The cornea is the most anterior layer of the eye and its transparent and avascular nature allows the transmission of light to the rest of the eye. Corneal clarity can be affected by a wide range of diseases or corneal treatments. Understanding the nature of corneal haze and its causes would give a better understanding of disease progression and disease treatment outcomes. This knowledge could be useful to the clinician when deciding which form of treatment is the best for the patients. The Oculus Pentacam is a device based on the schiempflug principle which can take 50 images in 2 seconds with the ability to give a numeric value to corneal densitometry. This project aimed to investigate corneal clarity and get a better understanding of the changes taking place which lead to corneal haze in health and disease. Using corneal densitometry software to analyse Oculus Pentacam images, we first defined how corneal clarity changes with age in healthy individual. We then identified corneal diseases and treatments that are associated with cornea haze and recruited 238 patients and followed them through diagnosis and treatment. We found corneal clarity changes in healthy participants with age which varies based on corneal layer and zone. When we compared the outcome of 2 different types of refractive laser surgery and found that corneal clarity appears to be localised to the wound healing processes in the area of injury. Likewise, in early keratoconus the Intra Stromal Corneal Ring Segments (INTACS) stabilize corneal clarity in comparison with patients managed by RGP contact lenses alone, suggesting haze is due to disease progressions and level of inflammation from the Rigid Gas Permeable (RGP) lenses. There are different corneal clarity outcomes post keratoplasty based on different transplant procedures and the disease been treated, again haze was related to the stromal interface, where inflammation and tissue repair was active. Corneal clarity response to disease progression, and treatment type based on different factors involved. Juvenile patients seem to react to the corneal cross linking treatment differently than adults which open more questions about safety of some procedures. Dividing the cornea into zones and layers help to get precise information on affected areas, which could help in the understanding of corneal transparency and help to improve and develop technique and treatment for corneal disease. The Oculus Pentacam provides an objective tool to monitor the cornea at different stages in health and disease.
|Date of Award
|1 Aug 2020
- The University of Manchester
|M Chantal Hillarby (Supervisor) & Fiona Carley (Supervisor)