New adaptive preprocessing algorithms based on the polar coordinate system were put forward to get high-precision corneal topography calculation results. Adaptive locating algorithms of concentric circle center were c...New adaptive preprocessing algorithms based on the polar coordinate system were put forward to get high-precision corneal topography calculation results. Adaptive locating algorithms of concentric circle center were created to accurately capture the circle center of original Placido-based image, expand the image into matrix centered around the circle center, and convert the matrix into the polar coordinate system with the circle center as pole. Adaptive image smoothing treatment was followed and the characteristics of useful circles were extracted via horizontal edge detection, based on useful circles presenting approximate horizontal lines while noise signals presenting vertical lines or different angles. Effective combination of different operators of morphology were designed to remedy data loss caused by noise disturbances, get complete image about circle edge detection to satisfy the requests of precise calculation on follow-up parameters. The experimental data show that the algorithms meet the requirements of practical detection with characteristics of less data loss, higher data accuracy and easier availability.展开更多
Laser in situ keratomileusis(LASIK)is a relatively new ophthalmic procedure in refractive surgery.It involves the use of a microkeratome to create a thin corneal flap followed by excimer laser ablation of the corneal ...Laser in situ keratomileusis(LASIK)is a relatively new ophthalmic procedure in refractive surgery.It involves the use of a microkeratome to create a thin corneal flap followed by excimer laser ablation of the corneal stroma and repositioning of the flap.However,complications are bound to occur when a surgical procedure is performed with increasing frequency.In some cases,serious complications such as keratectasia occurred.Risk factors for corneal keratectasia include a thin cornea at baseline,thick corneal flap,excessive ablation,irregular corneal thickness,diverse ablation rates,preexisting keratoconus or form fruste keratoconus,and high intraocular pressure(IOP)~[1].It is evident from incisional refractive surgery that the cornea is not mechanically inert.The mechanical environment of the central corneal tissue is also altered un-展开更多
基金Project(20120321028-01)supported by Scientific and Technological Key Project of Shanxi Province,ChinaProject(20113101)supported by Postgraduate Innovative Key Project of Shanxi Province,China
文摘New adaptive preprocessing algorithms based on the polar coordinate system were put forward to get high-precision corneal topography calculation results. Adaptive locating algorithms of concentric circle center were created to accurately capture the circle center of original Placido-based image, expand the image into matrix centered around the circle center, and convert the matrix into the polar coordinate system with the circle center as pole. Adaptive image smoothing treatment was followed and the characteristics of useful circles were extracted via horizontal edge detection, based on useful circles presenting approximate horizontal lines while noise signals presenting vertical lines or different angles. Effective combination of different operators of morphology were designed to remedy data loss caused by noise disturbances, get complete image about circle edge detection to satisfy the requests of precise calculation on follow-up parameters. The experimental data show that the algorithms meet the requirements of practical detection with characteristics of less data loss, higher data accuracy and easier availability.
基金supported by the National Natural Science Foundation of China(11032008)Natural Science Foundation of Shanxi Province(2012011046-2)
文摘Laser in situ keratomileusis(LASIK)is a relatively new ophthalmic procedure in refractive surgery.It involves the use of a microkeratome to create a thin corneal flap followed by excimer laser ablation of the corneal stroma and repositioning of the flap.However,complications are bound to occur when a surgical procedure is performed with increasing frequency.In some cases,serious complications such as keratectasia occurred.Risk factors for corneal keratectasia include a thin cornea at baseline,thick corneal flap,excessive ablation,irregular corneal thickness,diverse ablation rates,preexisting keratoconus or form fruste keratoconus,and high intraocular pressure(IOP)~[1].It is evident from incisional refractive surgery that the cornea is not mechanically inert.The mechanical environment of the central corneal tissue is also altered un-
