The L-1550 is a recognised projection perimeter, highly suitable for precise kinetic quantitative perimetry by lnami’s total technology. Accurately measures retinal sensitivity through combinations of brightness and target size; 120 target varieties possible by combining the density filters and targets (six different sizes) A single lamp simultaneously illuminates both the sphere and the projection system of the target. The luminosity of the sphere (31.5 asb) is controlled by sliding a diaphragm of the lamp housing socket, and brightness of the target (1000 asb) is adjustable with the light meter, photometer screen, and the rheostat. In some cases, patients may find it difficult to keep their gaze on fixation point due to tiredness or lack of concentration. The patient's viewpoint can be observed through telescope so that examiner can direct patient to fix viewpoint in the centre. Also controlling the shutter device can help examiner to confirm the patients' continued concentration on the examination.