Why does cone cornea need to be diagnosed early? Early screening for cone corneas is important for people with laser-treated myopia because if this group has myopia surgery, it means that the chances of postoperative complications of corneal bulging and thus vision loss are greatly increased. Systems that generally use Scheimpflug imaging have a higher sensitivity and specificity in diagnosing early cone corneas. And the importance of the posterior cone of the cornea is becoming increasingly evident. The invention rate of cone corneas in the population is approximately 1 in 2000, and the diagnosis of early cone corneas often relies on the combined evaluation of several tests to be certain. In addition, some of the more suspicious cases often require long-term follow-up observation. For those with astigmatism greater than 2D, the likelihood of cone corneas increases to 14.1% (6.3% true cone corneas and 7.8% subclinical cone corneas). What are our current diagnostic tools? Most of the early instruments were based on the principle of Placido disc to detect corneal curvature, for example, a higher area of corneal refractive power surrounded by a lower area of refractive power, asymmetry of refractive power in the upper and lower part of the cornea, and distortion of the steepest axis on or under the horizontal meridian were characteristic parameters of such instruments to diagnose cone corneas. Later, Orbscan I and II were equipped with a wide field of view for corneal thickness measurement and anterior and posterior corneal surface height map detection, and the main indices detected were as follows: maximum posterior surface elevation compared to BFS, central 3mm and 5mm irregularity index and thickness, elevation process of anterior surface apex, displacement of anterior surface apex, and thinnest point thickness. Another instrument, Penacam by Oculus, is also based on the Scheimpflug imaging principle and is a 3D topographic map obtained from 25,000 actual corneal points to measure: anterior and posterior corneal surfaces, thickness, and anterior chamber angle. the most remarkable feature of Penacam is the Belin/Ambrosio-based corneal bulge detection analysis function, which can facilitate the detection of subclinical cone corneal occurrence after laser myopia. In addition, there are wavefront aberrometers that can assist in the diagnosis of clinical and subclinical cone corneas by detecting the Zernike coefficient and higher-order phase differences on the anterior and posterior surfaces of the cornea. The Ocular Response Analyzer (ORA) can detect corneal hysteresis and corneal resistance parameters to assist in the assessment of corneal bulging tendencies. High-definition tomography of the cornea is available with anterior segment frequency-domain OCT. In conical corneas, the corneal stroma, especially the corneal epithelium, is thinned in the inferior temporal region. Polarization-sensitive OCT (PS-OCT) can confirm structural changes in the collagen fibers of the corneal laminae by detecting the mean face phase delay on the posterior surface of the cornea in cone-shaped corneas. In addition, corneal confocal microscopy can provide a reference value for the early diagnosis of cone corneas by analyzing the HD structure of corneal tomography in cone corneal patients, Fourier transform infrared spectroscopy, and optical quality analysis system.