the one month post-operative manifest refraction were assessed to evaluate the refractive outcomes of the two groups.

RESULTS

Mean pre-operative topographic corneal astigmatism was -1.94 ± 0.73 D (range 0.91 to 4.61 D) and -1.98 ± 0.60 D (range 1.07 to 3.43 D) for groups 1 and 2, respectively (p > 0.05). Mean axial length was 24.22 ± 0.73-mm (range 21.78 to 29.30-mm) and 24.60 ± 1.09-mm (range 21.82 to 25.95-mm) for groups 1 and 2, respectively (p > 0.05). Multivariate vector analysis of the remaining refractive error between the two groups (desired refraction minus achieved refraction) revealed no statistically significant difference (p > 0.05). Analysis within each group demonstrated a higher accuracy of refractive outcomes for the femtosecond laser-assisted cataract surgery eyes (p < 0.05) when compared to the traditional phacoemulsification (p > 0.05).

CONCLUSION

Femtosecond laser-assisted cataract surgery and traditional phacoemulsification demonstrate similar refractive outcomes after toric intraocular lens implantation, while femtosecond laser-assisted cataract surgery seems to provide a slightly higher accuracy.

Stability of a non-applanating handheld liquid patient interface for femtosecond laser-assisted cataract surgery

PURPOSE

A stable and reliable vacuum is crucial for the correct planning and performance of femtosecond laser-assisted cataract surgery (FLACS) in order to avoid complications such as suction loss and cyclorotation. This study investigates, for the first time, the impact of different vacuum levels on the stability of the application of a liquid patient interface for FLACS in view of break-away forces.

METHODS

Break-away forces were measured using a multifunctional material testing machine with a mounted digital manometer. Sixteen porcine eyes were docked to the patient interface of a femtosecond laser platform (FEMTO LDV Z8), and the impact of different vacuum levels between 300 and 500 mbar investigated.

RESULTS

Mean break-away forces for each vacuum level were as follows: 1.78 N (± 0.58 N) for 300 mbar; 2.24 N (± 0.68 N) for 350 mbar; 2.66 N (± 0.68 N) for 400 mbar; 2.86 N (± 0.77 N) for 420 mbar; and 3.49 N (± 0.86 N) for 500 mbar.

CONCLUSION

The stability increases with the vacuum in a nearly linear manner. Vacuum levels higher than 500 mmHg and lower than 350 mmHg are not recommended for FLACS.

Ocular Disease Therapeutics: Design and Delivery of Drugs for Diseases of the Eye

The ocular drug discovery field has evidenced significant advancement in the past decade. The FDA approvals of Rhopressa, Vyzulta, and Roclatan for glaucoma, Brolucizumab for wet age-related macular degeneration (wet AMD), Luxturna for retinitis pigmentosa, Dextenza (0.4 mg dexamethasone intracanalicular insert) for ocular inflammation, ReSure sealant to seal corneal incisions, and Lifitegrast for dry eye represent some of the major developments in the field of ocular therapeutics. A literature survey also indicates that gene therapy, stem cell therapy, and target discovery through genomic research represent significant promise as potential strategies to achieve tissue repair or regeneration and to attain therapeutic benefits in ocular diseases. Overall, the emergence of new technologies coupled with first-in-class entries in ophthalmology are highly anticipated to restructure and boost the future trends in the field of ophthalmic drug discovery. This perspective focuses on various aspects of ocular drug discovery and the recent advances therein. Recent medicinal chemistry campaigns along with a brief overview of the structure-activity relationships of the diverse chemical classes and developments in ocular drug delivery (ODD) are presented.

Comparison of real-world treatment outcomes of femtosecond laser-assisted cataract surgery and phacoemulsification cataract surgery: A retrospective, observational study from an outpatient clinic in France

PURPOSE

This study compared real-world safety and efficacy outcomes of cataract surgery performed with LenSx femtosecond laser-assisted cataract surgery or manual phacoemulsification cataract surgery procedures.

METHODS

A retrospective observational study used data from anonymised electronic medical records to compare mean cumulative dissipated energy, the proportion of eyes reaching emmetropia, mean change in best-corrected distance visual acuity and the proportion of eyes with post-surgical complications, including corneal oedema and posterior capsule opacification. Results were adjusted for multiple comparisons for primary and secondary objectives.

RESULTS

Data from 811 phacoemulsification cataract surgery and 496 femtosecond laser-assisted cataract surgery procedures were analysed. Mean cumulative dissipated energy was significantly lower for femtosecond laser-assisted cataract surgery (6.5 percent-seconds) than for phacoemulsification cataract surgery (14.3 percent-seconds; p < 0.0001) procedures. More femtosecond laser-assisted cataract surgery (81.2%) procedures achieved emmetropia (⩽ 0.5 dioptre) than did phacoemulsification cataract surgery (73.5%) procedures, although this difference was not statistically significant. Mean change in best-corrected distance visual acuity and the proportion of eyes with corneal oedema, posterior capsule opacification or other complications were not significantly different between cohorts when adjusted for multiple comparisons.

CONCLUSIONS

In this single-centre, single-surgeon retrospective electronic medical record database study using divide and conquer technique, femtosecond laser-assisted cataract surgery was associated with significantly lower cumulative dissipated energy when compared to manual phacoemulsification cataract surgery. This supports the hypothesis that femtosecond laser-assisted cataract surgery involves less mechanical trauma, which might lead to more consistent refractive and safety outcomes than manual phacoemulsification cataract surgery, though such outcomes were found to be comparable in this study.

Myricetin Prevents Cataract Formation by Inhibiting the Apoptotic Cell Death Mediated Cataractogenesis

Background

The current research work aimed to explore the protective role of myricetin against cataractogenesis in humans, in terms of its anti-apoptotic potential.

Material/Methods

Human eye lens epithelial cells were exposed to oxidative stress by treating with hydrogen peroxide (H₂O₂). The levels of superoxide dismutase (SOD), catalase (CAT), and glutathione (GSH) were determined using standard detection kits. DAPI (4′,6-diamidino-2-phenylindole), AO/EB (acridine orange/ethidium bromide) and Annexin V/propidium iodide (PI) staining assays were used for the assessment of cell apoptosis. Western blotting was used to examine the protein concentrations.

Results

The exposure of human epithelial eye lens cells to H₂O₂ led to significant accumulation of reactive oxygen species molecules. Treatment of the H₂O₂-stressed epithelial cells with myricetin caused significant (P<0.05) increased levels of SOD, CAT, and GSH. Western blot analysis also showed a significant (P<0.05) increase in the expression of SOD, CAT, and GSH levels in human epithelial eye lens cells. Additionally, myricetin administration to H₂O₂-treated epithelial eye lens cells caused a significant decline in cell apoptosis ratio. The induction of apoptosis was associated with upregulation of Bax and downregulation of Bcl-2.

Conclusions

The results of this study showed the potential of myricetin in protecting the apoptosis driven cataract formation in humans.

CARS-imaging guidance for fs-laser ablation precision surgery

Due to ageing populations the number of tumors is increasing worldwide. Successful surgical treatment requires complete resection of tumors to reduce recurrence rates. To reach this goal, novel methods combining in vivo tumor and tumor margin detection with low invasive precision surgical tools are needed. Coherent anti-Stokes Raman scattering (CARS) imaging is a highly promising optical tool for visualizing tumors based on characteristic changes in tissue morphology and molecular composition, while fs-laser ablation is to date the most precise surgical tool established in ophthalmology. In this contribution, CARS imaging has been combined with fs-laser ablation as a new approach for image-guided precision surgery for the first time. CARS guided fs-ablation has been applied to ablate brain, liver, skin, muscular and vascular tissues with μm-precision using sub-100 fs pulses of μJ level. We demonstrate superior imaging performance and contrast as well as detection of tissue margins by coherent Raman microscopy in comparison to laser reflectance imaging. The combination of CARS-image-guided tissue ablation is a promising tool for minimally invasive surgeries particularly in the vicinity of functional structures in the future.

Outcomes of Cataract Surgery Complicated by Retained Lens Fragments Requiring Pars Plana Vitrectomy

Objective

To analyze outcomes and complications related to cataract surgery complicated by retained lens fragment (RLF) requiring pars plana vitrectomy (PPV) in a county hospital where procedures are performed by trainees.

Methods

Retrospective study of consecutive patients who met inclusion criteria and underwent PPV for RLF in the vitreous cavity at an urban teaching hospital between January 2010 and January 2016 (N=20).

Main Outcomes/Measures

Visual acuity was recorded pre- and post-operatively over a follow-up period of 3 to 12 months. Complications and patient factors contributing to outcomes were assessed using paired and unpaired t-tests and multiple linear regression.

Results

The average rate of cataract surgery with RLF requiring PPV was 0.75%. Twenty patients met inclusion criteria. Mean pre-operative visual acuity (VA) was logMAR 1.7 (Snellen 20/1000). Nearly half (8/20) had nuclear cataracts grade 3+ or higher. The majority (14/20) had factors predisposing them to cataract surgery complications. Most patients underwent PPV within 1 week (median 6.5 days). At 12-month follow-up, significant (p=0.001) visual acuity (VA) improvement from initial VA was observed, with final mean logMAR 0.6 (± 0.75; Snellen 20/80) and median logMAR 0.35 (Snellen 20/45). Nearly half of the patients had a final Snellen VA ≥20/40. Factors associated with less VA improvement were older age and greater proportion of lens dropped (p<0.01). Complications following PPV included hypotony (5 patients), corneal edema (4), elevated intraocular pressure (IOP) (3), and cystoid macular edema (3).

Conclusions/Relevance

Despite patients with advanced pathology and trainee surgeons, rates of cataract surgery-associated RLF requiring PPV at a large tertiary care teaching hospital are similar to reported rates in the literature.

Topical Bromfenac Sodium in Femtosecond Laser-Assisted Cataract Surgery

PURPOSE

To evaluate the effect of preoperative 0.09% bromfenac ophthalmic solution for the reduction of intraoperative miosis and pain in patients who have undergone femtosecond laser-assisted cataract surgery.

METHODS

This prospective randomized clinical study included 65 patients with senile cataracts in the absence of significant ocular comorbidity. The patients received 0.09% bromfenac ophthalmic solution or control placebo twice a day for 3 days before surgery. Pupil diameter was measured at the initiation and finalization of femtosecond laser-assisted cataract surgery, and pain quantification was assessed by an analogous pain scale after one day of follow-up.

RESULTS

A total of 65 patients were randomly divided into two groups. Five patients were excluded due to defective coupling with the laser interface. Each of the 60 patients was randomized to receive preoperative topical treatment with either 0.09% bromfenac or 0.1% sodium hyaluronate. Baseline characteristics were similar between groups for age and gender. The mean change in horizontal and vertical pupil diameter from the preoperative to post-femtosecond laser measurements were significantly less in the bromfenac group than in the placebo group (0.43 ± 0.6 vs. 1.71 ± 0.9, P < 0.001 and 0.40 ± 0.6 vs. 1.78 ± 0.9, P < 0.001, respectively). Compared with untreated patients, the quantification of pain one day after the procedure was significantly lower in the 0.09% bromfenac group (46.7% with a score of 3 vs. 50% with a score of 1, P < 0.001, respectively).

CONCLUSIONS

The maintenance of pupil dilation and the prevention of miosis were more effective in the 0.09% bromfenac group than in the control group. Likewise, the greater control of postoperative pain represented an additional significant benefit.

The Evaluation of Laser Application in Surgery: A Review Article

There are several types of surgeries which use lasers in the operating room. Surgeons use lasers in general surgery or surgical specialties to cut, coagulate, and remove tissue. In modern medicine, the application of laser therapy is an attractive subject due to its minimal invasive effect. Today lasers are widely used in the treatment and diagnosis of many diseases such as various cancers, lithotripsy, ophthalmology, as well as dermatology and beauty procedures. Depending on the type of lasers, the wavelength and the delivery system, most lasers have replaced conventional surgical instruments for better wound healing results. Over time, by using many different tools and devices, new lasers have been created; as a result, they are used in a wide range of medical special cases. In this review, laser applications in surgery and its beneficial effects compared to previous surgeries with the aim of providing appropriate therapeutic and non-invasive solutions with minimal side effects after surgery are investigated.

Preoperative intraocular pressure as a strong predictive factor for intraocular pressure rise during vacuum application in femtosecond laser-assisted cataract surgery

PURPOSE

To evaluate the effect of preoperative intraocular pressure (IOP) and the vacuum level on IOP during femtosecond laser-assisted cataract surgery.

METHODS

Intraocular pressure was measured in 40 enucleated porcine eyes by intracameral manometry prior, during and after vacuum application using the VICTUS femtosecond laser platform (Bausch&Lomb, Technolas Perfect Vision GmbH, Germany). Twenty combinations of different preoperative IOP levels (12, 16, 20 and 24 mmHg) and different vacuum levels (350-550 mbar) were investigated.

RESULTS

Multivariate regression analysis indicated that both the vacuum level (beta = 0.138; p < 0.001) but much stronger the preoperative IOP (beta = 0.861; p < 0.001) were predictive factors for IOP rise during vacuum application. Mean IOP was 28.23 ± 3.86, 34.23 ± 3.92, 40.35 ± 4.41 and 46.82 ± 4.11 mmHg in groups with baseline IOP of 12, 16, 20 and 24 mmHg, respectively. In the 350, 450 and 550 mbar group, and mean IOP was 35.85 ± 7.85, 37.33 ± 7.90 and 39.00 ± 8.04 mmHg, respectively. Lowering the preoperative IOP by 2 mmHg and reducing the vacuum from maximum to minimum resulted in a similar reduction in IOP during vacuum application (-3.10 ± 0.79 mmHg versus -3.15 ± 0.88 mmHg; p = 0.015). Furthermore, decreasing the baseline IOP from 20 to 12 mmHg resulted in a 30.0% reduction in intraoperative IOP.

CONCLUSION

Preoperative IOP was a stronger predictive factor for intraoperative IOP rise than the applied vacuum level. Measurements and critical interpretation of preoperative IOP in a preliminary examination could help estimating the individual risk of significant IOP rise during femtosecond laser-assisted cataract surgery and could help taking early countermeasures in selected cases. Due to the porcine ex vivo model, further studies are needed to verify these findings.

Femtosecond laser-assisted cataract surgery in a spherophakic lens: An unusual case report

RATIONALE

Spherophakia is a rare diagnosis which is often associated with a shallow anterior chamber, angle-closure glaucoma, lens subluxation, and lenticular myopia. When cataracts occur with subluxation of the lens, vision is often markedly affected. This often presents surgeons with a unique challenge of maintaining good visual outcomes while minimizing potential complications.

PATIENT CONCERNS

A 48-year-old female was referred for ophthalmological assessment due to decreased vision in the left eye. In the left eye, the best-corrected visual acuity at distance was 20/125 with manifest refraction of -6.5D + (-0.75) D × 118°. The slit lamp examination showed iridodonesis and a significant nuclear cataract (C3N3) with tremor in the left eye. After pupil dilation, a subluxated lens, weak zonules, and "fake golden ring" within the lens was noted.

DIAGNOSIS

Due to the patient's symptoms, examination results, she was diagnosed with cataract, subluxation of the lens and spherophakia in left eye.

INTERVENTIONS

The patient underwent an uneventful femtosecond laser-assisted cataract surgery (Alcon Fort Worth, TX). The laser was able to perform a circular free-floating anterior capsulotomy and easy lens fragmentation.

OUTCOMES

There were no postoperative complications. At 3 months postoperatively, the uncorrected visual acuity was 20/25, and the manifest refraction was -0.25 D - 0.75 D × 148° with the corrected distance visual acuity of 20/16.

LESSONS

Femtosecond laser-assisted cataract surgery is an effective approach for cataract surgery in patients with subluxated and spherophakic lenses, with the benefits of causing minimal further zonular damage and easy lens fragmentation.

Challenges during femtosecond laser assisted cataract surgery with posterior chamber phakic intraocular lens

Femtosecond laser-assisted cataract surgery was performed in a patient with high myopia, who had undergone posterior chamber phakic intraocular lens surgery (Implantable Collamer Lens, ICL). During docking the machine erroneously focused the laser on the anterior surface of ICL and laser for lens fragmentation was also defocused, which were correctly positioned before laser delivery. During laser application for capsulotomy, air bubbles were entrapped under the ICL prohibiting lens fragmentation. One must be careful during focusing the laser in eyes with ICL. Additionally, gas bubbles under the ICL may lead to difficulties in completion of nuclear disassembly.

Femtosecond laser induced step-like structures inside transparent hydrogel due to laser induced threshold reduction

In the area of laser material processing, versatile applications for cutting glasses and transparent polymers exist. However, parasitic effects such as the creation of step-like structures appear when laser cutting inside a transparent material. To date, these structures were only described empirically. This work establishes the physical and chemical mechanisms behind the observed effects and describes the influence of process and material parameters onto the creation of step-like structures in hydrogel, Dihydroxyethylmethacrylat (HEMA). By focusing laser pulses in HEMA, reduced pulse separation distance below 50 nm and rise in pulse energy enhances the creation of unintended step-like structures. Spatial resolved Raman-spectroscopy was used to measure the laser induced chemical modification, which results into a reduced breakdown threshold. The reduction in threshold influences the position of optical breakdown for the succeeding laser pulses and consequently leads to the step-like structures. Additionally, the experimental findings were supplemented with numerical simulations of the influence of reduced damage threshold onto the position of optical breakdown.

In summary, chemical material change was defined as cause of the step-like structures. Furthermore, the parameters to avoid these structures were identified.

Presbyopia and the aging eye: Existing refractive approaches and their potential impact on dry eye signs and symptoms

Every part of the human body is subject to aging, including the eye. An increased prevalence of dry eye disease with age is widely acknowledged. Aging threatens ocular surface homeostasis, altering the normal functioning of the lacrimal functional unit and potentially leading to signs and symptoms of dry eye. Additional age-related processes take place within the crystalline lens, leading to presbyopia and cataractogenesis. Correction strategies for presbyopia and cataracts may directly or indirectly challenge the ocular surface. Contact lenses disturb the normal structure of the tear film and can interact negatively with the ocular surface, further deteriorating an already unbalanced tear film in presbyopes, however, newer contact lens designs can overcome some of these issues. Moreover, cataract and corneal refractive surgeries sever corneal nerves and disrupt the corneal epithelium and ocular surface, which can influence surgical outcomes and aggravate dryness symptoms in older age groups. This review summarises the current understanding of how the invasive nature of contact lens wear and cataract and refractive surgery influence signs and symptoms of ocular dryness in an aging population.

Precision pulse capsulotomy in challenging cataract surgery cases

Purpose

To evaluate the use of the precision pulse capsulotomy (PPC) device for challenging cataract surgery cases.

Patients and methods

This single-center retrospective case series study comprised of 43 eyes (from 35 patients) that were challenging cataract surgery cases with poorly dilated pupils, anterior subcapsular opacity, white cataract, brunescent cataract, and corneal opacity. This was  conducted at the Busan Sungmo Eye Hospital (Busan, Republic of Korea) to assess the performance of the PPC device through a 2.2-mm clear corneal incision width, followed by the phacoemulsification technique and intracapsular intraocular lens fixation. The main outcome measurement was the anterior capsulotomy performance of the PPC device and the development of intraoperative complications. At postoperative 2 months, visual acuity, endothelial cell count, and refractive error were measured.

Results

No cases of anterior capsule tears or tags occurred. All 43 eyes received circular, 360-degree, free-floating, and appropriately sized anterior capsulotomies. During 2 months of follow up, no postoperative complications occurred in association with the PPC device.

Conclusion

The PPC device facilitated the creation of a precise, round, appropriately sized anterior capsulotomy in challenging cataract surgery cases. Further investigations are required to understand the long-term safety and efficacy of the PPC device.

The advantages of femtosecond laser-assisted cataract surgery for zonulopathy

Zonulopathy is a major concern if found during cataract surgery as it can cause further complications. Such complications may occur during continuous curvilinear capsulorhexis (CCC), lens fragmentation and intraocular lens (IOL) implantation. Femtosecond laser-assisted cataract surgery (FLACS) devices, such as the LenSX (Alcon Laboratories) are advantageous because they can detect the area and largest point of zonulopathy via anterior segment optical coherent tomography (AS-OCT) before the manual part of the procedure. CCC and lens fragmentation can also minimize further zonular stress. A symmetrical CCC is ideal for IOL implantation in the sulcus with optic capture. In the present study, we did not detect significant zonular dehiscence preoperatively in either of the eyes of our 68-year-old patient when using AS-OCT (CASIA2 Tomey). However, LenSx AS-OCT revealed zonular dehiscence in both eyes, perioperatively. We created CCC and lens fragmentation without causing stress to the zonules. In the subsequent manual part of procedure, we found zonular dehiscence in the same area as indicated by LenSx AS-OCT, which extended to approximately 200° in the right eye and 180° in the left. After lens fragmentation by LenSx, we successfully removed the lens without further zonular dialysis. However, zonular dialysis (>180°) in the right eye was too large to insert an IOL, either in the capsule or the sulcus. Therefore, we performed scleral IOL implantation. In the left eye, we avoided using capsular tension ring (CTR) for IOL placement to avoid further iatrogenic damage to the zonule. Instead, an IOL was inserted into the sulcus with optic capture to reduce the possibility of further stress to the zonula and phimosis. Post-surgically, the patient regained good eyesight in both eyes. This case illustrates the advantages of FLACS in addressing zonulopathy. The consistent creation of CCC and lens fragmentation by FLACS may increase success rates, even in unexpectedly challenging cases.