Radial keratotomy, popularized by Fyodorov and Durnev,1 was one of the preferred refractive procedures for myopia correction until the early 1990s and many patients underwent this technique. The Prospective Evaluation of Radial Keratotomy (PERK) study,2 which evaluated cases during a 10-year follow-up, revealed a high percentage of eyes with residual refractive errors after this procedure. After radial keratotomy, patients want a solution to remove their residual refractive errors and improve visual acuity.
Photorefractive keratectomy (PRK) has been used for correcting residual refractive errors (myopia and hyperopia) following radial keratotomy.3,4 The outcomes appeared to be effective, predictable, and safe, although some concerns have been noted regarding haze, scarring, or rapid regression.5,6 The application of mitomycin C has been effective in preventing subepithelial haze after PRK in patients who have had radial keratotomy.7 Mitomycin C used with wavefront-guided PRK improved the outcomes and sight-threatening haze was rare.8 LASIK or femtosecond laser–assisted LASIK has been proposed as a surgical solution for this limitation, but reported complications in eyes with previous radial keratotomy include intraoperative incision opening and wound dehiscence, rupture of radial keratotomy incisions during suction, decentered ablation, epithelial defects, diffuse lamellar keratitis, epithelial ingrowth, and corneal haze.2,9–14
In 2008, both Srinivasan et al.15 and Kamiya and Shimizu16 reported their initial experience using Implantable Collamer Lenses (ICLs) (Staar Surgical, Monrovia, CA) in the management of hyperopic residual refractive errors after radial keratotomy. Srinivasan et al.15 analyzed 4 eyes of 3 patients with a follow-up of 5.5 months and Kamiya and Shimizu16 described 1 eye of 1 patient with a follow-up of 12 months. Both case series concluded that the implantation of a hyperopic ICL could be considered as an alternative option for hyperopia correction after radial keratotomy. However, as they indicated, a large sample of patients and longer follow-up times are needed to assess the predictability, efficacy, and safety of this procedure.
The purpose of the current study was to provide more knowledge on this. We present a series of 6 eyes of 4 patients with residual refraction after radial keratotomy who had implantation of an ICL to correct their residual refractive error.
Patients and Methods
We retrospectively examined 6 eyes of 4 consecutive patients with residual refraction after radial keratotomy who had implantation of an ICL to correct their residual refractive error at the Fernández-Vega Ophthalmological Institute (Oviedo, Spain) between April 2007 and December 2013. The mean age of the patients was 42.5 ± 6.1 years (range: 39 to 49 years). The mean sphere was −3.33 ± 5.93 diopters (D) (range: +3.50 to −12.00 D) and the mean cylinder was −2.42 ± 1.10 D (range: −0.75 to −3.75 D). Informed consent was obtained from all patients after the nature and possible consequences of the study were explained.
The inclusion criteria were a corrected distance visual acuity (CDVA) of 20/50 or better and a stable refraction with a refractive error in the range correctable with the ICL. The exclusion criteria included age younger than 20 years, anterior chamber depth (ACD) from the corneal endothelium of less than 2.8 mm, endothelial cell density (ECD) less than 2,000 cells/mm2, mesopic pupil larger than 7 mm, cataract, glaucoma, and retinal and neuro-ophthalmic diseases.
Before ICL implantation, patients had a complete ophthalmologic examination. The examination included uncorrected distance visual acuity (UDVA), CDVA, refraction, slit-lamp examination, corneal topography and pachymetry (Orbscan II; Bausch & Lomb, Rochester, NY), ECD measurement (SP 3000P; Topcon Europe Medical, Capelle aan den IJssel, The Netherlands), intraocular pressure (IOP) assessment, anterior segment Visante optical coherence tomography (OCT) (Carl Zeiss Meditec, Jena, Germany), and indirect ophthalmoscopy.
The ICL is a posterior chamber phakic lens made of collamer to correct myopia, hyperopia, and astigmatism. All surgeries in this study were performed by one experienced surgeon (JFA) through a 3-mm clear tunnel incision using peribulbar anesthesia. Thirty minutes before surgery, cycloplegic and phenylephrine eye drops were applied. Five minutes before surgery, povidone-iodine 5% was applied. The anterior chamber was filled with sodium hyaluronate 1%, which was completely removed at the end of the surgery. Tobramycin and dexamethasone 0.1% eye drops were used four times a day for 10 days, after which diclofenac sodium eye drops were started four times a day for 2 weeks. In the two cases with bilateral ICL implantation, the second eye had surgery during the first postoperative week of the first eye. The software provided by the ICL manufacturer was used to select the ICL power of the lens. One week before the surgery, all eyes had laser iridotomy. All eyes were targeted for emmetropia.
Preoperative and postoperative visual acuity outcomes were evaluated. In addition, a complete analysis of possible adverse complications was performed. The efficacy index (defined as the ratio between postoperative UDVA and preoperative CDVA measured in Snellen decimal) and the safety index (defined as the ratio between postoperative and preoperative CDVA) were also calculated. Snellen decimal visual acuity values were converted to logMAR visual acuity values for statistical purposes. All patients were observed during 1 year. One optometrist, without knowledge of the aim of the study, performed all postoperative examinations. All data analysis was performed using the Microsoft Office Excel package (Microsoft Corporation, Redmond, WA).
This study enrolled 6 eyes of 4 patients. Preoperative and postoperative data are shown in Table 1. Figure A (available in the online version of this article) shows an eye implanted with an ICL after radial keratotomy.
Preoperative and 1-Year Postoperative Outcomes of the Patients
Eye implanted with an implantable collamer lens after radial keratotomy.
The mean preoperative CDVA was 0.18 ± 0.13 logMAR (range: 0.40 to 0.05 logMAR). Postoperatively, the mean UDVA was 0.31 ± 0.36 logMAR (range: 1.0 to 0.0 logMAR) and the mean CDVA was 0.12 ± 0.10 logMAR (range: 0.22 to 0.0 logMAR). The mean efficacy index was 0.86. No eyes lost lines of visual acuity, two eyes did not change after surgery, two eyes gained one line, and two eyes gained two lines. The mean safety index was 1.17. Table 1 shows the refractive outcomes of the eyes evaluated. The postoperative spherical refractive error was 0.00 D in 4 eyes, −0.50 D in 1 eye, and +2.00 D in 1 eye. The cylinder values ranged from −0.50 to −2.00 D, except in 1 eye, which had no astigmatism. No complications were reported during the surgery and explantation or repositioning of the ICL was not required in any of the treated eyes. ICL decentration was not observed. Neither halos nor glare were reported in this sample of patients. No eye showed IOP values greater than 21 mm Hg postoperatively and pupillary block was not reported in any patient. Mean vault was 350 ± 263 µm.
This retrospective study of 6 eyes evaluated a new approach for eyes with radial keratotomy: implantation of a posterior chamber phakic ICL. To our knowledge, only two previous studies reported case series of small numbers of eyes.
Our results have shown good visual acuity in relation to mean safety index (1.17), with some eyes maintaining their CDVA and most eyes gaining multiple lines of CDVA. No patients lost one or more lines of CDVA, CDVA did not change in 33% of eyes, and 66% of eyes gained one or more lines of CDVA. Predictability was also good for the sphere (close to 0.00 D) and some residual values for the cylinder. The software provided by the ICL manufacturer to calculate the power of the lens has been demonstrated to be valuable in our sample of eyes after radial keratotomy.
Srinivasan et al.15 and Kamiya and Shimizu16 reported an initial experience using ICL implantation in these cases. Srinivasan et al.15 showed the outcomes in 4 hyperopic eyes of 3 patients implanted with the V3 ICL model. They reported no intraoperative complications with a high reduction in the residual refractive error (from 5.31 D preoperatively to 0.08 D postoperatively). Two eyes were within 0.25 D and all were within 0.50 D of the predicted refractive target with a follow-up from 3 to 7 months. Two eyes gained two lines of CDVA and none experienced any loss of CDVA. They concluded that ICL implantation may be considered as an effective surgical optical option for hyperopia residual refractive error correction after radial keratotomy. Kamiya and Shimizu16 also reported their experience with a patient in whom an ICL was implanted to correct hyperopia. In their case, the refraction changed from +5.50 −1.50 × 85 preoperatively (having a UDVA of 0.2 and a CDVA of 1.2) to +0.50 −1.25 × 90 postoperatively (having a UDVA of 0.8 and a CDVA of 1.2). This eye showed six corneal incisions. Staar Surgical performed the calculations for the ICL power and length. They reported no serious complications or progressive hyperopic shift during 12 months of follow-up. They concluded that, taking into account the biomechanical instability of the treated cornea, a hyperopic ICL implantation could be an effective option for the surgical management of these patients.
Our results agree with both previous studies. We did not find serious complications, and visual acuity improved after the surgery with a significant reduction of the spherical value. However, we have to note that our study, with a large sample of eyes, considered both hyperopic and myopic residual refractive errors after radial keratotomy. Sphere refraction varied from −12.00 to +3.50 D and cylinder from −0.75 to −3.75 D before the surgery. In fact, most eyes showed a myopic residual refractive error. As previously indicated,15,16 most hyperopic eyes are not suitable for hyperopic ICLs because these eyes have a lower anterior chamber depth. However, these authors noted that hyperopic eyes that have had radial keratotomy usually have deeper anterior chamber depth because they were originally myopic (consider that these eyes should show deeper anterior chamber depth values due to their previous refractive condition). This consideration for hyperopic eyes plus the reversibility of the procedure make ICL implantation a surgical option to consider in these cases. Refractive lens exchange has also been suggested, but inaccurate keratometry increases the risk of choosing the wrong intraocular lens power and consequently provoking an uncorrected residual refractive error.15,17
The current and previous15,16 studies show that ICLs are a possible solution to correct refractive errors in eyes after radial keratotomy. We had no complications during the surgery or the follow-up period in this series of eyes. Nevertheless, long-term prospective studies are necessary to evaluate this surgical technique and its possible complications. We have to take into account that radial keratotomy incisions on the cornea in these patients may generate refractive changes with time due to corneal instability. Therefore, it would be ideal to consider this surgical treatment only when both refraction and keratometry are stabilized. However, refraction in these eyes is not completely stabilized and changes are expected with time. Surgical solutions that are reversible (eg, ICL implantation) offer us the possibility to correct a residual refractive error in these cases, avoiding poorer outcomes due to changes in refraction with permanent surgical procedures.
The results reported in this study are promising. The use of ICLs in eyes after radial keratotomy with clear central corneas could be considered an option for correcting residual refractive errors. Future studies should focus on evaluating long-term outcomes with larger samples of patients to assess the efficacy, safety, predictability, and stability of this surgical technique.
- Fyodorov SN, Durnev VV. Anterior keratotomy method application with the purpose of surgical correction of myopia. In: Fyodorov SN, ed. Pressing Problems of Ophthalmosurgery. Moscow: Moscow Research Institute of Ocular Microsurgery; 1977:47–48.
- Waring GO 3rd, Lynn MJ, McDonnell PJPERK Study Group. Results of the prospective evaluation of radial keratotomy (PERK) study 10 years after surgery. Arch Ophthalmol. 1994;112:1298–1308. doi:10.1001/archopht.1994.01090220048022 [CrossRef]
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- Nassaralla BA, McLeod SD, Nassaralla JJ Jr, . Prophylactic mitomycin C to inhibit corneal haze after photorefractive keratectomy for residual myopia following radial keratotomy. J Refract Surg. 2007;23:226–232.
- Koch DD, Maloney R, Hardten DR, Dell S, Sweeney AD, Wang L. Wavefront-guided photorefractive keratectomy in eyes with prior radial keratotomy: a multicenter study. Ophthalmology. 2009;116:1688–1696. doi:10.1016/j.ophtha.2009.05.013 [CrossRef]
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Preoperative and 1-Year Postoperative Outcomes of the Patients
|Parameter||Eye 1||Eye 2||Eye 3||Eye 4||Eye 5||Eye 6|
| Age (y)||39||39||31||43||43||45|
| RK cuts||8||8||8||8||8||8|
| Refraction (D)||−12.00 −2.00 × 0||−9.00 −2.00 × 0||−2.00 −0.75 × 0||−1.00 −2.50 × 10||0.50 −3.50 × 155||3.50 −3.75 × 50|
| ICL model||ICMV4||ICMV4||ICMV4||VTICMO||VTICMO||VICH|
| ICL size (mm)||12.50||12.50||13.20||13.20||13.20||12.10|
| ICL power (D)||−15.00||−12.50||−3.00||−4.00 +2.50 × 100||−3.50 +4.00 × 65||+4.00|
| Refraction (D)||0.00 −2.00 × 10||0.00 −2.00 × 5||−0.50 −0.50 × 170||0.00 −0.75 × 30||0.00||2.00 −2.00 × 70|