Surgeons should be familiar with manual small-incision cataract surgery
The advent of Kelman phacoemulsification transformed cataract surgery by decreasing the incision size, increasing safety and improving efficiency.
For more than 99% of the cataract surgeries that we perform, modern-day phacoemulsification is our preferred technique, but it requires expensive equipment and the per case cost is high. Surgeons in other countries have evolved manual extracapsular cataract surgery into an efficient and safe procedure, well suited for dense brunescent cataracts. This technique, termed manual small-incision cataract surgery (MSICS), is easy to learn for an experienced phaco surgeon and can be summarized in four pearls that I have gleaned from colleagues in India.
The patient presents to your clinic with very dense nuclear cataracts that are so opaque that they preclude a view of the retina. The patient has a large degree of axial myopia, 2 D of with-the-rule corneal astigmatism and a lower than expected corneal endothelial cell count. The IOL power is so extreme that toric lens designs are not available in the desired dioptric value. The nucleus is so dense that using phaco to emulsify it would require a tremendous amount of ultrasonic energy and would put the cornea at risk. This is a great case for MSICS because the incision will help address the corneal astigmatism and we will be able to safely remove the nucleus without iatrogenic complications.
Pearl 1: The incision architecture
The incision for manual cataract extraction evolved from the von Graefe knife to corneoscleral scissors, but the MSICS incision is far better. The key to this incision is the architecture where it is at half scleral depth and shelved so that the contact area between the roof and floor of the incision is extensive. The incision is also trapezoidal in nature with the internal opening larger than the external (Figure 1). After a conjunctival peritomy is performed, the crescent blade is used to carefully construct this incision starting at least 1.5 mm behind the limbus. At this point, the keratome can be used to enter into the anterior chamber. After the capsulorrhexis is performed, the internal aspect of the incision is opened sufficiently to allow passage of the nucleus. For a very dense cataract that will be removed as a whole, the incision may be 9 mm wide. For a softer nucleus, the incision can be smaller, and if the nucleus is able to be bisected in the anterior chamber, the incision can be as small as 5 mm.
Pearl 2: The capsulorrhexis
For MSICS, a capsulorrhexis is preferred over the can-opener style capsulotomy. Trypan blue dye is helpful to visualize the capsule due to the absence of a red reflex because of the opaque cataract. The capsulorrhexis must be at least 5 mm in diameter because we need to be able to bring the entire nucleus out of the capsular bag (Figure 2). Using a 27-gauge cannula, gentle and persistent hydrodissection is performed to separate the nucleus from the capsular bag. This is often enough to partially prolapse the nucleus out of the capsular bag, and then the chopper can be used to rotate and fully bring the nucleus into the anterior chamber. At this point, the incision can be fully opened to the desired width.
Pearl 3: Push the nucleus out
By placing a paracentesis incision opposite the main incision, we can help to push the dense nucleus out of the eye (Figure 3). Dispersive viscoelastic is placed under the nucleus to protect the capsular bag and then over the nucleus to protect the corneal endothelium. We can also use the viscoelastic to pressurize the eye, which will help deliver the nucleus. A lens loop is placed under the nucleus, and then a spatula is used via the paracentesis to push the nucleus safely out of the eye. The old method of using a muscle hook to push on the eye externally in order to help deliver the nucleus is less effective and may damage the corneal endothelium.
Pearl 4: Suture the incision
While I have seen surgeons perform MSICS without using sutures, there is an advantage to sewing the incision shut (Figure 4). After the nucleus has been delivered, the incision can be closed with two 10-0 nylon sutures, equally spaced to divide the 9-mm wide incision into three segments of 3 mm. At this point, the standard coaxial irrigation/aspiration probe can be used to remove the lens cortex and clean the capsular bag. The new IOL can also be delivered through these small 3-mm openings using the appropriate lens injector. Sutures should be placed in such a manner that the astigmatism can be modulated, which, in this case, means allowing a relaxing effect to treat the preexisting with-the-rule 2 D. Finally, the conjunctiva is closed and secured over the incision.
This patient had a great result with MSICS and achieved the desired refractive outcome, including treatment of the astigmatism. The cornea also maintained a good endothelial cell count and was clear on postop day 1. While I do not often use MSICS in my practice, it is an important technique for certain patients. I encourage you to learn and use the MSICS technique as I am certain that you will find it useful.
See full video of this case at cataractcoach.com.
- For more information:
- Uday Devgan, MD, is in private practice at Devgan Eye Surgery, Chief of Ophthalmology at Olive View UCLA Medical Center and Clinical Professor of Ophthalmology at the Jules Stein Eye Institute, UCLA School of Medicine. He can be reached at 11600 Wilshire Blvd. #200, Los Angeles, CA 90025; email: firstname.lastname@example.org; website: www.CataractCoach.com.