Topographic analysis of changes in corneal shape as a function of age.

Swarna Udayakumar, - (2007) Topographic analysis of changes in corneal shape as a function of age. Masters thesis, Madras Medical College, Chennai.


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INTRODUCTION: Time is the fourth dimension, affecting all things living and nonliving. As time affects the structure of the body, the eye also undergoes certain inevitable consequences. With aging, the ability to maintain physiologic homeostasis under conditions of biologic stress declines. Further this decline is associated with an increase in vulnerability of individual and a decrease in viability potential. Although time and aging are on a continuum they begin at birth. AIM OF THE STUDY: To investigate the age related differences in corneal topography of a normal population. It is a well known fact that against the rule astigmatism has a considerably higher incidence in older age. Many kinds of keratorefractive surgeries have been developed and are now popular. When performing such kinds of surgery, it is necessary to actually evaluate each patients corneal shape. Further more, a good understanding of the changes in corneal shape due to aging is also considered to be essential. The present study was designed to evaluate the aging changes in corneal shape using computed videokeratography. MATERIALS AND METHODS: This documentation has been arrived at the end of study of 152 patients divided prospectively into three groups. The entire evaluation was carried out at RIO- GOH, Egmore, Chennai. The study began in June 2005 to May 2006 covering a period of 12 months. Similarity of the cases studied was maintained as far as possible. The strategy included selection of age factor and uncomplicated cases. DISCUSSION: Our study clearly shows that the normal cornea becomes steeper and shifts from with the rule astigmatism to against the rule astigmatism with age. The averaged map of the normal cornea at younger age showed vertical bow tie shaped steep area in central cornea which indicates with the rule astigmatism. RESULTS: 243 eyes of 152 patients were analysed in this study. 57 eyes had to be excluded because of either irregular mires, slit lamp abnormalities, corneal pathology, pterygium or because of pseudophakia. CONCLUSION: This study clearly demonstrates that the normal cornea becomes steeper and shifts from with the rule to against the rule astigmatism with age. The data analysis of change in refractive powers clarified that the against the rule shift occurs predominantly due to steepening of horizontal meridians. Advances in kerato refractive surgeries have led to development of many new surgical techniques, which needs appropriate changes to be made to accommodate the aging changes in corneal shape. It is therefore essential to have a thorough understanding of aging changes in the corneal shape to obtain a stable and enduring refractive state after kerato refractive surgery.

Item Type: Thesis (Masters)
Uncontrolled Keywords: corneal shape; topographic analysis
Subjects: MEDICAL > Ophthalmology
Depositing User: Devi S
Date Deposited: 11 Sep 2017 08:44
Last Modified: 11 Sep 2017 08:44

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