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Modified depth, incisions for LASIK flap increase strength, prevent strain on cornea
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BERLIN — Modifying flap depth and incisions during LASIK procedures increases the strength of the flap and prevents strain on the cornea, a surgeon said here.
 John Marshall, PhD, FRCPath, presented on recent improvements in LASIK flaps at the ESCRS meeting in Berlin. | ||
“I think that we have made [the flap] better by making it thinner and by actually changing the dynamic stress on the edge,” John Marshall, PhD, FRCPath, said at the European Society of Cataract and Refractive Surgeons meeting. Dr. Marshall’s presentation showed a comparison of corneal strain with three flaps: a traditional cut, a side cut and delamination.
In a traditional flap at a depth of 90 µm, there was a 7% change in strain; at a depth of 160 µm, the change was 30%. With those same depths, the side cut showed 7% and 25% change in strain, respectively. With delamination, strain changed by 3% and 2%, respectively, he said.
He suggested undercutting the edge of the flap to increase strength because not as many keratocytes are damaged.
“As you increased the undercut, the system is stronger. And as you decrease, as it were with a conventional microkeratome, it actually became weaker,” Dr. Marshall said.
These items appeared originally as daily coverage from the meeting on OSNSuperSite.com. Look for more in-depth coverage of these and other topics in upcoming issues of Ocular Surgery News.
Surgeon: LASIK successful in corporate practice setting
LASIK can be successful in large volumes, as performed in corporate practice settings, one surgeon said.
 Steven C. Schallhorn, MD, spoke about LASIK in the corporate practice setting. Image: Altersitz K, OSN | ||
“LASIK is safe and effective when offered as a corporate provider,” Steven C. Schallhorn, MD, said. “It certainly exceeds target goals in every category and greatly exceeds them in many.”
Dr. Schallhorn presented data from Optical Express, a European health care company with 34 laser centers and 27 surgeons. In the first 6 months of 2008, Optical Express performed myopic LASIK on 28,677 eyes targeted for emmetropia.
At 1-month follow-up, 89% were within 0.5 D of emmetropia, and 98% were within 1 D; 87% were 20/20 or better, and 95% were 20/25 or better. Looking at patient factors associated with outcomes, Dr. Schallhorn said preop sphere, cylinder and patient age were significant.
In a follow-up survey that had a 32% response rate, 87% of patients said they were very satisfied with their surgeon, he said.
New bag refilling procedure comes closer to restoring accommodation
The implantation of a 0.1-mm accommodative membrane IOL at the opposite sides of the capsular bag enhances results of the bag refilling procedure, preventing silicone leakage and posterior capsular opacification formation, according to a study.
 Okihiro Nishi Image: Altersitz K, OSN | ||
This new method presented by Ridley Medal lecturer Okihiro Nishi, MD, consists of in-the-bag implantation of a thin diaphragm similar to an IOL but with no refractive power to seal the anterior capsulorrhexis. The lens is kept in place by the pressure of the injected high molecular weight silicone polymer that refills the bag. A second lens can be implanted after performing a posterior continuous curvilinear capsulorrhexis to prevent PCO.
Monkey experiments demonstrated the presence of 2 D to 3 D accommodation after 4% pilocarpine application.
“Since the accommodative IOL has no refractive power, refraction changes may arise, not from the forward movement of the IOL but from an actual curvature change of the anterior membrane,” Dr. Nishi said.
Surgery required 20 to 30 minutes and was found to be highly reproducible.
Intraocular ring tonometry showed reproducible IOP values during corneal applanation with femto laser
Real-time IOP measurements can be taken during corneal applanation with a femtosecond laser by using intraocular ring tonometry, according to a surgeon.
“Needle tonometry revealed reproducible IOP values also during corneal applanation with the IntraLase (AMO),” H. Burkhard Dick, MD, said. “IOP increased during application of the ring, remained below 100 mm Hg for all measurements and returned to normal directly after suction ring release.”
The technique, which was applied for the first time in a living human eye by Dr. Dick, showed that IOP remains within a safe range during the entire IntraLase treatment.
The procedure was performed in the left eye of a 59-year-old male patient scheduled for enucleation. IOP measurements were taken dynamically by intraocular needle tonometry. The needle was placed in the anterior chamber, and IOP measurements were continually taken before, during and after application of the suction ring and personal interface gadget. The setting, procedure and IOP measurements were video recorded by two professional photographers.
Although there may be some intraindividual variation, Dr. Dick said this experience shows that there should be no fear of an IOP spike during femtosecond laser procedures, and this most probably applies to both Intra-Lase-assisted keratoplasty procedures and flap performance in LASIK.
Angle-supported phakic IOL shows efficacy, quality-of-life improvement
A global study showed that an angle-supported phakic IOL is efficacious and improved patient quality of life, experts said.
“Bilateral implantation of the Acry- Sof phakic angle-supported lens (Alcon) reduced the dependence on corrective lenses in patients with high myopia and improved quality of life … and certainly improved their satisfaction with uncorrected vision,” Stephen S. Lane, MD, said.
Ralf Gerl, MD, presented the scientific results of the 3-year international study that looked at 104 patients implanted with the IOL, and Dr. Lane presented the quality-of-life and functional status assessment.
Dr. Gerl showed that 80% of the mild or high myopes were 20/20 or better, and 100% were 20/40 or better, with nearly unchanged endothelial cell counts. Ten patients (2.8%) required IOP lowering, and seven patients (1.9%) developed cataract.
Dr. Lane presented data gathered with the Refractive Status and Visual Profile survey conducted at baseline and 3 months, 6 months and 1 year after surgery.
Overall, on the Refractive Status and Visual Profile scale of 0 to 100, with 0 being perfect, patients preoperatively scored their quality of life at 27.5. One year after the procedure, their average score was 17.9.
Preoperatively, 100% of the patients used lenses; postop, 79.3% were lens-free. About 96% of patients said they would undergo the procedure again if given the choice, Dr. Lane said.
Aspheric treatment zone algorithm shows good visual results
A customized aspheric treatment zone provides a safe and effective algorithm for myopic patients with astigmatism undergoing LASIK, according to data from a U.S. Food and Drug Administration study.
George O. Waring III, MD, FACS, FRCOphth, presented multicenter clinical results of the Nidek CXII customized aspheric treatment zone (CATz), examining its use in 135 eyes of 68 patients with manifest refraction sphere from –0.5 D to –7 D with up to –4 D of astigmatism.
Patients had better postoperative uncorrected visual acuity than preoperative best corrected visual acuity, he said. They also reported no driving difficulties at 6 months and fewer problems with light sensitivity, halos, star bursts and glare postop.
Dr. Waring said the topographically guided ablation algorithm creates a more prolate cornea, steeper in the center and flatter moving away from it.
Femtosecond-based intrastromal treatment shows promise in correcting presbyopic patients
A femtosecond-based intrastromal correction of presbyopia appears to be a fast, safe and reproducible procedure, according to a physician.
“The treatment requires no incision, no flap, no pocket. The epithelium remains untouched, and the treatment is completely performed intrastromally, creating a series of five consecutive rings at predefined distances,” Mike P. Holzer, MD, said.
At the University of Heidelberg, Germany, 20 consecutive patients were treated with the new procedure. Mean patient age was 56 years. All of the patients were presbyopic without any higher myopia or hyperopia.
“The procedure lasted just a few seconds. After surgery, the lines of the rings could be seen in transparency, but at 1 week, they had almost completely disappeared,” Dr. Holzer said.
Mean near visual acuity improved from 20/100 to 20/40, and no change in distance acuity was reported.
There was some degree of individual variation in the results, he said, but some slightly poorer results were probably due to corneal edema and will probably improve over time. However, the gain in some patients was remarkably higher compared with mean values.
The treatment has a potential to correct all refractive errors, he said.
Current methods of endothelial cell count, morphology have limitations
The lack of standardized methods to evaluate endothelial cell count and morphology makes it difficult to draw reliable conclusions and compare results of individual studies, according to one surgeon.
“The ideal setting would be one center, one technician, one microscope and one reading method,” Sanjay Patel, MD, said.
 ESCRS Treasurer Peter Barry, FRCS, poses in a Ferrari while enjoying entertainment at the European Society of Cataract and Refractive Surgeons Welcome Reception in Germany. The evening featured cuisine from various European nations, a live jazz band and vintage European cars. The event was sponsored by Advanced Medical Optics. Image: Boyle EB, OSN | ||
Every center uses different equipment, different microscope calibration and there is a variety of analysis techniques, Dr. Patel said.
“If we take into account that also repeated measurements taken on the same patient in the same center vary by more or less 7%, we understand how difficult it is to come to reliable conclusions. Current methods of endothelial cell count and morphology have considerable limitations, and this applies to phakic IOLs, cataract and grafting,” he said.
Corneal cross-linking with femtosecond laser gives good results, comfortable recovery
Femtosecond-assisted corneal cross-linking allows good results and comfortable recovery without removal of the epithelium, a surgeon said.
Corneal cross-linking with Intra-Lase (AMO) allows adequate riboflavin absorption and UV light delivery without epithelial removal, thus avoiding pain, corneal scars, epithelial defects and keratitis, according to Elias F. Jarade, MD.
The IntraLase is used to perform a “spiral pattern,” consisting of a corneal flap with a hinge of 345° and 30° side-cut angle.
“This is more or less the inverse cut-hinge proportion of a normal LASIK flap. A 20-gauge intravenous catheter is introduced through the cut to inject riboflavin. This technique allows a better stromal diffusion and quicker absorption of the photosensitizing agent, without leakage and dispersion. You can use less riboflavin and less UV light. Patients experience a faster, uneventful recovery, without any pain,” Dr. Jarade said.
Corneal inlay provides excellent near vision, good patient satisfaction
A corneal inlay employing the keratophakia approach to treating presbyopia has shown excellent visual results thus far in clinical research, according to a surgeon.
Stephen G. Slade, MD, FACS, and a colleague conducted a clinical evaluation of 22 patients using the PresbyLens (ReVision Optics) corneal inlay.
They found that all patients saw 20/25 binocularly and were satisfied with their distance vision after implantation of the inlay.
The inlay was placed under the corneal flap and produced pseudoaccommodation through steepening of the central cornea, he said. It altered the anterior corneal shape, creating a central near add zone with the keratophakia approach.
Biological differences could assist in IOL selection
Men tend to prefer better distance vision, whereas women tend to prefer better near vision, preferences that could be best satisfied by implanting refractive distant dominant IOLs in men and diffractive and refractive near dominant IOLs in women, an expert said.
By selecting IOLs based on gender preferences, overall patient satisfaction might be improved, according to Magda Rau, MD, who said visual preferences could possibly be explained by human biology, a factor that might aid in IOL selection.
Stratifying results from four previous multifocal IOL studies of 100 men and 100 women, Dr. Rau found that men complained more than women about glare and halos.
In addition, Dr. Rau found that women complained more than men about reading with glasses and being unable to see at close distances.
The studies separately examined results of implanting the Array, Tecnis and ReZoom (all from AMO) and the MF4 (Zeiss) in both male and female patients.
Clinician: IOL calculation for hyperopic eyes best with Haigis, Hoffer Q formulas
Selecting the best IOL power formula for hyperopic eyes can be key in IOL selection, an expert said.
Wolfgang Haigis, PhD, said problems with IOL calculation in hyperopic eyes include lens position prediction errors, manufacturing tendencies for high-powered lenses and difficulties in selecting the appropriate IOL power formula. He presented a study conducted with Frank Goes, MD, examining power formulas for hyperopic eyes.
“The best results for these hyperopic eyes were with Haigis and Hoffer Q,” Dr. Haigis said. “Don’t use SRK II and SRK/T for hyperopic eyes.”
Ninety-one eyes of 50 hyperopic patients underwent IOLMaster (Carl Zeiss Meditec) biometry and refractive lens exchange with AcrySof SA60AT and SN60AT (Alcon) lenses. Patients had mean arithmetic and median absolute refraction prediction errors determined for IOL power formulas using the Haigis, Hoffer Q, Holladay 1, SRK/T and SRK II, said Dr. Haigis, who devised the Haigis formula.
Drs. Haigis and Goes found that medians of the absolute prediction errors were significantly different, including the absolute prediction errors of all combinations with SRK/T and SRK II.
Pilot study finds lens, phaco system achieved good MICS results
A new microincisional lens showed promising results when used with a new phacoemulsification system optimized for biaxial and coaxial microincisional cataract surgery, a surgeon said.
 Rosa Braga-Mele, MD, FRCSC, presented results of a new microincisional lens at a Bausch & Lomb-sponsored media event. Image: Mullin DW, OSN | ||
“The MI60 was inserted through a 1.8-mm incision with minimal or little difficulty,” Rosa Braga-Mele, MD, FRCSC, said. “There was gentle insertion and no tissue damage.”
The MI60 acrylic microincisional IOL from Bausch & Lomb had good centration and contrast sensitivity after phaco by the Stellaris Vision Enhancement System (Bausch & Lomb), a pilot study by Dr. Braga-Mele found.
The study examined 40 patients with senile cataract who underwent either biaxial or coaxial microincisional surgery with the Stellaris system in two groups of 20. The groups had similar visual outcomes, with corneal clarity and all eyes with BCVA of at least 20/20 at 6 months postop, Dr. Braga-Mele said.
New femtosecond system improves LASIK outcomes
LASIK flap creation with a new femtosecond laser system is safe, effective and predictable, according to a surgeon.
Ziemer’s Femto LDV “is compact and mobile, easy to use and quite similar to a traditional LASIK microkeratome. It has a short focal length, a large numerical aperture and a small spot size, which results in less shockwave effect and less energy delivered to the tissue than other femto lasers,” Mohammad Ghoreishi, MD, said.
The first prototype created some “sticky bed” problems because of the typical residual collagen bridges of femtosecond cuts, but the new, upgraded model produces more accurate, clean cuts that make flap removal smooth and easy, he said.
The system was used in his clinic to perform the LASIK flap on 210 eyes of 105 patients with myopia and myopic astigmatism. The Technolas excimer laser (Bausch & Lomb) was used to perform the ablation.
Flap thickness was highly predictable and reproducible, visual results were satisfactory and no significant complications occurred, he said.
Excimer laser platform shows excellent results in large series of patients
A new excimer laser platform allows a safe and effective treatment of a wide range of refractive errors, according to a study carried out in Greece.
The study, which used the Schwind Amaris excimer laser with the ORK-CAM ablation profile, looked at 160 eyes with myopia and myopic astigmatism and 15 hyperopic eyes treated since March.
“Results were extremely good, with 90% of the eyes achieving 20/20 uncorrected vision with both techniques, although PRK-treated eyes required a slightly longer time to recover. None of the eyes lost BCVA lines. All eyes were between ±0.5 and ±1 D from target refraction, with just a slight tendency to overcorrection in higher myopia,” George Charonis, MD, said.
Stability of results appears to be excellent at this point of the follow-up.
Millennium has been a turning point for multifocal IOLs
The beginning of the new millennium has been a crucial turning point for multifocal IOLs, a surgeon said.
Since the 1980s, the concept has evolved and the focus is now on optics evolution, Manfred Tetz, MD, said.
“Different refractive and diffractive models have been developed, with variable zone positioning, number and sizes,” he said. “Today’s patient needs are creating many challenging tasks for us, but this evolution is taking place. Our eyes are ready for multifocal IOLs, but we must still work on technical details.”
Traditionally, companies have aimed to achieve the higher possible near add, but the challenge in recent years has been that of achieving better intermediate vision, he noted.
Some companies are trying to combine near addition with accommodating mechanisms, with asphericity and a toric component.
Pseudophakic monovision better than multifocal IOLs in selected patients
Pseudophakic monovision is a promising method for managing loss of accommodation and is a better option than multifocal IOLs in certain patients, according to a surgeon.
In a study comparing the two techniques, Kimiya Shimizu, MD, found that monovision offers a better vision at near, excellent reading speed for newspaper print and better contrast sensitivity.
Concerning stereopsis, 82% of the patients were in the normal range. Patient satisfaction was higher (85%) in the monovision group than in the multifocal IOL group (77%).
Careful selection needed for successful high myopia multifocal implantation
Careful patient selection and low power multifocal IOLs could produce promising visual results in high myopia patients, a physician said.
Béatrice Cochener, MD, said when selecting high myopia patients for multifocal IOL implantation, physicians should choose only those with true cataract and no amblyopia, among other factors, to achieve best visual outcomes.
Dr. Cochener presented 18-month study results looking at 19 high myopia patients. The Acri.Lisa (Carl Zeiss Meditec), an acrylic IOL ranging from 0 D to 40 D, was then implanted.
After implantation, no patient had to wear glasses for far vision, and 63% had a near vision of J1. Dr. Cochener said results were promising, but follow-up is needed.
Add-on IOL technology enhances results of previous cataract surgery procedures
Preliminary experience with Human Optics’ Add-On IOL system suggest that this new method of correcting postoperative pseudophakic ametropia is promising, a surgeon said.
“We have so far implanted 22 eyes of 16 patients with these lenses,”
Detlef Holland, MD, said. “We had no intraoperative or postoperative complications. The intraocular pressure was in the normal range, all the IOLs were centered, and no iris capture or depigmentation occurred. Good uncorrected near and distance vision and a stable improvement of refraction were achieved.”
The procedure consists of the implantation of a second lens above the pre-existing IOL. The lens is a three-piece implant, with a 14-mm overall diameter for stable fitting in the sulcus. The concave 7-mm optic surface prevents contact with the underlying IOL. The implant is available in diffractive, toric and spherical models.
Rotational stability of the toric model still poses some problems, Dr. Holland said. In three cases, the Add-On IOLs needed repositioning, and one IOL was explanted because of multiple rotations.
Near activity visual questionnaire developed to supplement current testing
 James Wolffshon, PhD, MCOptom, FAAO, presented findings from a questionnaire on near vision testing and functional assessment. Image: Altersitz K, OSN | ||
In an effort to supplement current near vision testing with additional functional assessment, a speaker presented a 10-question survey that researchers have validated.
“There are questionnaires that have near vision scales in them, but there is no questionnaire to date that has been developed with the presbyopic population with the idea of assessing presbyopic treatments,” James Wolffsohn, PhD, MCOptom, FAAO, said.
Researchers looked to literature and consulted with professionals for questions to include in their work, Prof. Wolffsohn said, and they created a 26-item questionnaire. The first questionnaire was self-completed two times by 107 subjects to make sure that there was no administrator bias.
The subjects represented an array of presbyopic correction options.
Afterward, he said researchers validated reliability and identified 10 of the 26 items that met their criteria. These particular questions scored well in their relationship to one another while each identifying a separate element of near vision.
Adrenaline in irrigating solution might be necessary only for certain cataract cases
Pupils that received adrenaline in balanced salt solution and preoperative NSAIDs before cataract surgery appear to be more stable than pupils that did not receive adrenaline, a study found.
However, in the group that did not receive adrenaline, the change in pupil size was so small, the clinical outcome was unaffected, suggesting that adrenaline might not be needed for all pupils, Lindsay Ong-Tone, MBChB, FRCSEd, FRCOphth, FRCSC, said.
He conducted a study that looked at pupil size with adrenaline added to balanced salt solution during cataract surgery in 183 patients. Patients were randomly assigned to receive adrenaline in balanced salt solution or no adrenaline.
“Adrenaline in the irrigating solution is not necessary if the pupil is widely dilated,” Dr. Ong-Tone said. “It would still be beneficial if the pupils dilate poorly preoperatively.”
Study: Multifocal IOL position had no impact on contrast sensitivity
The position of the multifocal IOL in the capsular bag does not appear to alter visual results after cataract surgery, a study found.
“The IOL position did not affect the postoperative contrast sensitivity when it was implanted in the bag,” Hiroko Bissen-Miyajima, MD, said.
Dr. Bissen-Miyajima presented results from a study that she conducted with colleagues, examining 35 eyes of 19 patients implanted with the Tecnis ZM900 (AMO) multifocal IOL. They measured pupil size and diffractive rings of the IOL using an anterior segment analyzer with normal lighting and the distance between the pupil center and the IOL using computer software.
They found that contrast sensitivity was within the typical range for both low and intermediate spatial frequencies, with good visual acuity results.
However, patients with smaller pupils tended to be less satisfied with visual outcomes and had lower contrast sensitivity, Dr. Bissen-Miyajima said.
Injectable ring expands pupil safely, effectively
A new injectable iris ring enlarges the pupil during cataract surgery without causing trauma, protecting the iris sphincter intraoperatively and returning the iris to its normal shape postoperatively, according to a surgeon.
The temporary pupil expansion device has four circular loops to hold the iris at equidistant points, according to Boris Malyugin, MD, PhD. He conducted a study examining clinical results of the ring in 38 eyes of 37 patients. Patients were not responsive to conventional pupil dilation techniques.
Results from the study showed that the ring had minimal surgical complications and was well-tolerated. The most common complication was transitory IOP rise in six eyes, Dr. Malyugin said.
Intraocular mirror provides views of ocular structures during surgery
A newly designed intraocular mirror could assist in cataract surgery by showing the area behind the iris that typically cannot be viewed during surgery, the inventor of the device said.
Bong-Hyun Kim, MD, said he designed the mirror to help surgeons determine the position of the IOL and view structures behind the iris and the endothelial surface of the cornea with ease.
The mirror can assist surgeons in determining zonular dehiscence cases by clearly showing the presence of zonules, Dr. Kim said. It is also useful in detecting intraoperative corneal endothelial damage.
In addition, the mirror is simple to use, he said. After injection of viscoelastic, the mirror can be inserted into the anterior chamber. The device has a shank, handle and reflective, round head that measures 2.5 mm in diameter and 0.3 mm in width.
Guidelines assist when performing phaco in post-vitrectomy cases
Performing phacoemulsification after vitrectomy procedures requires specific techniques to avoid serious complications, a physician said.
“Adherence to proper guidelines will optimize the outcome, reduce the intraoperative complications and enhance the postoperative outcome,” Arup Chakrabarti, MS, said.
He outlined the most effective techniques for best outcomes in patients who have had previous pars plana vitrectomy and are undergoing cataract surgery. Preoperatively, he said, establishing a thorough surgical history of each case and providing counseling is important for patient expectations. Performing surgery early, before the cataract hardens, is also key.
Dr. Chakrabarti presented results of a retrospective analysis that he and colleagues performed. They examined data of 125 consecutive eyes that underwent vitrectomy, followed by phaco with IOL implantation.
They found that the most common complication was PCO in 75 eyes, or 60% of patients, at 1-year follow-up. Dr. Chakrabarti said earlier YAG capsulotomies should be expected in these cases.
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Cornea/External disease
Cefuroxime may protect vision in addition to preventing endophthalmitis
 Peter Barry, FRCS, spoke about intracameral cefuroxime and endophthalmitis. Image: Altersitz K, OSN | ||
Intracameral cefuroxime may not only protect patients against endophthalmitis, but may also protect final visual acuity in the case of infection, one expert said.
Peter Barry, FRCS, discussed visual results from the ESCRS Endophthalmitis Study Group.
In the four groups, four staphylococcal and five streptococcal cases developed without any periocular antibiotic; four staphylococcal and three streptococcal cases developed under topical antibiotic drops without injection; two staphylococcal cases developed with intracameral cefuroxime and placebo drops; and one staphylococcal infection developed under intracameral cefuroxime and levofloxacin.
Final visual acuity range in the 11 staphylococcal cases was 20/80 to 20/20, and no cases were declared legally blind. Final visual acuity for the eight streptococcal cases was 20/20 to no light perception with five cases declared legally blind.
“None of these five have received cefuroxime. So not only does cefuroxime reduce your incidence of endophthalmitis, but if you’re unfortunate enough to get it, it seems to protect your ultimate visual outcome,” Dr. Barry said.
Femtosecond laser-assisted lamellar procedures gaining in popularity, surgeon says
Femtosecond laser-assisted lamellar keratoplasty may be the future of corneal transplantation, a surgeon said.
“In the Netherlands, the rate of [penetrating keratoplasty] has dropped from 90% to 60% in just a few years,” Rudy Nuijts, MD, said.
Some of the typical femtosecond laser cuts, such as zigzag, are now applied to lamellar procedures, facilitating stromal excision and donor-recipient adherence.
Dr. Nuijts said he was one of the first surgeons to perform femtosecond laser-assisted posterior lamellar keratoplasty and to advocate the advantages of accuracy, reproducibility and endothelial preservation. “Endothelial cell damage is 3.4% after femtosecond dissection, compared to the 6.5% of manual dissection,” he said.
In a study, he compared the results of femtosecond Descemet’s stripping automated endothelial keratoplasty in 36 eyes with those of 40 PK eyes.
“Although visual acuity remains better with PK, astigmatism is lower with the lamellar technique. Recovery is faster, and patient comfort is better,” Dr. Nuijts said, adding that the steeper learning curve of the femtosecond procedure is a disadvantage for the surgeon.
DLK with air bubble shows good results
Deep lamellar keratoplasty with air bubble dissection is a promising method of treating keratoconus, according to one surgeon.
Alaa El-Danasoury, MD, FRCS, said residual refractive error can be corrected with LASIK or toric ICL implantation, but not earlier than 15 months after grafting or 3 months after suture removal.
“In less severe cases, cross-linking can be used to stabilize vision, and an ICL can be implanted after 1 year. However, if the keratoconus has evolved to more severe stages, lamellar keratoplasty should be performed without waiting too long, to avoid having to do a penetrating graft,” he said.
He treated 113 eyes of 87 patients. Surgery was successful in more than 90% of the cases and only 7% had microperforations. At 1 year, 84% of the patients were 20/40 or better, and 80% were 20/20 or better. No secondary procedure was needed in about 60% of the cases.
Expert shows intracorneal rings stable over 10 years
In the 10 years after first implantation, intracorneal rings have been used in 50,000 keratoconus cases worldwide and 37,000 grafts have been avoided, according to one expert.
“The technique is now pretty standardized, and we have reliable parameters to make the technique successful according to the type, shape and stage of keratoconus,” Joseph Colin, MD, said.
Results with intracorneal rings (Intacs, Addition Technology) are generally satisfactory, with 70% to 80% of the patients gaining lines of vision, 20% remaining stable and only a few decreasing.
Dr. Colin said results are stable over time. In his first patient, implanted in 1997, the maximum keratometric readings decrease and visual acuity gain have been stable. Of the 65 eyes implanted in the last 8 years, five have needed PK.
He said the use of femtosecond laser has improved the procedure, but the insertion of the segments in the channels can be cumbersome because of the collagen bridges that the laser does not cut.
Collagen cross-linking can be a complementary technique to Intacs implantation. Sequence and combination of the two procedures should be adapted to single cases, Dr. Colin said.
UV exposure with higher fluence, shorter duration shows promise in corneal cross-linking procedure
Corneal cross-linking with shorter duration, higher fluence ultraviolet light exposure appears to be an effective approach, according to one surgeon.
“With a different modality of administering riboflavin intracorneally … we can increase UV light fluence and shorten exposure time,” John Kanellopoulos, MD, said. He comparatively evaluated the effects of this procedure in a group of 30 keratoconus patients. Half of them were cross-linked with 7 mW/cm² for 15 minutes and half with the traditional 7 mW/cm² for 30 minutes.
“No difference was found in the results of the two groups. The shorter procedure may, in fact, result in less keratocyte loss,” he said.
Dr. Kanellopoulos said he uses this shorter procedure as a prophylactic measure in refractive surgery patients who may be at risk of developing ectasia.
Clinician: Lenticule extraction refractive outcome comparable to excimer laser
Not only is lenticule extraction with a femtosecond laser safe for myopia treatment, the refractive outcome with the procedure is similar to excimer laser technology, an expert said.
At an event sponsored by Carl Zeiss Meditec, Walter Sekundo, MD, presented 6-month final results of a multicenter prospective study that he conducted with Marcus Blum, MD, on 107 eyes that underwent femtosecond lenticule extraction (FLEX) with the VisuMax femtosecond system (Carl Zeiss Meditec).
Visual results were excellent with FLEX, Dr. Sekundo said. For uncorrected visual acuity, 74% of patients saw 20/20 or better at 6 months, he said.
Two eyes had poor visual acuity at 3 months; there were no cases of diffuse lamellar keratitis or transient light sensitivity syndrome.
Indications and contraindications show cross-linking results still preliminary
Cross-linking is increasingly proving to be a successful technique for strengthening the cornea and halting keratoconus progression. However, indications and contraindications are not yet clear, one expert said.
“Prospective studies have only started in 2003, 2004, and we must wait a few more years to draw conclusions on the long-term results of the technique,” said Theo Seiler, MD, who first introduced the technique some years ago.
These studies are taking place in Europe. The Siena group of Italy, for example, showed keratocyte death hystologically but then showed subsequent repopulation. The Zurich, Milan and Brussels international group showed a significant difference between the treated and untreated eye in a series of patients.
In all groups, haze and demarcation lines between cross-linked and non- cross-linked areas were found in the majority of patients.
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