Correlation of the pilo-pupil ratio average, a new test for autonomic denervation, to the severity of diabetic retinopathy

Can J Ophthalmol. 1997 Apr;32(3):170-4.


Objective: To evaluate the association between the degree of diabetic retinopathy and autonomic neuropathy, and to test whether ocular parasympathetic denervation is correlated to the degree of diabetic retinopathy.

Design: Cross-sectional pilot study.

Setting: The tertiary ophthalmic centre for the Atlantic provinces in Halifax.

Patients: Twelve randomly selected patients (six women and six men with a mean age of 36.6 years) with insulin-dependent diabetes mellitus who had diabetic retinopathy.

Outcome measures: Degree of diabetic retinopathy, hemoglobin Alc level, orthostatic change in systolic and diastolic blood pressure and in serum catecholamine levels, degree of pupillary supersensitivity to 0.125% pilocarpine (pilo-pupil ratio average [PPRA]).

Results: The degree of diabetic retinopathy was significantly correlated with the duration of diabetes (p = 0.035), the hemoglobin Alc level (p = 0.004), the orthostatic change in diastolic blood pressure (p = 0.022) and the PPRA (p = 0.0007).

Conclusions: The degree of diabetic retinopathy was significantly correlated with autonomic neuropathy and with the PPRA. Given these results, further study is indicated to determine whether autonomic neuropathy is a predictor of the severity of diabetic retinopathy.

Publication types

  • Clinical Trial
  • Randomized Controlled Trial

MeSH terms

  • Adult
  • Autonomic Denervation
  • Autonomic Nervous System Diseases / diagnosis*
  • Autonomic Nervous System Diseases / physiopathology
  • Blood Glucose / metabolism
  • Blood Pressure
  • Catecholamines / blood
  • Cross-Sectional Studies
  • Diabetes Mellitus, Type 1 / blood
  • Diabetes Mellitus, Type 1 / complications
  • Diabetic Retinopathy / complications
  • Diabetic Retinopathy / diagnosis*
  • Diabetic Retinopathy / physiopathology
  • Female
  • Humans
  • Iris / innervation*
  • Male
  • Middle Aged
  • Ophthalmic Solutions
  • Parasympathetic Nervous System / drug effects
  • Parasympathetic Nervous System / physiopathology
  • Parasympathomimetics*
  • Pilocarpine*
  • Pilot Projects
  • Predictive Value of Tests
  • Pupil / drug effects*
  • Pupil / physiology
  • Retrospective Studies


  • Blood Glucose
  • Catecholamines
  • Ophthalmic Solutions
  • Parasympathomimetics
  • Pilocarpine