Are clear corneal incisions safe? Veteran practitioner says 'yes'.

June 1, 2007

Are clear corneal incisions safe? Veteran practitioner says 'yes'

Are clear corneal incisions safe? Veteran practitioner says 'yes'

Properly constructed clear corneal incisions can ensure immediate sealing following phacoemulsification and are a key component in endophthalmitis prophylaxis, according to I. Howard Fine MD, clinical professor of ophthalmology at the Casey Eye Institute, Oregon Health & Science University, USA.Dr Fine has been using a single-plane incision technique to create 2 mm long and 2.5 mm wide incisions, since 1992. Recently, he and his colleagues, Richard S. Hoffman MD and Mark Packer MD, studied these incisions with optical coherence tomography (OCT). They found the single-plane incision to be arcuate and longer than the chord length, producing a tongue-and-groove architecture (similar to paneling). They also discovered that stromal hydration persisted for longer than 24 hours.Side-port incisions were also analysed with OCT. Different blades and incision sizes were studied, indicating that these tools provide good architecture if the incision is properly constructed.With more than 10 years' experience and more than 10,000 cases completed with no endophthalmitis, Dr Fine said he is confident that clear corneal incisions are safe and effective for cataract surgery.

Realistic expectations urged for bilateral multifocal lens implantation

He conducted a prospective, non-randomized study comparing real-world multifocal lens performance after bilateral implantation of either a second-generation refractive IOL (ReZoom, AMO) or an apodized diffractive lens (AcrySof ReSTOR, Alcon). Results for 15 consecutive patients receiving each lens were compared.

"What is unique about this study is that I limited the people who were under the age of 70, thinking these would be the people who were more demanding in their visual tasks - out at night, using the computer etc..." Dr Chang said.

Patients were not randomly assigned to receive either lens "because I wanted to at least try to pick the lens that I thought would best match the needs of that patient by understanding their differences," he said.

The study found that "both of these lenses do what they set out to do, improving uncorrected vision compared with a monofocal, with good lifestyle evaluation and satisfaction." Results "give the edge" to the refractive lens for distance vision, he added, and "a clearer edge" to the diffractive lens for near vision.

The lenses performed similarly for intermediate vision, but 25% of patients in both groups continued wearing glasses for computer use, "so I wouldn't say either group has excellent intermediate vision, at least in my patient population," Dr Chang said.

The study found that 50% to 70% of patients continued using glasses for something after lens implantation. "That tells me that the expectation has to be decreased spectacle dependence, and if it is, that's 70% of people who are happy," he said.

Dr Chang's paper was named the best of the session in which it was presented (2-L, Intraocular Surgery: Multifocal IOLs).

Thin flap LASIK: safe and effective

Thin flap LASIK in patients with thin corneas appears to be safe and is associated with good refractive stability and visual acuity (VA) outcomes during long-term follow-up, according to S.S. Iyengar, MD.

In collaboration with John F. Doane, MD, Dr Iyengar conducted analyses of data from 114 eyes with thin corneas (mean 499 μm, range 460 to 520 μm) operated on since 2001. All flaps were created using an automatic corneal shaped (Automated Corneal Shaper, Bausch & Lomb) with a 130 μm plate; ablations were performed using an excimer laser (STAR S4 laser, AMO/VISX).

The eyes were divided into three groups based on type of procedure: standard myopic LASIK, custom myopic LASIK and monovision LASIK. Mean preoperative spherical equivalent in the three groups ranged from –4.62 D (custom LASIK) to –6.6 D (myopic LASIK).

Mean flap thickness, calculated with intraoperative subtraction ultrasound pachymetry, ranged from 77 μm (custom myopic LASIK) to 90 μm (myopic LASIK). Mean residual stromal bed thickness ranged from 311 μm (myopic LASIK) to 326 μm (monovision).

All patients were contacted by phone when they reached the time for an annual follow-up visit. Thirty-nine percent of patients returned for a one-year follow-up; UCVA was 20/25 or better in 87.5% of the eyes and 20/20 or better in 78.1%.

"One of the limitations of our study is that relatively few patients who became eligible for later follow-up returned. However, among those who did, we documented no cases of ectasia, even within the group seen at a five-year postoperative visit," Dr Iyengar said.

"We believe there is a role for both thin-flap LASIK with a mechanical microkeratome and for sub-Bowmans keratomileusis with a femtosecond laser-created flap," he concluded. "However, regardless of the technique, surgeons must be cautious not to be too thin and we have to avoid these lamellar techniques in patients with suspicious topographic patterns."