|Year : 2018 | Volume
| Issue : 4 | Page : 420-424
Three-piece add-on posterior chamber intraocular lens implantation for the correction of symptomatic pseudophakic ametropia: a retrospective study
Mahmoud F Rateb1, Mohammed N El-Mohamady2, Ibrahim M Ahmed3
1 Department of Ophthalmology, Assiut University, Asyut, Egypt
2 Department of Ophthalmology, Benha University, Banha, Egypt
3 Department of Ophthalmology, Al-Azhar University, Cairo, Egypt
|Date of Submission||30-Dec-2018|
|Date of Acceptance||20-Mar-2019|
|Date of Web Publication||23-Apr-2019|
Ibrahim M Ahmed
Department of Ophthalmology, Faculty of Medicine, Al-Azhar University, Cairo, 71524
Source of Support: None, Conflict of Interest: None
Purpose To evaluate the implantation of secondary low-power sulcus piggyback posterior chamber intraocular lenses (PCIOLs) for the correction of unaccepted postoperative refractive surprises or anisometropia.
Patients and methods We retrospectively reviewed 17 cases with uncomplicated cataract extraction using phacoemulsification with in-the-bag PCIOL implantation and undesired residual postoperative refractive error. Patients underwent secondary piggyback intraocular lens implantation with add-on monofocal SECURA-sPB through a 3.2-mm clear corneal incision. The primary outcome measure was uncorrected distance visual acuity. Moreover, we evaluated intraoperative or postoperative complications.
Results The mean age of patients was 65.2±10.1 years. The mean time to piggyback lens insertion was 6.5±3.1 months, and the mean follow-up period was 14.4±4.6 months. The mean preoperative uncorrected distance visual acuity was 20/80, and it increased significantly to be 20/30 postoperatively (P<0.001). The mean preoperative cylinder was 1.30±0.70 D, and it decreased significantly to be 0.54±0.45 postoperatively (P<0.001). The mean preoperative spherical deviation from emmetropia was 3.4±0.73 D, and the postoperative arithmetic prediction error mean was −0.32±0.55 D. No major intraoperative or postoperative complications were recorded.
Conclusion Low-power add-on sulcus PCIOLs provided safe and effective refractive results in pseudophakic patients with refractive surprises.
Keywords: correction, posterior chamber intraocular lens implantation, pseudophakic ametropia
|How to cite this article:|
Rateb MF, El-Mohamady MN, Ahmed IM. Three-piece add-on posterior chamber intraocular lens implantation for the correction of symptomatic pseudophakic ametropia: a retrospective study. Al-Azhar Assiut Med J 2018;16:420-4
|How to cite this URL:|
Rateb MF, El-Mohamady MN, Ahmed IM. Three-piece add-on posterior chamber intraocular lens implantation for the correction of symptomatic pseudophakic ametropia: a retrospective study. Al-Azhar Assiut Med J [serial online] 2018 [cited 2020 Feb 20];16:420-4. Available from: http://www.azmj.eg.net/text.asp?2018/16/4/420/256750
| Introduction|| |
Despite the advances in operative techniques, and the accuracy of biometric formulae, postoperative refractive surprises are not rare events. With increased patient expectations, refractive surprises can be disappointing to both the surgeon and the patient. The resultant anisometropia can also be difficult for the patient to tolerate. The most common causes for refractive surprises include errors in corneal curvature measurements in patients with past history of refractive surgery, A-scan errors, intraocular lens (IOL) mislabeling, lack of precision in eyes with smaller dimensions, and human error ,.
The management of postoperative pseudophakic refractive errors is challenging. Methods of treating this condition include contact lens or spectacle use as well as refractive surgery [laser-assisted in situ keratomileusis (LASIK) and photorefractive keratectomy]. IOL exchange can also be performed, as well as secondary piggyback IOL implantation . The piggyback technique for the correction of refractive surprises was first espoused by Gayton et al. . It involves implanting a secondary IOL in an overcorrected or undercorrected pseudophakic eye.
Some of the complications associated with the piggyback technique include interlenticular opacification , commonly associated with in-the-bag implantation of the secondary lens, especially if both lenses are of the same material. Optic capture and iris chafing with resultant pigment dispersion can occur when the lens is placed in the ciliary sulcus ,. The objective of this study is to evaluate the use of piggyback sulcus placed posterior chamber IOLs for the correction of postoperative refractive surprises or anisometropia.
| Patients and methods|| |
This retrospective study reviewed a total of 17 pseudophakic eyes of 15 patients collected from private center. The included patients had previous uneventful phacoemulsification with in-the-bag implantation of IOLs but later presented with undesired residual postoperative refractive error.
Preoperatively, all eyes were carefully examined by the slit lamp, as well as by anterior segment optical coherence tomography to ensure there was enough potential space between the primary lens and the back of the iris to accommodate a second IOL. IOL power calculation was performed using the refractive vergence formula. No axial length measurements were required. All surgeries were performed under peribulbar local anesthesia, and 3.2-mm clear corneal incisions were fashioned. Viscoelastic material was injected in the anterior chamber. The secondary IOL was implanted in the ciliary sulcus using the injector, and the primary IOL was left untouched in the capsular bag.
All patients received Add-On SECURA-sPB IOL MS714PB (HumanOptics, Erlangen, Germany). The Add-On SECURA-sPB is a monofocal, three-piece foldable IOL. Optic diameter is 7.0 mm, and the overall length is 14.0 mm. The optic is made of silicone elastomer with UV absorber. It has a convex–concave shape and round anterior edge to prevent iris irritation. The modified C-loop haptics have 0° angulation and are made in high-molecular-weight polymethylmethacrylate. The sphere range varies in 0.50 D increments between −6.0 and +6.0 D. The primary outcome measure was uncorrected distance visual acuity (UDVA), and the secondary outcome measures were manifest spherical deviation from emmetropia and best-corrected distance visual acuity. We also recorded intraoperative or postoperative complications.
Statistical analysis was performed using SPSS for Windows (IBM Corp., Armonk, New York, USA) and MS Excel (Microsoft Corporation, Redmond, Washington, USA). Snellen visual acuity was converted to log-MAR values for analysis. Data analysis was based on the number of eyes. Paired t-test was used to evaluate the significance of the difference between preoperative and postoperative values. Data were expressed as the mean±SD. The probability value of less than 0.05 was considered significant.
| Results|| |
Seventeen eyes of 15 (six males ‘40%’ and nine females ‘60%’) patients were retrospectively evaluated ([Figure 1],[Figure 2],[Figure 3]). The mean age of patients was 65.2±10.1 years. The mean time to piggyback IOL implantation was 6.5±3.1 months, and the mean follow-up period was 14.4±4.6 months.
|Figure 1 Anterior segment optical coherence tomography of a patient showing the posterior chamber intraocular lens and add-on posterior chamber intraocular lens in the sulcus.|
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|Figure 2 Photograph of surgical microscope view of add-on lens in the sulcus.|
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The mean preoperative UDVA was 20/80, and it increased significantly to be 20/30 postoperatively (P<0.001; [Figure 4]). However, the mean preoperative cylinder was 1.30±0.70 D, and it significantly decreased to 0.54±0.45 postoperatively (P<0.001; [Figure 5]). The mean preoperative spherical deviation from emmetropia was 3.4±0.73 D. The postoperative arithmetic prediction error mean was −0.32±0.55 D. No major intraoperative or postoperative complications were recorded in all studied cases.
|Figure 4 Preoperative and postoperative mean of uncorrected distance visual acuity of studied patients.|
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|Figure 5 Preoperative and postoperative cylinder mean of studied patients.|
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The results showed that there was a statistically significant difference between postoperative mean arithmetic prediction error and mean absolute error (P<0.001). There was also a statistically significant improvement in UDVA, with no change in best-corrected distance visual acuity. The linear regression analysis revealed good correlation (r=0.7) between preoperative and postoperative spherical equivalents.
There were no major intraoperative complications, and none of the patients required vitrectomy. Postoperative complications included four (23.5%) cases of transient increase in intraocular pressure (IOP) and two (11.7%) cases needed lens reposition under operating microscope, which became stable thereafter ([Figure 6]).
| Discussion|| |
Our results demonstrated that piggyback implantation of a secondary IOL in the ciliary sulcus in front of a primary, in-the-bag IOL, provides safe and effective refractive results for patients with postoperative refractive surprises. Our results are comparable to previous studies evaluating sulcus piggyback IOL implantation. Gills and Fenzl  reported effective refractive results in myopic pseudophakic patients who received secondary piggyback minus-power IOLs, where 72% of their patients were within ±0.50 D of the target refraction. They used the Holladay 2 refractive formula for IOL power calculation. Gayton et al.  also used the Holladay IOL consultant software to calculate the IOL power of their piggyback lenses. They reported a mean absolute deviation of 1.21 D from emmetropia in their cases. In a study by Habot-Wilner et al. , they reported a refractive outcome within 0.46±0.4 D of target in hyperopic eyes, and 0.5±0.7 D in myopic eyes using the following formula: power of IOL=(1.4×desired spherical equivalent change)+1 D. As similar to our results, Häberle et al.  applied the refractive vergence formula to a cohort of anisometropic patients and reported a mean absolute deviation from target refraction of 0±0.92 D.
There are some complications associated with the piggyback technique such as interlenticular opacification, postoperative elevation of IOP, pupillary optic capture after mydriasis, iris chafing, pigment dispersion syndrome, and secondary pigmentary glaucoma. The SECURA-sPB was designed to avoid these complications. The convex–concave configuration of the optic aids for increasing the space between the two IOLs and helps to avoid the interlenticular opacification. The diameter of the optic (7.00 mm) contributes to avoid the capture of the IOL during pupil dilation. Nevertheless, optic capture is a well-described finding in patients following sulcus piggyback IOL implantation ,; we reported one case in this study. Fibrosis of the lens zonular complex reduces the space available in the ciliary sulcus and can precipitate optic capture .
Pigmentary glaucoma secondary to iris chafing has also been reported in the literature ,,. The incidence of iris chafing has been reported to be related to the thick textured square edges of the three-piece hydrophobic acrylic lenses. The anterior round edge of the Add-On SECURA-sPB IOL reduces iris irritation and consequently pigmentary dispersion and secondary pigmentary glaucoma. Although less likely to cause iris chafing, we nevertheless encountered a single case of pigment dispersion in our patients. This was associated with IOP increase, which was medically controlled.
The refractive vergence formula used in our study provided an effective means of calculating IOL power. The formula allows the surgeon to calculate the amount of optical power to add or subtract to an eye depending on the site of IOL implantation, in the anterior chamber, the ciliary sulcus, or the capsular bag. The IOL power is determined by the effective lens position, the vertex distance of the patient’s current refraction, keratometry readings, as well as preoperative and desired postoperative refraction. In the case of sulcus piggyback lens implantation, determining the effective lens position involves subtracting 0.65 mm from the manufacturer’s ‘bag’ anterior chamber depth.
Piggyback implantation offers multiple advantages to IOL exchange. The procedure is technically easier, and is less traumatic to the posterior capsule and the zonular apparatus. The extraction of an IOL, in which there is noticeable fibrosis of the capsular bag, may have serious consequences, such as capsular rupture with vitreous loss, which may lead to retinal tears/detachment or macular edema, zonular damage, and cyclodialysis, as well as an increased difficulty in the implantation of an IOL. The calculation of the power of the required secondary piggyback IOL is more predictable than that of an IOL exchange because it is planned solely depending on patient’s subjective refraction and it is not required to know the power of the primary IOL.Refractive surgery can provide an alternative means of correcting postoperative refractive errors. The implantation of a secondary IOL is a reversible procedure. It enables the correction of a wide range of refractive errors and has stable long-term refractive results compared with laser ablation procedures . Jin et al.  retrospectively compared the efficacy of LASIK versus lens-based surgery in correcting postoperative residual refractive errors. However, the authors did not distinguish between piggyback IOL implantation and IOL exchange. They found no significant difference between groups in postoperative spherical equivalent, with significantly improved astigmatism in the LASIK group. Furthermore, myopic LASIK patients had greater improvement of log-MAR UDVA; moreover, no difference was found between groups for hyperopic eyes.
| Conclusion|| |
Piggyback IOL implantation with large optic/length silicone, low-power posterior chamber IOLs placed in the ciliary sulcus provided excellent refractive precision when the refractive vergence formula was used for IOL power calculation. There was excellent IOL centration and design biocompatibility. All of our patients had improved UDVA, and there was no loss in best-corrected distance visual acuity. Iris chafing with possible resultant pigment dispersion and optic capture are the principal concerns with the sulcus-based piggyback technique.
Mahmoud F. Rateb designed the work and data collection. Mohammed N. El-Mohamady did analysis of the data and writing of the manuscript. Ibrahim M. Ahmed did writing of the manuscript and publishing.
Financial support and sponsorship
Conflicts of interest
There are no conflicts of interest.
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[Figure 1], [Figure 2], [Figure 3], [Figure 4], [Figure 5], [Figure 6]