A pre-surround division technique performed before phacoemulsification during posterior polar cataract surgery divides the nucleus and avoids posterior opacity.
Koju Kamoi, MD, PhD, a junior associate professor at Tokyo Medical and Dental University in Japan, came up with the idea 7 years ago.
Having specialized in the management of patients with uveitis and other autoimmune and infectious ocular diseases, Kamoi told Ocular Surgery News, “I encountered many challenging surgical cases that required minimum aggression and maximum safety.”
Kamoi had been employing standard nucleus-dividing techniques, such as divide and conquer, phaco chop and prechop, as well as his own developed techniques, such as phaco dislocation and phaco forward-chop, to match the features of cataract.
“Through my surgical experience, however, I realized that the prechopper used for the prechop technique was the best device for making precise cracks in the division process,” he said. “Also, for posterior polar cataract surgery, I discovered that precise division of the lens avoided polar opacity before phacoemulsification, which was the key to the success of the surgery. This naturally linked the surgical device to the strategy of posterior polar cataract surgery.”
Candidates for the pre-surround division technique have posterior polar cataract that requires phacoemulsification to remove the lens, with nuclear sclerosis ranging from grade 2 to grade 3.
“In patients with soft nucleus, only irrigation and aspiration can remove the lens,” Kamoi said. “In cases of dense hard nuclei, on the other hand, using a prechopper is not realistic, so other methods such as intracapsular cataract extraction should be considered.”
Kamoi has used his technique over the past 7 years in only six eyes due to the rarity of a posterior polar cataract.
“Still, I have confirmed the technique’s efficacy and safety,” he said. No intraoperative or postoperative complications have been observed, and all IOLs were successfully implanted.
In the Journal of Cataract and Refractive Surgery, Kamoi and colleague Manabu Mochizuki, MD, PhD, described the technique. The creation of incisions and the continuous curvilinear capsulorrhexis is followed by hydrodelineation. Then for pre-surround nucleus division, an ophthalmic viscosurgical device is inserted to maintain the anterior chamber space. Next, the prechopper is inserted into the left side of the nucleus, and the nucleus is divided.
“The surgeon should avoid making cracks over the polar opacity,” Kamoi said.
The same step is then performed on the right side of the nucleus.
“You want to ensure that the nucleus is separated into three complete pieces,” Kamoi said.
The pre-surround division technique can divide the lens into three pieces without any rotation before phacoemulsification. Two cracks surrounding the posterior opacity can be precisely achieved. The prechopper blade should move slowly away from the center. Blue: hydrodelineation line (golden ring). Yellow: posterior opacity. Gray: prechopper blade.
The pre-surround division technique can avoid unintentional cracks over the posterior opacity and can result in a safe division whether the hydrodelineation is successful or not.
Images: Kamoi K
Afterward, the lens is removed by phacoemulsification, using a hook throughout, by first shaving the central piece of the divided nucleus and then removing the side pieces of the nucleus. The final step is separating the cortex and the polar opacity from the posterior capsule with the ophthalmic viscosurgical device.
“Several methods for dividing the nucleus into more than two pieces without rotating the lens have been reported; however, they require a high skill level,” Kamoi said. “In contrast, my pre-surround division technique can easily divide the nucleus into three pieces, again without rotating the lens. Furthermore, making accurate cracks before phacoemulsification with this technique can avoid accidental cracks over polar opacity. Taken together with surgical results, this technique is safe and effective compared with previously reported methods.”
Kamoi said that producing cracks over the polar opacity by using conventional division techniques can lead to posterior capsule rupture “when hydrodelineation is performed imperfectly. Creating precise cracks surrounding the polar opacity with a prechopper is highly safe, despite whether the hydrodelineation is successful or not. Also, dividing the lens into three pieces without rotation before phacoemulsification can greatly avoid surgical complications.”
To increase the likelihood of success with the pre-surround division technique, surgeons should be familiar with the prechopper.
“Inserting the prechopper into the lens at the exact depth and having an opening motion with precise force are keys to successful lens division,” Kamoi said. “Careless movement of the prechopper blade will stress the fragile capsule; therefore, the prechopper blade should be inserted into the lens slowly. Also, the blade should move slowly away from the center with proper force.”
Because it is difficult to insert the prechopper blade into a dense hard nucleus without exerting pressure on the capsule, the technique is not recommended for this type of nucleus.
“Successful hydrodelineation is a critical point in posterior polar cataract surgery,” Kamoi said. “Surgeons may divide the lens with their preferred techniques without any difficulty, when hydrodelineation is performed perfectly. But if surgeons do not have confidence in creating a perfect hydrodelineation line and do not have confidence in dividing the lens without unintentional downward pressure on the posterior capsule and/or without unintentional cracks over the posterior opacity, I recommend my pre-surround division technique.” – by Bob Kronemyer
Kamoi K, et al. J Cataract Refract Surg. 2014;doi:10.1016/j.jcrs.2014.09.002.
For more information:
Koju Kamoi, MD, PhD, can be reached at Department of Ophthalmology and Visual Science, Graduate School of Medicine and Dental Sciences, Tokyo Medical and Dental University, 1-5-45 Yushima, Bunkyo-ku, Tokyo 113-8519, Japan; 81-3-5803-5302; email: firstname.lastname@example.org
Disclosure: Kamoi has no relevant financial disclosures.