Goniotrans is a simple, free and useful to reference an image of the eye on the angular position of the ocular structures tool. You capturing a photographic image of the eye is copied and pasted into the program which overlaps a template that simulates a conveyor with two hemi-meridians superimposed with marks from 0 ° to 180 ° in steps of 5 ° or 10 °.
References as nevus or iris crypts, aqueous veins, etc. they can very accurately determine the appropriate meridians to incisions, marking toric lenses, etc. Also allows results lens positions, stability thereof, incisional axes, etc.