Palpebral Fissure Response to Phenylephrine Indicates Autonomic Dysfunction in Patients With Type 1 Diabetes and Polyneuropathy

PURPOSE. The superior and inferior tarsal muscles are sympathetically innervated smooth muscles. Long-term diabetes often leads to microvascular complications, such as, retinopathy and autonomic neuropathy. We hypothesized that diabetes induces (1) sympathetic paresis in the superior and inferior tarsal muscles and that this measure is associated with (2) the severity of diabetic retinopathy, (3) the duration of diabetes, and (4) autonomic function. In addition, association between the severity of retinopathy and autonomic function was investigated. METHODS. Forty-eight participants with long-term type 1 diabetes and confirmed distal symmetrical polyneuropathy were included. Palpebral fissure heights were measured bilaterally in response to topically applied 10% phenylephrine to the right eye. The pres-ence of proliferative diabetic retinopathy (PDR) or nonproliferative diabetic retinopathy and disease duration were denoted. Time and frequency derived heart rate variability parameters obtained from 24-hour continuous electrocardiography were recorded. RESULTS. The difference in palpebral fissure heights between phenylephrine treated and untreated eyes (APFH) was 1.02 mm +/- 0.29 (P = 0.001). The APFH was significantly lower in the PDR group (0.41 mm +/- 0.43 vs. 1.27 mm +/- 1.0), F(1,35) = 5.26, P = 0.011. The APFH was lower with increasing diabetes duration, r(37) = & minus;0.612, P = 0.000. Further, the APFH was lower with diminished autonomic function assessed as total frequency power in electrocardiogram (r = 0.417, P = 0.014), and sympathetic measures of very low (r = 0.437, P = 0.010) and low frequency power (r = 0.384, P = 0.025). CONCLUSIONS. The APFH is a simple ambulatory sympathetic measure, which was associated with the presence of PDR, disease duration, and autonomic function. Consequently, APFH could potentially be an inexpensive and sensitive clinical indicator of autonomic dysfunction.

Automated summary

This study aimed to investigate the effects of diabetes on sympathetic paralysis in the superior and inferior tarsal muscles and its association with the severity of diabetic retinopathy, duration of diabetes, and autonomic function. The results showed that sympathetic paralysis in the tarsal muscles was associated with the presence of proliferative diabetic retinopathy, longer duration of diabetes, and diminished autonomic function.