W. Andrew Maxwell, MD, PhD
PHAKIC IOLs' ADVANTAGES
The concept of a phakic IOL is gaining popularity in the field of refractive surgery. Advanced technologies, biocompatible materials, and innovative design concepts are a few of the factors improving the phakic IOL options currently available. Renewed interest in this lens type may also be attributed to the fact that the insertion procedure offers a mode of correction that is both reversible and predictable. A phakic IOL allows the cornea to remain essentially intact without permanent alteration. Furthermore, these IOLs deliver excellent refractive results with rapid visual recovery and high rates of predictability compared with other procedures in which visual results are dependent on corneal healing. The phakic IOL is an option that preserves accommodation, and, if necessary, it may be used in combination with other procedures such as LASIK to correct residual refractive error (ie, astigmatism). Ideal candidates for phakic IOLs include individuals with stable, high myopia, contact lens intolerance, or prescriptions or corneal thicknesses out of range for LASIK as well as patients seeking independence from spectacles.ACRYSOF PHAKIC
The Acrysof angle-supported phakic refractive IOL (Alcon Laboratories, Inc., Fort Worth, TX) is a foldable IOL designed for implantation into the anterior chamber angle for the correction of stable, high myopia. Constructed from Acrysof material, the single-piece phakic IOL has the advantage of proven biocompatibility as evidenced by more than 20 million pseudophakic Acrysof IOL implants globally. The Acrysof phakic IOL is manufactured in a 5.5- or 6.0-mm–diameter meniscus optic with an overall length of 12.5 to 14.0mm and a dioptric range of -6.00 to -16.50D in 0.50D increments. Implanting the IOL with the Monarch II IOL Delivery System (Alcon Laboratories, Inc.) allows surgeons to use small incisions.Implantation Technique
Prior to surgery, I make sure the patient's pupil is constricted to protect the natural crystalline lens from potential direct physical contact with the IOL during surgical maneuvers. I make a corneal incision 3.0 to 3.5mm wide to access the anterior chamber, which I inflate and maintain with injections of a cohesive viscoelastic. The Monarch II Injector delivers the Acrysof phakic IOL into the anterior chamber in a slow, controlled manner. I tuck the trailing haptics into the anterior chamber individually. For optimal results, surgeons should extract the viscoelastic using I/A via bimanual or single-port phacoemulsification. The use of a cohesive viscoelastic allows for easier removal. I confirm the placement of the lens haptic's footplates by gonioscopic examination.Complications Avoidance and Management
Some complications typically associated with ACIOLs include losses of corneal endothelial cell density, increased IOP requiring treatment, pupillary ovalization, pupillary block, and cataractogenesis. Surgeons can prevent and manage complications through surgical technique, IOL design, and advanced technologies. Additionally, a rapid recovery and a reduced likelihood of induced astigmatism can be achieved. Familiarity with the procedure and fine-tuning of surgical maneuvers, such as modifying the technique for I/A can also improve surgical outcomes.
The Acrysof phakic IOL delivers low compression forces, provides rotational stability, and is constructed from a material with proven biocompatibility. Furthermore, advanced imaging technologies such as Scheimpflug imaging, ocular coherence tomography, and very high-frequency ultrasound allow for enhanced visualization of the anterior chamber angle's anatomy as well as modification of IOL-sizing practices.Clinical Results
Clinical investigations with the Acrysof phakic IOL are ongoing in the US and in Europe.1 Results gathered in the clinical trials have demonstrated a successful reduction in stable, high myopia. The UCVA results gathered 6 months postoperatively, in US (n=10) and European (n=70) trials, demonstrated that ≥ 90.1% of subjects achieved a visual acuity of 20/40 or better1 (Figure 1).
In terms of BSCVA, ≥ 97% of subjects saw 20/40 or better. The Acrysof phakic IOL demonstrated accuracy in predictability of refraction as evidenced by 95.7% of European subjects, and 100% of US subjects achieved a refraction within 1.00D of their target. Furthermore, 67.1% of European subjects and 90% of US subjects were within 0.50D of their target refraction; statistics demonstrated accurate predictability surpassing FDA guidance recommendations for this postoperative data point versus indicator.
Primary safety endpoints included endothelial cell density counts and the maintenance of BSCVA. Acute losses in endothelial cell density related to surgical trauma were 1% centrally and 4.5% peripherally, when calculated 6 months postoperatively in the US phase I study.
Subjects whose preoperative BSVCA was 20/20 or better and reached 20/40 or better was maintained in 100% of subjects, thus meeting FDA guidance. At 6 months postoperatively, 50% of US phase I subjects gained one line of vision, 20% gained two lines, and 20% experienced no change.
Clinical outcomes in the US phase I study showed minimal endothelial cell loss and no incidences of persistently raised IOP, pupillary ovalization or block, lens-related cataract formation, or significant dislocation of the phakic IOL.CONCLUSION
Clinical investigations of the long-term outcomes with the Acrysof phakic IOL are underway in the US and in Europe. Results captured to date demonstrate significant reductions in stable high myopia, accurate predictability, and minimal endothelial cell loss. Innovative technology, optimized surgical techniques, and advances in IOL design are allowing the phakic IOL to enter refractive surgery as a potential future option for the correction of stable, high myopia.
W. Andrew Maxwell, MD, PhD, is in practice at the California Eye Institute in Fresno. He is a consultant to Alcon Laboratories, Inc., but states that he holds no financial interest in any product mentioned herein. Dr. Maxwell may be reached at (559) 449-5010; email@example.com. Maxwell WA. US clinical results of the angle-supported Acrysof phakic refractive IOL. Paper presented at: The ASCRS 2004 Annual Meeting; May 2, 2004; San Diego, CA.
VERISYSE PHAKIC IOL
George Beiko, BM, BCh, FRCSC
The development of phakic IOLs began in the 1950s. José I. Barraquer, MD (data on file at Advanced Medical Optics, Inc., Santa Ana, CA), reported the results of 239 eyes that received a phakic IOL in 1959. However, the early lens models were plagued by poor outcomes, primarily due to chronic uveitis, glaucoma, and recurrent hyphema, known as UGH syndrome. These complications resulted from poor quality lenses and surgical technique.
In 1978, Jan Worst1 proposed an innovative lens design whereby the lens attached to the midperipheral iris. In 1980, an aphakic biconvex lens was introduced that was well tolerated by patients, and they did not have complications comparable to this lens' predecessors. In 1986, a phakic refractive lens with a biconcave design was introduced, and its first implantation occurred shortly thereafter. Five years later, the current design of the Verisyse VRSM 50 (Advanced Medical Optics, Inc.) (Figure 2), consisting of an anterior meniscus and a posterior-concave configuration, became available. This design increased the effective power range of the lens and minimized endothelial cell damage by increasing the distance from the lens to the endothelium.The one-piece, compression-molded PMMA lens has an overall length of 8.5mm and an optic diameter of either 5 or 6mm. It is available in powers of -3.00 to -23.50D.
In 2004, the Verisyse phakic IOL (Advanced Medical Optics, Inc.) was the first lens to be FDA approved for phakic use in myopes.2 In Europe, the same design was approved for use in myopes and hyperopes.3 A toric design has been available since 1999 (cylinder correction of up to 7.00D [ranges, -3.00 to -20.00D and +2.00 to +12.00D]). The versatility of the design is also evident in its utility for iris reconstruction. Currently, a foldable version of the Verisyse named Artiflex is in clinical trials in Europe.4 The Artiflex has a silicone optic and PMMA haptics, and it is available in both spheric and toric designs (Figure 3).implantation
I implant the Verisyse lens into the anterior chamber of the eye under topical or peribulbar anesthesia. With topical pilocarpine 4%, I induce miosis preoperatively.
I create two paracenteses at the 10- and 2-o'clock positions that are directed posteriorly toward the 8- and 4-o'clock iris positions, respectively. I inject a cohesive viscoelastic (I prefer Healon GV [Advanced Medical Optics, Inc.]) into the anterior chamber. I carefully inject the viscoelastic from the angle toward the center of the pupil and avoid injection under the iris. Next, I make the main incision at the 12-o'clock position. The length of this incision depends on the size of the lens' optic (either 5 or 6mm). Surgeons can perform a corneal, limbal, or scleral incision, depending on their preference. I insert the lens using a customized lens forceps (Advanced Medical Optics, Inc.) and place more cohesive viscoelastic on the lens as a protective layer between it and the endothelium.
Surgeons attach the Verisyse lens to the midperipheral iris with a specialized enclavation needle supplied by the manufacturer (Figure 4). This part of the iris is normally immobile, and its capture does not interfere with the pupil's dilatation. The surgeon inserts the enclavation needle through the paracentesis sites and gently draws a fold of iris in between the split haptics (a technique termed enclavation) while holding the optic with the lens forceps in his other hand. The enclavation is performed at the horizontal axis, at the 3- and 9-o'clock positions. By simply pushing back on the area of capture, the surgeon can release the iris and reattach or explant the lens with minimal damage to the iris.
The wound is closed using interrupted 10–0 nylon sutures. Either manual or automated I/A removes the viscoelastic. A cohesive viscoelastic is recommended due to its ability to maintain the anterior chamber and its relative ease of removal; dispersive (Viscoat; Alcon Laboratories, Inc., Fort Worth, TX) and super cohesive (Healon5; Advanced Medical Optics, Inc.) viscoelastics should not be used.A peripheral iridotomy under the upper eyelid (performed preoperatively using a laser or intraoperatively using surgical incisions) will prevent pupillary block glaucoma.
I use the same topical medications as in my routine phaco cases, Tobradex (Alcon Laboratories, Inc.) and Acular (Allergan, Inc., Irvine, CA) q.i.d. for 2 days preoperatively and for approximately 3 weeks postoperatively. I do not use antiglaucoma mediations prophylactically. However, if IOP spikes occur postoperatively, then I may use a standard IOP-lowering medications.complications avoidance and
When considering intraocular surgery in healthy eyes, the FDA was most concerned about increased endothelial cell loss leading to decompensated corneas. Normal endothelial cell loss has been reported as 0.33% to 0.60% per year; the FDA set a limit to cell loss of 1.5% per year for the first 3 years following surgery.2 The FDA clinical trial2 and European multicenter trial3 found endothelial cell loss rates within these guidelines with the Verisyse. In fact, a 10-year follow-up of patients demonstrated a rate of endothelial cell loss of 0.7% per year. The studies' results indicate that there is a minimal loss of endothelial cells at the time of surgery and that the rate does not increase as a result of the presence of the Verisyse lens in the anterior chamber.George Beiko, BM, BCh, FRCSC, is in private practice in St. Catharine's, Ontario, Canada. He states that he holds no financial interest in any product or company mentioned herein. Dr. Beiko may be reached at (905) 687-8322; firstname.lastname@example.org.
1. Budo CJR. The Verisyse lens. Panama City, Panama: Highlights of Ophthalmology International; 2004:3-16.
2. US FDA's Center for Devices and Radiological Health page. Artisan (Model 206 and 204) Phakic Intraocular Lens (PIOL), Verisyse (VRSM5US and VRSM6US) Phakic Intraocular Lens (PIOL) - P030028. Available at: http://www.fda.gov/cdrh/pdf3/p030028.html. Accessed February 17, 2005.
3. Budo C, Hessloehl JC, Izak M, et al. Multicenter study of the Artisan phakic intraocular lens. J Cataract Refract Surg. 2000;26:1163-1171.
4. Dick HB, Buchner S. Foldable iris-claw phakic IOL: clinical results. Paper presented at: The XXII Congress of the ESCRS; September 2004: Paris, France.
The Visian Toric ICL
John Vukich, MD
My personal clinical experience as well as the clinical outcomes reported to date from the FDA multicenter clinical investigation support that the Visian Toric Implantable Collamer Lens (ICL; Staar Surgical Company, Monrovia, CA) is a viable alternative to current modes of refractive correction for that portion of the refractive patient population living with the daily challenges of moderate-to-severe myopic astigmatism.DESIGN
The Visian Toric ICL features a single-piece lens design with a central concave or convex optical zone diameter of 4.85 to 5.50mm. The lens is composed of a proprietary, biocompatible, UV-absorbing, porcine collagen/PolyHEMA copolymer. The lens features an optic with an overall diameter that varies with the desired dioptric power and is quite similar to the existing plate haptic design of Staar Surgical Company's IOLs for aphakia/cataract surgery. The Visian Toric ICL, however, incorporates forward vaulting to minimize contact between the lens and the center of the anterior capsule.IMPLANTATION TECHNIQUE
Using commonly available IOL injection systems, I place the Toric ICL within the posterior chamber, directly behind the iris and in front of the human crystalline lens. It is easy to insert the lens with standard, posterior, intraocular, temporal insertion techniques through a small surgical incision of ≤ 3.5mm (Figure 5).
The technique for implanting the Visian Toric ICL is identical to that for the myopic (spherical only) ICL except as regards the toric optic's axis rotation of up to 22.5º (less than 1 clock hour) from the horizontal meridian. Surgeons have the flexibility of ordering customized lenses to individualize refractive corrections on a patient-by-patient basis.Ophthalmologists routinely perform two 0.5-mm, peripheral YAG iridotomies (placed superiorly 90º apart) several weeks prior to surgery.
To date, 188 phakic eyes of 119 patients with between 2.38 and 19.00D of myopia and 1.00 to 4.00D of refractive cylinder have undergone implantation of the Toric ICL at seven US clinical sites.
Six months after lens implantation, the UCVA in the highly myopic patient population has been excellent, with 84.2% of eyes obtaining 20/20 or better UCVA compared to 95.1% with a preoperative BSCVA of 20/20 or better. At 6 months, 80.2% of eyes achieved a UCVA better than or equal to their preoperative BSCVA (Figure 6). In the subset of eyes with a BSCVA of 20/20 or better, the postoperative UCVA was 20/20 in 88.4%, 20/25 in 98.8%, and 20/32 or better in 98.8% of eyes.
Mean refractive cylinder dropped from 1.98 ±0.87 to 0.45 ±0.47D at 6 months, and there was a decrease of 77.3% in astigmatism. The MRSE improved from 9.10 ±2.51D preoperatively to 0.07 ±0.48D postoperatively. Also at 6 months, 98% of eyes had an MRSE ≤1.00D. Predictability was excellent: 73% of eyes were within 0.50D, 97% within 1.00D, and 99% within 2.00D of the predicted outcome.Patient Satisfaction
At 3 months, 100% of patients were satisfied with their surgical outcome. Impressively, 97.4% reported being very/extremely satisfied, a statistic highlighting patients' overall acceptance of the Visian Toric ICL.
Complications after Visian Toric ICL surgery have been rare. Similar to the myopic ICL, the Visian Toric ICL is excellent at preserving or improving patients' BSCVA.
At 6 months, 33% of study eyes had a BSCVA of 20/12.5 or better compared with only 4.3% preoperatively, and 97% saw 20/20 or better versus 86% preoperatively. The mean improvement in BSCVA was 0.95 lines at 6 months. None of the eyes lost two or more lines of BSCVA, and 24% gained two or more lines. Seventy-three percent of eyes at 6 months gained more than one line of BSCVA, with only 4% losing one line.
To date, there have been no clinically significant opacities observed. Adverse events included one retinal detachment unrelated to the Toric ICL and two ICL removals (1.1%) with no significant loss of BSCVA. The explantation of the ICLs was not due to poor vision or complications. There have been no required repositionings of the Visian Toric ICL due to errors in axis and no infections or clinically significant persistent elevations in IOP.CONCLUSION
The customized axis correction combined with the ease of insertion and vaulting capabilities of the current lens design have produced an extremely safe means of permanent refractive correction for moderate-to-severe myopia/astigmatism.
The Visian Toric ICL effectively improves both UCVA and BSCVA while dramatically decreasing refractive sphere and cylinder. Combined with the absence of adverse events and overwhelming patient satisfaction, the Visian Toric ICL represents a potential future choice for correcting moderate-to-high myopia.
John A. Vukich, MD, is Assistant Clinical Professor at the University of Wisconsin, Madison. He is a consultant to Staar Surgical Company. Dr. Vukich may be reached at (608) 282-2002; email@example.com.