The findings presented this year run the gamut from a new antibiotic/fluoroquinolone to manage methicillin-resistant Staphylococcus aureus (MRSA), to the use of a femtosecond laser to modify the crystalline lens, to an examination of the effects of an intraocular lens (IOLs) tilt on a post-cataract surgery patients quality of vision. Optometry plays a significant role in perioperative care, and this years research will help O.D.s better serve their patients.


Infection Prevention

Researchers in New York tested the new fluoroquinolone besifloxacin against MRSA-induced endophthalmitis in a rabbit model.839/A418

Eyes were inoculated with a MRSA suspension and treated topically with saline, moxifloxacin, levofloxacin, gatifloxacin or besifloxacin for the next 24 hours. Researchers found that all agents (except saline) successfully eradicated viable bacteria, but besifloxacin was the only treatment to effectively improve the clinical score and significantly reduce clinical signs of endophthalmitis.

Another New York-based study of besifloxacin demonstrated higher exposure in ocular tissues than moxifloxacin or gatifloxacin, while
systemic exposure was lower for besifloxacin than the other two.866/D684 Researchers note that, in conjunction with its spectrum of activity, this tendency warrants further testing of the new fluoroquinolone.


Refractive Surgery

Researchers in Germany examined the possibility of using a femtosecond laser to increase the flexibility of the crystalline lens, as opposed to the cornea, to restore accommodation.3798/A75 They created microincisions in human autopsy eyes and analyzed the results with optical coherence tomography (OCT), a lens-stretching device and Fishers spinning test. Results demonstrated a significant gain in lens flexibility.

A related study examined the effects of the procedure on the retina.3796/A73 Using a rabbit model, researchers found no degenerative or inflammatory changes, or thermal alterations of the retina. These preliminary results, they say, reinforce the procedures safety and efficacy.

Central corneal thickness (CCT) plays a great role in the decision to proceed with laser vision correction in a patient, be it laser in situ keratomileusis (LASIK) or photorefractive keratectomy (PRK). Researchers in Mexico set out to determine the incidence of post-refractive surgery corneal ectasia in a retrospective study population of 1,170 eyes.2923/A154 The incidence of ectasia was 0.17%, and the most important risk factor was the deepness of ablationnamely, if it exceeded 100m. Every diopter of correction accounts for approximately 15m of cornea, so if a patients needed correction approaches 100m, make certain that he or she is educated about the potential risks to visual quality and corneal stability.

How should you handle patients with CCT of less than 500m? Researchers in New York and Texas suggest that, contrary to current belief, PRK, LASIK and laser-assisted sub-epithelial keratectomy (LASEK) are no less safe in patients with corneas of 500m or less than they are in patients with thicker central corneas.2906/A137 In this long-term retrospective study, the mean preoperative CCT less than 500m was 482m, and that greater than 500m was 551m. They found that, out of 5,038 eyes, none of the included eyes developed ectasia. Researchers suggest that there is no difference in risk for complications between the two groups.


The AcuFocus ACI 7000 corneal inlay may improve reading ability in presbyopes.
IOLs and Refractive Surgery

In Missouri, researchers created a fly through video to analyze the success of a single human trial of a new corneal inlay.2260/D808 The ACI 7000 (AcuFocus)is a nanotechnology corneal inlay that is inserted under a LASIK flap in the center of the visual axis of the non-dominant eye. It increases depth of focus and may allow presbyopic patients to read without spectacles. Under independent third-party analysis of the video, the implant was found to be well tolerated, with no surrounding inflammatory cells or epithelial alteration. Confocal microscopy supported this finding.

Likewise, researchers in Austria found that the ACI 7000 significantly improves reading ability in presbyopic patients.1800/D665 Implanted eyes of the 15 study participants demonstrated an increase in reading ability and a decrease in reading distance.

Researchers in California and Mexico examined the efficacy of an enhanced monovision corneal inlay, the Presbylens (ReVision Optics), and found that it significantly improved near vision while decreasing distance vision less than expected.3353/A171 Of 33 patients treated, 95% experienced improved visual acuity, and more than half the patients attained better than 20/25 at near. Researchers note that all patients could read the 20/25 line.
Researchers in Mexico successfully implanted a toric IOL in a 55-year-old male patient with nonprogressive forme fruste keratoconus and a stable refraction.4325/D725 Two months after the procedure, the patient had an acuity of 20/25 O.S. with a refraction of -0.25 -0.50 x 140, and an acuity of 20/20 O.D. with a refraction of plano -0.50 x 150. Researchers noted that the lens had rotated less than four degrees, but still warranted further observation.

IOLs and Cataracts

Two studies presented this year dealt with the possibility that an IOL implanted post-cataract may tilt and cause visual aberrations. Researchers in China and Boston measured coma aberrations in 11 eyes.5652/A567 They were able to measure the coma of the eye and subtract the coma of the cornea to determine the coma of the internal optics. They then analyzed these relative to the tilt of the IOL. Results demonstrated that coma was highly correlated to the lateral tilt of the IOL; researchers note that controlling this would produce a more successful surgical procedure.

Researchers in Spain examined the optical quality of several IOLs in vitro on an artificial eye, looking for tilt-based and rotational effects.3340/A123
They found that tilt, decentration and rotation caused astigmatism and higher-order aberrationsnamely, coma. They note that their testing method may benefit patients and surgeons prior to surgery. In the United Kingdom, researchers set out to determine the effect that posterior chamber IOL implantation in children has on the survival of their corneal endothelial cells over the long term.402/A96 After accounting for age, researchers found no significant difference between initial cell counts and follow-up cell counts over an eight-year period. Therefore, say researchers, posterior chamber IOL implantation in children with congenital cataracts will not significantly reduce corneal endothelial cell counts over the long term, reassuring practitioners that the procedure is both safe and effective.

Bromfenac sodium ophthalmic solution effectively prevents cystoid macular edema (CME) following IOL implantation in cataract patientsespecially in patients who have nonproliferative diabetic retinopathy, say researchers in Japan.3470/A559 In this study, 62 patients were randomized to use either bromfenac sodium or a steroidal solution for post-phacoemulsification prophylaxis. At two weeks, four weeks and six weeks post-op, anterior chamber flare was significantly lower in the bromfenac group. Researchers note that, although neither group experienced adverse effects, bromfenac was more efficacious when considering foveal thickness and flare.


Secondary Cataract Formation

Researchers in Germany and the Netherlands attempted to find a method to successfully prevent secondary cataract formation through polymer lens refilling surgery.3780/A57 In a rabbit model, the empty capsular bag was treated during the surgery and again after phacoemulsification with a viscoelastic mixture of actinomycin, methotrexate and sodium hyaluronate for five minutes.

Results demonstrated that all eyes were successfully filled by the procedure, with no complications during wound healing. Control eyes, which did not undergo the refilling procedure, showed opacification at two weeks and maximum opacification at six weeks. But, those eyes that underwent the refilling surgery evidenced no opacification at 12 months and no low posterior capsule opacification at three years postoperatively.
Researchers point to their findings as a strong basis to advance to non-human primate studies.

Dr. Karpecki is Review"s education advisor and co-author of "Research Review." He practices with the CInncinnati Eye Institute in Edgewood, Ky.


839/A418. Zhang J, Ward KW. Efficacy of besifloxacin in a rabbit model of methicillin-resistant Staphylococcus aureus-induced endophthalmitis.

866/D684. Chappa AK, Proksch JW, Ward KW. Comparison of the ocular and systemic pharmacokinetics of besifloxacin, a novel fluoroquinolone antibiotic, with moxifloxacin and gatifloxacin in pigmented rabbits.

3798/A75. Schumacher S, Fromm M, Bock P, et al. Femtosecond lentotomy: changing the crystalline lens tissue by high repetition rate femtosecond lasers.

3796/A73. Oberheide U, Schumacher S, Bock P, et al. Femtosecond lentotomy: retinal changes after treatment of the crystalline lens with a 100Khz femtosecond laser in rabbits.

2906/A137. Eccles Brown SE, Reilly CD, Panday VA, Roberts S. Refractive surgery outcomes: corneas thinner than 500m versus corneas thicker than 500m.

2923/A154. Benitez A, Velasco R, Carmona C, et al. Incidence and risk factors to develop corneal ectasia after refractive surgery.

2260/D808. Waring IV GO, Durrie DS, Sutphin JE, Stahl JE. Three-dimensional endoscopic confocal corneal fly through video for qualitative analysis of the cornea following AcuFocus corneal inlay.

1800/D656. Seyeddain O, Hohensinn M, Garbner G, Dexl AK. Testing reading performance with the Salzburg Reading Desk after implantation of the AcuFocus 7000 corneal inlay in presbyopic patients.

3353/A171. Lang AJ, Icenogle T, Franz S, et al. Clinical efficacy of the Presbylens intracorneal inlay for the correction of presbyopia.

4325/D725. Navas A, Haber A, Suarez R. Toric intraocular lens in a patient with keratoconus.

5652/A567. Fang Y, Lu Y, Wang L, He JC. Association of the tilts of intraocular lens with the coma aberrations for the eye with cataract surgery.

3340/A123. Lopez-Gil N, Bonaque S, Monts-Mic R, et al. In vitro measurement of the optical quality of an intraocular lens considering translations, rotations and tilts.

402/A96. Markhan R, Hussin H, Vortruba M. Survival of corneal endothelial cells after congenital cataract surgery with intraocular lens implantation in childhood.

3470/A559. Kitano S, Endo N, Shoji M, et al. Effect of bromfenac sodium ophthalmic solution on preventing cystoid macular edema and inflammation after phacoemulsification and implantation of intraocular lens in diabetic patients.

3780/A57. Guthoff RF, Stachs O, Sternberg K, et al. Long-term effect of antiproliferative lens epithelial cell treatment followed by polymer lens refilling surgery in rabbits.

Vol. No: 145:05Issue: 5/15/2008