A closed-loop control system for altering the optical characteristics of a patient’s cornea includes an algorithm for predicting the shape of the cornea after one or more gas bubbles resulting from intrastromal photoablation have collapsed. A first processing step implements a first path-tracking operation using a front marching technique denoted Filiation Front Marching Technique for supplying at least one First Track of the threadlike structure, formed by succeeding points denoted Fathers and Children, by marching a Front of points forwards from a fixed Start point to a fixed End point. Preferably, about 5 grams of the composition are contained in the teabag, which is steeped in about 150 mL of boiling water for between about three minutes and about five minutes. The electrode with clusters exhibits improved performance with respect to the intrinsic material of the electrode absent the clusters. An external recipient can then store the data portions of the constructed data packets based on the data addresses in the constructed data packets.