Abstract
Abstract: :
Purpose: Disturbances of ocular tear flow and tear film stability know as Dry–Eye–Syndrome (DES) have become a widespread ocular disease in many industrialized countries. Although much research is focussed on changes in quality and quantity of tear production and changes in morphology and biochemistry of the ocular surface, there is little information about changes of corneal transparency and biometry in DES, also in combination with other ocular diseases. This study investigated changes in corneal thickness and transparency of DES patients affected also by other ocular or general diseases, using the Scheimpflug photography and subsequent image analysis. Methods: A total of 208 patients with DES were enrolled into this study after obtaining informed consent from all of them. The individual patient case history was recorded by using an anamnestic questionaire. Additional ocular diseases included into this study were glaucoma and diabetes mellitus. Images were recorded on 400 ASA B/W film in 0° and 90° meridians from the anterior eye segments of all patients using a Scheimpflug camera (Topcon SL–45). Corneal light scattering and curvature were determined by using a custom made image analytical software operating a microdensitometer. All corneal data obtained form the study patients were compared to age–related corneal biometry and density data from a large cohort of normal patients. Results: Optical density of the epithelium, Bowman’s layer and descemet’s membrane were significantly lower in DES patients than in controls. In addition, the thickness of the central cornea decreased significantly in comparison to the normal cases which demonstrated an age–related constant increase. Diabetes mellitus in combination with DES caused a significant increase in corneal thickness and density, especially in Bowman’s layer. DES in combination with glaucoma lead to an age–related significant decrease of corneal thickness. Conclusions: DES affected the overall thickness of the cornea and caused changes in density in distinct layers. Diabetes reversed such effects while glaucoma demonstrated an enhancing potential. These results point to a tissue dehydration and potentially also reflect a negative effect of DES in epithelial and endothelial cell viability. With the exception of Dry Eye medication containing hydroxypropyl–methylcellulose, all other DES medications used by the patients did not affect any of the parameters evaluated in this study.
Keywords: cornea: tears/tear film/dry eye • cornea: clinical science