Authors: Stephen A LoBue, Allison E Rizzuti, Curtis R Martin, Sinan A Albear, Ekjyot S Gill, Christopher L Shelby, Wyche T Coleman, Edward F Smith
Categories: Review Article, Anterior capsular tears, Argentinian flag sign, intumescent cataract, surgical techniques
Source: Indian Journal of Ophthalmology
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.
Keywords: Anterior capsular tears, Argentinian flag sign, intumescent cataract, surgical techniques
The Argentinian flag sign (AFS) is a complication that can occur during cataract surgery in the setting of intumescent cataracts. As trypan blue dye is routinely used to better visualize the capsule of white cataracts, the expansion of two anterior capsular tears results in a blue-white-blue appearance that is reminiscent of the national flag of Argentina [Fig. 1].
Propagation of tears can lead to posterior capsule rupture, vitreous loss, and a dropped nucleus.[1] This study aims to review the literature on AFS, describing the epidemiology, risk factors, and pathophysiology, as well as present evidence for surgical techniques used to prevent AFS.
A literature search was done on PubMed, Google Scholar, EMBASE, Cochrane Library, MEDLINE, and PubMed Central up to May 2023 by using MESH terms such as “intumescent cataract,” with variable combinations of terms such as “anterior capsular tears,” “capsular runout,” “Argentinian flag sign,” “surgical technique,” “complications,” “posterior capsular tear,” “posterior capsule rupture,” “and “vitreous loss” with interposition of Boolean operators “AND” and “OR.” Only articles written in English were reviewed and collected for analysis. Articles were assessed for various techniques used for preventing capsular tearing during intumescent cataract extraction.
White cataracts are most often associated with AFS. Utilizing ultrasound, white cataracts have been categorized into three intumescent with liquified cortex (type 1), voluminous nuclei with little amount of solid cortex (type 2), and fibrosed anterior capsule with solid cortex (type 3).[2] Among these types of white cataracts, intumescence cataracts (type 1) are the most common risk factor for AFS, ranging from 3.85% to 28.3%.[1,3,4]
Anterior-segment optical coherence tomography (AS-OCT) is another documented technique to preoperatively classify high-risk, intumescent cataracts.[5] AS-OCT can be used to determine the presence of subcapsular fluid in intumescent cataracts, improving preoperative planning.[5]
More recently, intraoperative optical coherence tomography (iOCT) has been used to further classify the spectrum of white, intumescent cataracts into four regularly arranged lamellar cortical fibers (iOCT-type 1), hyperreflective bands of cortical fibers with intralenticular clefts (iOCT-type 2), intralenticular clefts combined with areas of homogenous ground-glass appearance (iOCT-type 3), and homogenous ground-glass appearance of the anterior lens cortex (iOCT-type 4).[6] Among these varying iOCT criteria, type 2 is associated with the highest risk of capsulorhexis extension secondary to raised intralenticular pressure.[6]
Intumescent cataracts are advanced cataracts that result from swelling and congestion of the crystalline lens due to degeneration of lens protein. Intumescent cataracts may be caused by cataract maturity or traumatic eye injury.[7] On slit-lamp examination, they appear opaque and visually swollen with prominent sectoral markings within the anterior cortex [Fig. 2].
Figure 2 (a–c) An intraoperative image demonstrating swollen, intumescent cataracts with prominent sectoral markings within the anterior cortex
Liquification of the lens cortex in an intumescent cataract causes a build-up of fluid in the anterior and posterior subcapsular spaces, resulting in increased intralenticular pressure. This increased intralenticular pressure is thought to contribute to the capsular stress and tearing seen during AFS. When the anterior capsule is punctured to create the capsulotomy, the anterior subcapsular space is depressurized, and the cataract is displaced anteriorly by pressure within the posterior subcapsular space. Anterior movement of the cataract exerts stress on the anterior lens capsule, resulting in the propagation of capsular tears. If there is total liquefaction of the lens nucleus, as seen in Morgagnian cataracts, only one pressurized compartment exists and the incidence of capsular tears is reduced.[8]
Posterior pressure on the lens capsule from Valsalva can also be problematic intraoperatively.[9] Comorbid conditions such as COPD and chronic bronchitis may lead to Valsalva, but intermittent coughing or bearing down due to perceived pain intraoperatively can also lead to increased posterior pressure. Increased posterior pressure from Valsalva may lead to complications during cataract extraction associated with anterior movement of the capsular bag.[9] In our experience, increased posterior pressure on the lens capsule may also be seen in patients with significant hyperopia or anterior chamber depths <2 mm in the setting of a mature cataract.
Some authors have also hypothesized that trypan blue staining in diabetic patients can lead to a more stiff and brittle anterior capsule, increasing the risk of anterior capsular tears.[10,11,12] Congenital aniridia also alters capsule thickness and may confer greater capsular tear risk.[13,14]
Prevention is key when operating on patients who are at risk for AFS. Thus, there are several techniques a surgeon can utilize to counteract anterior and posterior intralenticular pressure associated with AFS. Using a broad literature review, we highlight a wide variety of preoperative and intraoperative techniques.
The use of ophthalmic viscosurgical devices (OVDs), or viscoelastic agents, is the primary step for the prevention of AFS.[1] OVDs create space in the anterior chamber, provide tissue stabilization, and protect the corneal endothelium during phacoemulsification. Specific formulations such as dispersive (Viscoat, Alcon Laboratories, Fort Worth, Texas), cohesive (Healon GV Abbott Medical Optics, AMO, Santa Ana, California), and viscoadaptive OVDs (Healon 5, Johnson & Jonson Vision, Jacksonville, FL) have all been deemed equivalent in safety and efficacy during cataract surgery.[15]
Highly cohesive viscoelastic agents are the most effective in AFS prevention because of their ability to maintain the anterior chamber depth and anterior chamber pressure, which are the most important factors in preventing capsular tears and AFS.[14,16] Without the proper use of viscoelastic during the creation of a capsulorhexis, posterior pressure may cause the anterior movement of the lens nucleus, which subsequently produces a centrifugal force, initiating a capsular tear.[8] The use of highly cohesive OVDs (e.g. Healon GV or Healon 5) flattens the convex anterior surface of the lens, counteracts the intralenticular pressure, and reduces the peripheral extension of the capsulorhexis edge.[17,18]
In a small variation to standard capsulorhexis creation by using a Utrata forceps, a 25- or 23-G microcapsular forceps can be used to create a capsulorhexis.[19] This method maintains a pressurized anterior chamber that would ensure no additional force vectors are created to induce capsular tears.[19]
The soft-shell technique (SST) utilizes a low-viscosity dispersive and high-viscosity cohesive OVD to form an outer and inner shell before capsulorhexis, respectively.[20] The dispersive OVD is injected first to create positive anterior pressure, and the cohesive OVD is injected above the anterior capsule (and under the dispersive OVD) to create space and stabilize tissues in the anterior chamber before initializing the capsulorhexis.[20] A slight modification resulted in the ultimate SST, which uses a balanced salt solution (BSS) or trypan blue as the low-viscosity fluid to be injected under a viscoadaptive OVD, a high-viscosity fluid.[21] The most recent modification to SST (tri-SST) utilizes a dispersive OVD to form the outermost layer, cohesive or viscoadaptive OVD as the second layer, and BSS below as the innermost layer closest to the anterior lens capsule.[22] Although not exclusively studied in relation to capsular tear prevention, the maintenance of anterior chamber pressure in combination with localized OVD injection for preferable intraocular lens (IOL) insertion may prevent uncontrolled radial capsule tearing.
Furthermore, LoBue et al.[23] described utilizing both cohesive and dispersive OVD in intumescent and mature cataracts before manual continuous curvilinear capsulorhexis (CCC). In their study, two types of OVD, along with a pupillary expansile ring, facilitated mydriasis and stabilization of the iris in patients with miosis and intraoperative floppy iris syndrome (IFIS). Sealed paracentesis utilizing cohesive OVD maintained anterior chamber pressure, countering intralenticular pressures and resulting in no anterior capsular tears.
Needle aspiration is an effective method to depressurize the anterior subcapsular space.[24] In this technique, a small-gauge needle is introduced through the initial paracentesis to puncture the anterior capsule and aspirate cortical fluid. In a study by Nabil that compared routine manual capsulorhexis to needle aspiration for intumescent cataracts, 20% of subjects in the routine capsulorhexis group had an anterior capsular tear compared to no tears in the needle aspiration group.[25]
Numerous modifications of the needle aspiration technique have been performed. One study involving 60 eyes of 60 patients with white cataracts underwent needle aspiration via a ~ 1.8-mm main wound. A 30-G needle was inserted through a limbal stab incision and was used to decompress the anterior intralenticular compartments. The posterior intralenticular compartment was then decompressed by tipping the edge of the nucleus posteriorly with the needle tip so that the fluid trapped between the posterior surface of the nucleus flowed anteriorly. An adequately sized and centered CCC was achieved in 100% of the cases with no AFS noted. Of the patients enrolled, 72% were type-1 white cataracts with liquefied cortex.[26]
“Capsule milking” is a technique that begins with needle aspiration but continues with a circular sweep of the anterior lens toward the center of the cataract with an OVD cannula.[27] This method aspirates more liquefied cortex compared to simple needle aspiration in an attempt to further reduce the transmission of intralenticular pressure.
In another variation of needle aspiration, the lens nucleus is rotated to release cortical fluid from the posterior intralenticular compartment. Again, the use of substantial OVD is important to compensate for the loss of intralenticular volume by flattening the anterior capsule and opposing posterior pressure.[28]
A final modification to needle aspiration involves attaching a needle to aspiration tubing from the phacoemulsification instrument set to the cortex mode [Fig. 3].[29] The needle is inserted bevel up to prevent blockage by the anterior capsule, OVD, or epinuclear material, and “rocking the needle” is performed to manipulate the lens position to further depressurize the posterior intralenticular compartment.[29]
Figure 3 (a) Intumescent cataract. (b) A 30-G needle attached to aspiration tubing from the phacoemulsification instrument is used to decompress the capsular bag while rocking the nucleus. (c) A 5.5-mm CCC is performed with liquefied cortex seen in the periphery
Phaco capsulotomy is a technique in which the anterior capsule is punctured using the phacoemulsification tip while aspirating liquefied cortex and nucleus simultaneously.[30,31] Capsular forceps can subsequently be used to complete the capsulorhexis. Phaco capsulotomy maintains the ability to debulk increased cortical and nuclear material, whereas needle aspiration may still leave a pressurized capsule, which can initiate capsular tears [Fig. 4].[32]
Figure 4 (a) An intumescent cataract stained with trypan blue. (b) Needle decompression is performed with a 30-G needle. (c) Dispersive OVD is replenished in the anterior chamber. (d) A cystotome is used to start a CCC. (e) AFS occurs. (f) A cystotome is used to create a can opener capsulorhexis
A randomized case study comparing manual capsulorhexis with phaco capsulotomy exhibited 22 cases of capsular tearing in the manual capsulorhexis group, whereas the experimental group only contained two.[30] Of the 22 eyes with capsular tearing with manual capsulorhexis, posterior capsule rupture also occurred in two procedures.[30] Although effective in preventing radial tears during capsulorhexis, wound burn was noted to occur.[30]
Femtosecond laser-assisted cataract surgery (FLACS) is an automated instrumentation system utilizing intraoperative imaging to produce cleavage planes for corneal incision, capsulotomy, and lens fragmentation.[32,33,34] FLACS was approved for cataract surgery in 2010 by the FDA as it achieves high levels of reproducibility in capsulotomies and overall minimized ultrasound power.[32,33,34] In a meta-analysis of 2941 eyes spanning 11 studies, the precision and overall safety of FLACS in creating consistent circularity and diameter capsulotomies was superior in comparison to manual CCC.[35] Although it has been deemed safe to implement for cataract extraction, the technology retains the risk of incomplete anterior capsulotomy, capsular tags or bridges, capsular tears, miosis, and endothelial damage.[36] Incomplete capsulotomies are more prone to occur in the context of opacities in the cornea or bubbles in the anterior chamber [Fig. 5].
Figure 5 An intraoperative image after FLACS in a patient with conductive keratoplasty (CK). (a) Areas of capsular tags are noted under previous CK scars (black arrows) with 1 clock hour of incomplete capsulotomy (white arrows). (b) A capsulotomy completed using Utrata forceps. (c) A continuous capsulotomy is noted before IOL insertion
A steep learning curve may potentially have a role in the formation of FLACS-associated capsular tears as an analysis of the same surgeons performing 1500 FLACS highlighted that the first 200 cases had a higher incidence of anterior (4% vs. 0.31%) and posterior capsular tears (3.5% vs. 0.31%), as well as greater incidence of posterior lens dislocation (2% vs. 0%) than the last 1300 procedures.[37] To further the idea of a steep learning curve, Roberts et al.[38] analyzed an additional 3355 FLACS cases and had a total incidence of capsular tearing of 0.21% or seven cases. Of those seven, two tears extended to the posterior capsule. Compared to the previous analysis of 1500 cases, authors reinforced the idea of increased experience with FLACS minimized capsular tearing.[38]
As surgeons gained more experience with FLACS, capsulotomies were attempted on more difficult cases, including white and intumescent cataracts, arguably the major surgical challenge in these cases. A prospective study comparing manual CCC to FLACS on 80 patients with white cataracts found no difference in terms of visual outcomes and intraoperative complications.[39] In the FLACS group, free-floating circular capsulotomies were obtained in 52.5%, micro-adhesions in 37.5%, and incomplete capsulotomy in 1–2 clock hours in 10% of patients [Fig. 6]. The incidence of residual adhesions increased with the release of milky cortical fluid (P = 0.003).[39]
Figure 6 (a) FLACS demonstrating a large lens nucleus on imaging. (b-d) A capsulotomy is highlighted with black arrows. (e,f) Complete capsulotomy is seen with the presence of air bubbles. (g) Intumescent cataract with capsular tags with adjacent bubbles after FLACS (white arrows). (h) Increased visibility of capsular tags with trypan staining
Zhu et al.[40] composed a study of 132 eyes comparing either conventional phacoemulsification cataract surgery (CPCS) or FLACS in white cataracts. White cataracts were also graded as type I or type II. Type I had a liquefied cortex, and type II had a solid cortex.[40] Incidence of anterior capsular tears in CPCS and FLACS was 12.1 and 0%, respectively.[40] The peripheralizing tears of the CPCS group were all type-I cataracts with a liquefied cortex. Six FLACS cases developed incomplete capsulotomies, four of which were type-I cases. The incidences of PCRs and vitreous loss were the same between groups. Capsulotomy produced better circularity index and diameter stability than the CCC group. IOLs were better centered in the FLACS group than in the CPCS group. Overall, the authors concluded that FLACS was adequate in preventing AFS.[40]
However, AFS has been documented to occur in FLACS involving a 27-year-old male patient with a type-1 intumescent cataract.[41] This case further highlights the limitations of FLACS in cataracts with significant liquified cortex.
The use of intravenous mannitol has demonstrated efficacy in reducing globe volume and intraocular pressure and maintaining the vitreous and anterior chamber depth with positive pressure.[42,43,44,45] Mannitol is often used in combination with the previously described techniques.[24,27,28]
O’Keeffe et al.[43] reported that anterior chamber depth increased by 0.2–0.4 mm in patients receiving at least 100 mL of a 20% mannitol solution given before cataract surgery. An inverse correlation between IOP and anterior chamber depth was also demonstrated.[43] However, some studies have concluded that mannitol was either shown to have a negative or no effect on anterior chamber depth.[45,46] Nevertheless, mannitol use has postoperative side effects, including thirst, diuresis, headache, and nausea.[44] These side effects may be disadvantageous in patients with specific comorbidities.
Plasma blade technology involves traction-free tissue dissection through the formation of microscopic plasma and cavitation bubbles. Cavitation bubbles cause mechanical tissue dissection, resulting in minimal collateral tissue damage. Successful plasma blade capsulotomy has been performed by two different devices, including the pulsed electron avalanche knife (PEAK-fc, Carl Zeiss Meditec) and the Fugo Plasma Blade (MediSURG Research and Management Corp.)[47,48] Unlike FLACS, capsulotomy is not standardized in size and shape but is rather performed freely, with the surgeon guiding the instrument over the capsule. The technology has shown effectiveness on fibrotic capsules, but little data has been reported on intumescent lenses. As a result, plasma blade capsulotomy requires further testing but has potential, especially in the hands of experienced surgeons.
Precision pulse capsulotomy (PPC), or trade name Zepto (Centricity Vision, Carlsbad, California USA), employs a disposable nitinol ring that delivers a series of electrical pulses to create a circular capsulotomy.[49] Much like FLACS, the capsulotomy size is predetermined and reproducible. Initial studies have demonstrated that PPC is as equally safe as manual CCC and may be superior in preventing capsular tearing.[50] A comparison of manual CCC, FLACS, and PPC capsulotomy edge strength demonstrated that PPC tear strength was greater than that in the other two capsulotomy methods.[51]
Initial surgical experiences with PPC showed no intraoperative complications related to the capsulotomy edge.[52,53,54,55] The PPC device maintains suction to the anterior capsule to create a precise capsulotomy.[52] With this feature, high intralenticular pressures associated with intumescent cataracts are instantaneously relieved due to the swift aspiration of cortical fluid as soon as the capsulotomy is created [Fig. 7].[52] PPC in a pediatric population also showed safety and reproducibility during capsulorhexis.[55] A retrospective case series showed a singular case that failed to create a free-floating capsulotomy due to faulty suctioning, but the PPC probe was replaced and capsulotomy was attempted again without complication.[55]
Figure 7 (a) Intumescent cataract. (b) The Zepto device is inserted in the eye with suction applied, adhering to the anterior capsule. (c) Activation of the Zepto device creates a circular capsulotomy. (d) A free-floating capsulotomy is noted on top of the cornea with liquefied cortex seen by the temporal main wound
Conversely, some literature has shown some fault with capsulotomy creation that should be investigated. A prospective study in an Indian population reported that capsulorhexis extension occurred in seven of 123 PPC cases.[56] Another study reported that anterior capsular tears occurred in 4% of PPC cases, potentially due to the electrical conductivity or rheologic properties of OVD (Viscoat) used in the study.[57] Analysis of the capsulotomy edge by scanning electron microscopy showed frayed edges, which may have led to an increased risk of capsular tear.[58] A follow-up to the initial investigation by the manufacturer led to an updated procedure and design for PPC that improved the ability to make a free-floating capsulotomy, but the anterior capsule tear rate was 4%.[59,60] Another study demonstrated an intraoperative radial capsular tear due to an air bubble underneath the nitinol ring.[61]
We noted an anterior capsular tear after PPC in a patient with a dense cataract [Fig. 8]. Typically, in mature cataracts, we prefer a 5.5–5.75-mm CCC as dense nuclear pieces can be more difficult to remove through a smaller capsulorhexis. In our case, tearing of the anterior capsule occurred during nucleus removal from contact with the phaco probe, not from the initial capsulotomy. However, with the recent launch of a larger PPC device extending the capsulotomy to 5.4 mm, anterior capsular tears in dense cataracts will likely decrease.
Figure 8 (a) Intraoperative image of a 4 + nuclear sclerotic cataract with a dense endonucleus. (b) The Zepto device is inserted in the eye with suction applied. (c) Activation creates a circular capsulotomy. No capsular tears are identified. (d) Anterior capsular tear is noted with a bottom-up cortex removal with a silicone irrigation/aspiration device. (e) Cohesive OVD is inserted in the anterior chamber. (f) IOL is placed perpendicular to the capsular tear
Sewing needle microcapsulotomy is a technique that involves creating a small, round opening in the anterior capsule. The surgeon can create a single or multiple microcapsulotomies to adequately decompress the anterior and posterior intralenticular compartment with various manipulations of the nucleus with the OVD cannula.[62] A prospective study examining 20 patients with intumescent cataracts compared the sewing needle microcapsulotomy technique with needle decompression, demonstrating 0% capsular extensions versus 60% (6/10) anterior capsular tears.
The reverse triangular anterior capsulotomy technique begins with the injection of OVD, followed by a bent 26-G needle to create a triangle capsulotomy with the subsequent aspiration of any cloudy cortical fluid. OVD is then injected into the capsular sac to prevent collapse and injury to the posterior capsule. The completion of the capsulotomy is achieved with Vannas scissors. In 20 patients with hypermature cataracts undergoing cataract extraction with a reverse triangular anterior capsulotomy, no capsular tearing was observed.[63]
Vacuum capsulorhexis is a technique that implements an “anterior chamber maintainer” (23-G needle with tubing attached to BSS on an elevated IV stand) through a corneal incision to maintain the anterior chamber depth and pressure. The anterior chamber has also been stabilized with an irrigating chopper or an irrigation probe from a bimanual I/A setup.[64,65] Next, a cannula attached to a catheter/aspiration handpiece is used to hold the free edge of the capsule for manipulation to a desired diameter. Of the 2500 cases reported, equatorial extension occurred in 2% of cases, and the author proposed that the utilization of suction gave surgeons better control of the capsulorhexis edge during intumescent cataract extraction.[66]
Cannula-vacuum capsulotomy differs from vacuum capsulorhexis in that the cannula is connected to a syringe handpiece instead of the phacoemulsification handpiece.[67,68] In the 197 cases studied, capsulorhexis runoff occurred in 1.5% of cases.[67] Another group of surgeons anecdotally states that over 500 intumescent cataracts have been completed without any uncontrolled anterior capsule tears.[68] The authors postulate that the simultaneous suction applied during capsulotomy aspirates cortical fluid and reduces intralenticular pressures. In a follow-up retrospective study, cannula-vacuum capsulotomy was utilized in 870 cases, where capsulorhexis extension occurred in eight cases and two of those cases extended to the posterior capsule.[69]
A modification of the cannula-vacuum capsulotomy has been performed, called Star CanVac CCC. Small centripetal tears in the shape of a star are created in the center of the anterior lens capsule with a cystotome. Multiple tears allow equal distribution of forces secondary to increased intralenticular pressure, limiting tear extension. A 25-G flat-tipped fine cannula connected to a syringe is used to hold the free capsular flap and create a CCC.[70]
It has been hypothesized that in creating a peripheral iridotomy intraoperatively or preoperatively, anterior and posterior chamber pressures would equalize, minimizing the role of posterior pressure inducing tear.[71]
Two-stage capsulorhexis entails making a small central capsulorhexis to emit a phacoemulsification probe and I/A tool.[9] After debulking some cortical material and manipulating the lens, a larger capsulorhexis can be formed to further remove the lens cortex and nucleus [Fig. 9].[9] In intumescent cases, two-stage capsulorhexis can maximize visualization of the lens and minimize the formation of radial tears.[9]
Figure 9 (a) Intumescent cataract. (b) A mini 3.5-mm capsulorhexis is completed through a 6-mm superior scleral tunnel. (c) Manual irrigation/aspiration with a Simcoe cannula is performed to aspirate the cortex and rotates the nucleus. (d) Utrata forceps are used to enlarge the CCC to 5.5 mm
In a prospective study, one-stage and two-stage capsulorhexis methods were compared regarding intraoperative complications.[72] One-stage capsulorhexis exhibited anterior capsule tears in 23% of cases, whereas two-stage capsulorhexis exhibited no anterior or posterior capsule tears.[72] Two-stage capsulorhexis was adequate in preventing radial tears from increased intracapsular pressures.[72]
The “Brazilian” technique begins with needle aspiration to equalize pressure in the anterior chamber, and a mini-rhexis of approximately 3 mm is created to introduce the bimanual irrigation/aspiration probes to manipulate the lens and depressurize the posterior intralenticular pressure.[8] Two hooks can be utilized to fracture the lens nucleus in quadrants (Akahoshi pre-chop technique), and aspiration of the lens fragments is performed with the bimanual irrigation/aspiration probe to prevent posterior capsule blow-out.[8]
A method similar to the Brazilian technique combines the use of OVD and characteristics from the two-stage capsulorhexis to optimally prevent AFS.[73] First, OVD is injected to achieve positive pressure in the anterior chamber and flatten the anterior capsule.[73] Bimanual irrigation/aspiration probes are used to puncture the anterior capsule and aspirate the liquid cortex. A mini-rhexis is made to manipulate the lens nucleus and equilibrate intralenticular pressures. Enlargement of the mini-rhexis is performed followed by phacoemulsification.[73] Two out of 92 cases exhibited radial extension of the capsulorhexis, and a posterior capsular tear was not observed.[73]
Utilizing a 1.5–1.8 mJ (neodymium-doped yttrium aluminum garnet (Nd: YAG) laser maintains equal pressure on the anterior capsule and prevents uncontrolled tearing.[74] The initial capsulotomy is made with a Nd: YAG laser and is confirmed by the presence of milky liquefied material in the anterior chamber.[75] In comparing Nd: YAG laser anterior capsulotomy with two-stage capsulorhexis for intumescent cataracts, the frequency of complications was not statistically significant between the two groups and thus deemed equally safe in the 11 cases studied.[75]
A case report of a 23-year-old patient with bilateral intumescent cataracts in poorly controlled insulin-dependent diabetes mellitus underwent Nd: YAG laser capsulotomy in one eye.[76] Initial cataract extraction of the left eye with conventional manual capsulorhexis exhibited radial tearing, whereas the right underwent successful CCC completion.[76]
The closed-chamber air bubble capsulotomy technique involves introducing a bent 26-G needle through the limbus without a side-port incision to aspirate aqueous humor to maintain a closed system.[77] A large air bubble is introduced to pressurize the anterior chamber and flatten the capsule. Next a “punching incision” is made centrally on the anterior capsule, and a free flap is reflected.[77] A cystotome manipulates a free edge to complete the capsulorhexis, and lighting is repositioned to fully illuminate the capsulorhexis for optimal visualization.[77] In this experiment, seven out of 82 eyes exhibited capsulorhexis extension.[77] The air bubble was efficient in countering intralenticular pressures and preventing liquefied cortex from obstructing the view.[77]
Due to the higher elasticity of lens capsules and increased posterior pressures in pediatric populations, different techniques may be employed for a successful capsulotomy.[78] Vitrectorhexis, or previously mechanized circular anterior capsulectomy, is a commonly used technique for pediatric cataract extraction.
However, vitrector-assisted anterior capsulorhexis has been documented in adult intumescent cataracts. This technique involves using a vitrectomy cutter to create an initial tear in the anterior capsule while simultaneously removing liquefied cortex and nuclear material.[79]
First, identifying high-risk intumescent cataracts is crucial and the foundation for success. The prominent sectoral markings within the anterior cortex are a hallmark clinical feature that may be more obvious under the surgical microscope. However, unclear white cataracts can be further analyzed with AS-OCT or ultrasound. Alternatively, the intumescent nature of the cataract can be assessed intraoperatively by feeling the elasticity of the anterior capsule with a cannula. Pressurized lenses have a “trampoline” nature when pressing down on the anterior capsule.
Second, patient positioning should be optimized for comfort and posterior pressure. In a procedure with a higher rate of complications and extended case time, do not settle for suboptimal positioning (e.g., hyperextension of the neck or greater than 15° perpendicular angle from the 3D heads-up display), which can predispose long-term muscle-skeletal injury. Next, posterior pressure can be improved by placing the patient in a mild reverse Trendelenburg position with a relaxed lid speculum which is not overexposed to decrease IOP.[80]
Third, the capsule should be stained to enhance the view of the anterior lens. Even in cases where we utilize FLACS, trypan blue is used intraoperatively to verify a complete capsulotomy or areas of possible tags and rents.
Fourth, anterior chamber pressure should be maintained at all times. Be generous with OVD and do not underinflate the eye. We prefer a dispersive OVD, but a combination OVD technique can be utilized to flatten the anterior capsule and counteract positive intralenticular forces.
Lastly, decompressing both the anterior and posterior intralenticular compartment is associated with the lowest rate of capsular tears [Table 1]. A variety of successful approaches exist; thus, we recommend surgeons tailor a technique that works best in their hands.
AFS can still occur despite the use of the preventative techniques described above. Tears in the anterior capsule can extend to the equator and posterior capsule 67% and 48% of the time, respectively, during AFS. Approximately 19% of anterior capsular tears result in vitreous loss, requiring a vitrectomy.[81] However, proper identification and management of anterior capsule tears can result in favorable patient outcomes.
Flap motility sign (FMS) is a technique that allows surgeons to determine whether a tear has extended past the equator to the posterior capsule. A pre-equatorial tear creates a flap that is fluttering and everted in presentation.[82] Progression of the case with modified phacoemulsification techniques can occur, which is described later in the discussion. However, conversion to a non-fluttering and inverted flap suggests a posterior capsular tear, creating a potential endpoint of safe phacoemulsification.[82] Once a posterior tear is identified with the FMS, phacoemulsification can be transitioned to manual small-incision cataract surgery (MSICS) earlier, decreasing the risk of nuclear drop. The decision to convert to MSICS with a fluttering, everted flap may be considered by some surgeons, especially in patients with severe zonular loss or significant nuclear density.
When a capsular runout is identified, additional OVD is injected to unfold and flatten the capsulorhexis edge.[83] Capsular forceps are then used to create traction backward (opposite the direction of the capsulorhexis) and then centrally (center of capsulorhexis) to predictably redirect the tear back toward the center of the capsule.[83] The manual capsulorhexis can then be completed as normal.
To make a safety flap, an initial incision in the peripheral anterior capsule is created and the flap is reflected.[14] A second flap is made from the initial incision, and capsulorhexis can proceed in the clockwise direction as normal.[14,84] If the capsulorhexis moves radially, the safety flap can be used to initiate another capsulorhexis in the counterclockwise direction and connected with the original capsulotomy tear.[14,84] Any notches left from the creation of a safety flap can be cleared using capsular scissors, and the tear can be redirected to create a complete anterior capsulotomy.[14,84]
A “pivot” can be made to avoid AFS when an initial capsular tear is observed intraoperatively.[85] When a runoff tear is seen during manual capsulorhexis, a capsular cut is applied to the center of the initial capsulorhexis incision.[85] This central cut relieves capsular tension, which would potentially cause a tear toward the capsule periphery.[85]
Once a capsulorhexis has been completed and an anterior capsular tear has been identified, prevention of posterior extension becomes critical. At our institution, we utilize several strategies to prevent posterior extension. Because an anterior capsular tear represents a weak point in the capsule, we introduce several small slits in the capsulorhexis, 2–3 clock hours apart, with a cystotome to spread out the distribution of radial forces [Fig. 10], thus minimizing the risk of posterior capsular extension.
Figure 10 (a) Intraoperative image with a subincisional capsular runout. (b, c) A cystotome is used to create a tear in the capsule to complete the CCC. (d) Three incisions are created in the capsulorhexis (white arrows). (e) Cohesive OVD is used to gently fill the capsular bag. (f) The IOL is placed with good capsular overlap with areas of capsular tears (white arrows)
Once a capsulorhexis is complete, hydrodissection should be performed gently to prevent the extension of the tear posteriorly. During phacoemulsification, we recommend lowering the infusion pressure and avoiding frequent lens rotation during nuclear disassembly. Supra-capsular phacoemulsification within the central 3-mm zone is also an effective way to minimize capsular stress and inadvertently grab the free capsule, resulting in the posterior extension of anterior tears.
The lens cortex should be removed carefully using the “hurricane cortical aspiration technique,” where tangential forces are used, pulling the aspiration handpiece toward rather than away from the location of the tear.[86] If possible, cortex from the area of capsular compromise should be performed last. If a capsular-friendly I/A device is available, a “bottom-up peel” can be performed by grabbing the free cortex attached to the posterior capsule and moving anteriorly.
Once cortex removal is completed, the anterior chamber should be maintained with OVD to prevent collapse and subsequent stress on the capsule. The IOL should be placed perpendicular to the capsular tears [Fig. 8f] with limitation of aspiration of OVD posterior to the IOL [Table 2].
During cataract extraction, the risk of capsular tears is most prevalent in intumescent cataracts due to lens morphology. The 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 or beyond the lens equator, causing an AFS among other intraoperative complications. Due to this risk, it is important to identify intumescent cataracts and utilize a combination of techniques discussed above to relieve both anterior and posterior intracapsular pressures.
However, once anterior capsular tears have occurred, mitigating extension to the posterior capsular is critical. Several techniques have been discussed in this review that the surgeon can utilize to mitigate posterior extension by reinforcing the integrity of the capsular bag.
All participants provided informed consent, in accordance with the Declaration of Helsinki.
Nil.
There are no conflicts of interest.