2025年3月16日 · The corneal q value provides information about the asphericity of the cornea, which is the deviation of its shape from a perfect sphere. It is used to assess the optical quality of the cornea and can be indicative of conditions such as keratoconus, corneal ectasia, and post-refractive surgery complications.

2024年8月30日 · Corneal Q value is a commonly used term to characterise the asphericity of the cornea and is a critical parameter in describing the eye model. Researchers in the past have attempted to study the corneal Q values with respect to a number of different parameters such as age, gender and ethnicity.

2017年5月18日 · The results included the mean corneal Q values (mean ± SD) of the anterior and posterior surfaces at different aperture diameters, the Q value distributions of the anterior and posterior surfaces at large aperture (7.0mm diameter), and analysis of the relationship between the Q values and age, sex and refractive powers.

2020年4月20日 · Q-val: Describes the corneal shape factor, or eccentricity of the cornea. The ideal value is -0.26. More negative values may suggest keratoconus or hyperopic correction whereas positive values may suggest myopic correction.

2025年3月16日 · Corneal asphericity Q-value is a measure of the curvature of the cornea, which plays a crucial role in vision and eye health. The Q-value of the cornea affects the quality of vision and can impact the fitting of contact lenses. Measurement of corneal asphericity Q-value is typically done using corneal topography or tomography.

We revealed that eyes with lens decentration had much higher corneal asphericity (Q-value) differences between the nasal–temporal and superior–inferior quadrants than eyes without lens decentration. This significant asymmetry of corneal Q-value explains why orthokeratology lenses easily shift to the temporal and inferior quadrants.

Q value of 25° had high correlation (r=0.673, P=0.000) with corneal spherical aberration, but low correlation (r=0.241, P=0.016) with total spherical aberration. “Q值”来表示。 大多数人的角膜呈扁长形(prolate)，即Q<0，少部分人的角膜由中央向周边部逐渐变陡，呈扁圆形(oblate)，Q>0[1]。

2017年5月18日 · The corneal Q values of anterior and posterior surfaces were measured at 3.0, 5.0 and 7.0mm aperture diameters using Bausch & Lomb Orbscan IIz (software version 3.12). Age, gender and refractive power were recorded.

The corneal asphericity coefficient (Q value) describes the rate of radial curvature variation of the corneal quadric surface from its center to the periphery. It is a quantitative topographic indicator of the degree of corneal asphericity, describing the corneal shape and its optical properties [ 4 , 6 ] .

MORE AIM：To investigate the corneal Q value of asphericity distribution in myopic patients. METHODS： 106 myopic eyes （53 cases） were divided into three groups including low myopia, moderate myopia and high myopia. All corneal Q values were measured with Astramax corneal topographer and were analyzed statistically.