A system for controlling focal parameters of a visual display based on ocular features, the system comprising: at least one processor; a head mounted display, HMD, comprising a visual display including at least one eye tracking sensor; and at least one memory communicatively coupled to the at least one processor and comprising computer program code, the at least one memory and the computer program code configured to, with the at least one processor, cause the at least one processor to: collect, via the at least one eye tracking sensor, ocular metric data associated with at least one ocular feature of a user's eye; the computer program code being characterized in that it is configured to, with the at least one processor, cause the at least one processor to: calculate a user age estimate based on analysis of the ocular metric data using at least one machine learning algorithm and an associated ocular metric data set comprising ocular metric data from a plurality of users; calculate a confidence value associated with the user age estimate based on the analysis of the ocular metric data; and control at least one focal parameter of the visual display based on the calculated user age estimate and the associated confidence value, wherein the ocular metric data includes at least one of pupil size data, pupil accommodation data, pupil shape data, blink dynamic data, saccade dynamic data, eye lid characteristic data, and progressive lens data. at least one processor; a head mounted display, HMD, comprising a visual display including at least one eye tracking sensor; and at least one memory communicatively coupled to the at least one processor and comprising computer program code, the at least one memory and the computer program code configured to, with the at least one processor, cause the at least one processor to: collect, via the at least one eye tracking sensor, ocular metric data associated with at least one ocular feature of a user's eye; the computer program code being characterized in that it is configured to, with the at least one processor, cause the at least one processor to: calculate a user age estimate based on analysis of the ocular metric data using at least one machine learning algorithm and an associated ocular metric data set comprising ocular metric data from a plurality of users; calculate a confidence value associated with the user age estimate based on the analysis of the ocular metric data; and control at least one focal parameter of the visual display based on the calculated user age estimate and the associated confidence value, wherein the ocular metric data includes at least one of pupil size data, pupil accommodation data, pupil shape data, blink dynamic data, saccade dynamic data, eye lid characteristic data, and progressive lens data. collect, via the at least one eye tracking sensor, ocular metric data associated with at least one ocular feature of a user's eye; the computer program code being characterized in that it is configured to, with the at least one processor, cause the at least one processor to: calculate a user age estimate based on analysis of the ocular metric data using at least one machine learning algorithm and an associated ocular metric data set comprising ocular metric data from a plurality of users; calculate a confidence value associated with the user age estimate based on the analysis of the ocular metric data; and control at least one focal parameter of the visual display based on the calculated user age estimate and the associated confidence value, wherein the ocular metric data includes at least one of pupil size data, pupil accommodation data, pupil shape data, blink dynamic data, saccade dynamic data, eye lid characteristic data, and progressive lens data. calculate a user age estimate based on analysis of the ocular metric data using at least one machine learning algorithm and an associated ocular metric data set comprising ocular metric data from a plurality of users; calculate a confidence value associated with the user age estimate based on the analysis of the ocular metric data; and control at least one focal parameter of the visual display based on the calculated user age estimate and the associated confidence value, wherein the ocular metric data includes at least one of pupil size data, pupil accommodation data, pupil shape data, blink dynamic data, saccade dynamic data, eye lid characteristic data, and progressive lens data.