- Email: [email protected]
Clear lens extraction for the correction of high myopia
Clear Lens Extraction for the Correction of High Myopia Luis Ferna´ndez-Vega, MD,1,2 Jose´ F. Alfonso, MD,2 Toma´s Villacampa, MD1 Objective: To evaluate the postoperative outcomes and intraoperative and postoperative complications of clear lens extraction (CLE) with posterior chamber intraocular lens (IOL) implantation in highly myopic eyes. Design: Retrospective case series. Participants: One hundred seven patients (190 eyes) who had undergone CLE with posterior chamber IOL implantation and who had been observed for at least 3 years after surgery. Methods: Medical records of patients who had undergone CLE with posterior chamber IOL implantation to treat high myopia (axial length ⬎26.00 mm) over 7 years (January 1990 to December 1996) were reviewed. Visual acuity and refractive error were assessed before and after surgery, and perioperative, intraoperative, and postoperative complications were recorded. Main Outcome Measures: Axial length, preoperative and final best spectacle-corrected visual acuity (BSCVA), preoperative and postoperative spherical equivalent (SE), argon laser treatments, surgical complications, neodymium:yttrium–aluminum– garnet (Nd:YAG) laser capsulotomy, retinal detachment (RD), time from surgery or Nd:YAG capsulotomy to RD, subfoveal choroidal neovascularization (CNV), and follow-up period. Results: The mean postoperative follow-up period was 4.78 years (range, 3.10 – 8.03 years). Final BSCVA was better than preoperative BSCVA in 159 eyes (83.68%), equal in 24 eyes (12.63%), and worse in 7 eyes (3.68%). Postoperative BSCVA was 20/40 or better in 136 eyes (71.60%) vs. 52 eyes (27.36%) before surgery (P⬍0.001). The mean final postoperative SE was ⫺1.22 diopters. The risk of Nd:YAG laser capsulotomy was 77.89%. The incidence of RD was 2.10%; retinal reattachment was achieved in all cases, and none of these eyes had worse final BSCVA than before surgery. Subfoveal CNV developed in 4 eyes (2.10%) of 3 patients; all of these eyes presented with a macular lacquer crack. Conclusions: Clear lens extraction with posterior chamber IOL implantation has good outcomes with acceptable predictability and improvement in best-corrected visual acuity. During follow-up, patients tended to remain stable, and the risk of retinal detachment was low. We attribute our favorable results to careful patient selection and follow-up. Ophthalmology 2003;110:2349 –2354 © 2003 by the American Academy of Ophthalmology.
Various surgical options for treatment of high myopia are currently under evaluation. Extracting the clear lens is one procedure that has been used to treat high myopia for a long time.1,2 The primary concern with this procedure is its association with an increased risk for retinal complications.1,3 To evaluate the effectiveness and safety of this procedure, we retrospectively reviewed visual acuity outcome and intraoperative and postoperative complications of clear lens extraction (CLE) and posterior chamber intraocular lens (IOL) implantation in 190 highly myopic eyes.
Originally received: June 4, 2001. Accepted: April 9, 2003. Manuscript no. 210374. 1 Ophthalmology Service, Asturias General Hospital, Oviedo, Asturias, Spain. 2 Ferna´ndez-Vega Eye Institute, Oviedo, Asturias, Spain. None of the authors has any commercial (proprietary or financial) interest in any product, drug, or device mentioned in this article. Reprint requests to Luis Ferna´ndez-Vega, MD, Instituto de Oftalmologı´a Ferna´ndez-Vega, Avenida Doctores Ferna´ndez-Vega, S/N, Oviedo 33012, Asturias, Spain. E-mail: [email protected]. © 2003 by the American Academy of Ophthalmology Published by Elsevier Inc.
Materials and Methods The medical records of patients who had undergone CLE and posterior chamber IOL implantation between January 1990 and December 1996 were reviewed, and those who had been followed up for ⱖ36 months were included in the study. Criteria for offering surgery were severe preoperative myopia (axial length, ⱖ26.00 mm) as determined by A-scan, a best spectacle-corrected distance visual acuity (BSCVA) of 20/100 or better, intolerance to contact lens use, and age between 30 and 55 years. Patients with prior retinal detachment (RD), glaucoma, or previous ocular surgery were excluded. All surgery was performed by two surgeons at the Ferna´ndezVega Eye Institute. In eyes with lattice degeneration, retinal tear, or hole, we performed argon laser photocoagulation before surgery. Intraocular lens power calculations were performed with the Sanders–Retzlaff–Kraff II formula. Surgery was begun by creation of a 6- to 6.5-mm groove 2 mm posterior to the limbus at approximately one third the scleral depth. A scleral tunnel incision of 3.2 mm was made by dissecting forward in the sclera up to the peripheral cornea. A viscoelastic material was instilled into the anterior chamber, and capsulorhexis and hydrodissection were performed. The lens was extracted by phacoemulsification or phacoaspiration followed by irrigation/aspiration. The incision was then widened to 6.5 mm, and a posterior chamber one-piece ISSN 0161-6420/03/$–see front matter doi:10.1016/S0161-6420(03)00794-2
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Ophthalmology Volume 110, Number 12, December 2003 Table 1. Demographic Data No. of patients Bilateral cases Unilateral cases Sex Female Male Mean age (yrs)
107 83 24 71 36 43.03 ⫾ 6.63 (range, 30–55)
polymethylmethacrylate IOL (UI 80; Pharmacia, Peapack, NJ) was implanted in the bag. The anterior chamber was restored with balanced salt solution. Sutures were not used unless there was leakage when pressure was placed on a sponge over the incision, and, if necessary, closure was performed with one or two interrupted nylon 10-O sutures. Data recorded for this study included patient age and sex and each eye’s axial length, preoperative and final BSCVA, preoperative and postoperative spherical equivalent (SE), previous argon laser treatment, use of neodymium:yttrium–aluminum– garnet (Nd:YAG) laser capsulotomy, complications such as RD and choroidal neovascularization (CNV), time from surgery or Nd:YAG laser capsulotomy to RD, and follow-up time. To evaluate differences between eyes with RD and eyes without RD and between eyes with CNV and eyes without CNV, the Mann–Whitney U test was used to compare variables that were not normally distributed, and comparisons of categoric data were performed with Fisher exact test. All statistical analyses were performed with the SPSS package (SPSS Inc., Chicago, IL). Significance was defined as P⬍0.05 for all tests. Informed consent for the CLE and IOL implantation was obtained from all patients before surgery. Institutional review board approval was not required for this study.
Results During the study period, CLE and posterior chamber IOL implantation was performed on 195 eyes of 110 patients. Three patients (5 eyes) did not complete the 3-year minimum follow-up and were excluded because of poor follow-up; we have no evidence of RD or other complications within their follow-up. The study included 190 eyes of 107 patients. Patients’ demographic data are shown in Table 1, and their clinical data are shown in Table 2. They all had high myopia documented by an axial length of at least 26.00 mm (Fig 1) and by SE (Fig 2).
Figure 1. Distribution of axial length (mm; standard deviation, 2.35 mm; mean, 30 mm; n ⫽ 190).
vision when vision worsened one line or more. Final BSCVA was better than preoperative BSCVA in 159 eyes (83.68%), equal in 24 eyes (12.63%), and worse in 7 eyes (3.68%). Postoperative BSCVA was 20/40 or better in 136 eyes (71.60%) vs. 52 eyes (27.36%) before surgery (P⬍0.001; Fig 3). Seven eyes had loss of visual acuity because of subfoveal CNV (n ⫽ 3), progressive myopia-related maculopathy (n ⫽ 3), and open-angle glaucoma (n ⫽ 1) that developed 3 years after surgery. The mean preoperative SE was ⫺17.84 ⫾ 5.59 (range, ⫺7.00 to ⫺34.00). The mean final postoperative SE was ⫺1.22 ⫾ 1.24 diopters (D; range, ⫺5.00 to ⫹2.25 D; Fig 4). The postoperative SE was within ⫾1.00 D of emmetropia in 41% of eyes and within ⫾2.00 D of emmetropia in 79% of eyes.
Visual and Refractive Results We considered better vision when vision improved one line or more, equal vision for vision stable within one line, and worse Table 2. Clinical Data Variable Axial length (mm) Preoperative spherical equivalent Preoperative BSCVA Power of IOL used Follow-up (yrs) Preoperative argon laser therapy
Mean ⴞ SD
Range
30.13 ⫾ 2.35 26.00 to 39.20 ⫺17.84 ⫾ 5.59 ⫺7.00 to ⫺34.00 0.37 ⫾ 0.17 0.34 to 0.39 3.29 ⫾ 5.53 ⫺10.00 to 14.50 4.78 ⫾ 1.19 3.10 to 8.03 34 eyes (17.89%)
BSCVA ⫽ best spectacle-corrected visual acuity (decimal score); IOL ⫽ intraocular lens; SD ⫽ standard deviation.
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Figure 2. Preoperative spherical equivalent distribution (standard deviation, 5.59; mean, ⫺17.7; n ⫽ 190).
Ferna´ ndez-Vega et al 䡠 Clear Lens Extraction for High Myopia
Figure 3. Scatterplot of preoperative vs. postoperative best spectaclecorrected visual acuity (BSCVA; decimal score). The spikes resemble petals for each case where there are overlapping cases in the scatterplot. Each petal represents a case.
Complications The only notable intraoperative complication was rupture of the posterior capsule in one eye (0.53%). There was no loss of vitreous, and the IOL was successfully implanted in the posterior chamber. The final corrected visual acuity in this eye was 20/25. Posterior capsule opacification was the most frequent postoperative complication. It occurred and was treated by Nd:YAG laser capsulotomy in 148 eyes (77.89%). The mean time from CLE to capsulotomy was 21.72 ⫾ 11.16 months (range, 2.60 – 63.20 months). Three years after surgery, one patient had an open-angle glaucoma, defined by visual field defects in a pattern consistent with glaucoma (30-2 test of the Humphrey automated perimeter device).
Retinal detachment occurred in 4 (2.10%) of 190 eyes (3.73% of patients). Retinal detachments occurred 28 to 39 months after surgery. The characteristics of these eyes are listed in Table 3. The retina was reattached in 100% of these eyes, and final BSCVA in all eyes was equal to or better than preoperative BSCVA. The fellow eyes of these patients, which were also treated by CLE, did not have RD. Patients who had CLE in only 1 eye (24 unilateral cases) did not have any RD in fellow eyes during the same period of follow-up. There was a statistically significant difference in patient age between eyes with DR and eyes without this complication (P ⫽ 0.004; Mann–Whitney U test); however, there was no statistically significant difference in axial length, preoperative SE, sex, Nd:YAG capsulotomy performance, or previous laser argon treatment (Table 4). Subfoveal CNV developed in 4 eyes of 3 patients (1 bilateral case; 2.10% of eyes). The characteristics of these eyes are shown in Table 5. All eyes had been found on previous macular examination to have a lacquer crack. In total, macular lacquer crack had been identified in 15 of the 190 eyes. There was a statistically significant difference in the presence of lacquer crack between eyes with subfoveal CNV and eyes without this complication (P⬍0.001; Fisher exact test); however, there was no statistically significant difference in patient age, sex, axial length, or preoperative SE (Table 6). No clinical cystoid macular edema or endophthalmitis was observed.
Discussion The results of our study confirm findings in previous studies that CLE and implantation of an IOL in the posterior chamber have good effectiveness and acceptable predictability and that postoperative improvements in visual acuity are stable over a long follow-up period.2,4,5 Nevertheless, CLE remains a controversial technique because it is an invasive procedure and carries an increased risk of RD.3,4,6 –10
Retinal Detachment
Figure 4. Postoperative spherical equivalent distribution (standard deviation, 1.24; mean, ⫺1.22; n ⫽ 190).
The incidence of this complication after CLE reported in other studies3,4,6,8 –10 is variable, ranging from 0% to 8%. We propose that the causes of this variability are different patient characteristics and study designs. These and other3,5,10 previously reported studies have found associations between the risk of RD and one or more of the following factors: younger age, axial length, history of RD or surgery in the contralateral eye or lesions predisposing to RD, surgical technique and integrity of the posterior capsule, use of Nd:YAG capsulotomy, and longer follow-up time after surgery. Patient Age. All 4 of our patients with this complication were younger (aged 30, 32, 33, and 38 years) than the mean age in our study (43.03 years; range, 30 –55 years). We analyzed differences between eyes with RD and eyes without RD in patient age, axial length, preoperative SE, sex, Nd:YAG capsulotomy performance, and previous laser argon treatment, and we found a statistically significant difference only in patient age (P ⫽ 0.004; Mann–Whitney U test; Table 4). Barraquer et al3 reported an RD incidence of 7.3% after CLE in aphakic eyes. They found that 58% of the RDs occurred in patients younger than 30 years of age, whereas only 31% of patients younger than 30 years did not
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Ophthalmology Volume 110, Number 12, December 2003 Table 3. Characteristics of Eyes with Retinal Detachment Variable
Case 1
Case 2
Case 3
Case 4
Age (yrs) Sex Axial length (mm) Preoperative SE Preoperative BSCVA Surgery–RD interval (mos) Nd:YAG/postoperative interval (mos) Nd:YAG–RD interval (mos) Previous argon laser RD treatment Final BSCVA
32 Male 29.60 ⫺15.00 0.30 35 16 19 No SB ⫹ VTM 0.35
30 Female 29.89 ⫺19.00 0.30 28 18 10 No SF6 ⫹ laser 0.30
38 Female 29.99 ⫺18.00 0.25 37 21 16 No SF6 ⫹ laser 0.25
33 Male 32.30 ⫺17.00 0.40 39 19 15 No VTM ⫹ laser 0.45
Mean 33.25 30.44 ⫺17.25 0.31 34.75 18.50 15 0% 0.33
BSCVA ⫽ best spectacle-corrected visual acuity; Nd:YAG ⫽ neodymium:yttrium–aluminum– garnet laser; RD ⫽ retinal detachment; SB ⫽ scleral buckling; SE ⫽ spherical equivalent (decimal score); VTM ⫽ vitrectomy.
have RD. A history of detachment of the posterior vitreous, which is inversely related to the risk for RD after posterior chamber surgery, is a factor that we think is closely linked to patient age. Colin and Robinet2,5 and Colin et al6 reported that the prevalence of a history of posterior vitreous detachment before CLE and implantation of an IOL in the posterior chamber was 57.7% in their study group as a whole but was ⬎70% among the group’s elderly patients. Unfortunately, most of the medical records we examined in our retrospective study did not document whether the patient had a history of detachment of the posterior vitreous, so this was not a parameter we could analyze in our study. History. Another reason why the incidence of RD varies among studies is the use and timing relative to surgery of laser photocoagulation for conditions such as lattice degeneration, retinal tear, or retinal hole. In our study, none of the eyes that had prophylactic treatment developed RD, and the eyes that developed RD did not receive prophylactic treatment. We did not find a statistically significant difference in this factor (previous argon laser treatment) between eyes with RD and eyes without RD (P ⫽ 1.00; Fisher exact test; Table 4). From our study, there is no way to determine whether the prophylaxis treatment influenced the risk of Table 4. Statistical Data to Evaluate Differences between Eyes with RD and Eyes without RD
Variable Mean age (yrs) Mean axial length (mm) Mean preoperative SE Sex (male:female) Nd:YAG capsulotomy [yes (%):no] Previous argon laser [yes (%):no]
Eyes with RD (n ⴝ 4)
Eyes without RD (n ⴝ 186)
Significance (P Value)
33.25 30.12 ⫺17.25 2:2 4 (100%):0
43.31 30.44 ⫺17.04 62:124 144 (77.42%):42
0.005* (S) 0.546* (NS) 0.720* (NS) 0.604† (NS) 0.577† (NS)
0 (0%):4
34 (18.28%):152
1.000† (NS)
Nd:YAG ⫽ neodymium:yttrium–aluminum– garnet laser; NS ⫽ no significant difference; RD ⫽ retinal detachment; S ⫽ significant difference; SE ⫽ spherical equivalent (decimal score). *Mann–Whitney U test. † Fisher exact test.
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RD. Although there is controversy in this matter and more prospective randomized studies are necessary, we are convinced from our clinical experience that selective photocoagulation of lesions that predispose to RD helps to decrease the risk of RD as a complication of CLE and IOL implantation. Surgical Considerations. In addition to patient factors, the technique of surgery for high myopia affects the risk of RD. Studies show that phacoemulsification is a safer technique than extracapsular extraction of the lens and that implantation of an IOL (whether CLE is extracapsular or by phacoemulsification) also helps to decrease the risk of this complication.3,10 Nd:YAG Laser Capsulotomy. Nd:YAG laser photocoagulation is used to treat opacification of the posterior capsule, the most frequent complication of this surgery. The incidence of opacification increases in direct proportion to longer follow-up after CLE for high myopia,2,4,5,7 and the incidence of RD increases with use of Nd:YAG capsulotomy to treat opacification.3,6 –9 In our study, the 4 eyes that developed RD had required Nd:YAG capsulotomy for posterior capsule opacification. The mean time from CLE to capsulotomy was 18.5 months (mean time from CLE to capsulotomy in all treated eyes was 21.72 ⫾ 11.16 months), and the mean time from capsulotomy to the appearance of RD was approximately 15 months. The incidence of posterior capsule opacification varies widely in the different studies, and it can depend on the age of the patient, surgical technique, time of follow-up, and type of IOL placed. Furthermore, not all surgeons have the same criterion for deciding the moment for performing capsulotomy. In our study, capsulotomies were performed when opacities were noted and patients reported concerns with the quality of their vision. Follow-up Period. The effect of follow-up period on the incidence of RD is shown in the study reported by Colin and Robinet2,5 and Colin et al.6 They observed an initial group of 52 eyes for 7 years. At 4 years, 49 eyes remained in the study, and there was 1 case of RD, which represents an incidence of 1.9% based on the original group of 52 or an incidence of 2.0% based on “last observation.” However, between years 5 and 6 of follow-up, 3 more cases of RD
Ferna´ ndez-Vega et al 䡠 Clear Lens Extraction for High Myopia Table 5. Characteristics of Eyes with Subfoveal Choroidal Neovascularization Variable
Patient 1
Patient 2
Patient 3, Right Eye
Patient 3, Left Eye
Age (yrs) Sex Axial length (mm) Preoperative SE Preoperative BSCVA Surgery–subfoveal CNV interval (mos) Lacquer crack Final BSCVA
36 Male 29.18 ⫺10.50 0.50 7 Yes 0.10
45 Male 33.06 ⫺22.00 0.35 2 Yes 0.05
47 Female 28.40 ⫺15.50 0.20 13 Yes 0.05
47 Female 28.37 ⫺12.50 0.30 1 Yes 0.30
Mean 43.75 29.75 ⫺15.12 0.31 5.75 100% 0.12
BSCVA ⫽ best spectacle-corrected visual acuity; CNV ⫽ choroidal neovascularization; SE ⫽ spherical equivalent.
appeared; this represents an incidence of 8.16% based on “last observation.”2,5,6 In the Colin series,2,5,6 3 of the 4 RDs occurred between postoperative years 4 and 7. Studies with a follow-up of ⱕ4 years tended to have excellent results,5,8,9 suggesting that the risk of RD may increase with time and, therefore, that the RD rate can be higher with a longer follow-up time. Other Factors. In addition to the factors just described, small sample size can have a large effect on the incidence of a complication. A single case in a small series can result in a high incidence in that series.
Vision Loss In our series, RDs did not result in any severe loss of vision: all 4 retinas reattached, and the final BSCVA was better than or equal to the preoperative BSCVA in the 4 cases. Conversely, subfoveal CNV occurred 1 to 13 months (mean, 5.75 months) after surgery and did cause severe visual loss in 3 of the 4 eyes with this complication (Table 5). All had been found on previous macular examination to have a lacquer crack. In total, macular lacquer crack had been identified in 15 of the 190 eyes. There was a statistically significant difference in the presence of lacquer crack between eyes with subfoveal CNV and eyes without this complication (P⬍0.001; Fisher exact test); however, there was no statistically significant difference in patient age, sex, axial length, or preoperative SE (Table 6). We suggest Table 6. Statistical Data to Evaluate Differences between Eyes with Subfoveal CNV and Eyes without Subfoveal CNV
Variable Mean age (yrs) Mean axial length (mm) Mean preoperative SE Sex (male:female) Macular lacquer crack (yes:no)
Eyes with Eyes without Subfoveal Subfoveal CNV CNV Significance (n ⴝ 4) (n ⴝ 186) (P Value) 43.75 29.75 ⫺15.12 2:2 4:0
43.08 29.75 ⫺17.10 62:124 11:175
0.771* (NS) 0.546* (NS) 0.467* (NS) 0.604† (NS) ⬍0.001† (S)
CNV ⫽ choroidal neovascularization; NS ⫽ no significant difference; S ⫽ significant difference; SE ⫽ spherical equivalent (decimal score). *Mann–Whitney U test. † Fisher exact test.
careful examination of the macula before intraocular surgery on patients with high myopia. In our opinion, lacquer crack should be considered a contraindication to CLE. Other causes of decreased final BSCVA in our study, although they developed more gradually than subfoveal CNV, were progressive myopia-related maculopathy (3 eyes) and development of open-angle glaucoma 3 years after surgery (1 case).
Future Developments In conclusion, CLE and implantation of an IOL in the posterior chamber continues to be an alternative for many patients with high myopia. It can provide rapid, predictable, and stable improvement in visual acuity. Continued advances in surgical techniques and the design of IOLs will improve these results even more. Nevertheless, both the patient and the surgeon must have a clear understanding that this procedure carries risks to vision and that one is operating on otherwise healthy eyes. The primary concern for this procedure is the risk of retinal complications, and as Goldberg1 has pointed out, CLE usually needs to be bilateral to avoid substantial aniseikonia. Clear lens extraction should be considered as an alternative only for patients who have been carefully selected on the basis of the results of thorough vitreoretinal examinations and after consideration of other techniques for treatment. In addition, all patients must be closely followed up after surgery to manage possible complications and to determine the long-term results of this procedure.
References 1. Goldberg MF. Clear lens extraction for axial myopia: an appraisal. Ophthalmology 1987;94:571– 82. 2. Colin J, Robinet A. Clear lensectomy and implantation of low-power posterior chamber intraocular lens for the correction of high myopia. Ophthalmology 1994;101:107–12. 3. Barraquer C, Cavelier C, Mejia LF. Incidence of retinal detachment following clear-lens extraction in myopic patients. Retrospective analysis. Arch Ophthalmol 1994;112: 336 –9. 4. Lyle WA, Jin GJ. Phacoemulsification with intraocular lens implantation in high myopia. J Cataract Refract Surg 1996; 22:238 – 42.
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Ophthalmology Volume 110, Number 12, December 2003 5. Colin J, Robinet A. Clear lensectomy and implantation of a low-power posterior chamber intraocular lens for correction of high myopia: a four-year follow-up. Ophthalmology 1997; 104:73–7, discussion 77– 8. 6. Colin J, Robinet A, Cochener B. Retinal detachment after clear lens extraction for high myopia: seven-year follow-up. Ophthalmology 1999;106:2281– 4. 7. Koch DD, Liu JF, Gill EP, Parke DW II. Axial myopia increases the risk of retinal complications after Nd:YAG laser posterior capsulotomy. Arch Ophthalmol 1990;107:986 –90.
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8. Jacobi FK, Hessemer V. Pseudophakic retinal detachment in high axial myopia. J Cataract Refract Surg 1997;23:1095–102. 9. Javitt JC, Tielsch JM, Canner JK, et al. National outcomes of cataract extraction. Increased risk of retinal complications associated with Nd:YAG laser capsulotomy. The Cataract Patient Outcomes Research Team. Ophthalmology 1992;99:1487–7, discussion 1497– 8. 10. Fritch CD. Risk of retinal detachment in myopic eyes after intraocular lens implantation: a 7-year study. J Cataract Refract Surg 1998;24:1357– 60.
Various surgical options for treatment of high myopia are currently under evaluation. Extracting the clear lens is one procedure that has been used to treat high myopia for a long time.1,2 The primary concern with this procedure is its association with an increased risk for retinal complications.1,3 To evaluate the effectiveness and safety of this procedure, we retrospectively reviewed visual acuity outcome and intraoperative and postoperative complications of clear lens extraction (CLE) and posterior chamber intraocular lens (IOL) implantation in 190 highly myopic eyes.
Originally received: June 4, 2001. Accepted: April 9, 2003. Manuscript no. 210374. 1 Ophthalmology Service, Asturias General Hospital, Oviedo, Asturias, Spain. 2 Ferna´ndez-Vega Eye Institute, Oviedo, Asturias, Spain. None of the authors has any commercial (proprietary or financial) interest in any product, drug, or device mentioned in this article. Reprint requests to Luis Ferna´ndez-Vega, MD, Instituto de Oftalmologı´a Ferna´ndez-Vega, Avenida Doctores Ferna´ndez-Vega, S/N, Oviedo 33012, Asturias, Spain. E-mail: [email protected]. © 2003 by the American Academy of Ophthalmology Published by Elsevier Inc.
Materials and Methods The medical records of patients who had undergone CLE and posterior chamber IOL implantation between January 1990 and December 1996 were reviewed, and those who had been followed up for ⱖ36 months were included in the study. Criteria for offering surgery were severe preoperative myopia (axial length, ⱖ26.00 mm) as determined by A-scan, a best spectacle-corrected distance visual acuity (BSCVA) of 20/100 or better, intolerance to contact lens use, and age between 30 and 55 years. Patients with prior retinal detachment (RD), glaucoma, or previous ocular surgery were excluded. All surgery was performed by two surgeons at the Ferna´ndezVega Eye Institute. In eyes with lattice degeneration, retinal tear, or hole, we performed argon laser photocoagulation before surgery. Intraocular lens power calculations were performed with the Sanders–Retzlaff–Kraff II formula. Surgery was begun by creation of a 6- to 6.5-mm groove 2 mm posterior to the limbus at approximately one third the scleral depth. A scleral tunnel incision of 3.2 mm was made by dissecting forward in the sclera up to the peripheral cornea. A viscoelastic material was instilled into the anterior chamber, and capsulorhexis and hydrodissection were performed. The lens was extracted by phacoemulsification or phacoaspiration followed by irrigation/aspiration. The incision was then widened to 6.5 mm, and a posterior chamber one-piece ISSN 0161-6420/03/$–see front matter doi:10.1016/S0161-6420(03)00794-2
2349
Ophthalmology Volume 110, Number 12, December 2003 Table 1. Demographic Data No. of patients Bilateral cases Unilateral cases Sex Female Male Mean age (yrs)
107 83 24 71 36 43.03 ⫾ 6.63 (range, 30–55)
polymethylmethacrylate IOL (UI 80; Pharmacia, Peapack, NJ) was implanted in the bag. The anterior chamber was restored with balanced salt solution. Sutures were not used unless there was leakage when pressure was placed on a sponge over the incision, and, if necessary, closure was performed with one or two interrupted nylon 10-O sutures. Data recorded for this study included patient age and sex and each eye’s axial length, preoperative and final BSCVA, preoperative and postoperative spherical equivalent (SE), previous argon laser treatment, use of neodymium:yttrium–aluminum– garnet (Nd:YAG) laser capsulotomy, complications such as RD and choroidal neovascularization (CNV), time from surgery or Nd:YAG laser capsulotomy to RD, and follow-up time. To evaluate differences between eyes with RD and eyes without RD and between eyes with CNV and eyes without CNV, the Mann–Whitney U test was used to compare variables that were not normally distributed, and comparisons of categoric data were performed with Fisher exact test. All statistical analyses were performed with the SPSS package (SPSS Inc., Chicago, IL). Significance was defined as P⬍0.05 for all tests. Informed consent for the CLE and IOL implantation was obtained from all patients before surgery. Institutional review board approval was not required for this study.
Results During the study period, CLE and posterior chamber IOL implantation was performed on 195 eyes of 110 patients. Three patients (5 eyes) did not complete the 3-year minimum follow-up and were excluded because of poor follow-up; we have no evidence of RD or other complications within their follow-up. The study included 190 eyes of 107 patients. Patients’ demographic data are shown in Table 1, and their clinical data are shown in Table 2. They all had high myopia documented by an axial length of at least 26.00 mm (Fig 1) and by SE (Fig 2).
Figure 1. Distribution of axial length (mm; standard deviation, 2.35 mm; mean, 30 mm; n ⫽ 190).
vision when vision worsened one line or more. Final BSCVA was better than preoperative BSCVA in 159 eyes (83.68%), equal in 24 eyes (12.63%), and worse in 7 eyes (3.68%). Postoperative BSCVA was 20/40 or better in 136 eyes (71.60%) vs. 52 eyes (27.36%) before surgery (P⬍0.001; Fig 3). Seven eyes had loss of visual acuity because of subfoveal CNV (n ⫽ 3), progressive myopia-related maculopathy (n ⫽ 3), and open-angle glaucoma (n ⫽ 1) that developed 3 years after surgery. The mean preoperative SE was ⫺17.84 ⫾ 5.59 (range, ⫺7.00 to ⫺34.00). The mean final postoperative SE was ⫺1.22 ⫾ 1.24 diopters (D; range, ⫺5.00 to ⫹2.25 D; Fig 4). The postoperative SE was within ⫾1.00 D of emmetropia in 41% of eyes and within ⫾2.00 D of emmetropia in 79% of eyes.
Visual and Refractive Results We considered better vision when vision improved one line or more, equal vision for vision stable within one line, and worse Table 2. Clinical Data Variable Axial length (mm) Preoperative spherical equivalent Preoperative BSCVA Power of IOL used Follow-up (yrs) Preoperative argon laser therapy
Mean ⴞ SD
Range
30.13 ⫾ 2.35 26.00 to 39.20 ⫺17.84 ⫾ 5.59 ⫺7.00 to ⫺34.00 0.37 ⫾ 0.17 0.34 to 0.39 3.29 ⫾ 5.53 ⫺10.00 to 14.50 4.78 ⫾ 1.19 3.10 to 8.03 34 eyes (17.89%)
BSCVA ⫽ best spectacle-corrected visual acuity (decimal score); IOL ⫽ intraocular lens; SD ⫽ standard deviation.
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Figure 2. Preoperative spherical equivalent distribution (standard deviation, 5.59; mean, ⫺17.7; n ⫽ 190).
Ferna´ ndez-Vega et al 䡠 Clear Lens Extraction for High Myopia
Figure 3. Scatterplot of preoperative vs. postoperative best spectaclecorrected visual acuity (BSCVA; decimal score). The spikes resemble petals for each case where there are overlapping cases in the scatterplot. Each petal represents a case.
Complications The only notable intraoperative complication was rupture of the posterior capsule in one eye (0.53%). There was no loss of vitreous, and the IOL was successfully implanted in the posterior chamber. The final corrected visual acuity in this eye was 20/25. Posterior capsule opacification was the most frequent postoperative complication. It occurred and was treated by Nd:YAG laser capsulotomy in 148 eyes (77.89%). The mean time from CLE to capsulotomy was 21.72 ⫾ 11.16 months (range, 2.60 – 63.20 months). Three years after surgery, one patient had an open-angle glaucoma, defined by visual field defects in a pattern consistent with glaucoma (30-2 test of the Humphrey automated perimeter device).
Retinal detachment occurred in 4 (2.10%) of 190 eyes (3.73% of patients). Retinal detachments occurred 28 to 39 months after surgery. The characteristics of these eyes are listed in Table 3. The retina was reattached in 100% of these eyes, and final BSCVA in all eyes was equal to or better than preoperative BSCVA. The fellow eyes of these patients, which were also treated by CLE, did not have RD. Patients who had CLE in only 1 eye (24 unilateral cases) did not have any RD in fellow eyes during the same period of follow-up. There was a statistically significant difference in patient age between eyes with DR and eyes without this complication (P ⫽ 0.004; Mann–Whitney U test); however, there was no statistically significant difference in axial length, preoperative SE, sex, Nd:YAG capsulotomy performance, or previous laser argon treatment (Table 4). Subfoveal CNV developed in 4 eyes of 3 patients (1 bilateral case; 2.10% of eyes). The characteristics of these eyes are shown in Table 5. All eyes had been found on previous macular examination to have a lacquer crack. In total, macular lacquer crack had been identified in 15 of the 190 eyes. There was a statistically significant difference in the presence of lacquer crack between eyes with subfoveal CNV and eyes without this complication (P⬍0.001; Fisher exact test); however, there was no statistically significant difference in patient age, sex, axial length, or preoperative SE (Table 6). No clinical cystoid macular edema or endophthalmitis was observed.
Discussion The results of our study confirm findings in previous studies that CLE and implantation of an IOL in the posterior chamber have good effectiveness and acceptable predictability and that postoperative improvements in visual acuity are stable over a long follow-up period.2,4,5 Nevertheless, CLE remains a controversial technique because it is an invasive procedure and carries an increased risk of RD.3,4,6 –10
Retinal Detachment
Figure 4. Postoperative spherical equivalent distribution (standard deviation, 1.24; mean, ⫺1.22; n ⫽ 190).
The incidence of this complication after CLE reported in other studies3,4,6,8 –10 is variable, ranging from 0% to 8%. We propose that the causes of this variability are different patient characteristics and study designs. These and other3,5,10 previously reported studies have found associations between the risk of RD and one or more of the following factors: younger age, axial length, history of RD or surgery in the contralateral eye or lesions predisposing to RD, surgical technique and integrity of the posterior capsule, use of Nd:YAG capsulotomy, and longer follow-up time after surgery. Patient Age. All 4 of our patients with this complication were younger (aged 30, 32, 33, and 38 years) than the mean age in our study (43.03 years; range, 30 –55 years). We analyzed differences between eyes with RD and eyes without RD in patient age, axial length, preoperative SE, sex, Nd:YAG capsulotomy performance, and previous laser argon treatment, and we found a statistically significant difference only in patient age (P ⫽ 0.004; Mann–Whitney U test; Table 4). Barraquer et al3 reported an RD incidence of 7.3% after CLE in aphakic eyes. They found that 58% of the RDs occurred in patients younger than 30 years of age, whereas only 31% of patients younger than 30 years did not
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Ophthalmology Volume 110, Number 12, December 2003 Table 3. Characteristics of Eyes with Retinal Detachment Variable
Case 1
Case 2
Case 3
Case 4
Age (yrs) Sex Axial length (mm) Preoperative SE Preoperative BSCVA Surgery–RD interval (mos) Nd:YAG/postoperative interval (mos) Nd:YAG–RD interval (mos) Previous argon laser RD treatment Final BSCVA
32 Male 29.60 ⫺15.00 0.30 35 16 19 No SB ⫹ VTM 0.35
30 Female 29.89 ⫺19.00 0.30 28 18 10 No SF6 ⫹ laser 0.30
38 Female 29.99 ⫺18.00 0.25 37 21 16 No SF6 ⫹ laser 0.25
33 Male 32.30 ⫺17.00 0.40 39 19 15 No VTM ⫹ laser 0.45
Mean 33.25 30.44 ⫺17.25 0.31 34.75 18.50 15 0% 0.33
BSCVA ⫽ best spectacle-corrected visual acuity; Nd:YAG ⫽ neodymium:yttrium–aluminum– garnet laser; RD ⫽ retinal detachment; SB ⫽ scleral buckling; SE ⫽ spherical equivalent (decimal score); VTM ⫽ vitrectomy.
have RD. A history of detachment of the posterior vitreous, which is inversely related to the risk for RD after posterior chamber surgery, is a factor that we think is closely linked to patient age. Colin and Robinet2,5 and Colin et al6 reported that the prevalence of a history of posterior vitreous detachment before CLE and implantation of an IOL in the posterior chamber was 57.7% in their study group as a whole but was ⬎70% among the group’s elderly patients. Unfortunately, most of the medical records we examined in our retrospective study did not document whether the patient had a history of detachment of the posterior vitreous, so this was not a parameter we could analyze in our study. History. Another reason why the incidence of RD varies among studies is the use and timing relative to surgery of laser photocoagulation for conditions such as lattice degeneration, retinal tear, or retinal hole. In our study, none of the eyes that had prophylactic treatment developed RD, and the eyes that developed RD did not receive prophylactic treatment. We did not find a statistically significant difference in this factor (previous argon laser treatment) between eyes with RD and eyes without RD (P ⫽ 1.00; Fisher exact test; Table 4). From our study, there is no way to determine whether the prophylaxis treatment influenced the risk of Table 4. Statistical Data to Evaluate Differences between Eyes with RD and Eyes without RD
Variable Mean age (yrs) Mean axial length (mm) Mean preoperative SE Sex (male:female) Nd:YAG capsulotomy [yes (%):no] Previous argon laser [yes (%):no]
Eyes with RD (n ⴝ 4)
Eyes without RD (n ⴝ 186)
Significance (P Value)
33.25 30.12 ⫺17.25 2:2 4 (100%):0
43.31 30.44 ⫺17.04 62:124 144 (77.42%):42
0.005* (S) 0.546* (NS) 0.720* (NS) 0.604† (NS) 0.577† (NS)
0 (0%):4
34 (18.28%):152
1.000† (NS)
Nd:YAG ⫽ neodymium:yttrium–aluminum– garnet laser; NS ⫽ no significant difference; RD ⫽ retinal detachment; S ⫽ significant difference; SE ⫽ spherical equivalent (decimal score). *Mann–Whitney U test. † Fisher exact test.
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RD. Although there is controversy in this matter and more prospective randomized studies are necessary, we are convinced from our clinical experience that selective photocoagulation of lesions that predispose to RD helps to decrease the risk of RD as a complication of CLE and IOL implantation. Surgical Considerations. In addition to patient factors, the technique of surgery for high myopia affects the risk of RD. Studies show that phacoemulsification is a safer technique than extracapsular extraction of the lens and that implantation of an IOL (whether CLE is extracapsular or by phacoemulsification) also helps to decrease the risk of this complication.3,10 Nd:YAG Laser Capsulotomy. Nd:YAG laser photocoagulation is used to treat opacification of the posterior capsule, the most frequent complication of this surgery. The incidence of opacification increases in direct proportion to longer follow-up after CLE for high myopia,2,4,5,7 and the incidence of RD increases with use of Nd:YAG capsulotomy to treat opacification.3,6 –9 In our study, the 4 eyes that developed RD had required Nd:YAG capsulotomy for posterior capsule opacification. The mean time from CLE to capsulotomy was 18.5 months (mean time from CLE to capsulotomy in all treated eyes was 21.72 ⫾ 11.16 months), and the mean time from capsulotomy to the appearance of RD was approximately 15 months. The incidence of posterior capsule opacification varies widely in the different studies, and it can depend on the age of the patient, surgical technique, time of follow-up, and type of IOL placed. Furthermore, not all surgeons have the same criterion for deciding the moment for performing capsulotomy. In our study, capsulotomies were performed when opacities were noted and patients reported concerns with the quality of their vision. Follow-up Period. The effect of follow-up period on the incidence of RD is shown in the study reported by Colin and Robinet2,5 and Colin et al.6 They observed an initial group of 52 eyes for 7 years. At 4 years, 49 eyes remained in the study, and there was 1 case of RD, which represents an incidence of 1.9% based on the original group of 52 or an incidence of 2.0% based on “last observation.” However, between years 5 and 6 of follow-up, 3 more cases of RD
Ferna´ ndez-Vega et al 䡠 Clear Lens Extraction for High Myopia Table 5. Characteristics of Eyes with Subfoveal Choroidal Neovascularization Variable
Patient 1
Patient 2
Patient 3, Right Eye
Patient 3, Left Eye
Age (yrs) Sex Axial length (mm) Preoperative SE Preoperative BSCVA Surgery–subfoveal CNV interval (mos) Lacquer crack Final BSCVA
36 Male 29.18 ⫺10.50 0.50 7 Yes 0.10
45 Male 33.06 ⫺22.00 0.35 2 Yes 0.05
47 Female 28.40 ⫺15.50 0.20 13 Yes 0.05
47 Female 28.37 ⫺12.50 0.30 1 Yes 0.30
Mean 43.75 29.75 ⫺15.12 0.31 5.75 100% 0.12
BSCVA ⫽ best spectacle-corrected visual acuity; CNV ⫽ choroidal neovascularization; SE ⫽ spherical equivalent.
appeared; this represents an incidence of 8.16% based on “last observation.”2,5,6 In the Colin series,2,5,6 3 of the 4 RDs occurred between postoperative years 4 and 7. Studies with a follow-up of ⱕ4 years tended to have excellent results,5,8,9 suggesting that the risk of RD may increase with time and, therefore, that the RD rate can be higher with a longer follow-up time. Other Factors. In addition to the factors just described, small sample size can have a large effect on the incidence of a complication. A single case in a small series can result in a high incidence in that series.
Vision Loss In our series, RDs did not result in any severe loss of vision: all 4 retinas reattached, and the final BSCVA was better than or equal to the preoperative BSCVA in the 4 cases. Conversely, subfoveal CNV occurred 1 to 13 months (mean, 5.75 months) after surgery and did cause severe visual loss in 3 of the 4 eyes with this complication (Table 5). All had been found on previous macular examination to have a lacquer crack. In total, macular lacquer crack had been identified in 15 of the 190 eyes. There was a statistically significant difference in the presence of lacquer crack between eyes with subfoveal CNV and eyes without this complication (P⬍0.001; Fisher exact test); however, there was no statistically significant difference in patient age, sex, axial length, or preoperative SE (Table 6). We suggest Table 6. Statistical Data to Evaluate Differences between Eyes with Subfoveal CNV and Eyes without Subfoveal CNV
Variable Mean age (yrs) Mean axial length (mm) Mean preoperative SE Sex (male:female) Macular lacquer crack (yes:no)
Eyes with Eyes without Subfoveal Subfoveal CNV CNV Significance (n ⴝ 4) (n ⴝ 186) (P Value) 43.75 29.75 ⫺15.12 2:2 4:0
43.08 29.75 ⫺17.10 62:124 11:175
0.771* (NS) 0.546* (NS) 0.467* (NS) 0.604† (NS) ⬍0.001† (S)
CNV ⫽ choroidal neovascularization; NS ⫽ no significant difference; S ⫽ significant difference; SE ⫽ spherical equivalent (decimal score). *Mann–Whitney U test. † Fisher exact test.
careful examination of the macula before intraocular surgery on patients with high myopia. In our opinion, lacquer crack should be considered a contraindication to CLE. Other causes of decreased final BSCVA in our study, although they developed more gradually than subfoveal CNV, were progressive myopia-related maculopathy (3 eyes) and development of open-angle glaucoma 3 years after surgery (1 case).
Future Developments In conclusion, CLE and implantation of an IOL in the posterior chamber continues to be an alternative for many patients with high myopia. It can provide rapid, predictable, and stable improvement in visual acuity. Continued advances in surgical techniques and the design of IOLs will improve these results even more. Nevertheless, both the patient and the surgeon must have a clear understanding that this procedure carries risks to vision and that one is operating on otherwise healthy eyes. The primary concern for this procedure is the risk of retinal complications, and as Goldberg1 has pointed out, CLE usually needs to be bilateral to avoid substantial aniseikonia. Clear lens extraction should be considered as an alternative only for patients who have been carefully selected on the basis of the results of thorough vitreoretinal examinations and after consideration of other techniques for treatment. In addition, all patients must be closely followed up after surgery to manage possible complications and to determine the long-term results of this procedure.
References 1. Goldberg MF. Clear lens extraction for axial myopia: an appraisal. Ophthalmology 1987;94:571– 82. 2. Colin J, Robinet A. Clear lensectomy and implantation of low-power posterior chamber intraocular lens for the correction of high myopia. Ophthalmology 1994;101:107–12. 3. Barraquer C, Cavelier C, Mejia LF. Incidence of retinal detachment following clear-lens extraction in myopic patients. Retrospective analysis. Arch Ophthalmol 1994;112: 336 –9. 4. Lyle WA, Jin GJ. Phacoemulsification with intraocular lens implantation in high myopia. J Cataract Refract Surg 1996; 22:238 – 42.
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Ophthalmology Volume 110, Number 12, December 2003 5. Colin J, Robinet A. Clear lensectomy and implantation of a low-power posterior chamber intraocular lens for correction of high myopia: a four-year follow-up. Ophthalmology 1997; 104:73–7, discussion 77– 8. 6. Colin J, Robinet A, Cochener B. Retinal detachment after clear lens extraction for high myopia: seven-year follow-up. Ophthalmology 1999;106:2281– 4. 7. Koch DD, Liu JF, Gill EP, Parke DW II. Axial myopia increases the risk of retinal complications after Nd:YAG laser posterior capsulotomy. Arch Ophthalmol 1990;107:986 –90.
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8. Jacobi FK, Hessemer V. Pseudophakic retinal detachment in high axial myopia. J Cataract Refract Surg 1997;23:1095–102. 9. Javitt JC, Tielsch JM, Canner JK, et al. National outcomes of cataract extraction. Increased risk of retinal complications associated with Nd:YAG laser capsulotomy. The Cataract Patient Outcomes Research Team. Ophthalmology 1992;99:1487–7, discussion 1497– 8. 10. Fritch CD. Risk of retinal detachment in myopic eyes after intraocular lens implantation: a 7-year study. J Cataract Refract Surg 1998;24:1357– 60.