FIELD : medicine.SUBSTANCE : group of inventions relates to medicine. Module for forming, when used in conjunction with a mobile computing device, a portable wavefront aberrometer for measuring aberrations on a patient' s retina includes : a light tube having a proximal and a distal end and comprising a first group of optical components for transmitting light along a first light path from the distal end to the proximal end, and a second group of optical components for transmitting light along the second light path from the proximal end to the distal end, the second group of optical components comprising a microlens array; a light source comprising a laser; and a connector located at the distal end of the light tube, having at least one guiding component for locating the distal end of the light tube near the photodetector of the mobile computing device. When the distal end of the light tube is adjacent to the photodetector of the mobile computing device : the first group of optical components is configured to transmit light from a light source along the first light path to the proximal end of the light tube, and the second group of optical components is arranged to transmit light along the second light path from the distal end of the light tube to the photodetector of the mobile computing device, wherein the second group of optical components is configured to form an array of spots on the photodetector as a result of the passage of light through the microlens array. Method is disclosed for directing light to a photodetector of a mobile computing device for measuring retinal aberrations of a patient, comprising : installing the module adjacent to the mobile computing device so that the distal end of the light tube of the module is adjacent to the photodetector of the mobile computing device; arranging the module near the patient' s eye so that the proximal end of the light tube is located adjacent to the patient' s eye; directing light from the light source of the module through the light tube to the patient' s eye; and directing the light reflected from the patient' s eye through the light tube into the photodetector of the mobile computing device, wherein light reflected from the patient' s eye passes through the microlens array, leading to the formation of an array of spots on the photodetector.EFFECT : use of this group of inventions will reduce the size and complexity of the design of the optical system necessary to perform wavefront aberrometry.17 cl, 7 dwg