LETTERS
Toric intraocular lens rotation related to the capsulorhexis Miayke et al.1 described the long-term clinical outcomes of toric intraocular lens (IOL) implantation in cataract cases with preexisting astigmatism. The incidence of postoperative significant rotation (more than 20 degrees) of toric IOLs was 1.6% (6 eyes). The authors described 2 main risk factors for this large rotation: long axial length (AL) and with-the-rule (WTR) astigmatism. However, they did not describe the size of the capsulorhexis in these cases. The pictures of 4 (of 6) eyes that had large IOL rotations were shown in the article, and in all except case 2, one can see a very large capsulorhexis not covering the IOL optic. In case 2, the optic is only partially covered by the anterior capsule and in the remainder of cases, in only the haptics is there contact between the anterior capsule and the IOL. The optic is completely free of contact between the lens and the anterior capsule in these cases. The IOLs and both haptics should always be placed in the capsular bag through a capsulorhexis that ideally should be 0.5 mm smaller than the IOL optic diameter (Figure 1). After implantation of a toric IOL in the capsular bag, the anterior and posterior capsules fuse with the IOL, preventing IOL rotation.2 Strong IOL adhesions to the capsular bag are thought to prevent IOL rotation. Several in vitro studies have examined the interactions between IOL biomaterials and the capsular bag. Extracellular matrix proteins such as fibronectin, vitronectin, and collagen type IV are in the aqueous humor following cataract surgery and may be involved in IOL adhesion to the capsular bag. Fibronectin, in particular,
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is thought to play a major role in IOL–capsular bag adhesion.2 A larger area of contact between the capsules and the IOL could theoretically induce more adhesions and, consequently, better rotational stability. Therefore, in addition to the long AL and WTR astigmatism, the large capsulorhexis should be considered as an additional risk factor for significant postoperative toric IOL rotation. Leonardo Torquetti, MD, PhD Para de Minas, Brazil REFERENCES 1. Miyake T, Kamiya K, Amano R, Iida Y, Tsunehiro S, Shimizu K. Long-term clinical outcomes of toric intraocular lens implantation in cataract cases with preexisting astigmatism. J Cataract Refract Surg 2014; 40:1654–1660 2. Linnola RJ, Werner L, Pandey SK, Escobar-Gomez M, Znoiko SL, Apple DJ. Adhesion of fibronectin, vitronectin, laminin, and collagen type IV to intraocular lens materials in pseudophakic human autopsy eyes. Part 1: histological sections. J Cataract Refract Surg 2000; 26:1792–1806
Reply : We appreciate the insightful comments of Dr. Torquetti. We usually attempt to completely cover the IOL with the anterior capsule when toric IOL implantation is performed, since a larger area of contact between the capsules and the IOL could induce more adhesions and consequently better IOL rotational stability.1 Although a larger capsulorhexis, that is, incomplete coverage of the IOL with the anterior capsule, was found in 3 of 6 eyes that showed significant IOL rotation in this series, 4 eyes rotated significantly within 1 day postoperatively. Although we agree that the larger capsulorhexis can be a possible risk factor for postoperative IOL rotation, especially in the late postoperative period, we assume that it remains unclear whether complete coverage of the IOL with the anterior capsule prevents significant IOL rotation in the early postoperative period, as found in this series, and that a longer AL, younger patients, and WTR astigmatism are the major risk factors for significant postoperative toric IOL rotation.d Toshiyuki Miyake, MD, Kazutaka Kamiya, MD, PhD, Kimiya Shimizu, MD, PhD REFERENCE
Figure 1. Capsulorhexis covering the IOL optics for 360 degrees.
1. Linnola RJ, Werner L, Pandey SK, Escobar-Gomez M, Znoiko SL, Apple DJ. Adhesion of fibronectin, vitronectin, laminin, and collagen type IV to intraocular lens materials in pseudophakic human autopsy eyes. Part 1: histological sections. J Cataract Refract Surg 2000; 26:1792–1806
J CATARACT REFRACT SURG - VOL 41, FEBRUARY 2015
Toric intraocular lens rotation related to the capsulorhexis Miayke et al.1 described the long-term clinical outcomes of toric intraocular lens (IOL) implantation in cataract cases with preexisting astigmatism. The incidence of postoperative significant rotation (more than 20 degrees) of toric IOLs was 1.6% (6 eyes). The authors described 2 main risk factors for this large rotation: long axial length (AL) and with-the-rule (WTR) astigmatism. However, they did not describe the size of the capsulorhexis in these cases. The pictures of 4 (of 6) eyes that had large IOL rotations were shown in the article, and in all except case 2, one can see a very large capsulorhexis not covering the IOL optic. In case 2, the optic is only partially covered by the anterior capsule and in the remainder of cases, in only the haptics is there contact between the anterior capsule and the IOL. The optic is completely free of contact between the lens and the anterior capsule in these cases. The IOLs and both haptics should always be placed in the capsular bag through a capsulorhexis that ideally should be 0.5 mm smaller than the IOL optic diameter (Figure 1). After implantation of a toric IOL in the capsular bag, the anterior and posterior capsules fuse with the IOL, preventing IOL rotation.2 Strong IOL adhesions to the capsular bag are thought to prevent IOL rotation. Several in vitro studies have examined the interactions between IOL biomaterials and the capsular bag. Extracellular matrix proteins such as fibronectin, vitronectin, and collagen type IV are in the aqueous humor following cataract surgery and may be involved in IOL adhesion to the capsular bag. Fibronectin, in particular,
483
is thought to play a major role in IOL–capsular bag adhesion.2 A larger area of contact between the capsules and the IOL could theoretically induce more adhesions and, consequently, better rotational stability. Therefore, in addition to the long AL and WTR astigmatism, the large capsulorhexis should be considered as an additional risk factor for significant postoperative toric IOL rotation. Leonardo Torquetti, MD, PhD Para de Minas, Brazil REFERENCES 1. Miyake T, Kamiya K, Amano R, Iida Y, Tsunehiro S, Shimizu K. Long-term clinical outcomes of toric intraocular lens implantation in cataract cases with preexisting astigmatism. J Cataract Refract Surg 2014; 40:1654–1660 2. Linnola RJ, Werner L, Pandey SK, Escobar-Gomez M, Znoiko SL, Apple DJ. Adhesion of fibronectin, vitronectin, laminin, and collagen type IV to intraocular lens materials in pseudophakic human autopsy eyes. Part 1: histological sections. J Cataract Refract Surg 2000; 26:1792–1806
Reply : We appreciate the insightful comments of Dr. Torquetti. We usually attempt to completely cover the IOL with the anterior capsule when toric IOL implantation is performed, since a larger area of contact between the capsules and the IOL could induce more adhesions and consequently better IOL rotational stability.1 Although a larger capsulorhexis, that is, incomplete coverage of the IOL with the anterior capsule, was found in 3 of 6 eyes that showed significant IOL rotation in this series, 4 eyes rotated significantly within 1 day postoperatively. Although we agree that the larger capsulorhexis can be a possible risk factor for postoperative IOL rotation, especially in the late postoperative period, we assume that it remains unclear whether complete coverage of the IOL with the anterior capsule prevents significant IOL rotation in the early postoperative period, as found in this series, and that a longer AL, younger patients, and WTR astigmatism are the major risk factors for significant postoperative toric IOL rotation.d Toshiyuki Miyake, MD, Kazutaka Kamiya, MD, PhD, Kimiya Shimizu, MD, PhD REFERENCE
Figure 1. Capsulorhexis covering the IOL optics for 360 degrees.
1. Linnola RJ, Werner L, Pandey SK, Escobar-Gomez M, Znoiko SL, Apple DJ. Adhesion of fibronectin, vitronectin, laminin, and collagen type IV to intraocular lens materials in pseudophakic human autopsy eyes. Part 1: histological sections. J Cataract Refract Surg 2000; 26:1792–1806
J CATARACT REFRACT SURG - VOL 41, FEBRUARY 2015
