Corrección del queratocono con microlentes de alta excentricidad / Correction of keratoconus with highly eccentric microlenses

La adaptación de lentes de contacto en queratocono avanzado se torna compleja por la gran excentricidad de la zona apical. El lente de contacto rígido de diámetro pequeño con curva posterior parabólica o hiperbólica (diseño de alta excentricidad) es una excelente opción para el queratocono con ectasias de diámetro pequeño y alta elevación. Permite proteger la zona apical del cono y hace confortable la adaptación del lente en pacientes que aún no justifican una queratoplastia. El objetivo de este trabajo es mostrar cómo una adecuada adaptación permite retrasar o evitar una cirugía de alta complejidad para el paciente(AU)

The adaptation of contact lenses to treat advanced keratoconus is complex due to the great eccentricity of the apical area. The small diameter rigid contact lenses with parabolic or hyperbolic posterior curve (high eccentricity design) are an excellent choice for keratoconus with small diameter and highly elevated ectasias. It allows protecting the apical area of the cone and makes the adaptation of the lens more comfortable in those patients who do not require keratoplasty yet. The objective of this work is to show how an appropriate adaptation allows to retard or to avoid a surgery of high complexity for the patient(AU)

Alteraciones corneales en pacientes diabéticos / Corneal alterations in diabetic patients

La diabetes mellitus, afección frecuente a nivel mundial, tiene gran impacto en la sociedad no solo por su alta prevalencia, sino por sus complicaciones crónicas y su alta mortalidad. Afecta a unos 180 millones de personas en el mundo. La prevalencia de la diabetes (tipos I y II) se estima en el 13 % en pacientes mayores de 60 años. La estructura corneal sufre modificaciones en los pacientes diabéticos; la hiperglucemia afecta la hidratación de la córnea, y con esto varía el espesor corneal y aparecen cambios queratométricos visibles mediante topografía corneal. Las córneas de los pacientes con diabetes presentan alteraciones epiteliales, estromales y endoteliales. Además, existe una disminución de la permeabilidad endotelial durante la fase de hipoxia, que relacionan estos efectos de la diabetes en las células endoteliales. El objetivo de nuestro estudio es abordar las diferentes alteraciones corneales en los pacientes diabéticos(AU)

Diabetes Mellitus, a frequent disease worldwide, has a great impact on the society, not only for their high prevalence, but for their chronic complications and high mortality. It has an effect on 180 million people approximately in the world. The prevalence of diabetes (type I and II) is estimated to be 13 % in patients older than 60 years. The corneal structure undergoes changes in diabetic patients; the hyperglycemia affects the corneal hydration and causes variations in the corneal thickness, with occurrence of visible keratometric changes detected in the corneal topography. The corneas of diabetic patients show epithelial, stromal and endothelial alterations. Additionally, there is decrease in endothelial permeability during the phase of hypoxia that relate these effects of diabetes in the endothelial cells. The objective of our study was to deal with the different corneal alterations in diabetic patients(AU)

Visual acuity and corneal topography stability after 5 years of laser-assisted in-situ keratomileusis

Corneal topographic analysis has been established as an invaluable tool for the refractive surgeon. The use of corneal topography in assessment of corneal surface has tremendously advanced the development and evaluation of refractive surgeries. The analysis of corneal topography permits the recognition of normal and abnormal patterns of ablation, documentation of decentrations following Laser-Assisted In-Situ Keratomileusis [LASIK] surgery and also allows the refractive surgeon to quantify irregularities of corneal surface. Despite numerous follow-up studies on incidence of refractive regression and other complications after LASIK ablation, little attention has been paid to the long-term effect of LASIK surgery on corneal surface remolding and the consequential effects on the stability of vision. To evaluate the postoperative corneal changes on patients at the risk, after 5 years of undergoing LASIK surgery. Also, we tried to assess the stability of vision within this period to determine if there was a significant topographic pattern changes. Methods: Subdividing our subjects [40 eyes] to three groups of risk factors depending on their corneal topographic patterns. Mean age of subjects were 32.3 +/- 5.5 years [range: 23 to 41 years] with a spherical equivalent manifest refraction [SEMR] ranging from -1.75 D to -13.75 D and a manifest refractive cylinder of less than 4.00D. Intended ablation depth ranged from 26.5 to 107.7 microns and the retrospective pachymetry value of 501 and 607m. There was a 100% improvement [p = 0.0001] in visual acuity in the groups with steep cornea and asymmetric bow tie, and a 60% improvement [p = 0.0001] in the inferior steepening cornea group. Also, there was a change in topographic pattern of each group with normal patterns being only associated with Steep Cornea and Asymmetric Bow tie groups while corneal ecstasies were observed in 3 eyes belonging to the inferior steepening group. Decreased thickness of residual Stroma, depth and width of ablation, older ages, increased myopic correction and abnormal corneal topography are some predisposing factors to unstable vision after LASIK correction. A significant change in VA and corneal topography were returned on assessment

Pterígio e alterações da curvatura corneana / Pterygium and corneal curvature changes

Objetivo: Avaliar as mudanças de curvatura corneana ocorridas após a exérese do pterígio (Pt). Métodos: Foi realizado estudo prospectivo em 49 olhos com Pt primário avaliando-se idade, sexo, tamanho [grau (G)1, GII, GIII e GIV] e a morfologia da lesão (atrófica ou carnosa) à biomicroscopia. Todos os pacientes foram submetidos ao exame de videoceratoscopia computadorizada e ceratometria no pré-operatório (pré-op), e no 30e 60 dias após a cirurgia. Os dados foram submetidos à análise estatística. Resultados: 63 por cento dos indivíduos avaliados eram do sexo masculino e 80 por cento tinham mais de 41 anos. Houve predomínio dos Pt atróficos (77 por cento), GII e GIII (39 por cento e 28 por cento, respectivamente). Observou-se manutenção do astigmatismo (Astg) presente no pré-operatório no Segundo mês pós-operatório (PO), principalmente nos portadores de Pt GI e GIL A variação no valor de K do primeiro mês para o segundo mês de PO foi pequena. As variações observadas estiveram mais relacionadas com o tamanho do pterígio, do que com a idade do paciente, ou com as suas características morfológicas. Conclusões: A avaliação ceratométrica e topográfica da córnea em portadores de pterígio no pré e no pós-operatório mostrou, que os Pt menores, (GI e GII) estão associados com graus menores dé astigmátismo e no pós-operatório a córnea sofre menos mudanças que nos GIII e GIV+ Após 2 meses da cirurgia, o padrão da curvatura corneana é semelhante ao do pré-operatório, na maioria dos pacientes.