Astigmatismo y cirugía de catarata / Astigmatism and cataract surgery

RESUMEN La catarata es la primera causa de ceguera curable en el mundo y se produce por la opacidad del cristalino, con una disminución gradual, lenta y progresiva de la agudeza visual. La cirugía para extraer el cristalino es la única forma de curar esta discapacidad visual. La facoemulsificación ha evolucionado con el fin de lograr su perfección y el objetivo de restablecer la visión de los pacientes con la mayor calidad y cantidad en el menor tiempo posible. El desarrollo científico ha estado encaminado a controlar o eliminar el astigmatismo preoperatorio o inducido por la cirugía, y para esto se ha incluido en la actualidad el empleo de los lentes intraoculares trifocales flexibles tóricos y las incisiones menores a dos milímetros en la córnea clara, así como las incisiones relajantes limbares, las incisiones opuestas en la córnea clara, la cirugía refractiva fotoablativa y el láser de femtosegundo. Para lograr un resultado refractivo en la cirugía de catarata es imprescindible minimizar al máximo el astigmatismo inducido por el procedimiento. Este éxito se logra con un estudio personalizado preoperatorio exhaustivo, que permita satisfacer las necesidades visuales del paciente y su reincorporación temprana a sus tareas. De ahí la motivación para realizar una búsqueda de los últimos diez años de diversos artículos publicados, con el objetivo de describir los principios para evaluar el astigmatismo medio inducido posterior a la cirugía del cristalino, y su repercusión en la calidad visual y de vida de los pacientes. Se utilizó la plataforma google, específicamente la Biblioteca Virtual de Salud, con todos sus buscadores(AU)

ABSTRACT Cataract is the leading cause of curable blindness worldwide. It results from opacity of the crystalline lens with gradual, slow and progressive visual acuity reduction. Surgery for removal of the crystalline lens is the only cure for this visual impairment. Phacoemulsification technique has evolved to achieve perfection and the aim of restoring patients' vision with the greatest quality and quantity in the shortest possible time. Scientific development has been aimed at either controlling or eliminating preoperative or surgically induced astigmatism. To achieve this aim, recent inclusion has been made of the use of flexible toric trifocal intraocular lenses and minor incisions at two millimeters in the clear cornea, as well as limbal relaxing incisions, opposite incisions in the clear cornea, photoablative refractive surgery and femtosecond laser. To obtain a good refractive result in cataract surgery it is indispensable to minimize the astigmatism induced by the procedure. Such success is accomplished through an exhaustive personalized preoperative study allowing to meet the visual needs of patients and their early reincorporation to daily activities. Hence the motivation to conduct a search of a variety of papers published in the last ten years with the purpose of describing the principles applied to evaluate mean induced astigmatism after crystalline lens surgery and its effect on the patients' visual acuity and quality of life. Use was made of the Google platform, particularly the Virtual Health Library with all its search engines(AU)

Comparative evaluation of two toric intraocular lenses for correcting astigmatism in patients undergoing phacoemulsification

Purpose: To compare the efficacy of AT-TORBI plate haptic toric intraocular lens (IOL) (Carl Zeiss Meditec AG, Jena, Germany) and AcrySof loop haptic toric IOL (Alcon Laboratories, Inc., Fort Worth, TX, USA) for correcting preexisting astigmatism of ?1 diopters (D) in patients undergoing phacoemulsification and to compare the rotational stability of these two toric IOLs. Methods: In this prospective randomized controlled trial. Forty-two eyes of 42 cataract patients with preexisting astigmatism of 1 D or more were randomized to receive plate haptic toric (AT TORBI) or loop haptic toric (AcrySof) IOLs, with 21 in each group. Postoperative evaluation was done at day 1, 1 week, 1 month, and 3 months. Uncorrected distance visual acuity (UDVA), best corrected visual acuity (VA), and IOL position were noted in both the groups. Results: At 3 months postoperatively, the mean log MAR UDVA was 0.23 ± 0.20 and 0.20 ± 0.13 in Groups I and II, respectively (P = 0.7), the mean residual cylindrical refractive error in plate haptic toric group was 0.40 ± 0.31 D and in loop haptic group was 0.45 ± 0.33 D (P = 0.64). The mean IOL rotation at 3 months follow-up in plate haptic group was found to be 3.52 ± 3.84° and in loop haptic group was 2.05 ± 2.56° (P = 0.25). Conclusion: Both types of toric IOLs were equally efficacious for attaining good uncorrected VA and correcting preexisting astigmatism between 1–5 D. Both of them were rotationally stable at 3 months follow-up.

Diagnóstico y control del astigmatismo en la cirugía del cristalino / Diagnosis and control of astigmatism in the crystalline surgery

Se realizó una revisión bibliográfica con el objetivo de conocer las opciones quirúrgicas para la corrección del astigmatismo preoperatorio y posoperatorio en la cirugía de catarata. Fueron abordados tópicos como los estudios preoperatorios detallados que nos permiten realizar una planificación quirúrgica personalizada, así como las diferentes soluciones quirúrgicas actuales, tanto las incisiones anastigmáticas en la facoemulsificación, como las incisiones relajantes limbares combinadas o no con las lentes intraoculares tóricas y los procederes con excímer láser. Se consultaron investigaciones que abarcan varios años hasta el presente para conocer los diferentes resultados de la utilización de estos procederes quirúrgicos hasta llegar a técnicas más novedosas en estudio como el láser femtosecond y las lentes intraoculares ajustables con la luz. Todo esto puede maximizar la corrección refractiva total y lograr en el paciente una óptima calidad visual y una mejor calidad de vida. La corrección refractiva total no es fácil de lograr; no obstante, es posible y debe ser la meta de cada cirujano de catarata(AU)

The present literature review was aimed at finding out the surgical options for the preoperative and postoperative correction of astigmatism in the cataract surgery. The addressed topics were detailed preoperative studies that allow customized surgical planning as well as several current solutions including anartigmatic incisions in phacoemulsification and relaxing limbal incisions either combined or not and Excimer laser procedures. Several research studies comprising various years up to the present were consulted to learn about different results from the use of these surgical methods as well as the most state-of-the-art techniques under study such as fentosecond laser and light-adjustable intraocular lenses. All this may maximize the total refractive correction and achieve optimal visual quality and better quality of life for the patient. It is not easy to reach complete refractive correction but it is possible and should be the goal to be accomplished by every cataract surgeon(AU)

Surgical management of astigmatism with toric intraocular lenses / Uso de lentes intraoculares tóricas no tratamento cirúrgico de astigmatismo

Correction of corneal astigmatism is a key element of cataract surgery, since post-surgical residual astigmatism can compromise the patient's uncorrected visual acuity. Toric intraocular lenses (IOLs) compensate for corneal astigmatism at the time of surgery, correcting ocular astigmatism. They are a predictable treatment. However, accurate measurement of corneal astigmatism is mandatory for choosing the correct toric IOL power and for planning optimal alignment. When calculating the power of toric IOLs, it is important to consider anterior and posterior corneal astigmatism, along with the surgically induced astigmatism. Accurate toric lens alignment along the calculated meridian is also crucial to achieve effective astigmatism correction. There are several techniques to guide IOL alignment, including the traditional manual marking technique and automated systems based on anatomic and topographic landmarks. The aim of this review is to provide an overview on astigmatism management with toric IOLs, including relevant patient selection criteria, corneal astigmatism measurement, toric IOL power calculation, toric IOL alignment, clinical outcomes and complications.

O tratamento do astigmatismo corneal é um fator importante na cirurgia de catarata, uma vez que o astigmatismo residual pode comprometer a acuidade visual não corrigida do paciente após a cirurgia. Lentes intraoculares (LIOs) tóricas compensam o astigmatismo corneal no momento da cirurgia, corrigindo o astigmatismo ocular. Ademais, constituem um tratamento previsível. Entretanto, é necessário obter uma medida precisa do astigmatismo corneal para selecionar o poder correto da LIO tórica e para planejar o melhor alinhamento da mesma. No cálculo do poder da LIO tórica, é importante considerar o astigmatismo das superfícies anterior e posterior da córnea, além do astigmatismo induzido na cirurgia. O alinhamento da lente tórica no meridiano planejado é essencial para se obter uma correção efetiva do astigmatismo. Há várias técnicas para guiar o alinhamento da LIO, incluindo a técnica de marcação manual tradicional e sistemas que se baseiam em pontos de referência anatômicos e topográficos. O objetivo desse artigo de revisão é discutir o uso de LIOs tóricas no tratamento de astigmatismo corneal, incluindo os critérios de seleção dos pacientes, a medida do astigmatismo corneal, o cálculo do poder da LIO tórica, o alinhamento da LIO tórica, os resultados clínicos e as complicações.

Which Keratometer is Most Reliable for Correcting Astigmatism with Toric Intraocular Lenses?

PURPOSE: To evaluate the accuracy of preoperative keratometers used in cataract surgery with toric intraocular lens (IOL). METHODS: Twenty-five eyes received an AcrySof toric IOL implantation. Four different keratometric methods, a manual keratometer, an IOL master, a Pentacam and an auto keratometer, were performed preoperatively in order to evaluate preexisting corneal astigmatism. Differences between the true residual astigmatism and the anticipated residual astigmatism (keratometric error) were compared at one and three months after surgery by using a separate vector analysis to identify the keratometric method that provided the highest accuracy for astigmatism control. RESULTS: The mean keratomeric error was 0.52 diopters (0.17-1.17) for the manual keratometer, 0.62 (0-1.31) for the IOL master, 0.69 (0.08-1.92) for the Pentacam, and 0.59 (0.08-0.94) for the auto keratometer. The manual keratometer was the most accurate, although there was no significant difference between the keratometers (p > 0.05). All of the keratometers achieved an average keratometric error of less than one diopter. CONCLUSIONS: Manual keratometry was the most accurate of the four methods evaluated, although the other techniques were equally satisfactory in determining corneal astigmatism.