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Author Federico Augustovski |
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Analisis de Frentes de Onda en la Cirurgia Refractiva / Federico Augustovski / Buenos Aires [Argentina] : Instituto de Efectividad Clínica y Sanitaria (IECS) (2006)
Analisis de Frentes de Onda en la Cirurgia Refractiva = Wavefront analysis in refractive surgery [printed text] / Federico Augustovski, Editor ; Andrés Pichon Riviere, Editor . - Buenos Aires [Argentina] : Instituto de Efectividad Clínica y Sanitaria (IECS), 2006 . - 23 p.. - (Documentos de Evaluación de Tecnologías Sanitarias. Informe de Respuesta Rápida, ISSN 1668-2793; 68) .
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Languages : Spanish (spa)
Descriptors: Classification
WW 340 Refractive Surgery
Indexation
Diagnostic Techniques, Ophthalmological ; Refractive Errors ; Vision DisordersAbstract: Clinical setting
Approximately one third of the population has a refractive defect requiring correction. Refractive surgery may be defined as those surgical methods used to eliminate or attenuate refractive defects of the eye. The use of excimer laser on the cornea usually aims at correcting spherical, cylindrical or axial defects which are lower order optical aberrations (myopia, hyperopia and astigmatism). For years now, research has been done on the possibility to detect higher-order optical aberrations (coma, spherical aberration, triangular astigmatism, three-leaf clover, etc.) and to try to correct them. These aberrations are usually responsible for 17 to 20% of total refractive defects of the eye. Wave front guided corneal ablation is intended to personalize surgical correction of optical aberrations detected by the use of an aberrometer, a tool used to analyze the wave front.
Technology description
The wave front is a way the light propagates through the optical system. Wave aberration is defined as the difference between perfect (spherical) wave fronts and real wave fronts at each point in the pupil. The aberrometer is a tool used to assess these aberrations. The information obtained with the aberrometer is exported to the excimer laser operating system and is used to guide shooting and therapeutic sculpting. The cost of the procedure in our country is approximately $3,000 (argentine pesos).
Purpose
The purpose of this report is to assess the usefulness of wave front analysis in the diagnosis and management of refractive defects.
Methods
A search was started on the main literature databases (MEDLINE, Cochrane, DARE, LILACS, NHS NICE, EMBASE, Centre for Reviews and Dissemination, York University), on the Internet’s general search engines, health technology assessment agencies and health sponsors as well as in repositories of clinical practice guidelines and several institution coverage policies.
Main results
The simplest and safest way to correct refractive defects is by prescribing eye glasses or contact lenses. Refractive surgery is an alternative method intended to provide better comfort to the patient while avoiding the use of external optical tools, but the correction achieved does not exceed and, in many cases, is lower than that provided by eye glasses and lenses. That is why refractive surgical procedures are not considered medically necessary by many world health organizations. When deciding on refractive surgery, there are several techniques and, basically, there is no evidence coming from prospective randomized trials that one technique is better than the other. The most widely used is LASIK and with the coming up of wave front analysis technology, LASIK may be personalized by using aberrometer guidance. In 2002, Nuijts et al conducted a randomized prospective trial with 12 patients, comparing conventional LASIK versus wave front guided LASIK for the correction of low to moderate myopia after 6 months. Both methods showed an excellent safety rate. With front wave guided LASIK ablation depth was significantly lower, though the efficacy rate was slightly lower as compared to conventional LASIK. In 2003, Phusitphoykai et al compared conventional versus wave front guided LASIK. Twenty short-sighted eyes (10 patients) were randomized to undergo wave front guided ablation in the first eye and conventional ablation in the other. They concluded that the visual result with both procedures was not significantly different. Other studies compared the wave front with the conventional methods as regards induction of post surgical aberrations showing that, in general, a smaller number of higher order aberrations were found with personalized ablation methods. In terms of visual acuity, patient preferences and contrast sensitivity, personalized ablation sometimes resulted in slightly but not statistically significant better results. Several studies showed that the reproducibility of the measurement of higher-order aberrations was low thus restricting result interpretation.
Conclusions
The added value of higher order aberration correction using wave front guided surgical methods is difficult to assess as regards their clinical impact. Even though it is still necessary to keep doing research on this new technology, it is possible that a selected subgroup of patients had more benefits with this technique: Patients with high rate of refractive defect due to these higher order aberrations, retreatment of already operated patients presenting persisting symptoms attributable to higher order aberrations detected on aberrometry or those patients requiring visual acuities or contrast sensitivity higher than normal, either due to their occupation or to a significant individual sensitivity.Link for e-copy: https://ecommunities.belgium.be/ecomswitch/start/Technology_Evaluation_Center_As [...] Format of e-copy: Record link: https://kce.docressources.info/index.php?lvl=notice_display&id=771 Copies(0)
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