CRSToday Europe News — May 2007

Surgeon Volume and Risk Studied
The annual volume of cataract procedures is related to the final outcome of the surgery as well as the risk of adverse postoperative events, according to a study published Ophthalmology. This population-based cohort, which examined all cataract surgeries performed in Canada during a 2-year period, found that fewer than one in 200 patients experienced an adverse event (ie, vitrectomy, vitreous aspiration, dislocated lens).

Surgeons performing between 50 and 250 or 251 and 500 cataract surgeries per year had adverse event rates of 0.8% and 0.4%, respectively. High-volume surgeons (ie, 501 to 1,000 surgeries) had an adverse event rate of 0.2% and an adjusted odds ratio of 0.31 (95% CI, 0.22-0.43). Very high-volume surgeons (ie, more than 1,000 surgeries) had an adverse event rate of 0.1% and an adjusted odds ratio of 0.14 (95% CI, 0.09-0.23).

"Adverse event rates for surgeons performing more than 50 cataract surgeries per year are low," authors wrote. There "is a volume-outcome relationship for cataract surgery, and this relationship persists for very high-volume surgeons."

MRSA is Serious LASIK Complication
Methicillin-resistant Staphylococcus aureus (MRSA), which has been found in many health care settings, may be a serious postoperative complication. Researchers studied 12 eyes with MRSA infections after refractive surgery. The findings were published in the American Journal of Ophthalmology.

These are the first cases of MRSA infectious keratitis following refractive surgery, the first reports of MRSA keratitis after refractive surgery in patients who had not been inside a health care facility, the first report of MRSA keratitis after a LASIK enhancement, and the first reports of MRSA keratitis after prophylaxis with fourth-generation fluoroquinolones.

Colonization of MRSA has been found in 1.5% of the general population, but as many as 9.4% of those had been inside a health care facility.

The authors cite the case of a male nurse who underwent an uneventful bilateral LASIK procedure that resulted in 20/20 (right eye) and 20/70 (left eye) visual acuity. Within 2 weeks, he developed an infection in his left eye that worsened despite treatment. His vision decreased to 20/400. When the infection was cultured and found to be MRSA, his antibiotics were changed, and his vision recovered to 20/200 over the next 2 weeks. The patient is awaiting further surgical treatment.

In the article, Eric D. Donnenfeld, MD, of New York, advised that, "MRSA infectious keratitis is a potentially serious complication following refractive surgery. Health care workers may develop keratitis from microbes associated with nosocomial infection. In addition, surgeons should now be vigilant for community-acquired MRSA keratitis. All patients should be informed of the risk factors and warning signs of infectious keratitis and need to be advised to seek medical attention immediately if they develop signs or symptoms of infectious keratitis. A high degree of suspicion, coupled with prompt and appropriate treatment, may result in improved visual recovery."

DSAEK Results Similar to PK
Descemet's stripping and automated endothelial keratoplasty (DSAEK) uses a mechanical microkeratome to harvest the donor corneal lenticule and mechanically strip the diseased host endothelium and Descemet's membrane. Authors of a study published in Ophthalmology found that patients who underwent this procedure achieved excellent postoperative visual acuity. There was, however, a more than 30% chance of donor lenticules needing repositioned or replaced, authors found.

The study examined 26 eyes with corneal edema from Fuchs' endothelial dystrophy, pseudophakic bullous keratopathy, or aphakic bullous keratopathy. Donor corneal lenticule was prepared using a microkeratome and an artificial anterior chamber maintainer. Additionally, stripping of the diseased host endothelium was performed under viscoelastic using a 2.75-mm clear corneal temporal incision. The incision was enlarged to approximately 4.2 mm to allow placement of a folded 8.5-mm diameter donor corneal lenticule, which was positioned using a temporary air bubble. The wound was then closed with one 10–0 nylon suture.

At 3 months postop, all donor grafts remained clear, with an average BSCVA of 20/45. The average change in refractive astigmatism was 0.12 D ±1.15 D. Patients who underwent DSAEK had an average postoperative shift in spherical equivalent refractive error of 1.15 D ±1.35 D. Nine of 26 initial grafts dislocated postoperatively and had to be repositioned. Three of the repositioned grafts dislocated again and were replaced with new donor corneal lenticules; all remained clear.

Authors concluded that the average visual results for DSAEK were comparable with vision after deep lamellar endothelial keratoplasty. Additionally, "DSAEK offers significant advantages over standard penetrating keratoplasty for patients with Fuchs' dystrophy in pseudophakic bullous keratopathy," they wrote.

WaveLight Platform Received FDA Approval
The second Allegretto Wave system, the Eye-Q, (WaveLight Inc., Sterling, Virginia) recently received US Food and Drug Administration (FDA) approval for the reduction or elimination of naturally occurring mixed astigmatism of up to 6.00 D. The platform was also approved for the reduction or elimination of up to -7.00 D of spherical equivalent of myopia or myopia with astigmatism, with up to -7.00 D of spherical component and up to 3.00 D of astigmatic component at the spectacle plane.

"The latest Eye-Q wavefront approval is the fouth FDA approval for WaveLight in the past 12 months, and brings the approvals for the 400 Hz Eye-Q laser in line with those for the 200 Hz Allegretto," said Guy M. Kezirian, MD, FACS, President and Founder of SurgiVision Regulatory Consultants, Inc., in a news release.

Phaco Could Reduce IOP
Combining glaucoma and cataract surgery may be an effective method of reducing IOP, according to Ike K. Ahmed, MD, FRCSC.

In a study appearing in the Journal of Cataract and Refractive Surgery, 68% of 22 eyes treated with phacoemulsification and IOL implantation had controlled intraocular pressure (IOP). Of 25 eyes treated with trabeculectomy, 68% also had controlled IOP. Later, however, 15 eyes in the trabeculectomy group also developed cataracts.

Phacoemulsification reduced mean IOP from 21.4 mm Hg to 14.5 mm Hg, with 91% of patients maintaining IOP control at 2 years follow-up, Dr. Ahmed said.

Higher-Order Aberrations and LASIK Risk
Patients with visual symptoms after myopic LASIK have significantly lower visual acuity and contrast sensitivity than patients without visual symptoms, according to a study published in the Journal of Refractive Surgery. They also had higher root mean square values for higher-order aberrations.

In a retrospective study analyzing 103 eyes (62 patients), 36 eyes were found to have various symptoms (ie, blurred vision [41.6%], double image [19.4%], halo [16.7%], vision fluctuation [13.9%]). The difference between the symptomatic and control group root mean square values were 1.57 times to 2.06 times greater for the symptomatic group.

Authors concluded that root mean square values that were greater than two times the normal post-LASIK population for any given laser platform may increase the relative risk of symptoms.

Central Toxic Keratopathy After LASIK
LASIK and other laser-based vision correction surgeries may be followed by clouding of the central corneal and decreased visual acuity, according to a study published in the American Journal of Ophthalmology.

The retrospective observational case series examined 23 eyes with central corneal opacification after laser refractive surgery (19 LASIK, four PRK) in the area of laser treatment that extended posterior from the interface of the stromal bed. It was found that central toxic keratopathy could be characterized by central corneal opacification with a significant hyperopic shift.

Opacification persisted between 2 months and 18 months in all eyes. Nine eyes developed postoperative hyperopia of greater than 2.00 D, and three eyes lost one or more lines of BSCVA. Seven eyes that underwent LASIK enhancement after the cornea cleared achieved successful outcomes.

The authors concluded that central toxic keratopathy is not an inflammation, and therefore, corticosteroids should not be used to treat the cornea. Authors wrote that central toxic keratopathy is incited by an extermal factor since the corneal problems did not reoccur after LASIK.

Incision Type, Contrast Sensitivity Examined
Researchers from the Johannes Gutenberg-University (Mainz, Germany) examined whether microincisional IOL implantation with a modified anterior surface, designed to compensate for the positive spherical aberration of the cornea, results in improved pseudophakic quality of vision after biaxial microincisional phacoemulsification.

In a nonrandomized parallel cohort investigation, 52 eyes were unilaterally implanted with the aspherical Acri.Smart 36 A (Acri.Tec, Berlin, Germany). The Acri.Smart 46 S (Acri.Tec) was implanted in 25 eyes (25 age-matched patients). At 8 weeks postop, measurements including UCVA, BCVA, pupil size, and high- and low-contrast visual acuities were examined in both groups.

The study was published in the Journal of Cataract and Refractive Surgery. Researchers found that the aspherical and spherical IOL groups did not differ in baseline characteristics. Furthermore, no clinically relevant or statistically significant between-group differences were observed in the primary clinical endpoint. Implantation of both IOL types, however, was significantly different between the groups with a range of -0.09 µm aspherical and -0.29 µm aspherical at a pupil size of 4.5 mm.

"The development of microincisional IOLs, which fit through corneal incisions smaller than 2.0 mm and improved night driving conditions, could optimize modern biaxial cataract surgery," researchers wrote.

Steroids Induced Acuity Loss
Early onset steroid-induced elevation of IOP after LASIK may cause corneal edema and a sudden decrease in UCVA, according to a study published in the Journal of Refractive Surgery. Rapid diagnosis and treatment may control IOP and recover visual loss, authors suggested.

Researchers evaluated 29 eyes that received topical corticosteroids after uneventful myopic LASIK and had a decrease in UCVA within the first 3 weeks. An increase in IOP of 4 mm Hg to 30 mm Hg was found in all eyes, with 27 showing a decrease in UCVA or BSCVA.

All but one eye had edema without evidence of inflammation in the interface or the remainder of the cornea. Discontinuation of topical corticosteroids and application of antiglaucoma medications resulted in a return of IOP to normal levels, reduction or disappearance of the edema, and recovery of BSCVA.

Bimanual Versus Coaxial Phacoemulsification
Both bimanual microphacoemulsification and coaxial mini phacoemulsification are cataract surgery methods both safe and effective, according to a study published in the Journal of Cataract and Refractive Surgery. Bimanual microphacoemulsification, however, uses significantly less balanced salt solution and requires shorter total surgical time.

According to researchers from the University of Modena, in Italy, 50 of 100 eyes underwent bimanual phaco, while the remaining eyes underwent coaxial. The same surgeon, using the same machine, performed all surgeries in the controlled prospective clinical trial.

Researchers found no statistical differences in any other intraoperative parameters or postoperative parameters (ie, visual acuity, astigmatism, corneal thickness, endothelial cell count, the presence of flare, cells in the anterior chamber).

Wider Femtosecond Laser Channels Recommended
Wider femtosecond laser channels during Intacs (Addition Technology, Inc., Des Plaines, Illinois) implantation make the insertion easier and decrease the risk of complications, according to a presentation by Aylin Ertan, MD, of Turkey, at the 11th Annual European Society of Cataract and Refractive Surgeons Refractive Surgery Winter Meeting, in Athens.

Two groups of keratonic eyes underwent Intacs implantation with the IntraLase femtosecond laser (IntraLase Corp., Irvine, California). Wide channels of 6.7 mm X 8.7 mm were used in the first group; 6.6 mm X 7.6 mm channels were used in the other group. While Intacs were easily inserted to the wide channel, narrow channels had to be dilated. Comparisons were than made for changes in UCVA, BCVA, manifest spherical equivalent, mean K-value, and complications in the 6-month postop. No significant difference was found between the two groups, except in complications rates. Higher rates of minor complications were found with narrow channel implantation (ie, epithelial plug, yellow deposits, tunnel haze, possibility of the inferior segment to move upward and slightly out of the incision).

AMO Completed Acquisition
Advanced Medical Optics, Inc. (Santa Ana, California) completed the acquisition of IntraLase Corp. (Irvine, California) for approximately $808 million, at the end
of March.

The acquisition required AMO to pay $25 in cash per share of IntraLase stock and the individually determined cash value per share of outstanding stock options.

AMO expects to leverage the large installed bases of AMO and IntraLase and combine their international expansion strategies to further establish its position as the industry leader in laser diagnostics, flap creation, and ablation technologies.