Intraocular lenses for the correction of refraction errors. Part 1: phakic anterior chamber lenses

In this overview, the current status of intraocular lens surgery to correct refractive error is reviewed. The interventions are divided into additive surgery with intraocular lens implantation without extraction of the crystalline lens (phakic intraocular lens, PIOL) or the removal of the crystalline lens with implantation of an IOL (refractive lens exchange, RLE). Phakic IOLs are constructed as angle-supported or iris-fixated anterior chamber lenses and posterior chamber lenses that are fixated in the ciliary sulcus. The implantation of phakic IOLs has been demonstrated to be an effective, safe, predictable and stable procedure to correct higher refractive errors. Complications are rare and differ for the three types of PIOL; for anterior chamber lenses these are mainly pupil ovalization and endothelial cell loss.     

Intraokularlinsen zur Korrektur von Refraktionsfehlern

In this overview, the current status of intraocular lens surgery to correct refractive error is reviewed. The interventions are divided into additive surgery with intraocular lens implantation without extraction of the crystalline lens (phakic intraocular lens, PIOL) or removal of the crystalline lens with implantation of an IOL (refractive lens exchange, RLE). Phakic IOLs are constructed as angle-supported or iris-fixated anterior chamber lenses and posterior chamber lenses which are fixated in the ciliary sulcus. The implantation of phakic IOLs has been demonstrated to be an effective, safe, predictable and stable procedure to correct higher refractive errors. Complications are rare and differ for the three types of PIOL; for posterior chamber lenses these are mainly cataract formation and pigment dispersion. RLE is preferable in cases of high ametropia in which the natural lens has lost its accommodative effect. The main complications for myopic RLA include retinal detachment, while hyperopic refractive lens exchange may be associated with surgical problems in the narrower anterior eye segment.     

Intraocular lenses for the correction of refraction errors. Part II. Phakic posterior chamber lenses and refractive lens exchange with posterior chamber lens implantation

In this overview, the current status of intraocular lens surgery to correct refractive error is reviewed. The interventions are divided into additive surgery with intraocular lens implantation without extraction of the crystalline lens (phakic intraocular lens, PIOL) or removal of the crystalline lens with implantation of an IOL (refractive lens exchange, RLE). Phakic IOLs are constructed as angle-supported or iris-fixated anterior chamber lenses and posterior chamber lenses which are fixated in the ciliary sulcus. The implantation of phakic IOLs has been demonstrated to be an effective, safe, predictable and stable procedure to correct higher refractive errors. Complications are rare and differ for the three types of PIOL; for posterior chamber lenses these are mainly cataract formation and pigment dispersion. RLE is preferable in cases of high ametropia in which the natural lens has lost its accommodative effect. The main complications for myopic RLA include retinal detachment, while hyperopic refractive lens exchange may be associated with surgical problems in the narrower anterior eye segment.     

Phake Intraokularlinsen

Refractive surgical procedures are generally divided into additive procedures with, e.?g. implantation of an artificial lens and subtractive procedures with ablation of corneal tissue. In this article the current status of phakic intraocular lens (IOL) implantation for correction of refractive errors is reviewed. Phakic IOLs are constructed as angle-supported or iris-fixated anterior chamber lenses and sulcus-fixated posterior chamber lenses. The implantation of phakic IOLs has been demonstrated to be an effective, safe, predictable and stable procedure to correct higher refractive errors. Complications are rare and depend to a large extent on the location. For anterior chamber lenses the main concern is critical endothelial cell loss and for posterior chamber lenses early cataract formation.     

虹膜夹型人工晶状体矫正高度近视的前节OCT检查分析

目的:使用前节OCT分析高度近视植入虹膜夹型人工晶状体后眼内的结构变化。方法:植入前房晶状体矫正高度近视6眼(11.5D至22.0D),使用前节OCT采集前节图像测量术前前房深度,术后人工晶状体与角膜内皮间距离(内皮—晶状体距离),人工晶状体与正常晶状体间距离。结果:术前前房深度为3.27～3.91mm,术后内皮—晶状体距离为2.07～2.24mm。人工晶状体后表面与正常晶状体间的距离为0.82～1.32mm。图像显示虹膜色素层没有明显改变。结论:前房深度较术前减少36.1%～44.6%。前节OCT对于检测虹膜夹型前房晶状体的位置有帮助。     

Scheimpflug photographic imaging following implantation of anterior and posterior chamber phakic intraocular lenses: preliminary results

BACKGROUND: For the correction of refractive errors lenticular procedures are increasingly used in addition to corneal refractive surgery. One of those techniques is the implantation of intraocular lenses into phakic eyes (pIOL). Due to the close neighborhood of the implant to delicate intraocular structures, exact positioning and high postoperative stability are required. Scheimpflug photography has been shown to be a suitable instrument for the biometry of the anterior eye segment and the examination of IOL position. PATIENTS AND METHODS: Four anterior chamber phakic IOLs (pIOLs) (Bausch & Lomb NuVita) and 7 posterior chamber pIOLs (Staar ICL) were examined 1 week, 1 month and 3-6 months following implantation. At each examination 1 Scheimpflug slit image and 1 infrared retroillumination image were taken using the anterior eye segment analysis system EAS-1000 (Nidek Co., Gamagori, Japan). Evaluation of the images was performed with a personal computer and the software provided by the manufacturer. The distance of the pIOL to cornea and human lens was calculated and incidence and amount of pIOL rotation around the optical axis and potential crystalline lens opacification were assessed. RESULTS: The distance between the anterior chamber pIOL and the cornea 1 week after implantation was 1.61 +/- 0.10 mm. The distances between the myopic posterior chamber pIOL and the human lens were 0.34 +/- 0.11 mm and between the hyperopic posterior chamber pIOL and the human lens 0.26 and 0.29 mm, respectively. The values were constant over a period of 3-6 months. The pIOL showed no movement or change of position around the optical axis. There was no detectable cataract formation in the human lens. CONCLUSIONS: All implanted phakic anterior and posterior chamber IOLs showed a stable position in the eye within the observation period. Scheimpflug photography is proved to be a useful technique for the postoperative evaluation of the positioning of phakic IOLs.     

应用Pentacam三维眼前段分析仪对虹膜夹型人工晶状体植入术后的研究

目的 应用Pentacam术后追踪测量虹膜夹型有晶状体眼人工晶状体(PIOL)中央和周边部与角膜内皮和自然晶体之间的距离,倾斜度、偏心值以及前房深度的变化,评价其在前房的位置.方法 收集自2006年1月以来接受虹膜夹型人晶状体植入术的22例33只眼.术后6个月全部患者行Pentacam检查,测量VRSM50和VRSM60两组不同类型虹膜夹型PIOL中央和周边部与角膜内皮和自然晶体之间的距离,并测量术后1d、1、3及6个月人工晶状体的偏心量、倾斜度及前房深度值.结果 角膜内皮至PIOL光学部前表面距离为(1.94±0.36)mm.PIOL后表面与自然晶状体间的距离为(0.76±0.12)mm.分别比较各组在不同时期的平均偏心量与平均倾斜度,差异无统计学意义(P>0.05).在术后1d、1、3及6个月,比较2组的平均偏心量与平均倾斜度,差异无统计学意义(P>0.05).结论 Pentacam三维眼前段分析仪为PIOL植入术后提供高质量的Scheimpflug摄像,可以为有晶状体眼前房型人工晶状体提供精确的眼内定位,在这一方面具有重要的临床应用价值.     

有晶状体眼前房角固定型人工晶状体植入术的进展

有晶状体眼前房角固定型人工晶状体植入术是近年来发展起来的矫正高度和超高度近视的一项新技术，随着晶状体材料的改良和临床经验的积累，这种屈光手术逐渐显示出了安全、有效、预测性好、可逆性、保留调节功能和对角膜内皮损伤小等优点。因此，在未来的几年里，前房角固定型人工晶状体植入术作为一种屈光手术将会扩大它的临床应用范围。就该手术的历史、人工晶状体的设计、手术适应证与禁忌证、手术技术、并发症及其防治等方面进行综述。     

Intraocular lens implantation in phakic rabbit eyes

Three sizes (13.5 mm, 17.5 mm, and 18.5 mm) of open loop, one piece, poly(methyl methacrylate) anterior chamber intraocular lenses (IOLs) were implanted in 12 phakic rabbit eyes to evaluate the effect of the IOL on the crystalline lens and the anterior chamber. Six eyes were used as a control group. Minimum follow-up was four weeks. All the IOLs touched the crystalline lenses, and on the first postoperative day, round subcapsular lens opacities were found in all eyes in the area of IOL contact. The lens opacities became more dense with time. Only one eye in the control group showed a subcapsular opacity, which was linear rather than round. Anterior chamber inflammation was 1+ to 2+ in ten eyes (80%) in the IOL group during the first and second weeks, whereas minimal inflammatory changes occurred in the control group. These results suggest that with current IOL technology, IOL insertion in the phakic eye to correct refractive errors results in a high incidence of cataract if IOL-to-lens touch occurs.     

Intraocular pressure in myopic patients after Worst-Fechner anterior chamber phakic intraocular lens implantation

PURPOSE: To assess intraocular pressure measured with a Goldmann tonometer over a period of 1 year after implantation of a Worst-Fechner anterior chamber phakic intraocular lens to correct myopia of -7.00 D or more. METHODS: We performed a prospective, non-masked study of 100 patients (100 myopic eyes) who had a Worst-Fechner phakic intraocular lens implanted to correct myopia of -7.00 D or greater. Central corneal Goldmann tonometry was performed before surgery and 1, 3, 6, and 12 months after surgery. The influence of different variables was assessed. RESULTS: IOP showed a significant increase of a mean 2.1 mmHg at 3 months after surgery (P=.001). There was not a statistically significant difference between IOP before surgery and 6 months after PIOL implantation (P=.244) or 1 year after surgery (P=.845). In one eye, the lens was explanted 11 months after surgery because of the presence of ocular hypertension. No variables studied showed a statistically significant difference from before to after surgery. CONCLUSIONS: Worst-Fechner anterior chamber phakic intraocular lens implantation led to a slight transitory increase of intraocular pressure during the first 3 months after surgery, but returned to preoperative levels by 6 months after implantation.     

Ultrasound biomicroscopy of the iris-claw phakic intraocular lens for high myopia

PURPOSE: To study the in situ relative intraocular position of the Ophtec Artisan iris-claw phakic intraocular lens (PIOL) for high myopia using ultrasound biomicroscopy. METHODS: Three PIOLs (13.00, 17.00 and 18.00 D lens powers) were implanted in phakic myopic eyes. Using ultrasound biomicroscopy, echograms were taken in the anterior chamber to measure the preoperative anterior chamber depth, postoperative distance between the PIOL and the corneal endothelium (endothelial-optic distance), and the postoperative distance between the PIOL and the crystalline lens. RESULTS: Preoperative anterior chamber depth ranged from 3.10 to 3.40 mm and the postoperative endothelial-optic distance measured 2.11 to 2.44 mm. The distance between the crystalline lens and the posterior surface of the IOL ranged from 0.78 to 0.93 mm. Several echograms revealed the position of the PIOL on the iris. The pigment layer of the iris did not seem to be disturbed by the presence of the PIOL. CONCLUSION: The original anterior chamber depths were reduced by 28% to 34% after implantation. The PIOL-crystalline lens distance ranged from 0.78 to 0.93 mm. This study of 3 eyes revealed that echograms taken by ultrasound biomicroscopy are useful in verifying the intraocular position of the PIOL within the anterior chamber.     

Decentration and cataract formation 10 years following posterior chamber silicone phakic intraocular lens implantation

PURPOSE: To report a 10-year follow-up for bilateral implantation of a Chiron Adatomed silicone posterior chamber phakic intraocular lens (PIOL). METHODS: A 32-year-old man presented with bilateral blurred vision and monocular diplopia in the left eye of 2 years' duration. RESULTS: Slit-lamp microscopy showed bilateral anterior subcapsular cataract and temporal PIOL decentration, and no visible space between the PIOL and crystalline lens in the right eye. After explantation of the posterior chamber PIOL, lens aspiration, and IOL implantation, uncorrected visual acuity improved to 20/15 in the right eye. Scanning electron microscopy examination showed denser deposits on the central portion of the back surface when compared with the edges. CONCLUSIONS: Long-term follow up of certain designs of posterior chamber PIOLs may reveal late occurrence of complications. Cataract formation may be related to direct contact between the implanted and crystalline lenses.     

Position of angle-supported, iris-fixated, and ciliary sulcus-implanted myopic phakic intraocular lenses evaluated by Scheimpflug photography

PURPOSE: To examine postoperative positional stability of myopic phakic intraocular lenses (IOLs). DESIGN: Prospective, nonrandomized clinical study. METHODS: The study included 46 eyes which received an anterior chamber angle-supported (Bausch & Lomb NuVita; 10 eyes), anterior chamber iris-fixated (Ophtec Artisan; 20 eyes) or ciliary sulcus-implanted phakic IOL (Staar ICL; 16 eyes). The distance between the phakic IOL and the crystalline lens and the cornea as well as rotation around the optical axis was evaluated using Scheimpflug photography at 1, 3 to 6, and 12 months postsurgery. RESULTS: The anterior chamber phakic IOLs showed no significant movement in anteroposterior direction. The posterior chamber phakic IOL showed a significant movement toward the crystalline lens between postoperative months 3 and 12. The median amount of rotation around the optical axis between the 3- and the 12-month evaluation was 1.9 degrees (range = 0.0-33.5 degrees) for the NuVita, 0.6 degrees (range = 0.0-3.5 degrees) for the Artisan, and 0.9 degrees (range = 0.2-2.3 degrees) for the ICL. Four NuVita IOLs rotated more than 10 degrees. CONCLUSIONS: The angle-supported anterior chamber phakic IOLs showed a generally stable position regarding distance to cornea and natural lens, but rotation was observed in four IOLs. The iris-fixated phakic IOL showed the highest overall stability. The posterior chamber phakic IOL was stable in terms of rotation but had a tendency to decrease in distance toward the crystalline lens. Intraocular lenses implanted in phakic eyes followed for 12 months demonstrate stable IOL position overall.     

Intermittent myopic shift of 4.0 diopters after implantation of an Artisan iris-supported phakic intraocular lens

A 45-year-old man with bilateral high myopia and myopic astigmatism had uneventful implantation of a -10.5 diopters (D) Artisan iris-fixated anterior chamber phakic intraocular lens (PIOL) (Ophtec) in both eyes. In the first days after surgery, uncorrected visual acuity (UCVA) was 20/16 in the right eye and 20/16 in the left; the position of the PIOL was stable. Ten days after surgery, the left eye developed a myopic shift of 4.0 D. Further examination showed that the myopia disappeared when the pupil was medically dilated. After the pupil returned to a natural position, the myopic shift reappeared. Because there were no changes in the subsequent 4 months, we decided to exclavate the IOL, rotate it by 10 degrees, and reenclavate it with less tissue. The myopic shift did not return over the following 20 months, and the UCVA was 20/20. In rare cases, iris-fixated anterior chamber IOLs may induce refractive changes related to effects on the surrounding anatomic structures. This may be corrected by phakic IOL rotation or reenclavation of the phakic IOL with less tissue.     

Bioptics: where do things stand?

PURPOSE OF REVIEW: Bioptics treats complex refractive errors by combining refractive techniques with different mechanisms of action, usually using an intraocular implant (a phakic or pseudophakic intraocular lens) followed by a corneal procedure (laser ablation, intrastromal implant). RECENT FINDINGS: In myopia and hyperopia, bioptics with phakic intraocular lenses or refractive lens exchange and subsequent excimer laser yields improved predictability and unchanged safety, compared with sole intraocular lens surgery. Complications are related mainly to intraocular lenses. In keratoconus and pellucid marginal degeneration, intracorneal rings have been successfully combined with phacoemulsification or with phakic intraocular lenses in a limited number of eyes. In the author's series, angle-supported phakic intraocular lenses were implanted in 12 eyes to correct a mean regression of -8 D after excimer laser (reverse bioptics), achieving a mean spherical equivalent of -0.3 D, mean best spectacle-corrected visual acuity of 0.7, and mean uncorrected visual acuity of 0.5, with 83% of eyes within 0.5 D of spherical equivalent. SUMMARY: Bioptics improves vision and halos and adds no particular risks to phakic or pseudophakic intraocular lens implantation in either myopia or hyperopia. Reverse bioptics, with phakic intraocular lenses or refractive lens exchange, can be used to correct regressed corneal surgery.     

Phakic intraocular lenses and refractory lensectomy for myopia

Phakic intraocular lens implantation (IOLs) and clear lens extraction for high to extreme myopia have grown in popularity recently as a consequence of potentially unsatisfactory results with corneal refractive surgery in higher ranges of refractive errors. The refractive outcome of these alternative modalities has been encouraging to date, yet the potential for significant complications exists. Current evidence shows that the risk of retinal detachment after clear lens extraction for myopes is high. Trials with angle-supported phakic IOLs revealed unacceptable rates of pupillary ovalization, IOL rotation, and endothelial cell loss. Iris-fixated and posterior chamber phakic IOLs have proven sufficient safety, but long-term follow-ups of current cohorts are still to be awaited. The implantation of either of the latter two phakic IOLs followed by laser in situ keratomileusis or photorefractive keratectomy (bioptics) provides another option in refractive surgery for high ametropia.     

Silicone posterior chamber phakic intraocular lens dislocated into the vitreous cavity

PURPOSE: To report two highly myopic patients with silicone posterior chamber phakic intraocular lenses (Phakic Refractive Lens; CIBA Vision, Duluth, Ga) that luxated into the vitreous cavity without history of ocular trauma. METHODS: Two patients with posterior chamber phakic intraocular lenses (PIOLs) that luxated into the vitreous cavity of the right eye were examined. Each eye underwent pars plana vitrectomy and removal of the posterior chamber PIOL under retrobulbar anesthesia. RESULTS: Both patients were treated successfully. In the first patient, the posterior chamber PIOL luxated into the anterior vitreous cavity whereas in the second patient, the posterior chamber PIOL lay on the posterior pole. No ocular complications developed postoperatively. CONCLUSION: Luxation into the vitreous cavity is a rare, but potentially severe complication of posterior chamber PIOL refractive surgery in highly myopic eyes. Successful management includes pars plana vitrectomy and removal of the posterior chamber PIOL.     

Infections after intraocular lens surgery: implications for refractive surgery

Apart from the classical indication of removing an opaque lens that is compromising vision, extraction of the crystalline lens is gaining increasing importance as a refractive procedure. This literature review which considers the present guidelines of various ophthalmological societies and recently published studies is intended to give an estimate of the incidence of postoperative endophthalmitis and evidence-based recommendations for its prophylaxis, diagnosis, and therapy. The incidence of endophthalmitis after cataract extraction is reported to be 0.04 % to 0.3 % in most sizeable studies. Immediate sequential bilateral cataract surgery is internationally gaining popularity. It remains difficult to estimate whether or not the risk of endophthalmitis is affected with this approach. A toxic anterior segment syndrome (TASS) needs to be differentiated from postoperative endophthalmitis. TASS is an acute sterile inflammation after cataract surgery. Remnants of detergents and antiseptics on the surgical instruments are supposed to be main triggers. Additionally, the inappropriate preparation of solutions and antibiotics for intracameral use is considered to be a major cause. A case of TASS was also reported after implantation of an iris-fixated anterior chamber lens in a phakic eye. The cefuroxime solution that was prophylactically used in the ESCRS study and that is recommended for routine cataract surgery is not commercially available in Germany as a ready preparation for intraoperative application. Different measures are undertaken in different countries to prevent postoperative endophthalmitis, whose values are not exactly quantifiable. Antisepsis with povidone-iodine is still considered to be the component with the best evidence. For management of acute postoperative endophthalmitis, the systemic application of antibiotics is recommended in addition to their intravitreal injection. Few case reports have been published describing an infection after the implantation of refractive intraocular lenses (IOLs) in a phakic eye. However, we could not find meaningful information regarding the incidence of endophthalmitis after implantation of refractive IOLs. Based on the fact that these IOLs are not implanted into the capsular bag but in front of the crystalline lens or into the anterior chamber, and the presumably better anti-microbial immunity of this younger population compared to cataract patients, one may assume that the infection rate is lower than after cataract surgery. Nevertheless, a prospective register to document all endophthalmitis cases is desirable.     

Scanning electron microscopic characteristics of phakic intraocular lenses

OBJECTIVE: To analyze the surface quality of new generation phakic intraocular lenses (IOLs). DESIGN: Experimental materials study. MATERIALS: Three different new generation phakic IOLs: angle-fixated anterior chamber lens Chiron Vision NuVita MA20 (polymethylmethacrylate [PMMAD, iris-fixated anterior chamber lens Ophtec Artisan Iris-Claw (PMMA), posterior chamber lens Staar ICM (polymer from porcine collagen and 2-hydroxyethyl methacrylate [HEMA]). METHODS: Representative samples of three different phakic IOLs underwent surface and edge-finish examination with light microscopy (LM). The phakic IOLs were then examined by use of scanning electron microscopy (SEM), and particular attention was given to optic surface quality, edge finish, haptic, and optic/haptic junction. RESULTS: In all IOLs the LM examination showed a smooth and homogeneous surface. No irregularities, particularly at the optic front and back surface, optic edge, haptic, and the optic/haptic junctions, were detected by SEM. One exception was a minor surface roughness at the claws of an Artisan iris-fixated anterior chamber IOL. CONCLUSIONS: Phakic IOLs are implanted either in the anterior or posterior chamber of healthy eyes, and high standards for their surface quality are required. The evaluation of surface properties with LM and SEM did not reveal any defects that contraindicate the implantation of phakic IOLs.     

Contact between 3 phakic intraocular lens models and the crystalline lens: an anterior chamber optical coherence tomography study

Three phakic intraocular lens (IOL) models were implanted in 3 different patients. With the usual slitlamp examination, it was not possible to determine whether there was contact between the IOLs and the natural crystalline lens. Using the anterior chamber optical coherence tomography (AC OCT) scanner, direct contact between the natural crystalline lens and the 3 phakic IOLs was revealed. A dynamic study of the contact was performed during accommodation. These observations show that examination of the anterior segment with the AC OCT scanner provides new data about the status of the anterior segment after implantation of phakic IOLs.