Intumescent Cataract

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Article initiated by:

Ashraf F. Ahmad M.D.

All contributors:

Khalid El-Jack, Obaidah Bitar, Omer Elmahdi Saeed, Derek W DelMonte, MD, Ashraf F. Ahmad M.D., Michael Wildes, MD

Assigned editor:

Michael Wildes, MD

Review:

Assigned status Update Pending

 by Michael Wildes, MD on April 7, 2024.

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Disease Entity

Disease

Cataracts are the most treatable cause of blindness in the world. Cataracts develop from a variety of causes including age-related opacification, congenital abnormalities, as well as mechanical trauma. In the United States, most cataracts are extracted in their immature stage; however, globally, cataracts are often left to mature into more advanced stages. Mature cataracts are at risk of developing into intumescent cataracts, which are advanced cataracts that result from swelling and congestion of the lens due to degeneration of lens proteins.

Epidemiology

Cataract severity ranges from incipient, immature, intumescent, mature corticonuclear, hypermature Morgagnian, and finally shrunken Morgagnian. As mentioned above, in the United States cataracts tend to be treated in the incipient and immature phases prior to significant lens swelling. In areas with limited access to care, there is an increased risk of developing intumescent cataracts, making extraction more challenging.

Etiologies

There are numerous factors that may lead to the formation of an intumescent cataract. The main causative factors include untreated immature cataracts, exposure to UV rays, heatwaves, infrared light, and radiation over long periods of time.

Risk Factors

Risk factors include excessive alcohol consumption, tobacco, UV exposure, chronic steroid use, previous radiation treatment, thalassemia, previous chemotherapy.

Pathophysiology

On slit-lamp exam, the first sign of intumescent cataracts is vacuole and cortical spoke formation. Intumescent cataracts are characterized on histopathology by extrusions at the basement membrane-epithelial border, filaments, lamellation, and rarefaction. Movement of the inner basement membrane layers towards and between epithelial cells leads to splitting of the lens epithelial cells, and eventual degradation. The inciting factor is endothelial cell dysfunction which leads to gene and protein-related changes in Na–K pumps of epithelial cells. This in turn results in epithelial swelling from inward osmotic pressure within the lens. This process is what differentiates intumescent cataracts from nuclear cataracts. The epithelial cells show vacuole formation, and an absence of apoptosis. Therefore, there is a higher degree of debris in intumescent cataracts as compared to nuclear cataracts. Additionally, extrusions at the basement membrane-epithelial border are thought to occur in response to rid the cell of this debris. Epithelial cells may be using the destruction of the basement membrane to metabolize the damaged cells. Simultaneously, these epithelial cells are forming new layers of cells on top of damaged layers in order to prevent gap formation.

Management

Capsulorrhexis and Decompression

The first challenge in the surgical management of an intumescent cataract is the creation of a well-sized continuous curvilinear capsulorrhexis (CCC). CCC is the preferred surgical method, as alternatives such as the can-opener capsulotomy are associated with increased risk of complications. Some of these complications include anterior capsular radial tears, which in turn may destabilize the capsular bag leading to difficulty in removing cortical lens material, posterior capsular tears, vitreous prolapse and IOL instability.

Due to the high intralenticular pressures, puncture of the anterior capsule may lead to rapid uncontrolled tearing that extends to the lens periphery. These anterior capsular tears, colloquially termed the “Argentinian flag sign” (when stained with trypan blue), can extend posteriorly and result in posterior capsular rupture. In addition, egress of liquefied cortical material often occurs, causing immediate loss of capsule visibility. This, in addition to a compromised red reflex, pose significant visualization challenges.

Visualization can be improved via capsule dyes such as trypan blue or indocyanine green or illumination aids such as the endoilluminator or surgical slit illuminator. Intralenticular pressure reduction can be achieved via administration of osmotic agents such as intravenous mannitol, which desiccate the vitreous, reducing posterior pressure. In addition, viscoadaptive agents such as sodium hyaluronate (Healon GV) or sodium chondroitin sulfate sodium hyaluronate (Viscoat) are used judiciously to maintain anterior chamber stability. However, pressures are often too elevated despite these methods, so decompression of the intralenticular pressure may be warranted. A 27 gauge needle on an empty syringe is typically used with simultaneous capsule punctures and aspiration of the liquified cortex while maintaining downward pressure on the lens with an ophthalmic viscosurgical device (OVD). After decompression, the cystotome is then used to create the initial tear at the center of the anterior capsule, subsequently advancing the capsular flap into a circular shape using capsulotomy forceps. In addition to providing lens stability, a perfectly circular and properly sized capsulorrhexis allows for a more precise effective lens position (ELP) achieving optimal refractive outcome. General recommendations for capsulotomy size ranges between 5-6mm with an ideal size of 5.5mm, although different conditions may warrant different sizes.

Other methods for performing a controlled capsulorrhexis in these situations include phaco capsulotomy and the two-stage capsulorrhexis. Phaco capsulotomy involves creating a paracentesis followed by the main wound. After staining the capsule with trypan blue, the phaco tip is used to puncture the anterior capsule while also simultaneously removing the liquefied cortex and nuclear material. This allows for decompression of the lens/capsule apparatus, thereby removing the force that causes the capsulorrhexis to spontaneously tear outward. The two-stage capsulorrhexis is a technique that is especially useful in complicated cases such as intumescent cataracts. It involves first creating and completing a small capsulotomy to allow for lens material removal. Afterward, this small opening is converted to a larger CCC. The initial small opening ensures a continuous edge with no radial tears, which can then be enlarged under more controlled conditions.

Newer Automated Capsulotomy Devices have also proven to be useful for creating continuous capsulotomies in the setting of intumescent cataracts. A femtosecond laser may be used to create a capsulotomy which has the benefit of a closed anterior chamber and reduced risk of anterior capsule tear or extension. The The Zepto® precision pulse capsulotomy device is a novel technology. The device consists of a console attached to a disposable handpiece that is inserted into the anterior chamber and delivers energy to the anterior capsule to create an instantaneous round capsulotomy. The rapid creation of the capsulotomy reduces the change of radial extension which has proven beneficial in challenging cases.

IOL Selection

Regarding IOL selection for intumescent cataracts, 3-piece IOLs are preferred over one-piece IOLs due to the high-tension forces their haptics exert along the capsular fornix to enhance zonular stability. In addition, three-piece lenses provide more options for surgeons as they can be implanted in the ciliary sulcus. In patients with intact capsular bags and low risk for instability, either single or three-piece IOLs can be utilized, although studies have shown mixed results in various outcomes in postoperative stability and refractive outcomes.

Nuclear Disassembly

In terms of nuclear disassembly, techniques that require significant lens rotation, such as divide-and-conquer, increase the risk for zonular dehiscence. It may be prudent to consider techniques that minimize lens rotation and ultrasound power, such as phaco chop.

Femtosecond laser-assisted cataract surgery (FLACS) is a laser-guided technique that creates cleavage planes via photodisruption, which allows for the creation of wounds, CCC, nuclear disassembly, and arcuate keratotomies. Capsulotomies created by FLACS have less variation in centration and size, with reproducible and uniformly circular CCC when compared to manual CCC. However, there is insufficient evidence to suggest better long term outcomes with FLACS as compared to standard cataract surgical techniques.

With FLACS, studies have shown reduced ultrasound energy during phacoemulsification compared to conventional cataract surgery. Significant energy reduction was noted using the OptiMedica Catalys FLACS platform while a modest energy reduction was noted with the Alcon LenSx platform.

Other Considerations

Of note, these advanced cataracts often have underlying zonular instability, therefore surgeons should be prepared to manage zonulopathy with capsule hooks, CTR’s, and Ahmed segments. In addition, while hydrodissection is an integral part in facilitating epinuclear and cortical removal, nuclear rotation should be minimized as it may cause iatrogenic zonular dehiscence. Surgeons should also be aware that hydrodissection may result in a buildup of posterior pressure which in turn may lead to posterior capsular blowout. Therefore, hydrodissection should be done carefully to minimize this complication.