This prospective study was was divided into 2 parts and carried out at 2 sites in Germany.

Part 1 assessed Repeatability in healthy, non-diabetic population (Group "control").

Part 2 collected data to evaluate the diagnostic and prognostic value of using Heidelberg Engineering Retina Tomograph (HRT) 3 with the Rostock Cornea Module EyeGuidance functional module (HRT RCM-E) in subjects with early to moderate DPN (Groups"none" and "mild", respectively).

Part 1 aimed to evaluate the diagnostic and prognostic value of the optimized dynamic composite corneal nerve plexus image acquisitions done with HRT RCM-E compared to standard static composite image acquisition with Heidelberg Engineering Retina Tomograph (HRT) 3 with the Rostock Cornea Module (HRT RCM).

The part 2 (research part) evaluated changes in corneal nerve plexus parameters in diabetes patients without or with early to moderate Diabetic Peripheral Neuropathy (DPN) and correlated the observed changes with progression of early DPN.

Inclusion Criteria:

• All

  • Able and willing to undergo the test procedures, give consent, and to follow instructions.
  • Signed informed consent.
  • ≥18 years.

• Part 1, Site 1

  • Normal eyes of patients without Diabetes Mellitus
  • Fasting blood glucose < 100 mg/dl
  • HbA1c ≤ 6.5%

• Part 2, Site 2

  • Diabetes Mellitus Type 2 without coexisting DPN (NSS score ≤2 and / or NDS score ≤2)
  • Diabetes Mellitus Type 2 with coexisting early to moderate DPN. (NSS score 3-4 and / or NDS score 3-5)
  • 6.5% < HbA1c ≤ 9.5%

Exclusion Criteria:

• Vulnerable subjects (Such as: individuals with lack of or loss of autonomy due to immaturity or through mental disability, persons in nursing homes, children, impoverished persons, subjects in emergency situations, homeless persons, nomads, refugees, and those incapable of giving informed consent. Other vulnerable subjects include, for example, members of a group with a hierarchical structure such as university students, subordinate hospital and laboratory personnel (if linked to CI site), employees of the sponsor, members of the armed forces (if linked to CI site or sponsor), and persons kept in detention.)
• Subjects unable to read or write
• Contact lens wearers (soft and rigid)
• Patients with symptomatic dry eye
• Patients with conjunctivitis at the time of inclusion
• Patients with history of corneal surgery
• Patients with diabetic retinopathy
• Patients with history of neuronal diseases that according to the expertise of the investigator might have an influence on corneal nerve fiber plexus