A method for measuring a sensitivity level across a visual field of a subject defined by a set of locations using a visual test apparatus including a display, an input mechanism and a control system, said method comprising: presenting by the control system a sequence of visual stimuli on the display, wherein each stimulus in the sequence has a respective intensity level and is positioned on the display to correspond to a respective location from the set of locations; obtaining from the subject by the control system via the input mechanism, for each stimulus, a respective binary response indicating whether or not the stimulus was seen by the subject; and after receiving the response from the subject for a given stimulus in the sequence, using a statistical model in the control system to estimate, for each location in the set of locations, the sensitivity level at that location; wherein: the statistical model incorporates information about correlations in responses between different locations from the set of locations and takes, as input, the respective location, intensity level and response for multiple stimuli presented in said sequence up to and including the given stimulus; the method is iterative in approach, and after receiving the response from the subject for each stimulus in the sequence, uses the statistical model in the control system to make a new estimate of the sensitivity level for each respective location in the set of locations; the new estimate takes, as input, the respective location, intensity level and response for multiple stimuli presented in said sequence up to and including the new stimulus, but not information derived therefrom; characterised in that: the new estimate is derived using a maximisation algorithm, and an earlier estimate of sensitivity level derived earlier in the sequence is used only for initialization of the maximisation algorithm, whereby such initialization assists the maximisation algorithm to converge more quickly, but does not impact the value of the newly estimated sensitivity level for each location. presenting by the control system a sequence of visual stimuli on the display, wherein each stimulus in the sequence has a respective intensity level and is positioned on the display to correspond to a respective location from the set of locations; obtaining from the subject by the control system via the input mechanism, for each stimulus, a respective binary response indicating whether or not the stimulus was seen by the subject; and after receiving the response from the subject for a given stimulus in the sequence, using a statistical model in the control system to estimate, for each location in the set of locations, the sensitivity level at that location; wherein: the statistical model incorporates information about correlations in responses between different locations from the set of locations and takes, as input, the respective location, intensity level and response for multiple stimuli presented in said sequence up to and including the given stimulus; the method is iterative in approach, and after receiving the response from the subject for each stimulus in the sequence, uses the statistical model in the control system to make a new estimate of the sensitivity level for each respective location in the set of locations; the new estimate takes, as input, the respective location, intensity level and response for multiple stimuli presented in said sequence up to and including the new stimulus, but not information derived therefrom; characterised in that: the new estimate is derived using a maximisation algorithm, and an earlier estimate of sensitivity level derived earlier in the sequence is used only for initialization of the maximisation algorithm, whereby such initialization assists the maximisation algorithm to converge more quickly, but does not impact the value of the newly estimated sensitivity level for each location. the statistical model incorporates information about correlations in responses between different locations from the set of locations and takes, as input, the respective location, intensity level and response for multiple stimuli presented in said sequence up to and including the given stimulus; the method is iterative in approach, and after receiving the response from the subject for each stimulus in the sequence, uses the statistical model in the control system to make a new estimate of the sensitivity level for each respective location in the set of locations; the new estimate takes, as input, the respective location, intensity level and response for multiple stimuli presented in said sequence up to and including the new stimulus, but not information derived therefrom; characterised in that: the new estimate is derived using a maximisation algorithm, and an earlier estimate of sensitivity level derived earlier in the sequence is used only for initialization of the maximisation algorithm, whereby such initialization assists the maximisation algorithm to converge more quickly, but does not impact the value of the newly estimated sensitivity level for each location.