A system for monitoring phototoxicity during ophthalmic surgery comprising: a vitreous visualization device connected to an optical fiber operable to propagate an illumination beam, the illumination beam creating a light spot (110, 210) on a retina; a surgical microscope; the system being characterised by further comprising: a digital camera operable to detect the light spot and generate data relating to the light spot; and a processor operable to: receive data from the digital camera relating to the light spot, the data including a size (305, 308) of the light spot and an elapsed time the light spot has been focused on a focus area (380, 381, 382) of the retina; determine an amount of optical energy incident on the focus area, the amount of optical energy corresponding to the elapsed time; determine a cumulative amount of optical energy incident on the retina, based on the amounts of optical energy incident on a plurality of focus areas; determine whether the cumulative amount of optical energy meets or exceeds a warning threshold (318, 320), defined in relation to a maximum exposure limit for phototoxicity; generate a warning when the cumulative amount of optical energy meets or exceeds the warning threshold; and transmit the warning to a warning system. a vitreous visualization device connected to an optical fiber operable to propagate an illumination beam, the illumination beam creating a light spot (110, 210) on a retina; a surgical microscope; the system being characterised by further comprising: a digital camera operable to detect the light spot and generate data relating to the light spot; and a processor operable to: receive data from the digital camera relating to the light spot, the data including a size (305, 308) of the light spot and an elapsed time the light spot has been focused on a focus area (380, 381, 382) of the retina; determine an amount of optical energy incident on the focus area, the amount of optical energy corresponding to the elapsed time; determine a cumulative amount of optical energy incident on the retina, based on the amounts of optical energy incident on a plurality of focus areas; determine whether the cumulative amount of optical energy meets or exceeds a warning threshold (318, 320), defined in relation to a maximum exposure limit for phototoxicity; generate a warning when the cumulative amount of optical energy meets or exceeds the warning threshold; and transmit the warning to a warning system. a digital camera operable to detect the light spot and generate data relating to the light spot; and a processor operable to: receive data from the digital camera relating to the light spot, the data including a size (305, 308) of the light spot and an elapsed time the light spot has been focused on a focus area (380, 381, 382) of the retina; determine an amount of optical energy incident on the focus area, the amount of optical energy corresponding to the elapsed time; determine a cumulative amount of optical energy incident on the retina, based on the amounts of optical energy incident on a plurality of focus areas; determine whether the cumulative amount of optical energy meets or exceeds a warning threshold (318, 320), defined in relation to a maximum exposure limit for phototoxicity; generate a warning when the cumulative amount of optical energy meets or exceeds the warning threshold; and transmit the warning to a warning system. receive data from the digital camera relating to the light spot, the data including a size (305, 308) of the light spot and an elapsed time the light spot has been focused on a focus area (380, 381, 382) of the retina; determine an amount of optical energy incident on the focus area, the amount of optical energy corresponding to the elapsed time; determine a cumulative amount of optical energy incident on the retina, based on the amounts of optical energy incident on a plurality of focus areas; determine whether the cumulative amount of optical energy meets or exceeds a warning threshold (318, 320), defined in relation to a maximum exposure limit for phototoxicity; generate a warning when the cumulative amount of optical energy meets or exceeds the warning threshold; and transmit the warning to a warning system.