['To describe changes revealed by Zeiss Preferential Hyperacuity Perimeter (PreView PHP) in age-related macular degeneration (AMD), before and after photodynamic therapy (PDT), and determine usefulness of such monitoring.', 'Forty patients (40 eyes) with subfoveolar choroidal neovascularization (CNV) and 20 volunteers with cataract (40 eyes) were examined in a prospective study. Control group was screened for false positive results to evaluate reliability of the test. Subfoveolar CNV was confirmed by fluorescein angiography and optical coherence tomography (OCT). Best-corrected visual acuity (BCVA) and macular visual field in the PHP (area and intensity of distortion) were assessed 1 day before and 1 week and 4 weeks after PDT.', 'Four weeks after PDT there was improvement in PHP results in 20 eyes (50%), stabilization in 15 eyes (37.5%) and progression in 5 eyes (12.5%). At this time there was BCVA improvement in 9 eyes (22.5%), stabilization in 28 eyes (70%), and worsening in 3 eyes (7.5%). 1 week after PDT 30 eyes (75%) presented temporary progression in PHP but only 3 patients (7.5%) presented temporary decrease of visual acuity and progression in OCT. Correlation coefficient of BCVA and PHP results was low during whole study. There was no significant change in control group during observation. 17.5% false positive PHP results were obtained at baseline. In the PDT group no false negative results were noted.'] Does monitoring of photodynamic therapy result in age-related macular degeneration by means of preferential hyperacuity perimeter?