Orthokeratology on patient with ectasic cornea / Ortoceratologia no paciente com córnea ectásica

Abstract A 26-year-old man, single, business student, reveals a ectasic cornea during corneal topography exam. Among some procedures, the patient chose Orthokeratology to do a corneal reshape and got successfully a good visual acuity, going against the most authors guidance.

Resumo Estudante de 26 anos, masculino, estudante de economia, apresentou ao exame topográfico de córneas, ectasia corneal. Dentre todos os procedimentos apresentados, optou pela ortoceratologia para o remodelamento corneal, e obteve sucesso com melhora da acuidade visual, indo contra a orientação da maioria dos autores.

Principales métodos para el cálculo de la lente intraocular después de la cirugía refractiva corneal / Fundamental methods for calculation of intraocular lens after corneal refractive surgery

Con el surgimiento y el desarrollo de la cirugía refractiva corneal se han podido corregir quirúrgicamente a millones de pacientes con defectos refractivos. Con el cursar de los años comienza a opacarse fisiológicamente el cristalino, y disminuye la agudeza visual en estos pacientes a quienes se les modificó la curvatura corneal. Ante la necesidad de remover el cristalino y de calcular una lente intraocular de potencia adecuada para conseguir la emetropía, surge un nuevo reto a la Oftalmología. El cálculo de la lente intraocular en pacientes con cirugía refractiva corneal es mucho más complejo, pues además de tener longitudes axiales extremas, se añaden factores por la intervención previa que alteran la predictibilidad del resultado visual, con la aplicación de las fórmulas de cálculo de lente intraocular existentes. Se han descrito varios métodos que permiten determinar correctamente la potencia de la lente a implantar, dependiendo de los datos de los que se dispongan; de ahí la motivación para realizar una revisión de diferentes publicaciones con el propósito de describir los principales métodos empleados para realizar el cálculo de la lente intraocular en estos pacientes. Se utilizó la plataforma Infomed, específicamente la Biblioteca Virtual de Salud, con todos sus buscadores(AU)

With the emergence and development of the corneal refractive surgery, the refractive defects of millions of patients have been surgically corrected. As time goes by, the physiological opacification of the crystalline lens begins, thus reducing the visual acuity of those patients whose corneal curvature has been modified. Should the crystalline lens be modified and should the intraocular lens power be adequately calculated to achieve emetropia, ophthalmology faces then a new challenge. The intraocular lens calculation in patients with corneal refractive surgery is much more complex since, in addition to extreme axial lengths, there are factors derived from the previous surgery that alter predictability of the visual result, with the use of existing intraocular lens calculation formulae. Several methods have been so far described, which allow correctly determining the lens power to be implanted, depending on available data. This was the main reason for making a review of different publications to describe the main methods for intraocular lens calculation in these patients. Infomed platform, mainly the virtual library of health, was used with all its searchers(AU)

Effects of orthokeratology lenses on the magnitude of accommodative lag and accommodativeconvergence/accommodation / 中南大学学报(医学版)

OBJECTIVE@#To evaluate the change in accommodative lag and accommodation convergence/accommodation (AC/A) after patients with myopia wear orthokeratology lenses. 
@*METHODS@#A total of 48 myopic subjects (a test group), who wore orthokeratology lenses regularly, and 48 myopic subjects (a control group), who wore spectacles regularly, were enrolled for this study from January 2011 to January 2013 in Optometric Center, the Forth Hospital of Changsha. Accommodative lag was measured by fused cross cylinder method, where the patients should gaze at the front optotypes 40 cm away. Gradient of the AC/A ratio was measured by Von Grafe method to check closer distance heterophoria. Accommodative lag and AC/A ratio were analyzed by statistics.
@*RESULTS@#After 1-year follow-up, accommodative lag and AC/A rate in patients with low or moderate myopia in the test group was decreased in 1, 3, 6 months or 1 year compared with that in the control group (P<0.05). 
@*CONCLUSION@#Compared with spectacles, orthokeratology lenses are able to decrease accommodative lag and high AC/A rate in patients with low or moderate myopia. The relationship between accommodation and convergence is improved by orthokeratology lenses. Orthokeratology is an effective way to control myopia.

Effectiveness of Toric Orthokeratology in the Treatment of Patients with Combined Myopia and Astigmatism

PURPOSE: The purpose of this multi-institute, single-group clinical trial was to evaluate the effectiveness and safety of toric orthokeratology lenses for the treatment of patients with combined myopia and astigmatism. METHODS: A total of 44 patients were included in this clinical trial. The patients ranged in age from 7 to 49 years, with myopia of -0.75 to -6.0 diopters (D) and astigmatism of 1.25 to 4.0 D. After excluding 21 subjects, 23 subjects (39 eyes) were analyzed after toric orthokeratology lens use. The subjects underwent ophthalmologic examination after 1 day and 1, 2, 3, and 4 weeks of wearing overnight toric orthokeratology lenses. RESULTS: A total of 19 subjects (31 eyes) completed the trial after five subjects (eight eyes) dropped out. In the patients who completed the study by wearing lenses for 4 weeks, the myopic refractive error decreased significantly by 2.60 ± 2.21 D (p < 0.001), from -3.65 ± 1.62 to -1.05 ± 1.64 D. The astigmatic refractive error were also significantly decreased by 0.63 ± 0.98 D (p = 0.001), from 2.07 ± 0.83 to 1.44 ± 0.99 D. The mean uncorrected and corrected visual acuities before wearing the lenses were 2.14 ± 0.80 logarithm of the logMAR (logMAR) and 0.05 ± 0.13 logMAR, respectively, which changed to 0.12 ± 0.30 logarithm of the logMAR (p < 0.001) and 0.01 ± 0.04 logMAR (p = 0.156) after 4 weeks. No serious adverse reactions were reported during the clinical trial. CONCLUSIONS: Our results suggest that toric orthokeratology is an effective and safe treatment for correcting visual acuity in patients with combined myopia and astigmatism.

Novos conceitos em modelamento corneano: [revisão] / New concepts in corneal reshaping: [review]

A córnea possui grande influência no processo visual. Porém é passível de deformação, tal como o aplanamento. Quando esse aplanamento é causado pelo uso de lentes de contato, chamamos de "corneal warpage". Neste caso, alguns sintomas podem ocorrer como visão embaçada com os óculos, hiperemia conjuntival, sensação de corpo estranho, etc. Pensava-se que a córnea era mais rígida e, com o tempo, percebeu-se que a córnea possui entidade viscoelástica. Podemos dizer que a córnea possui uma entidade biomecânica e que, quando sofre instabilidade, ocorrem algumas alterações, como no caso do ceratocone, onde ocorre uma degeneração progressiva corneana. Com o intuito de buscar a estabilização corneana, foi desenvolvida a técnica de "crosslink", que consiste em promover ligações covalentes entre as lamelas da córnea para torná-la mais firme e menos elástica. Outra alteração corneana pode ser induzida, de forma planejada, através do modelamento corneano com o uso de lentes de contato rígidas, com coeficiente de transmissibilidade de oxigênio (DK/L) maior. Elas são usadas somente durante o sono, não sendo necessário o seu uso diurno. Esta técnica é conhecida como Ortoceratologia e seus conceitos serão abordados neste estudo.

The cornea has a great influence in the visual process. However, it is liable to distortion, such as flattening. When this flattening is caused by the use of contact lenses, we call "corneal warpage". In this case, some symptoms may occur as blurred vision with glasses, conjunctival hyperemia, foreign body sensation, etcà Used to think that the cornea was more rigid and, in time, realized that the cornea has viscoelastic properties. We can say that the cornea has a body biomechanics property and suffers instability when there are some changes, such as keratoconus, which is a progressive corneal degeneration. In order to preserve the cornea more stable, the cross-linking technique was developed to promote covalent bonds between the lamellae of the cornea to make it stronger and less elastic. Other corneal change that may occur is based on the induction in corneal reshaping by using rigid contact lenses (only during sleeping) with high oxygen transmissibility (DK / L). This technique is known as Orthokeratology and its concepts will be addressed in this study.