[Abstract] Objective To evaluate the safety and efficacy of implantable Collamer Lens (Visian) with intraocular IOL (PIOL) for the correction of high myopia in Asians. Methods In this prospective study, 61 eyes of 40 Chinese myopic patients with a mean equivalent spherical lens of -14.54 ± 3.61 D (-7.00 ~ -24.75 D) on preoperative primary optometry were selected for Visian PIOL implantation from May 2002 to December 2004. Anatomical differences were compared between Asians and Caucasians. Results The mean follow-up time was 13.67 ± 8.51 months (1 to 32 months). The predictability of primary optometric equivalent spherical lenses was 88% for those at ±1.0 D and 72.5% for those at ±0.50 D. The mean equivalent spherical lens for postoperative primary optometry was -0.10 ± 0.74 D. Best corrected visual acuity (BSCVA) remained unchanged or increased by ≥1 line in 97% of the operated eyes. 2 eyes had a 1 line decrease in BSCVA. Retinal detachment occurred in 1 eye at 15 months postoperatively. Given the statistical differences in anterior chamber depth and white-to-white distance between Caucasians and Chinese, it would be more accurate to calculate the Visian PIOL size with the following adjustment: if the anterior chamber depth is ≤3.0 mm, the crystal size is the white-to-white distance plus 0.5 mm, and if the anterior chamber depth is >3.0 mm, the crystal size is the white-to-white distance plus 1.0 mm. In our present group of cases, there was only 1 case resulted in cataract development due to inaccurate size calculated by the initial application of the original algorithm. Conclusion The safety and efficacy of implanting the Visian PIOL to correct high myopia in Asians is close to that of the FDA clinical trials in Caucasians. the calculation of Visian PIOL size is very important and there are some differences between the calculation in Asian eyes and Caucasians. [Journal of Refractive Surgery, 2006] For highly myopic patients who are not candidates for LASIK, implantation of a phakic intraocular lens (PIOL) has been shown to have good safety, efficacy, and predictability.1-6 The risk of vision loss is minimal.7 One type of PIOL is the Visian Implantable Collamer Lens (ICL; STAAR Surgial Co, Monrovia, Calif.) The Visian PIOL is a posterior chamber IOL made of Collamer, a copolymer of hydroxyethylmethacrylate and porcine collagen. the latest model, the V4, was developed in 1999 and is an important improvement over the previous V3 The most recent model, V4, was developed in 1999 and has a significant improvement over the previous model, V3, in that it has a significantly higher arch before the anterior lens capsule.8 Several studies have been reported for surgery on Caucasian eyes, and this article is the first to report on the use of Visian PIOL Type V4 in Asians. Due to slight anatomical differences between Asian and Caucasian eyes, the currently applied method of calculating crystal size was corrected in our case. Patients and Methods A total of 40 consecutive patients who underwent Visian PIOL implantation at a private hospital in Hong Kong were selected for this prospective study. Visual acuity, accuracy and safety results are reported. Anatomical differences between Caucasians and Asians, such as white-to-white distance, anterior chamber depth, and central corneal thickness, were compared, and these data were obtained from the Orbscan database of patients undergoing LASIK surgery from January to June 2004. GraphPad InStat software (GraphPad Software Inc, San Diego, Calif) was applied for statistical processing. Study population A total of 40 consecutive patients with high myopia (28 right eyes and 33 left eyes) who underwent Visian PIOL implantation from May 2002 to December 2004 were enrolled in this study in 61 eyes. Of the 40 patients, 31 were female and 9 were male. The mean age of the patients was 34.9 years (23-47 years). The mean equivalent preoperative primary optometry was -14.54 ± 3.61 D (-7.00 ~ -24.75 D). The mean preoperative columnar lens prescription in these eyes was 1.83 ± 1.12 D. All procedures were performed by the same surgeon (J.S.C.). All patients signed a preoperative informed consent form informing them of the potential risks and benefits of the lens implantation procedure. Fifty-one of the eyes (83.6%) followed the ortho-ortho design with a mean equivalent spherical lens preoperative primary optometry of -13.42 ± 2.38 D (-7.00 ~ -17.25 D). In the other 8 eyes (13.1%), the preoperative primary equivalent spherical lens was -21.52±2.52D (-18.25 ~ -24.75D) according to the binocular design, and the -23.0D Visian PIOL was applied to minimize myopia. 2 eyes (3.28%) were amblyopic with a preoperative best corrected visual acuity (BSCVA) of 20/150. Exclusion criteria included: previous internal eye surgery, glaucoma, progressive degenerative corneal disease, and shallow anterior chamber depth (for those with 3.0 mm, PIOL was horizontal white-to-white measurement plus 1.0 mm. In this group, the mean white-to-white measurement was 11.2 ± 1.32 mm, and the mean anterior chamber depth was In 61 eyes, 44 eyes (23%) had an anterior chamber depth between 2.8 mm and 3.0 mm, and the remaining eyes (77%) had an anterior chamber depth between 3.0 and 3.9 mm. White-to-white measurements were first measured by applying the Castroviejo gauge under the slit lamp and then confirmed by applying the Stahl gauge and Orbscan (PhD, Rochester, N.Y.) There was high agreement between the Castroviejo gauge and the Orbscan for white-to-white measurements. A four-sided atrial angle scope was routinely applied to all eyes to rule out atrial angle abnormalities. On the day of surgery, dilated pupils were applied sequentially with 1% cyclopentone, 10% benfotiamine, and Voltaren (Novartis International, Basel, Switzerland). The white-to-white distance was measured preoperatively in the supine position by applying the gauge again. The surgeon placed the Visian PIOL model V4 into the lens implantation chamber under the operating microscope and applied the STAAR MicroSTAAR lens pusher to push the lens into the eye. Surface anesthesia was applied with 0.5% bupivacaine hydrochloride. A 3.2 mm temporal lateral clear corneal incision was made by applying a diamond knife. The anterior chamber was punctured and hydroxypropylmethylcellulose was injected into the anterior chamber and drained out of the atrial fluid. The lens was then slowly pushed into the iris plane in the anterior chamber to spread it. The positioning holes of the distal and proximal plates of the lens are examined to ensure that the lens is orthotropic. The Vukich intraocular lens adjuster is applied and each corner of the plate is carefully positioned under the iris. After the crystal is positioned correctly, the viscoelastic irrigation is flushed by applying a balanced salt solution. The corneal incision was sealed with edema. In 38 of the eyes, a release incision was applied to correct the preoperative astigmatism. A Lab Instrument L320 micron diamond knife (Akorn Inc, Decatur) was applied to create an incision of 6 to 10 mm in length and 600 μm in depth. The length of the incision was determined according to the Gill formula, and the position of the incision was determined according to the axial direction of the preoperative column lens. Results Visual acuity In this study, preoperative naked eye visual acuity was index or below in all eyes. 32 eyes had a preoperative BSCVA ≥20/20. Of these 32 eyes, naked eye visual acuity (UCVA) at the last follow-up was higher than the preoperative BSCVA in 14 eyes (43.8%) and equal to the preoperative BSCVA in 9 eyes (28.1%), so that 71.9% of the postoperative UCVA was higher or All 32 eyes (100%) had a postoperative UCVA ≥20/40. 24 eyes (75%) of the 32 eyes had a UCVA ≥20/20. Cumulative distribution of preoperative best corrected visual acuity (BSCVA) and postoperative naked eye visual acuity (UCVA) for the 32 eyes with a preoperative BSCVA ≥20/20. Three eyes of 61 eyes had preoperative BSCVA ≤20/50, two eyes were amblyopic with BSCVA of 20/150, and one eye had preoperative BSCVA of 20/50 with a primary optometric equivalent spherical lens of -23.50 D. The remaining eyes had BSCVA ≥20/40. postoperatively, 43 eyes (70.5%) had BSCVA improved by 1 line in 61 eyes, 16 eyes (26.2%) remained unchanged, and BSCVA decreased by 1 row in 2 eyes (3.3%). No visual acuity loss of ≥2 rows was observed. Comparison of best corrected visual acuity between preoperative and last postoperative follow-up in 61 eyes. (Note: For those with retinal complications in 3 of the eyes, the BSCVA at the follow-up visit before the retinal complications occurred was taken instead of the last follow-up visit.) The mean preoperative subjective optometric equivalent spherical lens was -13.42 ± 2.38 D (-7.00 ~ -17.25 D) in 51 eyes with ortho-optic design. The primary optometric equivalent spherical lens at the last follow-up was -0.10 ± 0.74 D (+2.75 ~ -2.00 D). 37 eyes (72.5%) had a primary optometric equivalent spherical lens within ±0.5 D and 45 eyes (88.2%) were within ±1.0 D. The predictability of this 51 eyes in this study was demonstrated. Predictability of 51 eyes in the orthokeratology design. One eye that was significantly outside the straight line represents overcorrection, which was due to a preoperative optometric error (y=0.7545x-3.5234; R2=0.873). The subjective optometry at each postoperative review is shown for all eyes, and the stability of the refractive status was evaluated by the results of the postoperative optometry at different times. We evaluated the mean change in the value of the primary refraction at the following different times: 1 and 6 months postoperatively, 6 months and 1 year postoperatively, and 1 and 2 years postoperatively (see Table 1). at the 2-year follow-up, the stability of the primary refraction equivalent spherical lens was within ±1.0 D in all eyes, and 75% of them were within ±0.5 D. Figure 4: Stability of the primary optometric equivalent (MSE) spherical lens (error bars = standard deviation) in 61 eyes at 24 months postoperatively. Postoperative follow-up refractive stability in 61 Chinese eyes undergoing Visian PIOL implantation Postoperative interval Refractive change Eight eyes with binocular vision design (mean preoperative primary optometric equivalent spherical lens of -21.52 ± 2.52 D) had a mean primary optometric equivalent spherical lens of -2.11 ± 1.10 D at the last follow-up visit. all patients did not elect to undergo further refractive surgery, and all of them were satisfied with their results after Visian PIOL implantation despite residual myopia. The mean preoperative columnar lens correction in the 38 eyes that also underwent corneoscleral rim release incisions was 1.83 ± 1.12 D. The mean columnar lens correction at the last follow-up visit was 0.97 ± 1.00 D. Figure 5 shows the mean columnar lens correction at each postoperative follow-up visit. This figure shows that the stigmata achieved good stability after 3 months postoperatively, with minimal difference in stigmata correction at 3 months and 24 months. : Comparison of preoperative and postoperative mean stigmoscopy (error bars = standard deviation) in 38 eyes with intraoperative corneoscleral margin release incisions. The mean preoperative IOP was 16.8±2.72 mmHg (10-25 mmHg) and the mean IOP at the last follow-up was 16.98±3.19 mmHg (12-26 mmHg). At the 1-week postoperative follow-up, 5 eyes (8.2%) had IOP >21 mmHg, which increased to 16 eyes (26.2%) at 2 months. at 3 months, no IOP >21 mmHg was seen, and no IOP-lowering drugs were used in all patients. Complications There were no intraoperative complications in this group (Table 2). Sixteen eyes (26.2%) developed elevated intraocular pressure (range: 23 to 30 mmHg) within 2 months after surgery. In one of these eyes, an increase in intraocular pressure was detected at the time of review on postoperative day 1. After application of 2% pilocarpine, the intraocular pressure quickly returned to within the normal range. It was considered to be due to pupillary block. In another eye, the intraocular pressure was within the normal range in the first month after surgery, but increased to 30 mm Hg in the second month, which was considered to be induced by corticosteroids. The intraocular pressure returned to normal with the application of Silyta (Pfizer Inc, NewYork, NY) and acetazolamide (Wyeth, Madison, NJ) for 2 days. In the remaining 14 eyes in which elevated intraocular pressure occurred, intraocular pressure returned to the normal range within 1 month after application of beta-blockers. Long-term treatment was not required in all eyes. Three patients (4.9%) developed postoperative glare, which was caused by laser iris perforation prior to implantation of the Visian PIOL. This symptom lasted only a short time. Only one patient (1.6%) still had glare symptoms 6 months after the procedure. In 2 patients, macular hemorrhage occurred in 2 eyes (3.3%) 1 year after Visian PIOL implantation. One of them was a 35-year-old female with a retrovitreous detachment, a primary optometric equivalent spherical lens of -18.63 D, and a preoperative BSCVA of 20/40. This patient complained of blurred central vision at the 1-year postoperative follow-up and was diagnosed with macular hemorrhage by fundus fluorescence angiography (FFA). The current BSCVA of this affected eye is 20/30 and is under continued follow-up. The other case was a 39-year-old female with Visian PIOL implants in both eyes, who had a preoperative primary optometric equivalent spherical lens of -14.88 D and a BSCVA of 20/30, and complained of a dark spot in the right eye at the 1-year postoperative follow-up. A macular hemorrhage with choroidal neovascularization was diagnosed by FFA and photodynamic therapy (PDT) was subsequently performed. The naked visual acuity of the eye was 20/100, and the naked visual acuity of the contralateral eye with Visian PIOL implantation was 20/20. Retinal detachment occurred in one eye (1.6%) 15 months after Visian PIOL implantation. The eye had a preoperative primary optometric equivalent spherical lens of -18.25 D and an axial length of 31.0 mm. cryotherapy and scleral buckling surgery were performed, and the retina was successfully repositioned. Six months after the retinal repositioning surgery, the condition was stable with bare eye visual acuity stabilized at 20/60 and BSCVA restored to the level of 20/30 prior to retinal detachment. the Visian PIOL was not removed. Delayed anterior lens capsule clouding developed in 1 eye (1.6%) 14 months postoperatively. This patient was 34 years old and was found to have a slight decrease in naked eye visual acuity, which on examination decreased from 20/20 to 20/25, while the BSCVA remained at 20/15. distance between Visian PIOL and lens -8.0 D) after LASIK surgery. In addition to the calculation of the refractive index of the lens, the proper size of the Visian PIOL is an important factor in ensuring the postoperative results. Table 3 shows that Asian eyes have the following statistical differences from Caucasians: lower white-to-white measurements, shallower anterior chamber depth, and thicker central corneal thickness. These results were obtained from the Orbscan II database of patients who have had refractive surgery consultations in our clinic since January 2001. (The validity of Orbscan II for normal corneal measurements has been reported by Reddy et al.22) In general, for Caucasians, the recommended PIOL size is: if the anterior chamber depth is between 2.8 mm and 3.5 mm, the PIOL size is horizontal white-to-white measurement plus 0.5 mm; if the anterior chamber depth is >3.5 mm, the PIOL size is horizontal white-to-white measurement plus 1.0 mm.2,13 However, these criteria were established based on Caucasians. Since all patients in this group were Chinese from Hong Kong, application of this criterion resulted in three patients with implanted crystals that were too small. Because of the smaller Chinese eyes, we applied the following criteria: for anterior chamber depth ≤3.0 mm, PIOL is horizontal white-to-white measurement plus 0.5 mm; for anterior chamber depth >3.0 mm, PIOL is horizontal white-to-white measurement plus 1.0 mm. From our early experience, we learned that for Chinese eyes with anterior chamber depth* of 3.0 mm to 3.5 mm, if we follow white-to-white measurement plus 0.5 mm is calculated, the crystal would be too small. Only one patient in our group had an anterior subcapsular cataract because the implanted lens was too small, and the anterior chamber depth in that eye was 3.18 mm.(*Translator’s note: There was a clerical error in the original article here, which was corrected in the translation based on the article.) A Visian PIOL that is too small can result in insufficient arch and increase the risk of cataract. Gonvers et al14 found that with an arch greater than 90 μm, no have developed anterior subcapsular cataracts. In clinical practice, a Visian PIOL is judged to be too small if the distance between the posterior edge of the Visian PIOL and the anterior capsule of the lens is less than 250 μm. This distance is estimated by the physician by comparison with corneal thickness during a slit lamp examination. Conversely, if the Visian PIOL is white to white plus 1.0mm according to the Asian algorithm for Caucasian eyes with a white-to-white measurement of 3.0mm to 3.5mm, this would make the lens too large and consequently result in a larger pupil, halos, glare, and an increased rate of pigmentary seeding and pigmentary glaucoma. Pigment dispersion after Visian PIOL implantation has been of concern because the iris-to-crystal distance is significantly reduced after the procedure.15 In an early study, Trindade et al15 found that all patients implanted with Visian PIOL had iris-to-Visian PIOL contact. However, as the design of the Visian PIOL arch improves, the likelihood of iris-to-crystal contact decreases. According to STAAR’s recommendation, the Visian PIOL can be used in patients with a minimum anterior chamber depth of 2.8 mm. However, the U.S. FDA recently approved the lens only for those with an anterior chamber depth of at least ≥3.0 mm. In this group, 23% of patients had an anterior chamber depth between 2.8mm and 3.0mm, but no significant pigmentation was found in any of the operated eyes. In another group of 18 eyes studied, the anterior chamber depth was as low as 3.0 mm, and the authors did not find significant pigmentation.16 Three of the patients in this group with early implantation of the Visian PIOL were found to have an arch that was lower than the manufacturer’s recommendation and were therefore considered too small. All three patients had an anterior chamber depth of 3.0 to 3.5 mm. 2 of the eyes were asymptomatic at 24-month postoperative follow-up and continued to be followed. The other 1 eye had an unremarkable anterior subcapsular cataract 1 year after surgery. At the last review 1 year and 6 months after surgery, the patient had a bare eye visual acuity of 20/25 and a best-corrected visual acuity of 20/15. This was the only case of cataract in this group of patients (1.6%). Lackner et al17 suggested that the likelihood of cataract development with the implantation of Visian PIOL is increased in patients older than 45 years of age. The cataracts that occurred in our patients were due to the small size of the implanted Visian PIOL and insufficient arching in front of the lens. Only one of our patients was older than 45 years of age. All other patients did not develop early or late cataracts. The FDA clinical trial also reported a very low incidence of delayed anterior subcapsular cataract (0.4%, 2 eyes out of 526).1 Compared with the previous model of Visian PIOL, the V4 “had a significantly lower incidence of anterior subcapsular cataract, clinically significant cataract, and secondary ICL-related surgery. “8 Twenty-six percent of our patients experienced a transient increase in intraocular pressure within 2 months of surgery. Intraocular pressure peaked at the 1-month postoperative follow-up and decreased by 3 months postoperatively, commensurate with the application of IOP-lowering drops. At 6 months postoperatively, intraocular pressure stabilized to preoperative levels. Of the early IOP elevations, one case was considered to be due to pupillary block, while the other was thought to be due to residual viscoelastic (hydroxypropyl methylcellulose). If viscoelastic retention is more pronounced, the surgeon should remove the viscoelastic from the peripheral iridectomy site first at the end of the procedure, and then from the rest of the anterior chamber. This will significantly reduce the incidence of transient intraocular pressure elevation. Delayed intraocular pressure elevation may be induced by corticosteroids. In the US FDA clinical trial of Visian PIOL, retinal detachment occurred in 3 eyes (0.6%) of 526 eyes.1 Sanders7 estimated the incidence of visual loss associated with retinal detachment in IOL eyes after cataract extraction due to lens clouding induced after implantation of Visian PIOL to be 0.63%.1 Uusitalo et al3 reported 1 patient with significant visual loss 17 months after implantation of Visian PIOL due to progression of dry macular degeneration that began before the procedure. Among our patients, 2 eyes (3.3%) developed macular hemorrhage 1 year after Visian PIOL implantation and 1 eye (1.6%) developed retinal detachment 1.5 years after the procedure. The two eyes with macular hemorrhage had myopic degeneration before Visian PIOL implantation. A significant decrease in BSCVA was seen only in the eye with choroidal neovascularization. The other eyes in which macular hemorrhage and retinal detachment occurred did not show a decrease in BSCVA. The primary cause of macular hemorrhage and retinal detachment in these eyes may be due to high preoperative myopia and the presence of degeneration itself, rather than to the Visian PIOL procedure. It was confirmed through this group of patients that performing a corneoscleral rim release incision in conjunction with Visian PIOL implantation according to the Gills algorithm is an effective method of reducing preoperative astigmatism. Because the incision is small and located at the corneoscleral rim, it rarely causes corneal distortion or irregularity. Although complete correction was not achieved in this group of patients (see Figure 4), residual astigmatism of 0.97 D was achieved and was able to remain stable for 3 months, achieving acceptable naked eye visual acuity for most patients. This technique has also been applied to cataract surgery with good results.18,19 We confirmed with this group of patients that good visual acuity and stable results can be obtained with Visian PIOL implantation in Asians with moderate to high myopia. If the recommended criteria for Caucasian eyes are applied, the smaller size of the Chinese eyes may make the calculated lens too small, resulting in insufficient arch and possible cataract. We therefore recommend correcting the calculation of Visian PIOL size to fit smaller Chinese eyes to achieve the desired arching before the lens. The only 1 case of cataract development in this group of patients might also have been avoided if we had applied the new correction algorithm earlier. In addition, we particularly emphasize the importance of thorough postoperative removal of viscoelastic, especially at the peripheral iridectomy site, which is important to prevent postoperative transient intraocular pressure elevation. The results of our study are positive for patients with high myopia who are not suitable for LASIK surgery. The safety, efficacy, and predictability of our patients are close to the results of the FDA clinical trials1,2 suggesting that Visian PIOL implantation is a safe and effective alternative to LASIK for the correction of moderate to high myopia.