A computer-implemented method of processing functional OCT image data, which has been acquired by an OCT imaging device scanning a retina of a subject while the retina is being repeatedly stimulated by a light stimulus, to generate an indication of a response of the retina to the light stimulus, the method comprising: receiving (S10), as the functional OCT image data: OCT image data that has been generated by the OCT imaging device repeatedly scanning a scanned region (R) of the retina over a time period (T); and stimulus data defining a sequence (S) of stimulus indicators (s 1 , s 2 , s 3 ) each being a respective value which is indicative of a stimulation of the retina by the light stimulus in a respective time interval of a sequence of time intervals that spans the time period (T); and calculating a rolling window correlation between a sequence of B-scans that is based on the OCT image data and stimulus indicators (s 1 , s 2 , s 3 ) in the sequence (S) of stimulus indicators by: calculating (S20-1), for each stimulus indicator (s 1 ; s 2 ; s 3 ), a product of the stimulus indicator and a respective windowed portion of the sequence of B-scans comprising a plurality of B-scans (600-1; 600-2) which includes a B-scan that is based on a portion of the OCT image data generated while the retina was being stimulated in accordance with the stimulus indicator (s 1 ; s 2 ; s 3 ); and combining the calculated products to generate the indication of the response of the retina to the light stimulus. receiving (S10), as the functional OCT image data: OCT image data that has been generated by the OCT imaging device repeatedly scanning a scanned region (R) of the retina over a time period (T); and stimulus data defining a sequence (S) of stimulus indicators (s 1 , s 2 , s 3 ) each being a respective value which is indicative of a stimulation of the retina by the light stimulus in a respective time interval of a sequence of time intervals that spans the time period (T); and OCT image data that has been generated by the OCT imaging device repeatedly scanning a scanned region (R) of the retina over a time period (T); and stimulus data defining a sequence (S) of stimulus indicators (s 1 , s 2 , s 3 ) each being a respective value which is indicative of a stimulation of the retina by the light stimulus in a respective time interval of a sequence of time intervals that spans the time period (T); and calculating a rolling window correlation between a sequence of B-scans that is based on the OCT image data and stimulus indicators (s 1 , s 2 , s 3 ) in the sequence (S) of stimulus indicators by: calculating (S20-1), for each stimulus indicator (s 1 ; s 2 ; s 3 ), a product of the stimulus indicator and a respective windowed portion of the sequence of B-scans comprising a plurality of B-scans (600-1; 600-2) which includes a B-scan that is based on a portion of the OCT image data generated while the retina was being stimulated in accordance with the stimulus indicator (s 1 ; s 2 ; s 3 ); and combining the calculated products to generate the indication of the response of the retina to the light stimulus. calculating (S20-1), for each stimulus indicator (s 1 ; s 2 ; s 3 ), a product of the stimulus indicator and a respective windowed portion of the sequence of B-scans comprising a plurality of B-scans (600-1; 600-2) which includes a B-scan that is based on a portion of the OCT image data generated while the retina was being stimulated in accordance with the stimulus indicator (s 1 ; s 2 ; s 3 ); and combining the calculated products to generate the indication of the response of the retina to the light stimulus. <EOS>