Ординатура / Офтальмология / Английские материалы / Modern Cataract Surgery_Kohnen_2002

PCO as a postoperative complication of phacoemulsification and IOL implantation remains a major issue in cataract surgery [31]. Most techniques for objective quantification of PCO use evaluation of retroillumination photographs [7, 26, 30]. Lasa et al. [21] first developed a method of documenting PCO by means of Scheimpflug photography. However, this system found no wider application in clinical studies because it involved only the central 1-mm zone of the IOL optic. Hayashi et al. [14] presented a technique of PCO quantification by averaging the density values of the posterior capsule in Scheimpflug images taken on different meridians. They found this to be a valid and reliable method but pointed out that some improvements had yet to be made to establish this system as a routine technique. A close attachment of the posterior lens capsule to the IOL optic is seen as an important factor for PCO prevention [25]. Scheimpflug photography allows for documentation of changes in the distance between IOL optic and posterior capsule [15]. Klos et al. [15] reported about Scheimpflug evaluation of changes in IOL material such as the ‘glistenings’ in acrylic IOLs.

Recently, we published a study on Scheimpflug imaging of phakic anterior and posterior chamber IOLs (pIOL) for correction of refractive errors [3] and could show that this is a valuable tool for the postoperative monitoring of position and stability of the implants and of possible cataract development in the human lens that could be caused by phakic IOLs.

Conclusion

Centration in the capsular bag achieved with modern three-piece foldable IOLs is excellent and comparable with that of PMMA IOLs. Scheimpflug photography offers a noncontact biometric method that is fast and easy to perform and has been proven suitable for routine examinations of phakic and pseudophakic IOLs.

References

1Allarakhia L, Knoll RL, Lindstrom RL: Soft intraocular lenses. J Cataract Refract Surg 1987;13: 607–620.

2Auran JD, Koester CJ, Donn A: In vivo measurement of posterior chamber intraocular lens decentration and tilt. Arch Ophthalmol 1990;108:75–79.

3Baumeister M, Bühren J, Schnitzler EM, Ohrloff C, Kohnen T: Scheimpflug-fotografische Untersuchungen nach Implantation phaker Vorderund Hinterkammer-Intraokularlinsen: Erste Erfahrungen. Klin Monatsbl Augenheilkd 2001;218:125–130.

4Brown N: Slit-image photography. Trans Ophthalmol Soc UK 1969;89:397–408.

5Chen TT: Clinical experience with soft intraocular lens implantation. J Cataract Refract Surg 1987;13:50–53.

6Dragomirescu V, Hockwin O, Koch HR, Sasaki K: Development of a new equipment for rotating slit image photography according to Scheimpflug’s principle; in Hockwin O (ed): Gerontological Aspects of Eye Research. Basel, Karger, 1978, pp 118–130.

7Friedman DS, Duncan DD, Munoz B, West SK, Schein OD: Digital image capture and automated analysis of posterior capsular opacification. Invest Ophthalmol Vis Sci 1999;40:1715–1726.

8Hayashi H, Hayashi K, Nakao F, Hayashi F: Anterior capsule contraction and intraocular lens dislocation in eyes with pseudoexfoliation syndrome. Br J Ophthalmol 1998;82:1429–1432.

9Hayashi K, Harada M, Hayashi H, Nakao F, Hayashi F: Decentration and tilt of polymethyl methacrylate, silicone, and acrylic soft intraocular lenses. Ophthalmology 1997;104:793–798.

10Hayashi K, Hayashi H, Matsuo K, Nakao F, Hayashi F: Anterior capsule contraction and intraocular lens dislocation after implant surgery in eyes with retinitis pigmentosa. Ophthalmology 1998; 105:1239–1243.

11Hayashi K, Hayashi H, Nakao F, Hayashi F: Comparison of decentration and tilt between onepiece and three-piece polymethyl methacrylate intraocular lenses. Br J Ophthalmol 1998;82: 419–422.

12Hayashi K, Hayashi H, Nakao F, Hayashi F: Intraocular lens tilt and decentration after implantation in eyes with glaucoma. J Cataract Refract Surg 1999;25:1515–1520.

13Hayashi K, Hayashi H, Nakao F, Hayashi F: Intraocular lens tilt and decentration, anterior chamber depth, and refractive error after trans-scleral suture fixation surgery. Ophthalmology 1999;106: 878–882.

14Hayashi K, Hayashi H, Nakao F, Hayashi F: Reproducibility of posterior capsule opacification measurement using Scheimpflug videophotography. J Cataract Refract Surg 1998;24:1632–1635.

15Klos KM, Richter R, Schnaudigel O, Ohrloff C: Image analysis of implanted rigid and foldable intraocular lenses in human eyes using Scheimpflug photography. Ophthalmic Res 1999;31: 130–133.

16Kohnen T: Incision sizes with 5.5-mm total optic, 3-piece foldable intraocular lenses. J Cataract Refract Surg 2000;23:1765–1772.

17Kohnen T, Lambert RJ, Koch DD: Incision sizes for foldable intraocular lenses. Ophthalmology 1997;104:1277–1286.

18Korynta J, Bok J, Cendelin J: Changes in refraction induced by change in intraocular lens position. J Refract Corneal Surg 1994;10:556–564.

19Kozaki J, Tanihara H, Yasuda A, Nagata M: Tilt and decentration of the implanted posterior chamber intraocular lens. J Cataract Refract Surg 1991;17:592–595.

20Lakshminarayanan V, Enoch JM, Raasch T, Crawford B, Nygaard RW: Refractive changes induced by intraocular lens tilt and longitudinal displacement. Arch Ophthalmol 1986;104:90–92.

21Lasa MS, Datiles MB 3rd, Magno BV, Mahurkar A: Scheimpflug photography and postcataract surgery posterior capsule opacification. Ophthalmic Surg 1995;26:110–113.

22Leaming DV: Practice style and preferences of ASCRS members – 1999 survey. J Cataract Refract Surg 2000;26:913–921.

23Niesel P: Spaltlampenphotographie der Linse für Messzwecke. Ophthalmologica 1966;152: 387–395.

24Niesel P: Spaltlampenphotographie mit der Haag-Streit-Spaltlampe 900. Ophthalmologica 1966; 151:489–504.

25Nishi O: Posterior capsule opacification. 1. Experimental investigations. J Cataract Refract Surg 1999;25:106–117.

26Pande MV, Ursell PG, Spalton DJ, Heath G, Kundaiker S: High-resolution digital retroillumination imaging of the posterior capsule after cataract surgery. J Cataract Refract Surg 1997;23:1521–1527.

27Phillips P, Perez-Emmanuelli J, Rosskothen HD, Koester CJ: Measurement of intraocular lens decentration and tilt in vivo. J Cataract Refract Surg 1988;14:129–135.

28Sasaki K, Sakamoto Y, Shibata T, Emori Y: The multi-purpose camera: A new anterior eye segment analysis system. Ophthalmic Res 1990;22(suppl 1):3–8.

29Sasaki K, Sakamoto Y, Shibata T, Nakaizumi H, Emori Y: Measurement of postoperative intraocular lens tilting and decentration using Scheimpflug images. J Cataract Refract Surg 1989; 15:454–457.

30Tetz MR, Auffarth GU, Sperker M, Blum M, Volcker HE: Photographic image analysis system of posterior capsule opacification. J Cataract Refract Surg 1997;23:1515–1520.

31Tetz MR, Nimsgern C: Posterior capsule opacification. 2. Clinical findings. J Cataract Refract Surg 1999;25:1662–1674.

32Wang MC, Woung LC, Hu CY, Kuo HC: Position of poly(methylmethacrylate) and silicone intraocular lenses after phacoemulsification. J Cataract Refract Surg 1998;24:1652–1657.

33Yang CH, Hung PT: Intraocular lens position and anterior chamber angle changes after cataract extraction in eyes with primary angle-closure glaucoma. J Cataract Refract Surg 1997;23: 1109–1113.

Priv.-Doz. Dr. med. Thomas Kohnen, Department of Ophthalmology, Johann Wolfgang Goethe University, Theodor-Stern-Kai 7, D–60590 Frankfurt am Main (Germany)

Tel. 49 69 6301 6739, Fax 49 69 6301 3893, E-Mail Kohnen@em.uni-frankfurt.de

Fig. 1. First-generation ACR6 – round edges, nonangulated haptics: LEC proliferation at the capsulorhexis margin and on the posterior capsule.

Fig. 2. ACR6 SE – angulated haptics (10°) sharp edge technology: both anterior and posterior capsules are transparent at 8 months.

Material and Methods

IOL Characteristics

The lens is a copolymer of hydroxyethylmethacrylate (HEMA) and methylmethacrylate (MMA). The hydrophilicity percentage is 26%, refractive index is 1.46. Resistance to tearing is superior to 2 mPa, 3 times superior to hema and equivalent to silicone. It is a

one-piece lens, with an overall diameter of 12.5 mm. The haptics have a posterior angulation of 10°. Haptics and optic have a square edge (90°). The lens is manufactured by Cornéal SA, Pringy, France.

Experimental Surgery

We conducted an experimental study at the Bascom Palmer Eye Institute (Miami, Fla., USA): two groups of 8 young pigmented rabbits each were unilaterally implanted with an Acrysof (Alcon) IOL or with the modified IOL (ACR6D SE, Cornéal). Surgery consisted of a 2-mm wide clear cornea incision followed by a 4.5–5 mm capsulorhexis, lens matter extraction by infusion-aspiration, opening of the surgical entry to 4 mm, in the bag IOL insertion and closing of the wound with 10/0 nylon stitch. Two animals of each group were euthanized at postoperative days 7, 14, 21 and 28 and fixed in formalin or glutaraldehyde for Miyake’s view and histology readings. No statistical difference in PCO level was found among the groups at any of the four time periods. The optical zone was consistently more transparent with the ACR6D SE than with the acrylic IOL. No clinical or histological foreign body reaction, such as giant cells, were observed with any of the implants at any of the postoperative periods. The effect of the square edge could be demonstrated. No contact inhibition effect was observed with either material. Vacuoles were documented in the PEA-MMA (Acrysof) material.

Clinical Study

Two different groups of patients were enrolled independently in two different centers. In all cases a hydrophilic acrylic IOL (ACR6D SE, Cornéal) was implanted.

Group 1: 102 cataractous eyes of 102 patients, average age 76.4 (range 45–93) years. 13% had associated ocular pathologies: drusen, ARMD, glaucoma, diabetes. The surgical technique consisted of 4-mm unsutured temporal clear cornea incision, 4.5–5 mm capsulor-hexis, phacoemulsification, polishing of posterior capsule, in the bag implantation (forceps). Average best corrected preoperative visual acuity (BCVA) was 0.26. Average power of the IOL was 22.4 D (average constant 120). One surgeon (S.J.) operated. The postoperative regimen consisted of topical dexamethasone indomethacin 3 times a day for 1 month.

Group 2: 58 cataractous eyes of 52 patients, average age 70.5 (range 42–94) years. 47 eyes were diagnosed with cataract only. Seven of these presented with various degrees of ARMD and drusen. Two had uveitis, there was 1 case of trauma, and 2 diabetes. Nine eyes had a combined operation cataract glaucoma, 2 eyes had a combined cataract penetrating keratoplasty (PK). Average preoperative BCVA was 0.25 (SD 0.13). Average IOP was 16.44 (range 7–26) mm Hg. The surgical technique for cataract only was identical to group 1, combined glaucoma operations were nonpenetrating trabecular surgery done at the 12 o’clock position and separate temporal incision for cataract extraction. In the 2 PK cases the lens was removed through the corneal trephine. All IOLs were implanted in the bag. There was no intraoperative complication in the groups. Average power of the IOL was 23.4 D (average constant 120). One surgeon (Ph.S.) operated. The postoperative regimen consisted of dexamethasone indomethacin 3 times a day for 2 weeks, and then indomethacin alone (3 times) for 4 weeks (dexamethasone was prolonged for a further 2 months in case of combined PK).

Results

Group 1: All 102 patients were followed up at least 1 year, and 11 patients were re-examined at 18 months. 100% have a BCVA 0.5, 92% are 0.8, 68% are 1 (20/20). Best cases group (excluding 13% of eyes because of associated pathologies): 100% are 0.8, 78% are 1 (20/20). Average postoperative refraction is 0.2 D (refraction ranging from 1.25 to 1), stable during the whole follow-up period. 15% of patients demonstrated some nonprogressive deposits on the posterior capsule, they were related to incomplete intraoperative polishing of the capsule. One patient had a one-line drop of visual acuity, and 1 had a two-line drop (nonprogressive). The posterior capsule behind the optic remained clear, with no progression of LECs. Densification of the capsulorhexis margin was observed in less than 10% of the cases, without any cell proliferation on the anterior surface of the optic. No YAG capsulotomy had to be performed. The EPCO score was calculated for the 11 patients at 18 months and was 0.0207 (SD 0.12). This extremely low score corroborates the slit lamp results.

Group 2: All 58 patients were followed up for at least 8 months. Ten patients were re-examined at 1 year. Average BCVA was 0.86 (results ranging from 0.2 to 1 according to the associated pathologies). Average postoperative refraction was 0.32 D (refraction ranging from 1.25 to 1.25), stable after 2 weeks and during the whole follow-up period. Average postoperative IOP was 13.25 (range 10–22) mm Hg without treatment. No patient demonstrated any LEC progression behind the optic and the blocked LECs could consistently be seen at the equator of the optic (fig. 3–5). Two central capsular folds were documented, without VA decrease. Densification of the capsulorhexis margin was noted in 7 eyes, without any cell proliferation on the anterior surface of the optic. No YAG capsulotomy was performed.

Special attention was paid to capsule contact with the optic of the IOL, and to its stability. This was analyzed by slit lamp and by the Eye Analyzer System (EAS, Nidek).

The frontal distance of the IOL was measured from the center of the posterior cornea to the center of the optic anterior surface. This remained stable between the first week, the first month and the third month, with respective distances (expressed in mm) of 4.33 (SD 0.43), 4.32 (SD 0.31) and 4.18 (SD 0.35). No tilt, nor decentration could be detected. Contact of the anterior capsule with the anterior surface of the optic was absent in 57/58 eyes during the first week, absent in 48/58 during the first month and absent in 13/58 at 3 months. Contact of the posterior capsule at the center of the optic was absent in 54/58 eyes during the first week, absent in 37/58 during the first month and absent in 4/58 at 3 months. This absence of contact was only true for the central 3 or 4 mm of the optic. The equatorial zone had a consistent and firm contact.

Discussion

Globally these experimental and clinical results demonstrate the clinical safety and efficiency of the new IOL. No membrane or cellular formation was detected on the anterior or posterior surface of the optic. No deposit of any kind was noted on the surfaces or inside the IOL. The experimental comparison with the current ‘gold standard’ in terms of PCO prevention (Acrysof, Alcon) was logical and positive. But the highly active reproliferation of rabbit capsular bags is a limit to transposition of experimental surgery results in humans. Despite this limitation, our data, including histology readings, indicate an excellent tolerance and some decrease in lens regeneration, with a consistent greater posterior capsule clarity in the ACR6 SE group.

Our two groups of clinical results are not comparable: Group 1 has more standard indications of cataract operations, with VA results far above the FDA requirements. This group also demonstrated a clinically absent PCO during the 18-month follow-up period. Group 2 has been designed as a combination of various indications, potentially subject to more postoperative inflammation and to various ocular reactions than straightforward cataract cases. The average postoperative VA is lower, as expected, but no adverse reaction has been noted.

It is currently possible to document PCO very precisely: slit-lamp examination to assess capsule contact with IOL optic and haptics, LEC migration from the equator of the capsular bag, and capsular transparency between the equator and the optic will identify any early or secondary proliferation transformation of the LECs. EPCO software analysis offers a reproducible and objective measurement, and can be used in multicentric studies to compare surgical techniques, IOL designs and materials. The absence of anterior capsule-IOL optic contact will prevent LEC proliferation on the anterior surface of the optic, whether they come from the anterior capsule (early migration), or from the germinative zone of the equator (secondary migration). If the contact is durably absent the anterior capsule will remain transparent, and no anterior LEC migration is possible. Since the stability of the IOL does not rely on this adherence, no complication will occur from such an anatomical situation. On the contrary, the earlier the contact between with the posterior capsule and the posterior surface of the optic, the more efficient the prevention of LEC migration and transformation between the optic and the biologically active lens capsule. Assessment of consistent and total posterior contact by increased vaulting of the optic becomes a must of implantology.

While we are still expecting a clinically acceptable chemical treatment for the prevention of LEC migration and transformation, we now have a larger choice of IOLs that significantly decrease the incidence of PCO and the incidence of YAG capsulotomy.

References

1Hara T, Hara T, Yamada Y: ‘Equator’ ring for maintenance of the completely circular contour of the capsular bag equator after cataract removal. Ophthalmic Surg 1991;22:358–359.

2Nishi O, Nishi K, Sakanishi K: Inhibition of migrating lens epithelial cells at the capsular bend created by the rectangular optic edge of a posterior chamber intraocular lens. Ophthalmic Surg Lasers 1998;29:587–594.

3Nishi O, Nishi K: Preventing posterior capsule opacification by creating a discontinuous sharp bend in the capsule. J Cataract Refract Surg 1999;25:521–526.

4Nishi O, Nishi K, Wickstrom K: Preventing lens epithelial cell migration using intraocular lenses with sharp rectangular edges. J Cataract Refract Surg 2000;26:1543–1549.

5Menapace R, Findl O, Georgopoulos M, Rainer G, Vass C, Schmetterer K: The capsular tension ring: Designs, applications and techniques. J Cataract Refract Surg 2000;26:898–912

6Werner L, Apple DJ, Escobar-Gomez M, Ohrstrom A, Crayford BB, Bianchi R, Pandey SK: Postoperative deposition of calcium on the surfaces of a hydrogel intraocular lens. Ophthalmology 2000;107:2179–2185.

Dr. Philippe Sourdille, Clinique Sourdille,

3, place Anatole France, F–44040 Nantes (France)

Tel. 33 251 833 245, E-Mail philippesourdille@wanadoo.fr