A computer-implemented gaze tracking method comprising: obtaining one or more images of an eye, wherein an image of said one or more images has been captured by a camera at a time instance while the eye was illuminated by an illuminator, wherein the image captured by the camera shows a first reflection of the illuminator at a cornea of the eye, wherein an image of said one or more images has been captured by a camera at said time instance and shows at least a portion of an edge, wherein the edge is: an edge of a pupil of the eye; or an edge of an iris of the eye; detecting a position of the first reflection in the image showing the first reflection; detecting at least a portion (901, 904) of the edge in the image showing at least a portion of the edge; obtaining a preliminary position of the eye in space and a preliminary orientation of the eye in space; estimating, based on the preliminary position of the eye and the preliminary orientation of the eye, a first preliminary path for light travelling, via a reflection at the cornea, towards the camera by which said image showing the first reflection was captured; estimating a position where the reflection from the first preliminary path would appear in images of the eye captured by the camera by which said image showing the first reflection was captured; forming a first distance between the detected position of the first reflection in said image showing the first reflection and the estimated position where the reflection from the first preliminary path would appear; estimating, based on the preliminary position of the eye and the preliminary orientation of the eye, a second preliminary path for light travelling through at least a portion of the cornea of the eye towards the camera by which said image showing at least a portion of the edge was captured or for light travelling from a sclera of the eye towards the camera by which said image showing at least a portion of the edge was captured; estimating a position (902, 905) where the second preliminary path would appear to originate in images of the eye captured by the camera by which said image showing at least a portion of the edge was captured; forming a second distance (903, 906) between the edge and the estimated position where the second preliminary path would appear to originate; forming an objective function based on differences between predicted features and corresponding detected features of at least the first and second distances, wherein the objective function is configured to solve an optimisation problem for determining the position and orientation of the eye in space; and determining, using the objective function, an updated position of the eye in space and/or an updated orientation of the eye in space. obtaining one or more images of an eye, wherein an image of said one or more images has been captured by a camera at a time instance while the eye was illuminated by an illuminator, wherein the image captured by the camera shows a first reflection of the illuminator at a cornea of the eye, wherein an image of said one or more images has been captured by a camera at said time instance and shows at least a portion of an edge, wherein the edge is: an edge of a pupil of the eye; or an edge of an iris of the eye; an edge of a pupil of the eye; or an edge of an iris of the eye; detecting a position of the first reflection in the image showing the first reflection; detecting at least a portion (901, 904) of the edge in the image showing at least a portion of the edge; obtaining a preliminary position of the eye in space and a preliminary orientation of the eye in space; estimating, based on the preliminary position of the eye and the preliminary orientation of the eye, a first preliminary path for light travelling, via a reflection at the cornea, towards the camera by which said image showing the first reflection was captured; estimating a position where the reflection from the first preliminary path would appear in images of the eye captured by the camera by which said image showing the first reflection was captured; forming a first distance between the detected position of the first reflection in said image showing the first reflection and the estimated position where the reflection from the first preliminary path would appear; estimating, based on the preliminary position of the eye and the preliminary orientation of the eye, a second preliminary path for light travelling through at least a portion of the cornea of the eye towards the camera by which said image showing at least a portion of the edge was captured or for light travelling from a sclera of the eye towards the camera by which said image showing at least a portion of the edge was captured; estimating a position (902, 905) where the second preliminary path would appear to originate in images of the eye captured by the camera by which said image showing at least a portion of the edge was captured; forming a second distance (903, 906) between the edge and the estimated position where the second preliminary path would appear to originate; forming an objective function based on differences between predicted features and corresponding detected features of at least the first and second distances, wherein the objective function is configured to solve an optimisation problem for determining the position and orientation of the eye in space; and determining, using the objective function, an updated position of the eye in space and/or an updated orientation of the eye in space.