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Phakic posterior chamber intraocular lens for high myopia

Phakic posterior chamber intraocular lens for high myopia
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  Phakic posterior chamber intraocular lensfor high myopia   Angel Pineda-Ferna ´ndez, MD, Jorge Jaramillo, MD, Jose´ Vargas, MD,Miguel Jaramillo, MD, Jose´ Jaramillo, MD, Alicia Galı´ndez, MD  Purpose:  To evaluate the efficacy, predictability, stability, and safety of the surgi-cal correction of high myopia using a phakic posterior chamber intraocular lens(PPC IOL). Setting:  Centro Oftalmolo´ gico de Valencia-CEOVAL, Valencia, Venezuela.  Methods:  A retrospective study was performed to analyze 18 eyes of 12 patientswho had implantation of a modified PPC IOL, the implantable contact lens (ICL),for the treatment of high myopia. The target postoperative spherical equivalent(SE) refraction was emmetropia.  Results:  The mean follow-up was 26.6 months  11.3 (SD) (range 12 to36 months). The mean preoperative SE was  15.27  3.47 diopters (D) (range  10.0 to  21.25 D) and the mean postoperative SE,  0.62  0.81 D (range  2.75 to  0.75 D). Eleven eyes (61.1%) had an SE within  1.00 D of emmetro-pia. The best spectacle-corrected visual acuity was maintained or improved in allexcept 1 eye, which lost more than 2 lines of Snellen visual acuity. Two eyes(11.1%) developed pupillary block the first day after surgery. Four eyes (22.2%)had moderate pigmentary dispersion. Two eyes (11.1%) had lens opacification, 1with mild peripheral anterior capsule opacification and the other eye with centralanterior subcapsular opacification. One eye (5.5%) had a significant decrease inanterior chamber depth after surgery. Conclusions:  Implantation of an ICL was effective for the correction of high myo-pia. Predictability must be improved and the long-term safety of the ICL deter-mined. The main concerns over potential cataract formation, pigmentarydispersion, and angle-closure glaucoma remain.  J Cataract Refract Surg 2004; 30:2277–2283  ©  2004 ASCRS and ESCRS good results in terms of efficacy, predictability, and T he surgicalcorrection of myopia currentlyincludesquality of vision for low to moderate myopia. 2–6 How-intraocular surgery and techniques that produceever, these procedures are associated with significantchanges in the corneal shape. 1 Keratorefractive surgeriesoptical aberrations, poor quality of vision, and poorsuch as photorefractive keratectomy (PRK), laser in situpredictability when they are used to correct high myo-keratomileusis (LASIK), and radial keratotomy havepia. 7–12 Intraocular refractive surgery includes clear lensextraction 13,14 and phakic intraocular lenses (IOLs) im-  Accepted for publication March 9, 2004. planted in the anterior or posterior chamber, which From the Centro Oftalmolo´  gico de Valencia-CEOVAL (Pineda-Fer-  providegoodrefractiveresultsforhighercorrections. 15–17 na ´ ndez, Jorge Jaramillo, Vargas, M. Jaramillo, Jose ´  Jaramillo) and  However, they are associated with an increased risk  Centro Me ´ dico Guerra Me ´ ndez (Galı´ ndez), Valencia, Venezuela. for retinal detachment, endothelial cell loss, secondary  None of the authors has a financial or proprietary interest in any  glaucoma, and cataract formation. 18–22 material or method mentioned. The concept of a phakic IOL for myopia was devel- Reprintrequest to AngelPineda-Ferna ´ ndez, MD, Avenida Bolivar Norte, oped in the late 1950s with the design of a single-piece Edificio Torre Venezuela, Piso 2, Centro Oftalmolo´  gico de Valencia-CEOVAL, Valencia, Venezuela. E-mail:  poly(methyl methacrylate) plate-haptic IOL that was 󰂩 2004 ASCRS and ESCRS 0886-3350/04/$–see front matterPublished by Elsevier Inc. doi:10.1016/j.jcrs.2004.03.035  PPC IOL FOR HIGH MYOPIA  materialderivedfromcollagenthatisacopolymercomprising  fixated in the anterior chamber angle. The long-term porcine collagen and HEMA. It is 6.0 mm wide and comes data showed a significant incidence of corneal decom- in 5 diameters (11.0, 11.5, 12.0, 12.5, and 13.0 mm). The pensation and uveitis–glaucoma–hyphema syndrome 23 ; lens has a central convex–concave optic zone with a diameter thus, these IOLs were soon abandoned. of 4.5 to 5.5 mm, depending on dioptric power. The ICL Phakic IOL procedures began a new era with the  design has been modified many times. In this study, the first6 eyes had implantation of the ICM V3 model and the other introduction of the Worst iris-claw lens and Baikoff  12 eyes, of the newer ICM V4 model, which is presumed anterior chamber IOLinthemiddle1980s. 24,25 In1986, to offer better vaulting over the crystalline lens than the ICM Fyodorov developed a new model of posterior chamber V3 because the optical zone has greater convex–concave IOL made of silicone for phakic, highly myopic pa- curvature. tients 26 ; however, the lens led to a high incidence of  Lens power calculations were performed with formulas cataract formation. 22 In 1993, Staar Surgical AG intro-  developedbyStaar.Thevariablesintheformulaarepreopera-tive manifest and cycloplegic refractions (according to proto- duced a modified phakic posterior chamber intraocular col, the cycloplegic refraction was used in patients younger lens (PPC IOL), the implantable contact lens (ICL), than 40 years and the manifest refraction, in patients older for the correction of high myopia. Several studies report than 40 years), vertex distance, average keratometric power, good refractive outcomes and optical performance with corneal thickness, and central ACD. The length of the im- the ICL. 17,27–29 Some, however, report cataract forma- plantedICLwas determinedbasedonthepatient’s horizontal tion 21 and pigmentary dispersion. 30 corneal diameter (white to white) measured with the Nidek  AutoRef/keratometer.Thegoalwas toimplant anICL slightly  The purpose of this study was to evaluate the effi- larger than the ciliary sulcus to produce anterior vaulting and cacy,predictability,safety,andstabilityofthecorrection secure fixation. of high myopia with a PPC IOL. Surgical Technique  In all cases, 2 peripheral and superior iridotomies were Patients and Methods performed 2 weeks before surgery using a neodymium:YAG A retrospective study was performed using the data from(Nd:YAG) laser; they were positioned 90 degrees apart to18 eyes of 12 consecutive patients who had implantation of prevent postoperative pupillary block. All surgeries were per-an ICL since April 1998. The target postoperative sphericalformed by 1 of 2 surgeons (A.P., J.J.) using peribulbar anes-equivalent (SE) refraction was emmetropia. Inclusion criteria thesia and with good pupil dilation achieved by tropicamide were olderthan 18years, SEof   9.00diopters (D) orhigher,1% and phenylephrine 5%. Two paracenteses at the 6 anda best spectacle-corrected visual acuity (BSCVA) of 20/80 or12 o’clock meridians and a 3.2 mm temporal clear corneal worse, no preexisting ocular pathology, no previous surgery,incision were made with a diamond knife. Sodium hyaluro-nosystemicdisease, contactlensintolerance,intraocularpres-nate 1% (Healon  ) was injected into the anterior chamber.sure (IOP) between 10 mm Hg and 20 mm Hg, anteriorThe ICL was positioned in the lens insertion cartridge,chamber depth (ACD) of 3.0 mm or more, and endothelial which was previously filled with Healon. A small piece of a cell count greater than 2000 cells/mm 2 .3.0 mm diametersponge was placed in the insertion cartridge An ophthalmic examination was conducted before sur-behind the ICL to protect the eye from the injector arm.gery and postoperatively at 1 and 7 days and 1, 6, 12, 24, andThe injector tip was then placed in the wound, and the ICL36 months. The examinations included distance uncorrected was slowly injected into the anterior chamber anterior to thevisual acuity (UCVA) and distance BSCVA using a Snellen iris plane, ensuring proper orientation. A Sinskey hook waschart, manifest and cycloplegic refractions, slitlamp and fun- introduced through 1 paracentesis, and the 2 corners of thedus evaluation, Goldmann applanation tonometry, corneal temporal haptic were placed beneath the iris with gentletopography (EyeSys), and ultrasound (US) pachymetry. posterior pressure. The 2 corners of the nasal haptic wereThe ACD was measured with a US biometer (Nidek  positioned in a similar fashion. To avoid pigmentary disper-EchoScan US3300). The corneal endothelial cell count (cells sion, the ICL was not rotated.persquaremillimeter)wasmeasuredwithanoncontactspecu- Acetylcholine was injected into the anterior chamber.lar microscope (Topcon SP-2000P, Topcon Corp.). Up to Remaining viscoelastic material was aspirated using irriga-5 measurements in the central cornea were taken at each tion/aspirationwiththeMillenniumphacoemulsificationsys-examination, and the mean was recorded as the corneal endo- tem (Bausch & Lomb). Topical tobramycin–dexamethasonethelial density. (TobraDex   ) was given at the end of surgery. The eye wasThe ICL is a plate-haptic single-piece lens designed to patched for 24 hours, and mannitol 20% (250 cc) was givenbe implanted in the posterior chamber with support on the intravenously. TobraDex was prescribed 6 times a day for 2 weeks and then 4 times a day for 2 weeks.ciliary sulcus. It is made of Collamer, a flexible, hydrophilic  J CATARACT REFRACT SURG—VOL 30, NOVEMBER 2004 2278  PPC IOL FOR HIGH MYOPIA  Figure 2.  (Pineda-Ferna´ ndez) Stability of the SE refraction in 12eyes that completed a 24-month follow-up. Figure 1.  (Pineda-Ferna´ndez) Intended versus achieved correc-tion in 18 eyes at the last examination. The linear regression lineshows a tendency toward undercorrection. Statistical Analysis  Statistica software (version 4.3) was used to comparethe postoperative data by the Student  t   test. Results wereconsidered statistically significant when  P   .05. Results The mean age of the patients was 34.5 years  5.7(SD) (range 25 to 41 years) and the mean follow-up, Figure 3.  (Pineda-Ferna´ ndez) Cumulative UCVA at the last post- 26.6  11.3 months (range 12 to 36 months). All 18 operative visit. eyes completed at least 1 year of follow-up, 66.6%(12 eyes) completed 24 months, and 55.5% (10 eyes)completed 36 months.Themeanpreoperativespherewas  13.94  3.28D(range   9.75 to   20.00 ). The mean cylinder was  1.80  1.30 D (range  0.50 to  4.00 D) preopera-tively and  1.85  0.78 D (range  1.00 to  3.00 D)postoperatively. The mean SE was   15.27    3.47 D(range   10.00 to   21.25 D) preoperatively and  0.62    0.81 D (range   2.75 to   0.75 D)postoperatively. Figure 4.  (Pineda-Ferna´ ndez) Change in BSCVA at the last post- Figure 1 shows the predictability of the procedure. operative visit. Foureyes(22.2%)hadanSEwithin  0.50Dofemme-tropia and 61.1% (11 eyes), within   1.00 D. Figure UCVAof20/20orbetter(Figure3).Seveneyes(38.8%)2 shows the stability of the SE refraction ( P   .05 be- gained 1 or more lines of Snellen BSCVA. One eyetween each postoperative interval). (5.5%) lost more than 2 lines of BSCVA (Figure 4). At the last postoperative visit, 8 eyes (44.4%) had Table 1 shows the ACD. There was a statistically significantdecreaseinACDfrompreoperativelytopost-a UCVA of 20/40 or better and 1 eye (5.5%) had a   J CATARACT REFRACT SURG—VOL 30, NOVEMBER 2004  2279  PPC IOL FOR HIGH MYOPIA  Table 2.  Endothelial cell density (cells/mm 2  ). Table 1.  Anterior chamber depth (mm). Exam Mean    SD Eyes % Decrease Exam Mean    SD Eyes % Loss Preoperative 2545    298 18 —Preoperative 3.50    0.31 18 —PostoperativePostoperative6 months 2420    312 18 4.916 months 3.07    0.21 18 12.2812 months 2418    322 18 4.9912 months 3.09    0.18 18 11.7124 months 2309    309 12 5.3424 months 3.13    0.19 12 10.5736 months 2390    289 10 6.0936 months 3.12    0.20 10 10.85 value (6 months), when no lens opacification wasoperatively( P   .001).Therewerenostatisticallysignifi-present.cant differences between postoperative visits.One eye (5.5%) with a model ICM V3 lens devel-Table 2 shows the endothelial cell density. Theoped central anterior subcapsular opacification 3 yearspreoperative endothelial density was statistically signifi-after surgery that significantly decreased the UCVA tocantly greater than all postoperative measurements20/400 (Figure 5); this patient received phacoemulsifi-( P   .05).However,therewerenostatisticallysignificantcation with posterior chamber IOL implantation,differences between postoperative visits.achieving a final UCVA of 20/25.Five eyes (28%) had transient ocular hypertension Complications  in the first postoperative month. They were consideredTwo eyes (11.1%) developed pupillary block withcorticosteroid responders because their IOP returnedan IOP of 40 to 50 mm Hg on the first day after preoperative levels after withdrawal of postoperativeIn both cases, 1 of the iridotomies was too small. Aftertopical corticosteroids.the iridotomies were enlarged with an Nd:YAG laser,One eye (5.5%) had a significant decrease (50%the IOP returned to preoperative values.reduction from preoperatively) in ACD and a narrow Four eyes (22.2%), all with a model ICM V4 lens,anterior chamber angle (Figure 6). Because the IOPhad moderate, diffuse pigmentary dispersion on the was 16 mm Hg during the 1-year follow-up and theanterior surface of the ICL at 1 month. No case wasendothelial cell count showed no significant loss, theclinically significant.ICL was not removed.One eye (5.5%) with a model ICM V3 lens hadmild peripheral anterior capsule opacification (ACO) Discussion 1 year after surgery. The UCVA and BSCVA in thisManystudiesshowthatphakicIOLsareaneffectiveeye were not altered from the previous postoperativetreatment for the correction of high myopia and have Figure 5.  (Pineda-Ferna´ ndez)Centralanteriorsubcapsularopaci-  Figure 6.  (Pineda-Ferna´ ndez) Decrease in ACD after implantationof ICL model ICM V4.fication 3 years after surgery (model ICM V3).  J CATARACT REFRACT SURG—VOL 30, NOVEMBER 2004 2280  PPC IOL FOR HIGH MYOPIA  significant advantages such as reversibility, immediate ing than the earlier ICM V3 model. The vaulting in-creases the distance between the ICL and crystallinecorrection,stability,andrelativesimplicity. 15–17,27–29 How-ever, some studies describe complications with these lens but reduces the distance between the ICL and thepigment layer of the iris. Using ultrasound biomicros-lenses. Worst-Fechner iris-fixated lenses are associated with continuous endothelial cell loss 20 caused by persis- copy (UBM), Trindade and coauthors 38 found widecontactbetweentheIOLandirisinalleyestheystudied.tent inflammation. Pe´rez-Santonja et al. 31,32 report per-sistent subclinical inflammation (measured with laser Because of IOL–iris contact, the expected pigmentary dispersion may lead to pigmentary glaucoma, inductionflare–cell fluorophotometry) produced by alteration of the blood–aqueous barrier. They also report a decrease of synechias, iris sphincter erosion, and iris transillumi-nation. However, in our series, pigmentary dispersionin crystalline lens transmittance (measured by fluoro-photometry). Although the association between corneal had no clinical significance. Pigmentary dispersion hasbeen found after implantation of other phakic IOLs.endothelial loss and Baikoff angle-supported lenses ap-parently has been resolved with the ZB5M model, 15,33 Pop andcoauthors 39 studied theArtisaniris-clawphakicIOL in 3 eyes using UBM. They found distortion of otherproblemssuchasnighthalosandpupilovalizationremain. Implantation of the Fyodorov silicone PPC the pigment layer located at the iris entrapment that was produced by the 2 arms of the IOL haptics.IOL is associated with a risk for pigmentary dispersionand a high incidence of cataract formation (81.9%). 22 In our study, 2 eyes, both with the model ICMV3 lens, had lens opacification; 1 eye had mild periph- Atpresent, thedesignsofall these anterior andposteriorchamberphakicIOLshavebeenmodifiedtoavoidthese eral ACO, and the other eye developed central anteriorsubcapsular opacification. The subcapsular opacifica-problems; however, long-term studies are necessary toassess the potential risks to the corneal endothelium, tion was probably because the smaller vaulting of theICM V3 causes more anterior capsule–crystalline lensanterior uvea, and crystalline lens.In our study, a modified PPC IOL, the ICL, effec- contact. 30 Trindade and coauthors 38 found contact be-tween the ICL and crystalline lens in 8 eyes (89%)tively reduced high myopia. We found a different levelof efficacy than in other published studies. Limitations using UBM, but this unequivocal touch was impossibleto demonstrate because UBM is not able to separatein predictability are partly related to the selection of the phakic IOL power based on spectacle refraction. It distances smaller than 40   m (instrument resolution). Jime´nez-Alfaro et al. 40 found peripheral contact betweenis well known that refraction may be less reliable ineyes with more extreme levels of myopia. In our study, theICLandcrystallinelensin12eyes(60%)andcentralcontactin3eyes(15%).Theyalsofoundthatcrystalline22% of eyes had an SE within  0.50 D of emmetropia and 61.1% had an SE within   1.00 D. Zaldivar and lens transmittance measured by fluorophotometry de-creased during the entire 24-month follow-up. Thecoauthors 27 report 69% of eyes with an SE within  1.00 D and 44% within  0.50 D, Assetto and coau- decrease in crystallinelens transmittance afterimplanta-tion of PPC IOLs can be related to surgical trauma,thors 34 report 31% within  1.00 D, and Pesando andcoauthors 28 report 52.53% within  1.00 D. Although the effect of Nd:YAG laser treatment of iridotomies, 27 subclinical inflammation, and continuous or intermit-it is necessary to find more accurate phakic IOL powercalculation formulas, combining phakic IOL implanta- tent contact between the IOL and crystalline lens. 40  A decrease incrystallinelens transmittanceandsubclinicaltion with LASIK or PRK (bioptics) may improve thefinal visual outcome. 35–37 inflammationhas also been observedaftertheimplanta-tion of iris-fixated 32 and angle-supported 41 phakic IOLs. According to our results, PPC IOL implantationappears to be safe; only 1 eye lost lines of BSCVA, and It is important to use a surgical technique that avoidsinadvertent crystalline lens trauma.38.8% gained 1 or more lines. This gain is the resultof magnification of the retinal image by eliminating One eye had a significant decrease (50% reductionfrom preoperatively) in ACD after surgery. According the spectacle-induced minification patients with highmyopia experience preoperatively. to Staar Surgical AG communications, the optimumvault size is 10% of the ACD. In our study, all eyes Wefoundpigmentarydispersionin4eyes(22.2%). All had the model ICM V4 lens, which has more vault- except 1 had a decrease in ACD that ranged from 9%  J CATARACT REFRACT SURG—VOL 30, NOVEMBER 2004  2281
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