European Association for Vision and Eye Research

To develop and test a system of automated analysis of amount of decentration of anterior segment structures from a geometric axis defined either by pupil or limbal landmarks. The system should be freely available and accessible for use without specialised equipment.

The system consisted of a computer program developed using the Matlab programming platform. Standard digital images of anterior segments were used by the program to make measurements. The program code was also compiled for use on machines without the Matlab platform.
The geometric central axis is computed based on either limbal or pupil structure, as defined by the user. The object to be measured is also defined by the user.This object may be the pupil itself (to be measured relative to limbus) , crystalline lens, intraocular lens, corneal opacity, posterior capsule opacification or other anterior chamber body. The amount of decentration and angle of decentration of the object is calculated.
The system was tested for reliabiltiy and validity.

The compiled system is fully functional on PCs running Windows XP. It is easily adaptable to assess decentration of a variety of structures using standard digital images. The reliability of the system was found to be high. Ample evidence for validity of the program was demonstrated.

This paper presents as system of analysis of decentration of anterior segment bodies that requires no specialised equipment.The program and necessary files can be installed using the supplied software. The system is shown to be extremely versatile , valid and reliable. It may be used clinically to track progress of individual patients or as an objective measure for experimental studies.