To investigate the impact of diabetic retinopathy of varying severity on sleep.

Abstract

Purpose: Sleep is essential for life and the body’s metabolic systems require sleep of good quantity and quality for their proper functioning. Glucose metabolism can be affected adversely by several sleep disorders. Retinal ganglion cells have been reported to be affected by diabetes. Melanopsin-retinal ganglion cells (mpRGCs) are integral to the entrainment of 24-hour circadian cycle with rods and cones also involved. The purpose of our study is to investigate the impact of diabetic retinopathy on sleep in patients with varying severity of retinopathy.

Methods: Patients attending diabetic retinopathy clinics with no significant ocular co-morbidities completed the self-rated Pittsburgh Sleep Quality Index (PSQI) to assess subjective sleep quality and a Hospital Anxiety and Depression scale (HADS). The PSQI scores seven different sleep components (scale of 0 to 3), combined to produce a global sleep score of 0 to 21. A PSQI score ≥6 indicates poor sleep. The HADS scale consists of 14 questions, 7 items for depression (HADS-D) and 7 for anxiety (HADS-A) combined to produce a score of 0-21.Using ETDRS grading, patients were allocated to 3 groups depending on severity of retinopathy: no/mild 10-35, moderate 35-53, severe >61. Statistical analysis was performed using SPSS.

Results: 327 patients participated, (110 were excluded due to ineligibility/incomplete data). 217 completed questionnaires were analysed. The mean PSQI score across the three diabetic retinopathy severity groups did not reveal a statistically significant difference (mild =5.10, moderate =5.18, severe =5.45 p >0.05). Spearman’s correlation was significant with global PSQI and HADS-A, r = 0.254 (p <0.001) and HADS-D, r = 0.424 (p <0.001) but not with EDTRS score, r = 0.053 (p =0.427) and r = -0.010 (p=0.878).

Conclusions: Our study showed that no significant differences in the PSQI and HADS with increasing stages of diabetic retinopathy. The HADS did however correlate to global sleep quality suggesting that anxiety and depression score increases with decrease in sleep quality. Presumably therefore there are enough functioning melanopsin cells and or rods and cones for entrainment to be unaffected even in moderate and severe stages of diabetic retinopathy.

Keywords: 689 retina: distal (photoreceptors, horizontal cells, bipolar cells) • 648 photoreceptors • 499 diabetic retinopathy