Macular thickness, as measured by OCT, is one of the key outcome measures used in most clinical trials, especially those on diabetic macular edema and AMD. Because Stratus TD-OCT was the most common commercially available OCT instrument in the past decade, most trials are designed based on Stratus OCT.
A percentile (or a centile) is a measure used in statistics indicating the value below which a given percentage of observations in a group of observations fall. For example, the 20th percentile is the value (or score) below which 20% of the observations may be found. The term percentile and the related term percentile rank are often used in the reporting of scores from norm-referenced tests.
The Gini coefficient (or Gini ratio) is a summary statistic of the Lorenz curve and a measure of inequality in a population. (Dixon et al. 1987, Damgaard and Weiner 2000). (Dixon et al. 1988, Damgaard and Weiner 2000), correcting the typographical error in the denominator given in the original paper (Dixon et al.