Three-year results from a standardized, multicenter clinical investigation support the safety, efficacy and predictability of the implantable collamer lens (ICL) (Staar Surgical, Monrovia, Calif.) to treat moderate-to-high myopia.
Staar Surgical and the ICL in Treatment of Myopia Study Group report on the 526 eyes of 294 patients with between 3 D and 20 D of myopia participating in the U.S. Food and Drug Administration clinical trial of the ICL for myopia. Sixty percent of study subjects were female and 85 percent were Caucasian, with a mean age at time of implantation of 36.5 ± 5.8 years. Preop manifest refraction spherical equivalent averaged -10.06 ± 3.74 D. Fifteen eyes underwent LASIK after ICL implantation. Researchers called subject compliance with follow-up "extremely high," with approximately 89 percent accounted for through the two-year visit and 77 percent at the three-year follow-up period.
At three-year follow-up, 59 percent of eyes had 20/20 or better uncorrected visual acuity. Nearly 95 percent had 20/40 or better uncorrected VA if their best-corrected acuity was 20/20 and patients were targeted for emmetropia.
Nearly 68 percent of patients were within 0.5 D of predicted refraction and 88 percent came within 1 D.
The mean improvement in best-corrected acuity ranged from 0.5 to 0.6 lines. At three years postop, three eyes decreased by at least two lines, compared to 40 eyes that improved by a similar amount. Cumulative three-year corneal endothelial cell loss was under 10 percent.
In 14 eyes, researchers encountered anterior subcapsular opacities (trace or greater) that they described as "early, largely asymptomatic and presumably surgically induced." Five eyes of three patients developed nuclear opacities of grade >2 at two to three years postop.
Patient satisfaction was high, with 97 percent reporting they would choose ICL implantation again. Reports of glare, halos, double vision, night-vision problems and night-driving difficulties decreased or remained unchanged after ICL surgery.
As of October 2003, the ICL was determined "approvable" for commercial use in the United States by the Ophthalmic Devices Advisory Panel to the FDA.
The ICL Treatment of Myopia (ITM) Study Group
Home-use Monitor Underestimates IOP
Researchers at institutions in North and South Carolina have found a significant difference in the mean intraocular pressures measured by the Goldmann tonometer, the TonoPen (Mentor, Norwell, Mass.) and the Proview eye pressure monitor (Bausch & Lomb, Rochester, NY). The difference was independent of the central corneal thickness.
A total of 171 eyes of 86 patients with a diagnosis of glaucoma or glaucoma suspect completed this study. Researchers measured the IOP by using three methods in this order: Goldmann tonometer, TonoPen and Proview. Doctors used the Goldmann tonometer and the TonoPen; patients used the Proview themselves. The differences in mean IOP values between methods were assessed separately for each eye, using paired t tests and in multivariate models that tested the dependence of IOP difference on CCT.
The Proview eye pressure monitor, a pencil-like device that has a small, flat probe, an internal spring and a readable pressure scale, is designed for the patient to use at home. It measures IOP through the eyelid and doesn't require an anesthetic.
The IOPs obtained with the Proview were significantly lower than those measured with the Goldmann tonometer and the TonoPen, and variation of the central corneal thickness did not contribute to the difference. Intraclass correlations of IOP values obtained with the Goldmann and the Proview were not strong.
(Arch Ophthalmol 2004;122:1117-1121)
Li J, Herndon L, Asrani S, Stinnett S, Allingham RR
LASIK Beats LASEK for High Myopia
While both LASIK and LASEK can be used safely and effectively to treat high myopia, LASIK provides superior results in visual predictability and corneal opacity, report researchers in South Korea.
A total of 470 eyes of 240 patients with myopia greater than -6 D and astigmatism less than 4.5 D were treated with either LASIK (324 eyes) or LASEK (146 eyes).
At 12 months, the mean spherical equivalent was within ±0.5 D of emmetropia in 63 percent of LASIK-treated eyes and 56 percent of the LASEK group. Eighty-one percent of LASIK-treated eyes got to within ±1.0 D, while 76 percent of LASEK-treated eyes reached that level.
In LASIK-treated eyes, the mean postop astigmatism remained stable from one to 12 months. At one month, the magnitude of cylinder was within ±1 D of the intended correction in 94 percent of LASIK eyes and in 93 percent of the LASEK group.
Researchers found a greater than one-line loss in BSCVA in four eyes in the LASIK group and in 21 LASEK-treated eyes.
At one month, the corneal haze score was less than grade 1 in all eyes. At 12 months, the score was greater than 2 in 11 eyes in the LASEK group. No LASIK-treated eye had detectable haze.
The between-group differences in SE, magnitude of cylinder, UCVA and haze were statistically significant (P<.05).
(J Cataract Refract Surg 2004; 30:1405-1411)
Kim JK, Kim SS, Lee HK, Lee IS, Seong GJ, Kim EK, Han SH
Close Follow-up After Vitrectomy for Lens Fragments
Patients undergoing vitrectomy for retained lens fragments often develop delayed visual loss, say investigators in North Carolina. Investigators reviewed a retrospective, noncomparative, interventional case series of 42 consecutive patients who had undergone pars plana vitrectomy for retained lens fragments. A single surgeon performed all vitrectomy procedures. All patients had a minimum of six months' follow-up, with comparison of their BSCVA at that date to their acuity at three months and preop.
Nearly all eyes (95 percent) had significant anterior segment inflammation at the time of presentation. Corneal edema or folds were present in 67 percent, and lenticular fragments in the anterior chamber were present in 48 percent. An IOL had been placed at the time of cataract surgery in 81 percent of eyes, with a posterior chamber intraocular lens being present in 52 percent of eyes. None of these presenting characteristics were found to be predictive of final visual outcome, and neither was the interval from cataract surgery to vitrectomy.
Surgeons performed a vitrectomy within seven days of the cataract extraction in 54 percent of eyes. Vitrectomy took place the day after cataract surgery in 21 percent of eyes. Ten percent of eyes underwent vitrectomy more than 30 days after cataract surgery.
Although 67 percent of eyes achieved a postop visual acuity of 20/40 or better at three months, 17 percent had events during follow-up that resulted in vision less than 20/40. Investigators encourage long-term surveillance of these patients.
Twenty-one eyes (50 percent) saw worse than 20/40 best-corrected postop. The most common causes of poor visual outcome in these patients were retinal detachment (six eyes), progressive macular degeneration (five eyes), and cystoid macular edema (three eyes).
Greven C, Piccione K
Three-day Preop Ofloxacin Reduces Contamination
Researchers at Stanford and in Germany recommend use of topical ofloxacin for three days before cataract surgery to reduce possible contamination from surgical knives. In their prospective, randomized controlled trial, the researchers showed that this practice, when compared to a one-hour preop application of ofloxacin, significantly reduces the introduction of bacteria from the ocular surface into the anterior chamber during the initial paracentesis incision.
The research team randomly assigned 78 eyes of 75 patients to control or study groups (39 eyes in each). All patients from both groups received 0.3% topical ofloxacin one hour before surgery, as well as a 5% povidone-iodine scrub and two drops of PVI onto the ocular surface preop. Patients in the study group received ofloxacin four times per day for three days before surgery.
No intracameral antibiotic was used. In three patients, cataract surgery was performed on both eyes 14 to 125 days apart. In these three patients, one eye was randomly assigned to the control group and the other eye to the study group. All patients underwent small-incision cataract removal by phaco.
Surgeons placed the microsurgical knives in blood culture broth media immediately after the incision had been made. Among the 39 knives used in the control group, 26 percent were culture-positive, but only two of the 39 knives in the study group (5 percent) had positive cultures for bacteria (P=0.028).
Researchers isolated 14 different bacterial species from the 12 culture-positive knives. Among these, there were 11 coagulase-negative staphylococci (79 percent), and one each of ß-hemolytic streptococcus, Corynebacterium species and Micrococcus species.
Researchers say these data suggest that microsurgical knives used to make the paracenteses may serve as vehicles for transporting bacteria into the anterior chamber. The incision may create a pressure gradient that pulls bacteria from the tear film into the anterior chamber.
deKaspar HM, Chang R, Shriver E, Singh K, Egbert P, Blumenkranz M, Ta C