What Is Enophthalmos?

The cornea is a transparent film on the front of the eye. The cornea is completely transparent, located in the front of the eyeball, and has a horizontal oval shape. The cornea has very sensitive nerve endings. If foreign objects come into contact with the cornea, the eyelids will involuntarily close to protect the eyes. In August 2017, a case of porcine corneal transplantation aroused netizens' attention.

The cornea is completely transparent and located

The anatomy and physiology of the cornea are structurally divided into 5 layers: epithelial cell layer, Bowman layer, stroma layer, Descemet membrane, and endothelial cell layer. The cornea is transparent and free of blood vessels, but it is rich in sensory nerve tissue, has a certain shape, size, thickness, and radius of curvature. It also has a certain refractive power, and plays an important role in eye refractive. In addition, it also works with

Because the cornea is a transparent lens, there are no blood vessels on it. So the cornea is from

The refractive index of the corneal parenchyma is about 1.376, while the refractive index of the aqueous humor in contact with the posterior surface of the cornea is 1.336.

Regarding the surface refractive power, using the usual formula, we can get:

Front refractive power = 1000 (1.376-1) / 7.7 = 48.83D

Rear refractive power = 1000 (1.336-1.376) /6.8=-5.88D

Therefore, the equivalent refractive power of the entire cornea is about 43D, which accounts for the entire eye

Donation of cornea The law of the People's Republic of China stipulates that do nt donate cornea before living, because

Corneal keratopathy comprehensively applies theoretical knowledge and medical technology of practical medicine, ophthalmology, biology, physics, chemistry, etc. to study the incidence, nature, etiology, pathology, pathology and diagnosis of human keratitis diseases, An emerging discipline of treatment, prevention, principles, principles, methods, means, measures and procedures. A branch of ophthalmology ^[1]

Corneal transplantation

In August 2017, a 27-year-old Hubei man with near-blind right eye began to recover vision after transplanting a cornea of a pig's eye in a hospital in Changsha. As of August 17, the patient's vision had returned to 0.3.

Zhang Hua (pseudonym) had necrotizing keratitis in his right eye, and lamellar corneal transplantation was needed to avoid deepening the right eye infection. Later, the hospital decided to perform a biological corneal transplant on the patient, that is, corneal corneal transplantation. Corneal corneal transplantation does not directly transplant the cornea of a pig's eye to a human eyeball. Instead, a three-dimensional structure of the cornea is transplanted to the human eyeball through a special process to form a new corneal tissue.

The director of the Corneal Transplantation Center, Tang Renhong, said: There is no blood supply in the cornea of pigs, and no matching is required. The success rate of surgery is as high as 90%. The duration of maintaining vision depends mainly on the patient's rejection. Both the cornea of the transplanted pig and the cornea of the human may have a rejection. Corneal cornea is a temporary substitute, which is not as good as human cornea, but it is used clinically because there is no human corneal donation in the country, and many patients do not have the opportunity to obtain a human corneal transplant. The parameters of the cornea of the pig's eye are closer to those of the human body. Compared with the cornea of animals such as cats and dogs, the advantages of the cornea are much more prominent. Even the cornea of a pig must be screened. The cell components, etc., have to be figured out before they can be used. The case of porcine corneal transplantation was first developed by a company in Shenzhen and began to be used clinically in 2016. Since 2016, some domestic hospitals, including Beijing, Wuhan, and Hunan, have started to perform porcine corneal transplantation, but less than 10 cases have been successful ^[2] .