Keratoconic Cone using its Keratometry, Decentration, and Thickness as Staging Parameters

Abstract

Aim: To propose a new system of keratoconus staging using a set of parameters describing the keratoconic cone. Materials and methods: Retrospective case series study of 101 keratoconic eyes of 58 patients was undertaken. They all had complete eye examination including corneal topography (Oculus Pentacam). K mean , K max , higher order aberrations (HOAs) root mean square (HOARMS) value, pachymetry at thinnest point and steepest corneal meridian were obtained from Pentacam. Apex to thinnest pachymetry distance (D) was calculated using trigonometry. Pearson correlation coefficients between K max and HOARMS, between D on the one hand and the adjusted angle of steepest meridian, K mean and K max respectively on the other, were calculated. Results: There is a statistically significant positive correlation between K max and HOARMS (p < 0.00001). There is a negative correlation, a "horizontalization," of the steep meridian with D increase, although it fell short of statistical significance (p = 0.07). D and K mean (p = 0.003), and D and K max (p = 0.005) are significantly negatively correlated. Conclusion: K max correlates with significant changes in HOAs. D correlates with corneal astigmatic meridian change and has a divergent path to K mean and to K max. We propose a new keratometry, decentration, and thinnest pachymetry staging using the parameters K max (K), distance from the corneal apex to the thinnest pachymetry point (D), and corneal thickness at its thinnest point (T) to give a better, detailed description of a keratoconic cornea which could lead to improvements in assessment of its severity and treatment outcomes.

Characteristics and clinical outcomes of patients diagnosed with keratocone

“…(2) Em relação à classificação dos pacientes quanto à gravidade da doença, o Consenso Global de Ceratocone e Doenças Ectásicas de 2015 (2) colocou esta questão em pauta e concluiu que não haveria um sistema de classificação clínica adequado para a doença e, de fato, a sua classificação sofre bastante variabilidade entre os estudos. (9,28,29) Este trabalho optou por acessar a gravidade dos casos estudados a partir do critério proposto pelo estudo CLEK, (10) que utilizou um dado ceratométrico, especificamente o Ks (ceratometria mais curva -steep keratometry), para classificar os casos em leves, moderados e graves. Os resultados mostraram uma tendência considerável em direção ao encontro de casos considerados graves, 157 (58,80%), propensão esta também encontrada e já esperada pelo estudo CLEK (10) ao se optar pelo Ks como parâmetro.…”