Precision pulse capsulotomy in phacoemulsification: Clinical experience in Indian eyes

Preventing the Argentinian flag sign and managing anterior capsular tears: A review

The Argentinian flag sign (AFS) is a feared complication during cataract extraction. Intralenticular pressures, especially excessive posterior pressure, have been identified as potential mechanisms for capsular stress and tearing associated with AFS. Capsular tension is created by positive intralenticular pressures, which cause the irido-lens diaphragm to move anteriorly once the manual capsulorhexis has been initiated. This tension can cause inadvertent tears that self-propagate to the lens equator, causing an AFS, among other intraoperative complications. Thus, this review highlights the importance of identifying intumescent cataracts as well as a combination of techniques to relieve intracapsular pressures needed to prevent AFS. However, some instances of anterior capsular tears are unavoidable. Therefore, focus will also be placed on techniques during cataract extraction used to manage anterior capsular tears, mitigating extension to the posterior capsule.

Recent developments in anterior capsulotomy for cataract surgery

PURPOSE OF REVIEW

Successful anterior capsulotomy is an important step in cataract surgery. This article reviews the various anterior capsulotomy techniques available to surgeons to optimize the step, including those that have become available since the introduction of femtosecond-laser-assisted cataract surgery (FLACS). Studies comparing the relative advantages of each technique will be emphasized.

RECENT FINDINGS

Manual continuous curvilinear capsulorhexis (CCC) and FLACS remain the two most widely studied techniques for achieving anterior capsulotomy. Each technique has been shown to be effective for a wide range of patients and cataract surgery complications. Meta-analyses have shown that FLACS provides similar results to manual CCC for long-term cataract surgery outcomes. Several alternative methods for anterior capsulotomy have been described, which aim to provide some of the advantages of laser capsulotomy at a lower cost; among these, precision pulse capsulotomy (PPC) and selective laser capsulotomy (SLC) have been investigated the most in the literature so far.

SUMMARY

Cataract surgeons have an increasing number of techniques for anterior capsulotomy available. Manual CCC and FLACS remain the most widely used, and most well studied. The latest techniques, PPC and SLC, have shown promise in the few studies performed since they were introduced.

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.

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.

Factors Affecting Posterior Capsule Opacification in the Development of Intraocular Lens Materials

Posterior capsule opacification (PCO) is the most common complication arising from the corrective surgery used to treat cataract patients. PCO arises when lens epithelial cells (LEC) residing in the capsular bag post-surgery undergo hyper-proliferation and transdifferentiation into myofibroblasts, migrating from the posterior capsule over the visual axis of the newly implanted intraocular lens (IOL). The developmental pathways underlying PCO are yet to be fully understood and the current literature is contradictory regarding the impact of the recognised risk factors of PCO. The aim of this review is firstly to collate the known biochemical pathways that lead to PCO development, providing an up-to-date chronological overview from surgery to established PCO formation. Secondly, the risk factors of PCO are evaluated, focussing on the impact of IOLs’ properties. Finally, the latest experimental model designs used in PCO research are discussed to demonstrate the ongoing development of clinical PCO models, the efficacy of newly developed IOL technology, and potential therapeutic interventions. This review will contribute to current PCO literature by presenting an updated overview of the known developmental pathways of PCO, an evaluation of the impact of the risk factors underlying its development, and the latest experimental models used to investigate PCO. Furthermore, the review should provide developmental routes for research into the investigation of potential therapeutic interventions and improvements in IOL design in the aid of preventing PCO for new and existing patients.

Early results of circularity and centration of capsulotomy prepared by three different methods

AIM

To compare the difference of capsulotomy produced by precision pulse capsulotomy (PPC), manual (M-CCC), and femtosecond laser assisted capsulotomy (FLAC) in relation to intraocular lens (IOL) centration, circularity and its effect on visual outcomes.

METHODS

Prospective, non-randomized comparative study conducted at LV Prasad Eye Institute, Hyderabad, India. Sixty eyes of 52 patients were grouped into 3 (FLAC, PPC and M-CCC) based on capsulotomy techniques used. Twenty consecutive eyes with uneventful phacoemulsification and with no comorbidities affecting the capsulotomy or visual outcome were included in each group. The main outcome measure was IOL centration in relation to capsulotomy and pupil. Secondary outcome measures were post-operative visual acuity, manifest refraction and aberration profile between groups.

RESULTS

At 5wk the visual, refractive outcomes and endothelial cell density were comparable between the 3 groups. The median circularity index of FLAC was statistically significantly different to M-CCC or PPC (1-10) groups (P<0.01) but PPC (11-20) was comparable to FLAC. Decentration of IOL center in relation to capsulotomy was seen only between the PPC (1-10) group and FLAC group (P=0.02). The IOL was well centered in relation to the pupil in all the groups (P=0.46). The quality of vision parameters like the higher order aberrations, spherical aberration, coma, trefoil, modular transfer function, and Strehl ratio were comparable between the groups.

CONCLUSION

Our study shows that despite differences in the morphology of capsulotomy produced by PPC, M-CCC, FLAC a well-centered IOL can be achieved. The measured capsular morphology parameters do not affect visual outcomes.

Comparison of postoperative axial stability of intraocular lens and capsulotomy parameters between precision pulse capsulotomy and continuous curvilinear capsulotomy: A prospective cohort study

OBJECTIVES

The aim of this study was to verify the safety and stability of precision pulse capsulotomy (PPC) by comparison of the axial stability of the intraocular lens (IOL) and the capsulotomy parameters during 6 months of follow-up after cataract surgery using PPC or the conventional method (continuous curvilinear capsulorhexis, CCC).

DESIGN

Prospective observational study.

SETTING

Tertiary referral center.

SUBJECTS

Fifty nine eyes of 59 candidates for cataract surgery.

INTERVENTIONS

PPC (33 eyes) or CCC (26 eyes).

OUTCOME MEASURES

The anterior capsule opacification grade and effective lens position (ELP) were measured 1 week and 1, 3, and 6 months postoperatively.

RESULTS

No significant difference in the mean anterior capsule opacification grade or the effective lens position was found between the PPC and CCC groups at any time point; however, the standard deviation and root mean square of the effective lens position were significantly lower in the PPC group than in the CCC group during follow-up (P = .002 and P = .011, respectively). There was a significantly lower discrepancy between the intended vs achieved capsulotomy area and better circularity in the PPC group than in the CCC group at all time points.

CONCLUSIONS

The overall variability in effective lens position was less when cataract surgery was performed using PPC than when performed using CCC. Circularity was better and had a more predictable size with PPC than with CCC.

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.

Precision pulse capsulotomy: an automated alternative to manual capsulorhexis in paediatric cataract

Objective

To report our operative experience with precision pulse capsulotomy (PPC) for anterior capsulotomy in a paediatric cataract series.

Methods and analysis

This study is a retrospective interventional, descriptive series of consecutive paediatric eyes (≤16 years) undergoing cataract surgery using PPC. Surgical time and the time required to perform PPC was recorded. Any intraoperative and postoperative adverse events were noted. Postoperatively, visual acuity, anterior segment examination and intraocular pressure (IOP) were recorded for all children at day 1, 1 week and 1 month.

Results

21 eyes of 14 patients were included in the study, with the median age at surgery of 6.0 years (IQR; 5-7.75, range=1–16 years). Male to female ratio was 11:3. 13 eyes had lamellar cataract, 3 eyes had total cataract, 2 had posterior subcapsular cataract, 2 had traumatic cataract, while 1 eye had sutural cataract. Median surgical time was 26 min (IQR 21-32) and median PPC time was 75.0 secs (IQR 56-86.5). The anterior capsulotomy was round and complete in most cases, except in one case due to faulty suction. All patients underwent a successful in the bag implantation of intraocular lens with capsulotomy margins overlapping the optic edges in 19 eyes (90%). Median PPC size was 5.54 mm (n=9, IQR 5.39 -5.75) which was slightly larger than expected. None of the cases had any intraoperative or postoperative adverse events with no radial tears of capsulotomy. Postoperatively, the mean final follow-up was 5.71+3.20 weeks.

Conclusion

To conclude PPC can be used as an alternative to manual continuous curvilinear capsulorhexis in paediatric cataract surgery producing round well- centred and strong capsulotomy with an easier learning curve.

Advances in capsulorhexis

PURPOSE OF REVIEW

Continuous curvilinear manual capsulorhexis is currently the standard of cataract surgery. In the past several years, new technologies have been developed to improve the consistency and safety of capsulorhexis creation. This article reviews the most recent technologies in capsulotomy formation and their advantages and disadvantages.

RECENT FINDINGS

Guidance devices, femtosecond laser capsulotomy and precision pulse capsulotomy improve the centration, circularity and precision of anterior capsulorhexis and capsulotomy. These developments show particular promise for complex cataract surgeries, though clinical data on the refractive outcomes and complication rates of these technologies are currently limited and warrant additional investigation.

SUMMARY

New technological advances in capsulorhexis help surgeons achieve a more ideal capsulotomy geometry. Whether this translates into more predictable refractive outcomes and safer surgeries remains an area of future study.

[Precision pulse capsulotomy : The new capsulorhexis?]

The manual capsulorhexis created by Neuhann is still the standard procedure for opening the anterior capsule for cataract surgery. A limitation is the inaccuracy in the size and placement of the opening due to manual execution. In addition to the femtosecond laser a possible improvement in the standardization of capsulorhexis is provided by the Zepto procedure (precision pulse capsulotomy, PPC). In this case a 5.25 mm rhexis is created in a standardized fashion with a flexible suction adapter in which a nitinol ring is located. Whether the strength of PPC is comparable or better than that of the manual technique and how it behaves in terms of capsule shrinkage has not yet been finally clarified.