Feature ESCRS Symposium Report

Monte Carlo 2006 Strategies to achieve emmetropia after corneal surgery

Roibeard O’hEineachain implantation could improve the vision of patients.To begin with, children’s eyes The five-year results from the study are in Monte Carlo patients with suboptimal results following continue to grow until the age of 14, the now available, he noted.They show that corneal surgery. However, patients’ visual most rapid growth occurs in the first two postoperative refraction has remained THE many different approaches to outcomes have not been as good as those years of life. In addition, small children are fairly stable throughout the follow-up improving visual outcome in patients who achieved in patients who are implanted unlikely to cooperate under local period and that five children achieved an have unsatisfactory vision after corneal with the lenses as a primary refractive anaesthesia and their smaller apertures improvement in visual acuity. surgery were discussed at a symposium at procedure. make their eyes less easily accessible to The mean postoperative spherical the 10th ESCRS Winter Refractive Surgery He noted that over the past three years the surgeon. equivalent was -3.0 D, representing a Meeting. he has performed ICL implantations in 27 mean improvement of 7.0 D. “While we would wish one intervention eyes of 25 patients who had undergone Postoperative visual acuity ranged from to be perfect, that’s not always the case “Probably more than 15 previous corneal surgery. Eleven patients 6/6 to 6/60. One child gained no with refractive surgery, whatever guise it had undergone penetrating keratoplasty improvement because of non-compliance takes,” said Emanuel Rosen FRCS million LASIK procedures and 16 had undergone previous PRK. with postoperative patching. FRCOphth, Manchester, UK, who co- Over a follow-up ranging from eight “It is important to stress the chaired the session have been performed, but months to three years, refraction was importance of patching afterwards and Tobias Neuhann MD, Munich, Germany, fairly stable, although it fluctuated slightly. one has to follow these children closely. commenced the session by discussing his if you look at the literature However, the predictability was relatively You also have to do these surgeries early. experience in using the ICL phakic IOL poor and there were some under- and If you perform refractive surgery on a (Staar Surgical) as an adjunct to corneal on paediatrics, not more overcorrections. child of eight with dense amblyopia you refractive surgery. The majority of cases had a visual acuity than 1,000 have been done might do fantastic surgery but you will of around 20/40 and some achieved no probably get no improved visual better than 20/60. In some cases corneal in all the publications to outcome.” “Normally we try to do opacities may have contributed to their everything with LASIK but poor visual outcomes, he said. In addition, date” Michael O’Keefe MD Caution re: PRK after LASIK while BCVA remained unchanged in 16 In the next presentation, Dan Epstein MD, sometimes we can’t do eyes, the remaining eyes lost one or two Furthermore, pre-operative diagnostics PhD, Switzerland, cautioned against the lines. can also be much more difficult to use of surface ablations as an that. With the ICL and “We still have something to learn about perform and the results of refraction are enhancement procedure in eyes which ICL power calculation and biometry with much less accurate. have previously undergone LASIK. LASIK we can have the these lenses,” he added. Promising five-year results two types of surgery in a Paediatric refractive surgery The most important use of paediatric “The anecdotal Professor Michael O’Keefe, University refractive surgery is in the treatment of nice marriage; it’s very College Dublin, Ireland, turned the unilateral high myopia, which is the most impressions I have from discussion to the controversial topic of refractory form of anisometropic helpful if you have both refractive surgery in children. amblyopia. In all the studies done to date, colleagues who have used He noted that the main indications for compliance with unilateral contact lenses PRK after LASIK are that it tools to help the patient” paediatric refractive surgery are or high-power spectacle correction has Tobias Neuhann MD anisometropic amblyopia, refractive been poor. works or it sometimes “Normally we try to do everything with changes after congenital cataract surgery Dr O’Keefe noted that he has achieved LASIK but sometimes we can’t do that. and accommodative strabismus.While a promising results with LASIK in a small works; or that it doesn’t With the ICL and LASIK we can have the range of approaches have been used, series of children with unilateral and two types of surgery in a nice marriage; it’s including laser ablation, lens exchange and bilateral myopia.The two-year follow-up work and it’s dangerous, very helpful if you have both tools to help phakic IOLs, such procedures are rarely results of his study appeared in the the patient,” he said. performed and there is still no published January 2004 issue of the British Journal of or I don’t know” Indications for combined ICL long-term data on their outcome, he Ophthalmology. Dan Epstein MD, PhD implantation and corneal refractive surgery added. The study involved seven eyes of six include eyes with high refractive errors “Probably more than 15 million LASIK children ranging from two to 12 years in Surface ablation for LASIK enhancement beyond the range that can be corrected procedures have been performed, but if age. Five of the children had unilateral offers the theoretical advantage that it with either modality on its own, and eyes you look at the literature on paediatrics, amblyopia pre-operatively. One had leaves the residual stromal bed that require enhancement but are not more than 1,000 have been done in all bilateral high myopia.Their mean pre- untouched, but the inherent limitations of unsuitable for further corneal ablations. the publications to date,” Dr O’Keefe operative spherical equivalent was -10 D such procedures make their results said. and ranged from -5.00 D to -16.0 D and unpredictable, Dr Epstein said. Results not as good as when used in Paediatric patients present the their pre-operative visual acuity ranged He noted that enhancement procedures primary procedures refractive surgeon with a number of from hand movements to 6/18. are performed in around 5-15% of LASIK- special considerations compared to adult treated eyes and there is a wealth of Dr Neuhann said, in his experience, ICL Symposium Report

Emanuel Rosen Tobias Neuhann Michael O’Keefe Dan Epstein Mark Wevill Wayne Crewe-Brown Jack Holladay

information regarding the outcome of “PTK is another matter, but the within the range is more important than unhappy with their vision.The concept of repeat LASIK procedures. However, only principal guideline I would offer is to stay remaining in the range, he added. 20/20 versus ‘20/happy’ is very real.There one peer-reviewed paper has been away from using PRK after LASIK.” Factors that can alter the temperature is a group of unhappy patients out there published on surface ablations for LASIK and humidity of the operating who we are starting to make happy again enhancement and that study’s results were Treating hyperopic overshoot environment include additional people in and I think it is important that all of us far from optimal, he said. Mark Wevill FRCSEd, Manchester, UK, told the room.Addition of a laser plume are aware of what can be achieved with The study involved 17 patients who had the symposium that hyperopic overshoot extractor and the presence of air wavefront technology.” a residual refractive error ranging from - after LASIK is a problem that can be conditioning blowing onto the ablation He noted that in a recent FDA clinical 1.5 D to -3.75 D six months after largely prevented by a consistent practice zone increases evaporation and causes trial, wavefront-guided primary LASIK undergoing LASIK to correct myopia style and that, should it occur, there are a drying of the stromal bed. with the latest upgrade to the Ladarwave ® ranging from -8.1 D to -12.5 D.Their number of means to bring the patient to During surgery, stromal bed CustomCornea treatment system residual stroma ranged in depth from 255- the desired refraction. dehydration can also result from the flap reduced total higher aberrations in 38% 305µm and the intended thickness of the In young patients, a slight hyperopic being lifted for too long.The risk is and spherical aberrations in 45%. flap was 160µm.All underwent PRK to overshoot will not necessarily be a greatest with large refractive corrections maximum depth of 60µm. problem. Such individuals generally have a and large optical zones. Surgeons should While initial results were excellent, by good accommodative amplitude, and their also make sure that the time from “The concept of 20/20 three to six months postoperatively 14 residual hyperopia can help compensate opening the flap to starting ablation is as eyes developed grade 3-4 haze. In for the effects of a progressive myopia. consistent as possible and should versus ‘20/happy’ is very addition, in some eyes there was minimise steps that need to be taken once regression of up to -5.5 D. the flap has been opened. real. There is a group of The remaining evidence regarding Treatment of overcorrection involves enhancement of post-LASIK residual “The hyperopic overshoot first ruling out other factors such as striae unhappy patients out there refractive errors with PRK is anecdotal and higher order aberrations (HOAs). and inconclusive. occurs because of Striae should be treated as early as who we are starting to “The anecdotal impressions I have from possible with such techniques as hydrating colleagues who have used PRK after increased evaporation of the flap, lifting the flap or stripping the make happy again and I LASIK are that it works or it sometimes epithelium. Later treatments include lifting works; or that it doesn’t work and it’s fluid from the stromal bed and suturing or heating and smoothing. think it is important that all dangerous, or I don’t know.” HOAs can imitate a simple hyperopic where the ablation is done. overcorrection and the equivalent of us are aware of what Flap thickness unpredictable Then a higher proportion refraction of the eye is affected by the can be achieved with The risks of surface ablations after LASIK pupil diameter. HOA-related “hyperopia” may largely derive from the of corneal tissue relative to is best treated with a wavefront wavefront technology” unpredictability of the thickness of the retreatment, but such procedures require epithelium and the stroma of the flap, Dr fluid is ablated” good-quality raw data, good registration, Wayne Crewe-Brown, MB ChB M.Med (Ophth) Epstein noted.An underestimation of the Mark Wevill FRCSEd tracking and patient cooperation, he flap thickness can lead to perforation of emphasised. In addition, he and his associates the flap, which can in turn lead to Hyperopic overshoots present more of Pharmacological approaches are achieved even better results in their own epithelial ingrowth and DLK, he added. a problem in older patients, where controversial or unproven but include series of 33 patients, in whom 45% had In addition, for significant enhancement, accommodation is poor and such early cessation of steroids to induce reduction in their total HOAs and 61% had a substantial amount of stroma needs to problems as poor reading vision and other regression and the application of tightly reduction in their spherical aberrations. be ablated.The epithelium may be as thick near vision tasks are likely to occur, Dr fitting, extended-wear contact lenses in Dr Crewe-Brown said that they have as 80µm, while the rest of the flap may be Wevill pointed out. combination with topical ketorolac achieved similar results in eyes that as thin as 20-30µm, which may not be tromethamine 0.5% (Acular), Dr Wevill underwent wavefront-guided sufficient for the targeted correction, he Avoiding stromal dehydration said. enhancements. He noted that although When performing repeat LASIK, re- there was not always improvement in visual pointed out. Prevention of the complication involves lifting the original flap is generally better acuity, particularly in those cases that were ensuring a consistent surgical style and than cutting a new one, even years after a 20/20 already, patients consistently operating environment. Such measures will “PTK is another matter, primary procedure, he noted. However, reported an improvement in visual help prevent stromal dehydration, which is there are cases where cutting a new flap function. but the principal guideline one of the main causes of hyperopic is preferable.They include original flaps overcorrection. that have an edge in the conjunctival Case examples I would offer is to stay “The hyperopic overshoot occurs vascular arcade or flaps that are too small because of increased evaporation of fluid As examples of the kinds of improvement for a wavefront or hyperopic treatment away from using PRK after from the stromal bed where the ablation that can be achieved with wavefront-guided with large blend zones, he added. is done.Then a higher proportion of enhancements, Dr Crewe-Brown presented LASIK” corneal tissue relative to fluid is ablated,” details of two patients who underwent Dan Epstein MD, PhD Wavefront enhancements he explained. repeat LASIK with the CustomCornea In contrast to PRK, phototherapeutic In the operating theatre it is important Wayne Crewe-Brown, MB ChB M.Med system. keratectomy (PTK) is a surface ablation to have consistent temperature and (Ophth), Manchester, UK, told the The first patient was a young woman procedure that may be considered in eyes humidity, Dr Wevill stressed. Higher symposium that it is now virtually beyond who had good visual acuity (6/6-1) and that have undergone LASIK. It may be a ambient temperatures or lower humidity doubt that wavefront-guided enhancement fairly good refractive results +0.50/-0.75x5 useful option for indications where only a will result in increased evaporation and surgery can improve visual function even in one eye after primary LASIK. However, small amount of tissue needs to be drying of the stromal bed.The range of in eyes that have had good refractive and her total aberration RMS was 1.81. removed, for example, in eyes that require temperature and humidity advised by laser visual acuity results following conventional Wavefront-guided retreatment left visual reduction of post-LASIK spherical manufacturers can be quite broad (e.g. 15 LASIK. acuity unchanged, improved the refraction aberration. – 27 °C, and 35-65% humidity). Constancy “We have all seen patients who have to +0.00/0.25x73 and reduced the total what look like good results but are aberrations RMS to 0.74. Symposium Report

Another patient was undercorrected Texas, US, told the symposium that true He noted that laser ablations could be patient than is the case in the normal (-2.0 D/-0.25Dx8) and required customised ablation, whether for initial used to treat all of the aberrations of the human eye, in order to compensate for correction to achieve a visual acuity of treatments or retreatments, requires cornea, but only the spherical aberration the decreasing negative spherical 6/6. Moreover, he had total aberration customised diagnostics, customised laser of the crystalline lens.Treating crystalline aberration of the crystalline lens with age. RMS of 4.65 and experienced significant calibration and eye tracking and a lens aberrations beyond that will result in In a young patient, a slightly more prolate night vision problems as a result.After customised optical outcome. initially very good results, but the cornea can help anticipate changes that wavefront-guided enhancement refraction “Today custom ablation is the topic in aberrations will return over time. will take place in the crystalline lens later improved to -0.25 D /-0.25 D x70, excimer refractive surgery.The key to The reference axis of topographers, in life, he added. uncorrected visual acuity was 6/6 and the successful custom ablation is excellent keratometers, refractors and the total aberration RMS was reduced to diagnostic data for obvious reasons. But it aberrometers is the visual axis (near [email protected] 0.88. is only the first step and any induction of vertex normal). Since all the [email protected] aberrations during the preparing surgical measurements are referenced to this axis, [email protected] procedure or the laser ablation itself ideal centre for treatment should be the [email protected] “We did patient needs to be carefully avoided.” visual axis also, Dr Holladay said. Pupil- [email protected] Integration of topography and centred treatments will induce coma and [email protected] questionnaires and the aberrometry is necessary to determine tilt, he added. In addition, iris registration where in the eye an aberration occurs, the should become standard in eye trackers message of ‘20/happy’ cornea or the lens, and to detect certain because they can track both the rotational irregular features, such as central islands and translational movements of the eye. came through loud and following a LASIK ablation, that are invisible to aberrometry. Customised radial compensation clear. This has also been “Knowing the source of aberration can The calibration of the laser’s radial be essential for custom ablation. Corneal compensation function may also need to backed up by patients I and ocular aberrometry should ideally be be customised.The fall-off of radial energy have treated on the VISX integrated in one unit, measuring on the is not symmetrical in each eye and the same axis, in order to produce meaningful radial compensation of the left eye will platform and will be the internal aberration data.” generally need to be approximately the mirror image of the right eye. Radial subject of a future compensation will also need to be “Most companies now different for steep eyes than it is for flat presentation” eyes, he continued. have built-in radial energy “An individual compensation matrix will Wayne Crewe-Brown, MB ChB M.Med (Ophth) have to be used. If not corrected, compensation but there peripheral loss of ablation efficacy will “What came through when talking with may not be a ‘one size fits most likely induce spherical, coma and these patients was that there was so much other HOAs. Most companies now have improvement in their quality of vision.We all’ compensation matrix built-in radial energy compensation but did patient questionnaires and the message there may not be a ‘one size fits all’ of ‘20/happy’ came through loud and clear. and more sophisticated compensation matrix and more This has also been backed up by patients I sophisticated algorithms must be have treated on the VISX platform and will algorithms must be developed.” be the subject of a future presentation.” Finally, the optimal degree of asphericity developed” may differ between patients, Dr Holladay True customised ablation said. For example, the ideal postoperative Jack T Holladay, MD, MSEE, FACS, Houston, Q-value might be more prolate in an older

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