White-to-white insufficient for IOL sizing

ROME — Measurement of the white-to-white distance can no longer be accepted as a sufficient method for sizing posterior or anterior chamber IOLs, according to Philippe Sourdille, MD.

“White-to-white does not correspond to the internal diameter, and it’s the internal diameter that we need to measure precisely,” he told attendees here at the European Society of Cataract and Refractive Surgeons Winter Refractive Surgery Meeting.

Dr. Sourdille emphasized that patients have the right to be given the best treatment that is currently available, “and we currently have the sophisticated, highprecision technology for measuring scientifically both the anterior and posterior chamber and sizing the IOLs accordingly,” he said.

“Single ophthalmologists cannot have all the instruments, but there are evaluation centers in universities and large private practices where patients can receive all the necessary preoperative tests,” Dr. Sourdille said. “If we want to improve the results, enlarge the indications and prevent the complications of intraocular implants, we certainly need to implement these services and make this technology more widely available to patients and surgeons. But in the meantime, we cannot rely on obsolete, imprecise and unsafe methods.”

Other highlights from the ESCRS Winter Refractive Surgery Meeting follow. Look for in depth coverage of these topics and others from this meeting in upcoming issues of OSN.

IntraLase improved LASIK

The IntraLase’s femtosecond laser flapmaker improves the outcomes of LASIK, producing better quality flaps with fewer flap-related complications, according to several surgeons speaking here.

Jonathan H. Talamo, MD, compared a large cohort of 1,122 patients who underwent LASIK with a mechanical microkeratome with 1,240 cases in which the IntraLase FS laser was used to make the flap.

“With femtosecond laser cuts, there is no risk of buttonholes or free caps,” Dr. Talamo said. “Epithelial defects and ingrowth are far less frequent.”

The increased incidence of diffuse lamellar keratitis (DLK) that has been reported in some studies is, in his opinion, “only associated with the learning curve of the procedure, due to incorrect energy setting and excessive flap manipulation,” Dr. Talamo said. Once surgeons become familiar with the new technique, the DLK rate is comparable to, if not less than, the rate in standard LASIK, he said.

Visual outcomes, he added, are better with the IntraLase because “flap thickness is more predictable and consistent, flap shape is more uniform, flaps can be larger, with a better hinge and significantly less astigmatism,” he said.

“Quality of vision is also improved, and there are fewer induced aberrations. Limitations of the technique, at present, are the higher cost, the slightly longer surgical time and the so-called transient light sensitivity syndrome reported by some of the patients,” Dr. Talamo said.

Similar opinions on the device were related by Lucio Buratto, MD.

“Flaps are incomparably better, perfectly round and with smoother surfaces. Flap uniformity can be seen with pachymetry and corneal topography, and the Artemis system shows minimal variability in central thickness across different flaps and minimal regional variability within the same flap,” Dr. Buratto said.

IntraLase, Dr. Buratto said, improves safety, accuracy and quality of vision, improves results with customized ablation, improves patient satisfaction, and is likely to increase the number of patients interested in LASIK surgery.

A study performed with confocal microscopy at the Vissum Institute of Alicante also confirmed the “superior quality” of the femtosecond laser flaps, according to presenter Jaime Javaloy, MD.

Topography-guided ablation treated central steep island

Specially designed software used in conjunction with the WaveLight Allegretto excimer laser successfully treated a steep central island, said Hans Peter Iseli, MD.

Dr. Iseli told attendees about a “very unhappy patient” who had undergone LASIK 1 year earlier and who now had a best-corrected visual acuity of 20/40. Corneal topography showed the formation of a central steep island, Dr. Iseli said.

Dr. Iseli said that software he developed allowed him to create a Zernike fit of 3.5 mm inside an optical zone of 7 mm. Ablation was performed inside the 3.5 mm area using the Allegretto laser, and the central steep island was eliminated, he said.

Dr. Iseli reported that BCVA the day following treatment was 20/16, and post-op topography measurements showed that “the central island had almost disappeared,” he said.

Preliminary results good with femtosecond laser-assisted ALK

Patients with keratoconus who underwent anterior lamellar keratoplasty (ALK) using a femtosecond laser had “good preliminary results” at 6 months, said Methiye Nurozler, MD.

Six eyes of six patients with keratoconus who were unable to tolerate contact lenses were operated on using the IntraLase femtosecond laser to perform ALK, Dr. Nurozler said. The laser performed lamellar cuts with a thickness of 400 µm in the donor eyes as well as the recipient eyes. Stromal beds were prepared at a depth of 150 µm. Donor lamellas that were 0.1 mm to 0.4 mm larger in diameter than the recipient beds were sutured in place.

Dr. Nurozler said all six patients “were free of pain and irritation starting from the first day following the surgery.”

He said there were no complications. Anterior chamber depth decreased, and flattening and thickening of the cornea resulted, he said.

“IntraLase-assisted ALK is a promising approach for the management of keratoconus,” he said.

Orthokeratology flattened cornea without direct pressure on central cornea

Overnight orthokeratology treatment can change the shape of the cornea to improve refractive errors without applying pressure directly on the central cornea, according to one surgeon speaking here.

Antonio Calossi, MD, reported on a 6-month study of ortho-K in 50 eyes of 25 patients with myopia. All patients were treated with a customized hexa-curve reverse-geometry lens made of a hyper-DK gas-permeable material, for which Dr. Calossi holds the patent. Patients were between 11 and 44 years old, and baseline refractive error prior to treatment was between –1 D and–6 D, he said.

Patients were tested immediately following overnight wear the first night, then at 12 hours following removal of the lens after overnight wear at 1 night, 1 week, 2 weeks, and 1, 3 and 6 months, according to Dr. Calossi. Tests performed included uncorrected visual acuity, best corrected visual acuity, manifest refraction, ultrasound pachymetry, corneal topography and wavefront analysis.

Dr. Calossi said the corneal shape changed from oblate to prolate following 1 night of wear with the lens. Dr. Calossi found that corneal andvisual changes leveled off after 1 week, and the changes were sustained at subsequent visits.

“The preliminary results suggest the corneal epithelium can be molded very rapidly,” Dr. Calossi said.

Solid-state laser produces promising results at 1 year

The Lasersoft solid-state laser from Katana has produced promising results in laser refractive procedures with 1 year follow-up, according to Matteo Piovella, MD.

Dr. Piovella presented results of LASIK in 37 eyes of 37 patients using the Lasersoft no-gas, solid-state ultraviolet laser from Katana.

At 1-year follow-up he reported no postoperative complications. Patients have achieved a mean visual acuity of 0.78±0.14 with a mean refraction of –0.04 D. He reported no significant variability in refraction, as all eyes reached refractive stability within1 month.

Attendees at the European Society of Cataract and Refractive Surgeons Winter Refractive Surgery Meeting held in Rome.

Dr. Piovella said he is getting good results with the laser because it has a small spot size and it applies less energy to the eye than excimer lasers, therefore causing less damage to the cornea.

“The main characteristic of the laser is spot size,” he explained. “Common spot size for excimer lasers is between 0.8 mm and 1 mm, where Lasersoft uses a 0.2-mm beam.”

With a smaller beam, the Lasersoft needs more velocity to cover the same area as a wider beam, so the eye tracker operates at 1 kHz, he said.

“[The Lasersoft] applies less energy to the cornea, and the theoretical speculation is that this leads to less scarring,” Dr. Piovella said.

He added that the smaller beam “overlaps a true gaussian spot, ensuring an extremely homogeneous corneal surface.”

With the smaller beam, “Lasersoft may well fit the present requirement for custom ablation,” he said.

While not giving the laser a full endorsement, Dr. Piovella stressed that the laser has a promising future.

“I don’t want to support the idea that this is the best technology available today, but it could be a very good development for ablation. This is the reason for which I have until now had great interest regarding this technology, but it is at its starting point,”he said.

Lower ablation temperatures produce less corneal damage, better acuity, study suggests

Eyes that underwent PRK with the Lasersoft solid-state laser had faster visual recovery and less corneal haze than eyes that underwent PRK with the Carl Zeiss Meditec Mel 70 excimer laser, according to Paolo Garimoldi, MD. He noted that these differences correlated with lower intraoperative corneal temperatures during ablation with the solid-state laser than with the excimer laser.

Dr. Garimoldi presented results in 64 eyes of 34 patients treated with PRK for myopia or myopic astigmatism. He said 31 eyes were treated with an excimer laser and 33 were treated with a solid-state laser. Corneal temperature was measured with a thermal camera during ablation.

All corneas were examined with confocal microscopy before and immediately after surgery. Follow-up was at 1, 3, 6, 9 and 12 months, Dr. Garimoldi said. He calculated haze thickness and haze reflectivity, graded at slit-lamp examination, and compared them between the two procedures.

Corneal temperatures increased an average of 5.3° C in eyes undergoing PRK with the conventional excimer laser, but increased only 0.8° C in eyes undergoing PRK with the solid-state laser, he said.

The mean haze reflectivity and mean haze thickness were higher in the eyes treated with the standard laser, he said. Dr. Garimoldi said haze was higher in eyes treated with the excimer laser especially in the first 3 months, but the haze tended to decrease over time.

Device allows ablation of underside of LASIK flap

A new flap-holding instrument allows flying-spot laser ablation with an active eye tracker to be performed on the underside of a LASIK flap, said one surgeon speaking here.

Suphi Taneri, MD, described early experience with the device developed in coordination with Geuder.

“The instrument is just a simple flap holder with a pupil-shaped black marking in the center,” Dr. Taneri said. “It is placed under the reversed flap so that the round black marking is visible in transparency. The eye-tracker of the laser centers on the mark as if it was a pupil, and the treatment can be performed on the undersurface of the flap. The flap is then repositioned on the stroma.”

The flap-undersurface laser ablation can be used for LASIK re-treatment as well. This might be an effective way of avoiding the risk of keratectasia, Dr. Taneri said, because re-ablation performed on the stromal bed has been reported to lead to ectasia.

Dr. Taneri reported “good results” with the device used in conjunction with a Bausch & Lomb Technolaslaser.

LASEK innovator gives epi-LASIK high marks

Epi-LASIK with the Centurion epikeratome from Norwood Eyecare is a beneficial innovation of laser epithelial keratomileusis, according to Massimo Camellin, MD, who developed the LASEK technique in 1999.

“At first I wasn’t sure that mechanical separation could be an advantage, especially in eyes with a strongly adherent epithelium,” said Dr. Camellin. “Now that I have tried it, I must say that the mechanical device facilitates epithelial detachment in all eyes and makes surgery easier and more predictable also for beginner surgeons.”

Postoperative results in terms of patient comfort, recovery time and vision are comparable in the two techniques, but the epi-LASIK flap is easier to replace, smoother and more integral than the manually created LASEK flap,he added.

“I am going to introduce this innovation in my routine laser procedures,” Dr. Camellin said, “although I think there is still some scope for alcohol separation in some cases. In patients with retinal problems, suction is better avoided, and also re-treatment with LASEK will continue to be performed with alcohol. The two techniques can be quite complementary.”

Dr. Camellin is currently finishing a study comparing the mechanical and alcohol separation techniques in 80 patients. Each patient will be treated with standard LASEK in one eye and epi-LASIK in the fellow eye.