Ординатура / Офтальмология / Английские материалы / Phakic Intraocular Lenses_Hardten, Lindstrom, Davis_2004

Figure 9-14C. Cataract formation after implantation of PC phakic IOL. Distinct anterior subcapsular cataract in an eye with PC phakic IOL (courtesy of E. Rosen, England).

Figure 9-14D. Cataract formation after implantation of PC phakic IOL. Retroillumination of anterior subcapsular cataract in an eye with PC phakic IOL (courtesy of Jorge L. Alió,Alicante, Spain).

The specific complications of PC phakic IOLs are caused by their position between the iris and the natural lens. The most common complications—cataract formation (Figures 9-14A to 9-14D), pupillary block, and glau- coma—are dependent on the lens position, material, and original design, as well as the generation, of the different models. In the following, specific complications of PC phakic IOLs are discussed, especially for the ICL, the Adatomed IOL (Chiron, Claremont, Calif), and the phakic refractive lens (PRL) (CIBA Vision, Duluth, Ga).

Cataract Formation

Causative factors for cataract formation (see Figures 9- 14A to 9-14D) are lens materials, position, surgical trauma, as well as lens design/generation.

After implantation of Adatomed IOLs, Brauweiler et al reported 81.9% cataract formation after a follow-up of 2 years in which two of 17 eyes developed lens opacifica-

tion in the first 3 months after surgery.32 Fechner et al observed cortical opacification in the optical axis if there was no visible space between the Adatomed IOL and the natural lens, whereas the lenses with visible vault remained clear.33 The authors have recently examined one of these patients 10 years after implantation, and the crystalline lens was still clear (Figure 9-15). Another trigger that Fechner described in cataract formation is touching the natural lens while implanting the IOL. Because of this high rate of cataract formation, the Adatomed IOL is no longer in use.

In general, cataract appearance was more frequently seen after Adatomed IOL than ICL implantation.27 In a study of 124 eyes, none developed lens opacities due to ICL implantation.29 Nevertheless, they found one eye that developed subscribed peripheral lens opacification at the place where Nd:YAG-iridectomy was performed preoperatively. Zadok et al reported one case of focal lens opacification under the Nd:YAG laser iridectomy site that did-

Figure 9-15. Silicone PC phakic IOL (Adatomed) 10 years after implantation into a myopic eye. The crystalline lens is clear because, most likely, a vault existed throughout the whole postoperative period of time.

n’t enlarge after implantation of the ICL.34 Another study showed two eyes in one patient with anterior subcapsular cataractogenesis 1.5 years after ICL implantation.30 The ICLs were removed and phacoemulsification with capsular bag implantation of an IOL was performed in both eyes. Also, Trindade et al observed anterior subcapsular cataract formation in the eye of a 59-year-old patient 6 months after implantation of an ICL.35 The surgery was uneventful and atraumatic. With ultrasound biomicroscopy, they were able to measure a central vault between the ICL and the natural lens whereas in the mid-periphery, a contact was present. Anterior subcapsular lens opacities developed in the noncontact area. Therefore, they surmised that the proximity of the ICL to the natural lens could lead to metabolic disturbances, as well as pressure from the PC phakic IOL on the anterior surface could trigger cataract formation. Additionally, the age of the patient should be taken into account, too. As a differential diagnosis of lens opacities, residues of viscoelastic substances should be considered, in particular if the opacity is seen in the early postoperative period.

With various generations of the ICL, the appearance of cataract formation is different. The less vaulted model V3 of the ICL caused higher incidence of cataract formation than the newer models V4 and V5.27 With the V4 model the recently published US FDA study showed an incidence of 2.1% anterior subcapsular (AS) opacities, which were seen in 11 of 523 eyes.36 To prevent cataract formation, it seems to be important to have a vault between the PC phakic IOL and the lens. With ultrasound biomicroscopy, it was possible to measure a central vault after implantation of ICLs, while in the midperiphery a lensIOL contact mostly existed.37-39 Also, size changes and

even loss of the central vault as well as changes of the location and extension of the contact zone were measured (Figures 9-16A to 9-16C).38,39 These findings would indicate anterior-posterior shifts in position of the ICL. Such shifts may be due to the flexibility of the IOL material, which would allow the ICL to become deformed, perhaps while iris movements or accommodation occurred. Nevertheless, lens opacities did not influence visual acuity in any of the examined eyes.

After implantation of the PRL, Hoyos et al observed anterior cortical opacification in the immediate postoperative examination in one eye. This opacification remained stable until the 2-year follow-up. Therefore, the authors suspect natural lens touch during surgery as a trigger.40

As of the writing of this text, the authors haven’t seen any cataract formation after ICL and PRL implantation in their patients, all of whom have been operated on by one experienced surgeon. Nevertheless, especially with regard to cataract formation, it is necessary to evaluate long-term results over several years. Because of the long-term uncertainty of cataract formation with phakic posterior chamber lens implants, we currently implant PC phakic IOLs only in eyes of middle-aged or elderly patients (30 to 50 years). The implantation of a phakic IOL in older presbyopic patients will only be performed in exceptions. The procedure of choice in these patients is refractive lens exchange with natural lens removal and posterior chamber implantation.

Pupillary Block, Acute Glaucoma,

and Malignant Glaucoma

Because of the PC phakic IOLs, the iris can be pushed forward and narrow the anterior chamber angle, so a pupillary block with acute glaucoma can appear, especially in hyperopic eyes.29,31,38 This problem can be prevented by creating an intraoperative surgical iridectomy or two preoperative Nd:YAG-laser iridotomies, respectively.29-32,37 In some cases, preoperative iridotomies closed themselves over time, were too small, or were blocked by a PC phakic IOL haptic. This caused acute glaucoma. A second iridotomy with the Nd:YAG-laser or a surgical iridectomy has to be performed.29,30,40 In one case, pupillary block appeared 1.5 years after PRL implantation because of obturation obstruction of the iridectomy with the PRL haptic.40 After treatment with a second iridectomy, IOP in all eyes normalized.

For hyperopic treatment, the preoperative iridotomy is even more important in preventing early pupillary block. It is necessary to make two peripheral and sufficient sized iridotomies with the Nd:YAG-laser or surgical procedure, respectively.31

Kodjikian et al reported one case of malignant glaucoma with an IOP of 54 mmHg 3 days after ICL implanta-

Figure 9-16A. Contact between the PC phakic IOL and the crystalline lens. Myopic ICL, slit lamp image. Note the delicate opacities in the lower hemisphere (40-year-old male).

Figure 9-16C. Contact between the PC phakic IOL and the crystalline lens. Hyperopic ICL, Scheimpflug image.

tion to treat myopia.41 Both iridotomies, which were done preoperatively with a Nd:YAG-laser, were patent and seemed large enough. The iris was not bowed forward and the posterior segment did not have any pathology. Therefore, acute glaucoma due to pupillary block was ruled out. IOP still remained 50 mmHg despite medical treatment, so that 5 days after the implantation an explantation of the ICL had to be performed. After this, IOP normalized without medical treatment and BCVA with a contact lens was 20/25.

Intraocular Pressure Rise, Pigment

Dispersion, and Secondary Glaucoma

Menezo et al observed a slight increase of IOP after implantation of PC phakic IOLs (1.5 mmHg after ICL, 2.3 mmHg after Adatomed implantation) over a follow-up of 18 months.27 In contrast, other studies with ICL or PRL found only significantly increased IOP in some rare cases after 1 month post-ICL implantation. When postoperative steroid treatment was completed, IOP in all patients was totally normalized.29,38,40

Figure 9-16B. Contact between the PC phakic IOL and the crystalline lens. Myopic ICL, Scheimpflug image.

Zaldivar et al reported two of 124 eyes that showed IOL-related IOP spikes. One of these eyes with a decentered ICL had excessive pigment deposition on the phakic IOL surface. It remained unclear whether the pigment dispersion was related to the decentration or to the IOL itself. The ICL had to be removed and phacoemulsification with implantation of posterior IOL in the capsular bag was performed in both eyes. Subsequently, IOP was well controlled without medication.29

Although Jiménez-Alfaro et al observed contact of the ICL and the posterior iris in 100% of ultrasound biomicroscopy, they did not find pigment dispersion.38 The authors suggest that the similarity between the ICLCollamer (STAAR Surgical, Monrovia, Calif) and the anterior capsule of the natural lens could prevent the mechanical loss of pigment. In contrast, Menezo et al observed pigment deposits on the IOLs (Figure 9-17A) in more than 40% of PC phakic IOL implantations independent of the lens type (ie, Adatomed IOL, ICL).27 They suggested touch of the PC phakic IOL with the posterior iris as the trigger for this phenomenon. Davidorf et al found pigment deposition on the phakic IOL surface appeared stable over time in all eyes and no pigment dispersion glaucoma occurred, so they suggest that pigment dispersion was probably surgically related.31 Hoyos et al observed one case of window defects of the iris and increased angular pigmentation without raised IOP after PRL implantation for hyperopic treatment (Figures 9-17B and 9-17C).40 The explanation the authors suggested was too shallow of an ACD of 2.8 mm. The patient is currently under careful follow-up. According to this experience, they demand a minimum cut-off ACD of 3.0 mm for PC phakic IOL implantation.

In one eye after ICL implantation for hyperopic treatment, Davidorf et al observed the development of a progressive secondary glaucoma due to neovascularization of the angle.31 This complication developed despite repeated laser iridotomies, two trabeculectomies, and removal of the phakic IOL combined with phacoemulsification and posterior chamber IOL implantation in the capsular bag.18 Eighteen months after the phakic IOL implantation, the

Figure 9-17A. Myopic ICL with deposits from the insertion forceps and with pigment deposits, first postoperative day (40-year- old male).

Figure 9-17B. Transillumination defect of the iris at the site of surgical iridectomy, 1 month postoperatively (39-year-old male).

Figure 9-17C. Pigment dispersion after implantation of myopic ICL, gonioscopic view, 3 months after implantation (53-year-old male).

patient had lost three lines BCVA, and IOP was controlled with multiple medications. Rosen et al reported another hyperopic treatment with secondary glaucoma 6 weeks postoperatively.28 Here, even surgical iridectomy failed to deepen the anterior chamber, so that the removal of the ICL, vitrectomy, and phacoemulsification with implantation of an IOL in the capsular bag had to be performed 6 weeks later.

Decentration, Rotation,

and Oversized Intraocular Lenses

Decentration occurred more often after Adatomed IOL than ICL implantation.27 Preoperatively, it is necessary to measure exact white-to-white diameter for choosing an IOL with sufficient length to prevent decentration and rotation.27,42 In a few cases, Menezo et al reported decen-

tration with an adequate IOL length in relationship to corneal diameter.27 The consequences of decentration are diplopia, glare, and perhaps pigment dispersion syndrome because of mechanical trauma.29,31 In these cases, the ICLs had to be recentered or exchanged for an ICL with the correct diameter.

In a new study done over 12 months, Garcia-Feijoó et al measured with ultrasound biomicroscopy rotation of ICL in two cases.39 Although there was no decentration of the optic, the authors suggested that the diameter of the ICL was too small.

Also, decentration occurred after PRL implantation as too small of an IOL diameter was chosen.40 After exchanging the small PRL for a newer generation PRL with greater diameter, no more decentration was observed.

Trindade et al reported the exchange of an ICL because of oversized length of the ICL.43 Malpositioning with a very great vault and undercorrection occurred because the ICL was too long. Ten months after primary surgery, the ICL was exchanged for a smaller ICL with higher power. This procedure was uneventful, and the patient was satisfied with the final visual outcome. The authors suggested carrying out accurate measurements of the corneal diameter. The length of the ICL had to be calculated from this diameter (addition of 0.5 mm to the horizontal white-to- white diameter). The authors’ current research suggested that the most accurate value of horizontal white-to-white diameter can be determined by the IOL master (Zeiss, Jena, Germany).44

Anterior Chamber Depth

and Endothelial Cell Loss

Because the iris was pushed forward, ACD decreased after the implantation of PC phakic IOLs. In multiple stud-

94 Chapter 9

Figure 9-18. Central keratopathy after implantation of a PC phakic IOL (folds of Descemet’s membrane and stromal edema) on the first postoperative day (43-year-old male).

ies reported glare and diplopia in eyes with decentration of the ICL greater than 1 mm.29,31 Maroccos et al observed a high increase of postoperative glare and halos after ICL implantation compared to Artisan implantation into the anterior chamber.7 They explained these findings as being due to the edge effects of the small diameter of the whole ICL and the small optical diameter (4.5 to 5.5 mm) in relationship to the pupil size of the patients (5.3 to 7.4 mm). After PRL implantation, 25% of 31 patients reported halos and night glare.40 Because the PRL has an optical zone size of 4.5 to 5.0 mm, it has the same etiology of glare and halos than as after ICL implantation.

To avoid this complication it is very important to measure preoperative pupil size during mesopic lighting conditions and to implant phakic IOLs with large optical zone sizes. For example, one should use the Artisan 6.0 mm in the eyes of all patients with large scotopic pupil sizes or search for better ways to correct high myopia in these cases, respectively.

ies, it was possible to measure narrowing of ACD with ultrasound biomicroscopy.37-39 But in contrast to the implantation of AC phakic IOLs, Jimenez-Alfaro et al did not observe a significantly progressive endothelial cell loss after implantation of PC phakic IOLs. Nearly 5% of endothelial cells were lost from the surgical procedure itself.38

Davidorf et al31 reported one eye with excessive vaulting of a hyperopic ICL. Because of this, the ACD largely decreased and the trabecular meshwork was not seen with gonioscopy. Subsequently, after exchanging the ICL through a properly sized model, the patient did well.31,45

Sometimes, namely in cases of complicated surgery, significant keratopathy could be seen with foldable phakic IOLs in the early postoperative period (Figure 9-18). Folds in Descemet’s membrane and stromal edema will resolve within the first few days following the implantation. If not, significant endothelial trauma should be considered.

To prevent pupillary block with acute glaucoma and long-term problems, the ACD should be at least 2.8 mm for myopic and 3.0 mm for hyperopic patients, which excludes, in the authors’ experience, more than two-thirds of the higher hyperopic (>+4.0 D) patients for hyperopic ICLs.

Glare and Halos

The consequence of small optical diameter phakic IOLs and decentration in relationship to pupil size is that glare and halos may occur, especially at night; therefore, patients have great difficulty driving at night. Menezo et al reported a higher incidence of halos after Adatomed than ICL implantation.27 After implantation of ICLs, glare and halos increased significantly. For these complaints, two explanations exist: decentration and/or too small of an optical diameter in relationship to pupil size. Several stud-

Vitreoretinal and

Other Complications

One case of rhegmatogenous retinal detachment was reported 3 months after the operation, but it seemed unlikely that the problem was related to the surgery.29 It is important to consider that most patients with implantation of PC PIOL are high myopes and, therefore, predisposed to spontaneous rhegmatogenous retinal detachment. For that reason, preoperative as well as periodical retinal examinations after phakic IOL implantation in using mydriasis are important to detecting and treating retinal breaks as early as possible.

To detect intraocular inflammation, laser flare photometry was performed by Uusitalo et al 6 months after ICL implantation. In this study, all eyes showed normal aqueous flare values.30

SUMMARY

The implantation of PC phakic IOLs seems to be a safe method to correct high myopia and hyperopia with regard to immediate visual and refractive results if contraindications are excluded. Thus far, there are no long-term studies that have examined PC phakic IOL implantations for longer than 24 months. Therefore, it would be necessary to perform such long-term examinations after several years to prove the previous encouraging results.

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15.Alio JL, Mulet ME, Shalaby AM. Artisan phakic iris-claw intraocular lens for high primary and secondary hyperopia. J Refract Surg. 2002;18:697-707.

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17.Gross S, Knorz MC, Liermann A, et al. Results of implantation of a Worst iris-claw lens for correction of high myopia. Ophthalmologe. 2001;98:635-638.

18.Maloney RK, Nguyen LH, John ME. Artisan phakic intraocular lens for myopia: short-term results of a prospective, multicenter study. Ophthalmology. 2002;109:1631-1641.

19.Perez-Santonja JJ, Bueno JL, Zato MA. Surgical correction of high myopia in phakic eyes with Worst-Fechner myopia intraocular lenses. J Refract Surg. 1997;13:268-281.

20. Pop M, Mansour M, Payette Y. Ultrasound biomicroscopy of the iris-claw phakic intraocular lens for high myopia. J Refract Surg. 1999;15:632-635.

21.Pop M, Payette Y, Mansour M. Ultrasound biomicroscopy of the Artisan phakic intraocular lens in hyperopic eyes.

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22.Menezo JL, Avino JA, Cisneros A, et al. Iris-claw phakic intraocular lens for high myopia. J Refract Surg. 1997;13: 545-555.

23.Perez-Santonja JJ, Iradier MT, Benitez del Castillo JM, et al. Chronic subclinical inflammation in phakic eyes with intraocular lenses to correct myopia. J Cataract Refract Surg. 1996;22:183-187.

24.Perez-Torregrosa VT, Menezo JL, Harto MA, et al. Digital system measurement of decentration of Worst-Fechner irisclaw myopia intraocular lens. J Refract Surg. 1995;11:26-30.

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30.Uusitalo RJ, Aine E, Sen NH, et al. Implantable contact lens for high myopia. J Cataract Refract Surg. 2002;28:29-36.

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34.Zadok D, Chayet A. Lens opacity after neodymium:YAG laser iridectomy for phakic intraocular lens implantation.

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35.Trindade F, Pereira F. Cataract formation after posterior chamber phakic intraocular lens implantation. J Cataract Refract Surg. 1998;24:1661-1663.

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38.Jimenez-Alfaro I, Benitez del Castillo JM, Garcia-Feijoo J, et al. Safety of posterior chamber phakic intraocular lenses for the correction of high myopia: anterior segment changes after posterior chamber phakic intraocular lens implantation. Ophthalmology. 2001;108:90-99.

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INTRODUCTION

Until recently, refractive surgery has mainly been focused on extraocular surgery, namely, corneal surgery. Laser in-situ keratomileusis (LASIK) has become one of the most commonly performed surgeries in medicine today. With so many people with high myopia and hyperopia contemplating vision correction surgery, it has become increasingly obvious that the candidates for photorefractive keratectomy (PRK) and LASIK are declining as we learn who are good candidates and who may end up with less than quality results.1-8 Patients with higher corrections with or without thin corneas have other options like phakic intraocular lens implants (IOLs). Many of the same principles that ophthalmologists are comfortable with in cataract postoperative care apply to phakic IOL postoperative care.

Phakic IOLs that are implanted today can be posterior chamber, anterior chamber angle fixated, or anterior chamber iris-claw.9-14 There are some features of postoperative care that are unique to the style of phakic IOL that is being implanted, and these will be brought up when appropriate in this discussion.

THE IMMEDIATE

POSTOPERATIVE PERIOD

Postoperative care begins right after the surgery is completed, which is signified by removal of the lid speculum. After the speculum is removed, it is important to re-examine the pressure in the eye and make sure the pressure is some-

what normal and the wound is watertight. The author will occasionally repressurize the globe after removing the speculum if removing it significantly lowers the intraocular pressure (IOP) because it was causing pressure on the globe. Sometimes this can be done without replacing the speculum because the drape is still holding the lashes open, and sometimes the speculum needs to be reinserted to safely repressurize the globe. The author uses balanced salt solution (BSS) for this maneuver.

The author performs the majority of his phakic IOLs with peribulbar anesthesia. In those situations, he postoperatively administers an antibiotic drop, tapes the eyelid, places an eye patch, and tapes a metal shield. He then instructs the patient to remove the shield 5 hours postoperatively and begin topical drop therapy. In the case of topical anesthesia surgery, he administers an antibiotic drop and tapes on a clear shield. The patient is instructed to use topical antibiotic drops six times per day for the first 3 days and then go to four times a day unless instructed otherwise. A topical steroid drop is prescribed four times per day. The patient is instructed to wear the shield, except when putting in drops, until he or she sees the author the next morning. After that, the shield is used only when sleeping for the first 2 weeks.

In the immediate postoperative period, if the patient has had perior retrobulbar anesthesia, he or she is warned that when he or she removes the shield, patch, and tape, he or she will still see blurred because the anesthesia also anesthetizes the optic nerve. They may even have some double vision if the extraocular muscle anesthesia has not worn off.