EyeWorld Asia-Pacific September 2011 Issue

39 EW CATARACT/IOL September 2011 Views from Asia-Pacific Wan-Soo KIM, MD Professor of Ophthalmology, Heundae Paik Hospital, Inse University 1435 Jwa-Dong, Haeundae-Gu, Busan City, Korea Tel. no. +82-10-2809-5496 wansookim@paik.ac.kr I was pleased to read the article from Tassignon on taking control of PCO. PCO remains a concern in cataract surgery. In pediatric cataract surgery, prevention of PCO is critical because the visual axis obscuration can lead to permanent amblyopia. The correct sizing of the capsulorhexis is important in the capturing technique. The caliper can be a tool for the correct sizing of the capsulorhexis; however, the lens capsule is an elastic structure that can be shrunk or expanded. While making a posterior capsulorhexis, if too much viscoelastic is placed in the capsular bag, the lens capsule is expanded, the actual size of the capsulorhexis will become smaller than planned. I prefer not to fill the capsular bag with viscoelastics in order to have better control during posterior capsulorhexis. Elschnig’s pearls form in the capsular bag even after complete removal with polishing devices. As Elschnig’s pearls grow in the capsular bag, intracapsular pressure increases, then increased intracapsular pressure creates a slit like opening between the lens and the capsulorhexis margin. Escaped lens material can cause an inflammatory reaction in the vitreous, hence the vitreous opacity. Posterior capsulorhexis and optic capturing (haptic in the bag, optic capture through PCCC) is my routine procedure for pediatric cataract surgery. The advantage of this technique is that the capsule leaflet is open to the anterior chamber. The escaped lens material is quietly absorbed in the anterior chamber. In most cases, posterior capsulotomy alone can prevent posterior capsular opacification. An open posterior capsule would be a barrier to migrating lens cells. However, if the anterior vitreous face is attached to the posterior capsule (small Berger’s space), the cells can migrate on the vitreous face. Another advantage of posterior capsulotomy is refractive stability after surgery. References 1. Gimbel HV, DeBoff BM. Intraocular lens optic capture. J Cataract Refractive Surg. 2004;30:200-206. 2. Kim KH, Kim WS. Intraocular Lens Stability and Refractive Outcome after Cataract Surgery Using Primary Posterior Continuous Curvilinear Capsulorhexis. Ophthalmology 2010;117:2278-2286. Editors’ note: Prof. Kim has no financial interests related to his comments. YAO Ke, MD Professor & Chief, Eye Center, Second Affiliated Hospital, School of Medicine, Zheijiang University 88 Jiefang Road, Hangzhou, China Tel. no. +86-571-87783897 Fax no. +86-571-877839087 xlren@zju.edu.cn M any attempts have been made to control posterior capsular opacification (PCO) after IOL implantation. The bag-in-the-lens (BIL) procedure is proven to be able to decrease the incidence of PCO when it is performed using proper technique, and it also yields promising results in babies and children. According to the study in vitro and in vivo, both capsules fit tightly around the peripheral groove surrounding the optic, blocking LEC migration; thus, LEC proliferation is confined to the remaining peripheral capsular bag. Since infants and children are at great risk for PCO even when a PCCC is performed, it would be prudent to perform the BIL procedure in pediatric cataract surgery routinely if a suitably sized IOL is available. However, although it is suggested that this procedure has increased benefits, I still have some concerns. Firstly, the learning curve of this novel technique will be somewhat difficult for the surgeons, and the risk of anterior hyaloid rupture will be increased during PCCC performed by beginners despite the low incidence rate. And this complication will directly increase the incidence of retinal detachment especially in patients who already have potential retinal degeneration or hole. Secondly, I think it is still an open question whether to perform the BIL procedure in all cases, considering that the PCO rate is only about 10 to 20% in adult patients. It is known that PCO is also influenced by the IOL design and material. After the introduction of sharp-edged IOLs, the incidence of PCO decreased significantly. And our research group has attempted to control PCO using surface- modification IOLs. We have produced IOLs with hydrophilic anterior surfaces and hydrophobic posterior surfaces which have been found to have good uveal and capsular biocompatibility as well as a PCO prevention effect in animal models. More recently, we also produced IOLs by grafting the TGF-beta2 antibody onto the posterior surface using a plasma technique. This IOL also showed remarkable potential for the prevention of PCO. Editors’ note: Prof. Yao has no financial interests related to his comments. otherwise, the surgeon is never going to get both capsules within the groove. Surgeons must perform posterior continuous curvilinear capsulorhexis according to very precise protocol, perforating the posterior capsule only when the capsule is in the horizontal position. The risk of harming the anterior hyaloids is lower when the capsule is loose in the horizontal position instead of bent posteriorly with a filled capsular bag. In addition, never fill the capsular bag after having emptied it of its contents. I always perform the procedure under topical anesthesia; this way, the vitreous has no pressure and the eye is very quiet. I have had no incidences of vitreous loss. Potential complications of the procedure are the same as that of the traditional lens-in- the-bag implantation technique. The reason I use this technique routinely is because the posterior capsule is absent, allowing full transparency of the anterior segment of the eye and avoiding forward scatter of the incoming light completely. The lens can still be improved, of course, as can the lenses used in the traditional implantation technique. However, if optimal quality of vision is the goal, it cannot be obtained with classic lens implantation because patients will find decreases in visual acuity or contrast sensitivity with time as the capsular bag becomes more opaque due to conditions such as fibrotic reaction, capsular contraction, and proliferation of continued on page 42