Half-moon supracapsular phacoemulsification (HMSP) is a recently described cataract surgery technique. First, the nucleus is split supracapsularly; second, quadrant removal is accomplished endocapsularly.1 This technique is a derivative of two other phaco methods: Nagahara's horizontal chopping2 and Maloney's supracapsular phaco.3 It also closely parallels Pandit and Oetting's pop-and-chop technique.4 The aim of HMSP is to maintain these advantages of the techniques and avoid their disadvantages.
The first part of HMSP is based on hydrodissection and hydrodelineation. Because fluid is captured between the posterior capsule and nucleus, the anterior-pushing effect makes the distal part of the nucleus prolapse out of the capsulorrhexis rim during hydrodissection. At this stage, its appearance resembles a half moon. Horizontal chopping is performed under direct visualization in the anterior chamber, starting from the area of the prolapse. Once split, the heminuclei are replaced in the bag, and emulsification is continued within the capsular bag.1 Details of the technique are shown in Table 1 and Figure 1.
Nucleotomy and phacoemulsification techniques have gradually improved, reducing phaco energy; shortening operating time; and making the operation more effective, safe, and functional.5,6
Stop-and-chop. Currently, one of the most popular phacoemulsification techniques is Koch's stop-and-chop,7 which uses only manual energy generated by the chopper after the first sculpting phase. As a result, use of ultrasound energy is reduced. Koch's technique has higher efficacy versus earlier methods, such as chip-and-flip and divide-and-conquer.
Horizontal chopping. In Nagahara's horizontal chopping technique,2 the nucleus is divided in half within the capsular bag. Because no groove is sculpted with ultrasound power, horizontal chopping not only reduces energy but also lowers zonular stress by avoiding use of centripetal forces. Nagahara's technique has, therefore, more advantages than stop-and-chop in terms of safety and efficacy.8 However, horizontal chopping has two main disadvantages. Use of the chopper behind the iris may damage the zonules and posterior capsule because the surgeon cannot see peripherally. The technique also has a long learning curve.
Vertical chop and prechop. Pfiefer2 and Fukasaku,9 with their vertical chop technique, and Akahoski,10 with his prechop technique, tried to solve the problems associated with other phacoemulsification techniques. Both are performed without entering the periphery; however, these methods pose some challenges when performed in soft nuclei. Additionally, there is risk of posterior capsular rupture.
Supracapsular. Another group of phaco strategies, presumably developed to simplify phacoemulsification, is the supracapsular techniques, including Brown's phaco flip,5 Maloney's supracapsular,3 Davis and Lindstrom's tilt-and-tumble,11 and Pandit and Oetting's pop-and-chop.4 The common feature of these techniques is that splitting and quadrant removal are mostly performed in the anterior chamber. The only disadvantage of these effective and facilitative phaco techniques is more corneal endothelial cell damage, possibly due to working in close proximity to the endothelium.
When formulating the HMSC technique, we considered the pros and cons of supracapsular phaco. This half-moon technique has a short learning curve, with partial prolapse occurring during the nucleus stage. Chopping is performed under direct visualization, without any risk of capsular and zonular damage. Therefore, the procedure may be proposed to surgeons without any chopping experience. As in Nagahara's technique, centripetal forces decrease the amount of stress to the zonules. Additionally, because the nucleus is kept partially outside of the capsule, no pressure occurs on the capsule itself.
The HMSC technique increases the efficacy and safety of phacoemulsification, especially in patients with a high risk of zonular or capsular failure, such as those with high myopia, pseudoexfoliation, glaucoma or previous glaucoma surgery, and traumatic cataract. After dividing the nucleus, replacement of the heminuclei in the capsular bag transforms the procedure to standard endocapsular phacoemulsification, allowing the surgeon to safely work far from the corneal endothelium.
Similar endocapsular chopping techniques that split the nucleus within the bag, such as Nagahara's horizontal chopping technique, may cause some of the chopped nucleus to interlock—much like a jigsaw puzzle—within the capsule. This makes the operation difficult. With HMSC, after partial prolapse and division of the nucleus, distal parts of the heminuclei remain outside the capsule. Therefore, removing a small wedge to create more space will allow further movement inside the capsular bag. In this stage, rotating the heminuclei facilitates completion of phacoemulsification.
We recently compared the HMSC and stop-and-chop techniques1 and concluded that HMSC was more effective (ie, shorter and more effective phaco time) and similar to stop-and-chop in functionality and safety. The only disadvantage of HMSC compared with techniques that use manual energy to crack the nucleus in the bag is that the nucleus is partially prolapsed into the anterior chamber. Thus, chopping begins in the anterior chamber. Although HMSC caused increased central corneal thickness on the first postoperative day, this was statistically insignificant.
The HMSC technique, with the advantages mentioned in this article, may be performed easily in both hard and soft cataracts. We also recommend this technique for biaxial microincision cataract surgery.
Izzet Can, MD, is an Associate Professor and Chief of the Second Eye Department, Ankara Ataturk Education and Research Hospital, Turkey. Dr. Can states that he has no financial interest in the products or companies mentioned. He may be reached at tel: +90 312 4671997; fax: +90 312 4671998; e-mail: email@example.com.
Ipek Genç, MD, practices at the Ankara Ataturk Education and Research Hospital, Turkey. Dr. Genç states that he has no financial interest in the products or companies mentioned. He may be reached at tel: +90 532 4071388; e-mail: firstname.lastname@example.org.
Tamer Takmaz, MD, practices at the Ankara Ataturk Education and Research Hospital, Turkey. Dr. Takmaz states that he has no financial interest in the products or companies mentioned. He may be reached at e-mail: email@example.com.
- Can I, Takmaz T, Genc I. Half-moon supracapsular nucleofractis phacoemulsification: safety, efficacy, and functionality. J Cataract Refract Surg. 2008;34:1958-1965.
- Chang DF. Why learn chopping? In Chang DF, ed. Phaco chop, mastering techniques, optimizing technology and avoiding complications. Slack Inc; Thorofore, NJ; 2004;1: 3-12.
- Maloney WF, Dillman DM, Nichamin LD. Supracapsular phacoemulsification: a capsule-free posterior chamber approach. J Cataract Refract Surg. 1997;23:323-328.
- Pandit RT, Oetting TA. Pop and chop nucleofractis. J Cataract Refract Surg. 2003;29:2054-2056.
- Allen D. Cataract surgical techniques. CRST Europe. 2007;2:32-35.
- Dada T, Dada VK, Sethi HS, Dhawan M. Nucleotomy Techniques: Classification. In Mastering the Nucleotomy Techniques in Phaco. Dada T, Dada VK, Sethi HS, Dhawan M, eds. Jaypee Brothers; New Delhi; 2007;5:49-54.
- Koch PS, Katzen LE. Stop and chop phacoemulsification. J Cataract Refract Surg. 1994;20:566-570.
- Can I, Takmaz T, Cakici F, Ozgul M. Comparison of Nagahara phaco-chop and stop-and-chop phacoemulsification nucleotomy techniques. J Cataract Refract Surg. 2004;30:663-668.
- Fukasaku H. The snap and split phacoemulsification technique safely cracks the nucleus. Ocular Surgery News International Edition. 1995;6(8):5.
- Akahoshi T, Kammann J. Minimal energy chopping has advantages. Ophthalmology Times. 1997.
- Davis EA, Lindstrom RL. Tilt and tumble phacoemulsification. Dev Ophthalmol. 2002;34:44-58.