Contemporary cataract surgery makes use of a vast array of intraocular lens (IOL) options. For self-contained disposable preloaded IOL delivery systems that are packaged ready-to-use, there is a growing trend of eliminating the surgeon's step of mechanically loading the lens into an injection device intraoperatively. Typically, these newer products require only the introduction of an ophthalmic viscosurgical device before the IOL can be deployed. The resulting potential ease of use and efficiency of the preloaded systems is perhaps the main driver of its burgeoning trend in the past 5 years.
There are several perceived benefits of the preloaded IOL delivery concept. As the IOL is preloaded by the manufacturer for injection, the possibility of user error during loading is largely eliminated, hence theoretically eradicating loading variability1 and risk of damage or contamination of the lens by manual handling.2 Furthermore, the reduction of intraoperative IOL preparation could reduce surgical time,3 implying the potential to increase case throughput. The disposable nature of the devices also obviates the need to sterilize what would otherwise be reusable equipment, thus reducing chances of cross-contamination and incidences of toxic anterior segment syndrome.4
Despite the growing prevalence and the purported advantages of the preloaded delivery system, there is conflicting evidence in the current literature with regard to the predictability or success of IOL delivery into the capsular bag.1,5
Recently, a newer preloaded system has become available in Australia, the Bi-Flex POB-MA 877PA/877PAY (MEDICONTUR, Switzerland) which delivers a folded single-piece aspheric hydrophobic acrylic lens, measuring 13 mm overall with a 6-mm optic, through an incision size of 2.2 mm.6 The design of this preloaded system is distinct from other devices available, involving rotation of a ring adaptor, but there has not been any published data of its use in clinical practice.
The heterogeneity of the limited current literature about preloaded IOL delivery systems has been in part due to variability of IOL used and the main port incision size.1,5 As such, we aimed to obtain real-world data about the delivery characteristics of a single preloaded IOL delivery system, the POB-MA 877PA, and compare its use through different main port incision sizes.
A prospective observational study was performed to examine the IOL delivery characteristics of the POB-MA 877PA during elective phacoemulsification surgery performed by a single experienced ophthalmic surgeon (H.L.) from December 2017 to April 2018. All patients who received a POB-MA 877PA lens injected during phacoemulsification surgery during this time period were included in the study.
The cases were divided into 2 groups based on the incision size. The main port incisions were made using a 3-step wound construction technique. Group 1 had 2.4-mm main port incisions, whereas group 2 had 2.75-mm main port incisions. The groups were allocated based on location of surgery (2.4 mm at Dubbo Base Hospital and Dubbo Private Hospital, and 2.75 mm at Mudgee District Hospital and Orange Eye Centre in New South Wales, Australia). Otherwise, the surgical set-ups were identical, with the same instruments and equipment based around the Alcon INFINITI Vision System (Alcon Surgical Inc, US). All theaters were temperature controlled, and ambient temperature was recorded within a similar range of 20°C to 21°C during the study period.
The preloaded IOL delivery units were injected with the recommended ophthalmic viscosurgical device of hydroxypropyl methylcellulose, followed by rotation and removal of a ring adaptor, and prepared as per manufacturer instructions by a trained nurse or surgical assistant. The surgeon then depressed the plunger which then introduced the IOL through the flanged tip nozzle into the capsular bag. Intraocular lens delivery characteristics were observed and recorded by the authors intraoperatively. The main outcome was IOL delivery using the preloaded injector, with optic and both haptics positioned in the capsular bag using the device without additional manipulation. The proportion of cases that required secondary manipulation was recorded, and any other variances of delivery issues were defined as “minor” if immediately rectifiable without replacement of the device, or “major” if resulted in IOL or anatomical damage or required replacement with a new device.
Statistical analysis was carried out using GraphPad (GraphPad Software, US). Differences between the 2 groups were assessed for statistical significance using Fisher exact test. This study was conducted in accordance with the principles outlined in the Declaration of Helsinki.
A total of 110 patients were analyzed, and their demographic data are shown in Table 1. In group 1 (2.4-mm incision), 32 cases (54.2%) were recorded as having satisfactorily completed IOL delivery, and 24 (40.7%) required the introduction of a secondary instrument for adequate IOL positioning, due to the trailing haptic not being able to be directed into the capsular bag using the injector alone (Figs. 1, 2). Two cases experienced minor issues, and 3 cases had major issues. Recorded minor issues included 1 case of misdirected leading haptic with flipped orientation requiring intrawound rotation, and 1 case of haptic-optic adhesion that routine maneuver failed to dislodge, requiring use of a secondary instrument to directly separate and unfold the lens in its entirety. The 3 cases involving major issues included: 1 case of plunger obstruction requiring complete replacement; 1 case of IOL trauma during delivery that resulted in a defect at the haptic-optic junction, which was not considered visually significant and the IOL was not exchanged; and 1 case where a complication resulted from secondary manipulation of a tightly entrapped trailing haptic, with the distal haptic and optic already in the bag, leading to 2 clock-hours of zonular dehiscence. This case did not have any additional risk factors for zonular weakness, such as pseudoexfoliation syndrome.
In group 2 (2.75-mm incision), 40 cases (78.4%) achieved satisfactory complete IOL delivery, and 8 cases (15.7%) required the use of a secondary instrument for successful IOL positioning, due to the injector complex being unable to introduce the trailing haptic into the capsular bag without assistance. There was 1 case with a minor issue (misdirected leading haptic requiring intrawound rotation), and 3 cases with major issues. The 3 cases with major issues consisted of 2 cases of plunger obstruction requiring replacement, and 1 case of entrapped trailing haptic that the introducer alone was unable to release, requiring secondary manipulation that induced a small defect in the continuous curvilinear capsulorhexis.
Group 2 (2.75-mm incision) had a significantly lower proportion of cases that required secondary manipulation of the IOL compared with group 1 (2.4-mm incision), 15.7% versus 40.7%, P < 0.05 (Table 2). The majority of major issues that fit the inclusion criteria appeared to occur during the preparation stage before insertion into the main port incision, and thus these were not compared between the groups. There were no other major complications recorded during the study period.
The results of this study demonstrate that the incision size has a significant impact on the successful delivery of the preloaded POB-MA 877PA IOL into the capsular bag. Compared with a 2.75-mm incision size, the use of 2.4-mm incision size was associated with a significantly higher failure rate of the injector to achieve delivery lens optic and both haptics, requiring further manipulation with a secondary instrument.
The majority of cases that required secondary manipulation in the present study did not result in adverse outcome, but added an extra surgical step. However, additional manipulation of the IOL is a recognized hazard due to the increased risk of damage to the IOL or to ocular structures such as the capsular bag.1 This was highlighted in the 2 cases where compromise to the capsule was induced due to secondary manipulation necessary to release tightly entrapped trailing haptics that the plunger alone was unable to introduce.
The design of the POB-MA 877PA system, which includes a ring adaptor and a flanged plunger tip, is likely responsible for its delivery characteristics. Our impression is that the flanged introducer results in deposition of the trailing haptic very close to the nozzle tip, which implies smaller incisions that may suit “wound-assisted” injection requiring secondary manipulation to successfully dial the IOL fully into the capsular bag.
The manufacturer recommends that the POB-MA 877PA is suitable for use through main port incisions as small as 2.2 mm. With the overall trend of cataract surgery being performed with progressively smaller incisions, it is perhaps worth noting that the system performed optimally through the slightly larger main port incision in our study (2.75 mm).
Nevertheless, even through the optimal 2.75-mm incision, the POB-MA 877PA was associated with a 21.6% (11 of 51 patients) of abnormal delivery behavior. Furthermore, there were 3 cases (2.7%) of failure of the preloaded POB-MA 877PA delivery system that necessitated replacement in all patients.
In this study, although the groups were similar in age, nucleus density and IOL power, there was a higher proportion of females in group 1 than in group 2. Such disparity, however, appears unlikely to have confounded the results as males are associated with a higher risk in cataract surgery.7
In a rapidly growing market of preloaded IOL options, the POB-MA 877PA is a device that has its own advantages and disadvantages. To our knowledge, this study was the first to examine its intraoperative performance in clinical practice. We found that compared with a 2.4-mm main point incision, the delivery characteristics were different through a 2.75-mm main port incision based on its lower proportion of cases that required secondary manipulation. Nonetheless, despite an optimal 2.75-mm main incision, the preloaded POB-MA 877PA system may still exhibit variances in intraoperative delivery. This study also illustrates that abnormal delivery behavior requiring additional manipulation may cause damage to the lens or intraocular structures.
The authors would like to acknowledge Dr Chee-Fong Chong for his assistance in editing the manuscript.
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