Relevância da biomecânica da córnea no glaucoma

Abstract

RESUMORelato de caso de uma paciente, com córnea espessa, por distrofia de Fuchs em fase inicial, ainda com transparência corneana preservada (edema corneano subclínico), associado à pressão intraocular (PIO) normal por tonometria de aplanação de Goldman (TAG), que teve entretanto, o diagnóstico de glaucoma primário de ângulo aberto com base em alterações estruturais do nervo óptico. O estudo tomográfico demonstrou padrão de paquimetria espacial compatível com edema sub-clínico. O estudo biomecânico da córnea com o ORA (Ocular Response Analyzer, ® Reichert), associado à medida corrigida da PIO, possibilitou o entendimento da influência da córnea, que apesar de mais espessa, levava a uma TAG falsamente reduzida (hipoestimada). O estudo da PIO com sistema de tonografia digital de contorno (PASCAL) corroborou com os achados do ORA. Este exemplo ressalta a importância de novas tecnologias na avaliação de pacientes com suspeita de glaucoma, e destaca que a correção da TAG, com base em algoritmos lineares relacionados com a paquimetria central apenas, pode determinar sérios erros de interpretação clínica.Descritores: Córnea/fisiologia; Glaucoma; ORA; Distrofia endotelial de Fuchs; Tonometria ocular/métodos; Relatos de casos ABSTRACTCase report of a patient, with a thick cornea, for Fuchs dystrophy in its early stages, yet with preserved corneal transparency (subclinical corneal edema), associated with normal intraocular pressure (IOP) by Goldman applanation tonometry (GAT), which was however, the diagnosis of primary open-angle glaucoma on the basis of structural changes of the optic nerve. The tomographic study showed a pattern of spatial pachymetry compatible with subclinical edema. The corneal biomechanical study with ORA (Ocular Response Analyzer, Reichert ®) associated with corrected IOP measurement, allowed the understanding of the corneal influence, which, although thicker, leading to a falsely low TAG (underestimated). The IOP study with tonography system digital (PASCAL) corroborated with the findings of ORA. This example highlights the importance of new technologies in patients' evaluation with suspected glaucoma, and highlights that the correction of TAG, based on linear algorithms related to central corneal thickness alone, can determine serious errors in clinical interpretation.Keywords: Cornea/physiology; Glaucoma; ORA; Fuchs endothelial dystrophy; Tonometry, ocular/methods; Case reports

Corneal Biomechanics and Glaucoma

“…34,40,41 Also important to note that an increase in CCT caused by corneal edema is associated with a lower CH, stressing the importance of considering all parameters and not only CCT. 42 The sclera also plays a central role in the biomechanical effects of the eye, being an anatomic link between the cornea and lamina cribrosa. 43 Many studies are trying to investigate the central role of the sclera in glaucoma and its relationship with lamina cribrosa.…”

“…3 Corneal biomechanics also plays a significant role in managing patients with glaucoma. 5 First, evidence suggests a higher risk of glaucoma in patients with thin and stiffer corneas. [6][7][8] Second, corneal biomechanics affects and is affected by intraocular pressure (IOP).…”