PURPOSE: To assess if drusen volume can serve as structural clinical outcome marker in Malattia Leventinese, and to evaluate whether cones or rods are more affected by its progression, using multimodal imaging and mesopic and two-color scotopic microperimetry. METHODS: This was a prospective monocentric cross-sectional cohort study of participants with genetically confirmed Malattia Leventinese. Participants were classified according to morphology. Mean drusen volume, calculated from spectral-domain optical coherence tomography, was compared with microperimetry parameters (mesopic retinal sensitivity, scotopic red and cyan function, difference between scotopic cyan-red function). RESULTS: Fourteen participants (28 eyes) were enrolled. Mean drusen volume increased (bilaterally P = 0.028) and mesopic retinal sensitivity decreased with later stage (right eye: P = 0.028
left eye: P = 0.050). Scotopic microperimetry showed that scotopic cyan function was lower than scotopic red function in moderate stage. Scotopic red function decreased in severe stage. Mean drusen volume correlated to mesopic retinal sensitivity (right eye: P <
0.002
left eye: P = 0.007). CONCLUSION: Retinal sensitivity diminishes with Malattia Leventinese progression. Rod function declines before cone function, whereas at late stages, cone loss predominates. Drusen accumulation, initially speckled around the macula and optic disc and confluent with disease progression, correlates well with visual function loss and impaired quality of life. Thus, therapeutically reducing drusen accumulation could be efficacious.