Examining the added value of microperimetry and low luminance deficit for predicting progression in age-related macular degeneration

Purpose: To examine the added predictive value of microperimetric sensitivity and low luminance deficit (LLD; difference between photopic and low luminance visual acuity (VA)) to information from colour fundus photography (CFP) for progression to late age-related macular degeneration (AMD) in individuals with bilateral large drusen. Methods: 140 participants with bilateral large drusen underwent baseline microperimetry testing, VA measurements and CFP. They were then reviewed at 6-monthly intervals to 36 months, to determine late AMD progression. Microperimetry pointwise sensitivity SD (PSD), LLD and the presence of pigmentary abnormalities on CFPs were determined. Predictive models based on these parameters were developed and examined. Results: Baseline microperimetry PSD and presence of pigmentary abnormalities were both significantly associated with time to develop late AMD (p≤0.004), but LLD was not (p=0.471). The area under the receiver operating characteristic curve (AUC) for discriminating between eyes that progressed to late AMD based on models using microperimetry PSD (AUC=0.68) and LLD (AUC=0.58) alone was significantly lower than that based on CFP grading for the presence of pigmentary abnormalities (AUC=0.80; both p<0.005). Addition of microperimetry and/or LLD information to a model that included CFP grading did not result in any improvement in its predictive performance (AUC=0.80 for all; all p≥0.66). Conclusions: While microperimetry, but not LLD, was significantly and independently associated with AMD progression at the population level, this study observed that both measures were suboptimal at predicting progression at the individual level when compared to conventional CFP grading and their addition to the latter did not improve predictive performance.