A surgical challenge: hypermature cataracts

To remove these, you’ll need to be on your game.

By Priya Narang, MS and Amar Agarwal, MS, FRCS, FRCOphth

Right from the preoperative presentation, hypermature cataracts are considered to be a surgical challenge. Assessing the density of the nucleus and the increased intracapsular pressure is difficult. Getting these answers wrong can lead to complications and often the abandonment of the phaco procedure if these issues are not properly handled. Also, these complications cause difficulty in visualizing the capsular margins, jeopardizing the performance of a good capsulorhexis procedure. Additionally, a hypermature cataract can obscure a hard or brunescent nucleus underneath it with the nucleus often having a flocculent posterior cortical opacity.

The “pearly whites” you don’t want to see

Hypermature cataracts are pearly white and could have fluid within the capsule. When a high amount of fluid is present and the nucleus size shrinks, it is known as a Morgagnian cataract. Basti demonstrated that surgeons can differentiate between a normal hypermature cataract and a Morgagnian cataract by observing the slit beam of the slit lamp during preoperative examination.¹ This method works on the principle of raised intralenticular pressure of fluid that is expected to be greater in Morgagnian cataract, which leads to increased convexity of the anterior capsule.

Figure 1. Capsulorhexis being performed in a hypermature cataract with trypan blue stained anterior capsule.

Methods of attack

The surgical procedure can vary between an extracapsular cataract extraction (ECCE), small-incision cataract surgery (SICS) or a phacoemulsification procedure, depending upon the surgeon’s choice of surgery and competence to handle complications. With any cataract procedure you must be able to do a good capsulorhexis and safely implement the IOL. The choice of ophthalmic visco surgical device (OVD) is crucial to accomplish the desired goal. A high-viscosity OVD (Healon GV, AMO) is advisable in these cases as it offers a sufficient tamponading effect. It also allows good maneuverability of the capsulorhexis flap. Low- or medium-viscosity OVD does not offer adequate resistance to the high intralenticular pressure encountered in intumescent cataracts.

We recommend distending the eye with viscoelastic before performing the cataract surgery. To distend the eye, attach a 26-g needle to a 1 mL syringe laden with viscoelastic. Enter the eye at the site of the future side port incision, and inject viscoelastic. This makes the eye taut and helps to frame a better valvular corneal section.

Adequate visualization of the anterior capsule is essential to perform a capsulorhexis. Various methods exist to improve visibility of a white cataract’s anterior capsule.^2-11 Trypan blue is the most common drug used to stain the anterior capsule. After you create a clear corneal incision, inject trypan blue by a cannula into the anterior chamber between the air bubble and the lens capsule; the latter is flushed out of the eye after one to two minutes so that the anterior capsule is properly stained. Then, inject viscoelastic into the anterior chamber to remove the air bubble and the trypan blue.

Inject OVD in a sufficient amount so that it equalizes the amount of pressure in the intracapsular pressurized compartment and in the anterior chamber. Initiate capsulorhexis with a 26-g bent needle attached to a 1-mL OVD filled insulin syringe or a cystotome. Using an OVD-filled syringe ensures that the surgeon does not have to withdraw the syringe from the eye in case of any OVD egress from the incision. After puncturing the capsule, switch over to the forceps or continue with the same needle depending upon your comfort level and personal preference.

No OVD egress or Argentinian flags

During the entire procedure, ensure that there is no OVD egress, which leads to anterior chamber decompression and can cause a peripheral tear or extension of the continuous curvilinear capsulorhexis (CCC) or an Argentinian flag sign (more on these complications below).

Milky fluid often leaks when placing a nick with the cystotome. It is equally essential at this juncture to maintain the anterior chamber pressure and to remove the milky fluid to facilitate adequate visualization of the anterior chamber and capsule. To remove the fluid, inject a dispersive OVD to push the milky fluid out of the eye through the main incision (through which the cannula was introduced) without reducing the IOP. Complete the capsulorhexis in a well-guided manner.

Also, perform a controlled hydrodissection in these cases because injecting a large amount of fluid into the bag can lead to an increase in the intracapsular pressure and a posterior capsule rupture (PCR). Introduce a phacoemulsification probe, which allows removal of all liquefied cortex and epinuclear material. It also provides guidance, allowing adequate assessment of the hardness of the lens nucleus.

With Morgagnian cataracts, much of the cataract gets liquefied. The nucleus is often soft, small in size and is easily removed using a standard vertical chopping technique. In cases of a large brunescent nucleus, very little cortex is present. A vertical chop with a high vacuum setting helps to embed the nucleus and break it into small pieces. Follow this with standard irrigation/aspiration and removal of any remnant cortex and any fragments adherent to the capsular bag. Then, implant the IOL of choice into the capsular bag.

Figure 2. Phacoemulsification in hypermature cataract. (A) Capsulorhexis completed in a hypermature cataract. (B) Phacoemulsification being performed. (C) Phacoemulsification completed. (D) In-the-bag IOL implantation.

Figure 3. IOL scaffold for posterior capsule rupture. (A) Nonemulsified nuclear fragment levitated into anterior chamber. Three-piece IOL injected beneath the nuclear fragments. (B) Leading haptic placed above the surface of iris and trailing haptic is kept extruded at the corneal incision. (C) Nuclear fragments being emulsified with a phacoemulsification probe introduced into the anterior chamber. (D) IOL being placed into sulcus following complete emulsification of nuclear fragments.

Alternatively, if you are not confident performing a phacoemulsification procedure in these dense cataract cases, either perform an extracapsular cataract extraction or a small incision cataract procedure after following the initial rules of performing a good capsulorhexis.

Complications

You might encounter several different complications with hypermature cataracts. These include:

1. The Argentinian flag sign. Following a nick in the anterior capsule, the resultant tear will extend down the diameter of the white nucleus, leaving a blue band on either side of the white band in the center. These bands resemble the Argentinian flag. Handling this remains a challenge for surgeons regardless of their level of experience as further extension of this tear around the equator can lead to a PCR and a nucleus drop.¹²

At this juncture, try to prevent the tear from extending around to the posterior capsule, where the lens could drop into the vitreous. A careful in situ bisection of the nucleus with the phacoemulsification probe, followed by supracapsular phacoemulsification, helps to prevent the tear from extending beyond the equator. Perform irrigation/aspiration in a gentle manner followed by placement of a three-piece IOL in front of the capsular bag on the sulcus with the haptics placed at 90 degrees to the direction of the anterior capsular tear.

2. Posterior capsule rupture. This can occur due to raised intracapsular pressure caused by either an overzealous attempt to perform a hydrodissection or the tearing away of the anterior capsule, extending itself to the periphery and eventually into the posterior capsule. In the case of an inadvertent PCR, it often becomes difficult to place an IOL. After proper handling of the nuclear fragment, consider sulcus placement of a three-piece IOL in cases of an intact anterior capsule margin.

But, in cases of inadequate sulcus support, consider a method of secondary IOL fixation. We choose to perform a glued intrascleral fixation (glued IOL) in such cases that are often coupled with an IOL scaffold or a glued IOL scaffolding procedure depending upon the status of the residual nuclear fragments in the eye.^13,14

• IOL scaffold. An IOL scaffold is applicable in cases of an intact anterior capsular margin with PCR in an eye with nonemulsified nuclear fragments.^15,16 After PCR, inflate the anterior chamber with dispersive OVD to prevent further extension of the PC opening. All the nuclear fragments will levitate into the anterior chamber, allowing you to inject a three-piece foldable IOL beneath the fragments. Dial the IOL into the sulcus or place it over the iris’ surface, and introduce a phacoemulsification probe into the eye to emulsify the residual fragments. Then, dial the IOL into the sulcus if placed initially over the anterior surface of the iris. Perform vitrectomy from the side port incision or from the pars plana site depending upon the extent of PCR and the amount of residual fragments.



Figure 4. Glued IOL for posterior capsule rupture in Morgagnian cataract. (A) Morgagnian subluxated cataract. (B) Posterior capsule rupture noted during surgery. Two partial scleral thickness flaps made 180 degrees opposite from each other. Infusion is introduced into the eye. (C) A three-piece foldable IOL is introduced and the tip of the leading haptic is grasped for haptic externalization. (D) Both haptics externalized and tucked into scleral pockets. A well-centered IOL is seen.

• Glued IOL. Perform this procedure in cases of PCR with no nonemulsified residual fragments present in the eye.^13,14 After creating two, partial-thickness scleral flaps 180 degrees opposite from each other, introduce infusion to the eye. Perform sclerotomy approximately 1 mm away from the limbus beneath the scleral flaps, followed by vitrectomy. Make a corneal tunnel incision and introduce a three-piece foldable IOL into the eye. Grasp the tip of the leading haptic with the glued IOL forceps introduced from the left sclerotomy site with the tip externalized. Then, externalize the trailing haptic and create scleral pockets with a 26-g needle wherein you’ll eventually tuck the haptics.¹⁷ Perform vitrectomy at the sclerotomy site, inject an air bubble into the anterior chamber and apply fibrin glue to seal the scleral flaps and all the conjunctival incisions.

• Glued IOL scaffold. This involves the combination of both glued IOL and IOL scaffold.¹⁸ Perform the procedure in cases of deficient posterior capsule associated with inadequate sulcus support to place an IOL in the presence of nonemulsified nuclear fragments. In this technique, the nuclear fragments levitate into the anterior chamber and the surgeon performs a glued IOL procedure, at least initially. The IOL then acts as a scaffold for the emulsification of the residual fragments.

3. Dropped nucleus. This can occur due to a big PCR occurring during the surgery. This complication often calls for intervention from the posterior segment surgeon to effectively remove the nucleus from the vitreous cavity. Sulcus placement or a secondary IOL fixation can then be considered for these cases.

In hypermature cataracts, other complications, including damage to the corneal endothelium, could also occur in the endeavor to emulsify a hard nucleus. This complication could necessitate an endothelial keratoplasty procedure in extreme cases.

Conclusion

The surgical removal of a hypermature cataract can significantly improve the patient’s visual outcome, but creating a continuous curvilinear capsulorhexis in order to perform a phacoemulsification is more challenging. These eyes, if left untreated, could develop phacolytic glaucoma. Appropriate use of high viscous OVD can help maintain the equilibrium between the anterior chamber pressure and intracapsular pressure, thereby preventing further complications such as the Argentinian flag sign.

Surgeons can address the problem of poor visualization of the lens capsule by using trypan blue on the capsule to see it during the capsulorhexis. Neodymium:YAG laser has also been used to create an anterior capsulotomy just prior to surgery. The YAG laser opening of the anterior capsule helps the liquefied cortical material to be released into the anterior chamber, decreasing intralenticular pressure.

Be very careful while operating on hypermature cataracts, and follow the basic principles of cataract surgery that help to optimize the visual outcomes for your patients. OM

REFERENCES

About the Authors
	Dr. Priya Narang MS is director of the Narang Eye Care & Laser Centre, Ahmedabad, India.
	Dr. Amar Agarwal, MS, FRCS, FRCOphth is director of Dr. Agarwal’s Eye Hospital & Research Centre, Chennai, India. Contact him via e-mail at dragarwal@vsnl.com.
	They report no financial interest in any of the products or procedures mentioned in the article.