Photoreceptor Characteristics in Diabetic Retinopathy vs Controls Using Adaptive Optics Imaging: Systematic Review

Purpose: To assess the differences in morphological photoreceptor outcomes measured using adaptive optics (AO)-assisted imaging between individuals with diabetes or prediabetes and healthy controls. Methods: A systematic search was conducted across MEDLINE, Embase, and Cochrane databases from January 2000 to June 2023. Studies that used AO-assisted imaging modalities to quantitatively compare photoreceptor outcomes in patients with diabetes or prediabetes with healthy controls were included. Results: Eleven studies consisting of 551 eyes were included. Most studies reported significant differences in photoreceptor outcomes between diabetic and healthy populations, particularly as diabetic retinopathy (DR) severity increased. Cone regularity was the most sensitive parameter for detecting significant differences between groups. AO imaging was less reliable in distinguishing individuals with diabetes without DR or with mild DR severity from controls. Conclusions: AO imaging showed promise in detecting significant differences associated with diabetes and DR, in particular with increasing disease severity. Further research is warranted to assess AO's utility as a diabetes and DR screening tool. Standardizing imaging protocols in future studies is recommended to allow for more direct quantitative comparisons. These findings highlight the current evidence on photoreceptor changes in patients with diabetes and the potential of AO in advancing diabetic eye care.