Research licence agreement to access CCMetrics and ACCMetrics software


CCM represents a rapid (5-8 minutes) technique to image corneal c-fibres in subjects with peripheral neuropathy. CCM images are captured from the central / peri-central region of the cornea in the sub-basal layer using a Heidelberg HRT III confocal laser scanning microscope. Nerve fibres in CCM images from patients display different lengths, widths, patterns and orientations. In expert manual measurement of nerve fibres three main metrics have been used to date: Nerve fibre length (NFL), Nerve fibre density (NFD) and Nerve-branch density (NBD).

Manual quantification of nerve fibre morphology is highly labour intensive (~10-20 min) and requires a trained expert. With funding from the JDRF, we have developed ACCMetrics, an algorithm to extract and automatically quantify nerve fibres providing an output for all the main nerve parameters either for single images or for multiple images/patient in minutes rather than hours.


In order to fill in the online license agreement form, please create an account

Please email us at if you need any help.

CCMetrics user instructions

CCMetrics: Overview

CCMetrics is an image analysis software which was originally developed for manual quantification of nerve fibre metrics from IVCCM images (Dabbah et al. 2010). CCMetrics allows quantification of nerve fibre metrics in images obtained using the Heidelberg HRT III corneal confocal microscope.

It quantifies the following nerve fibre parameters from IVCCM images with a field of view of 400x400 um2:

  • Nerve Fibre Length (NFL): the total length of all nerve fibres in the whole image in mm/mm2
  • Nerve Fibre Density (NFD): the number of main nerve fibres per mm2
  • Nerve Branch Density (NBD): the number of intersections between the main nerves and secondary nerves per mm2
  • Nerve Fibre Tortuosity (NFT)

CCMetrics training

A 2 day practical hands on course has been established in Manchester to train researchers in CCM image acquisition and image analysis. To book yourself on a course please contact us at

The picture above of Corneal Confocal Microscopy (CCM) was taken by Georgios Ponirakis

ACCMetrics user instructions

ACCMetrics: Overview

ACCMetrics V.2 has been further refined to automatically extract and quantify nerve fibre metrics more consistently in images obtained using the Heidelberg HRT III corneal confocal microscope. The detection of nerve structures in IVCCM images is a challenging task: nerve fibers often show poor contrast on a relatively noisy background due to microscope properties and underlying structures. Automated corneal nerve fiber quantification consists of two steps: (1) IVCCM image enhancement and nerve fiber detection and (2) quantification of the morphometric parameters. A dual-model feature descriptor combined with a neural network classifier was used to train the computer to distinguish nerve fibers from the background (noise and underlying connective tissue). In the nerve fiber quantification process, all the end points and branch points of the detected nerve fibers are extracted and used to construct a connectivity map. Each segment in the connectivity map is then connected and classified as main nerve fibers or branches. Each automated parameter was shown to correlate highly significantly with manual data.

Nerve fibre parameters quantified:

  • Nerve Fibre Density (CNFD): The number of fibres per mm2.
  • Nerve Branch Density (CNBD): The number of branch points on the main fibres per mm2 - green points in the annotated image.
  • Nerve Fibre Length (CNFL): The total length of nerves mm per mm2.
  • Nerve Fibre Total Branch Density (CTBD): The  total  number of  branch points per mm2.
  • Nerve Fibre Area (CNFA): The total nerve fibre area mm2 per mm2.
  • Nerve Fibre Width (CNFW): The average nerve fibre width mm per mm2.
  • Nerve Fibre Orientation Histogram: The number of occurrences of different fibre orientations covering the range between 0 and 179, at 5 degree intervals.
  • Nerve Fibre Width Histogram: The  number  of occurrences  of  different fibre widths covering the range between 1 and 8 pixels, at 0.2 pixel intervals.

Benefits of ACCMetrics

  • Quantifies nerve parameters either for single images or for multiple images/patient in minutes compared to the manual assessment, which takes hours.
  • Allows objective corneal nerve quantification and eliminates inconsistencies.
  • Produces comparable outcomes across centres.
  • Enables the deployment of IVCCM for diagnosis in the clinic and as a surrogate end point in clinical trials of peripheral neuropathies.

Validition of ACCMetrics

The evaluation of ACCMetrics was conducted on a database that contained 1494 IVCCM images captured from 186 diabetic patients and 55 age-matched control subjects. ACCMetrics was highly correlated with human expert analysis for the three main corneal nerve morphometric parameters (r CNFD = 0.90, P < 0.0001, r CNFL = 0.89, P<0.0001 and r CNBD  = 0.75, P<0.0001) and showed the highest validity in identifying patients “with” or “without” neuropathy based on gold standard measures of peripheral nerve damage and in relation to human analysis (figure 1).

Figure 1. ROC curves for manual (solid black) and automated (red) CNFD (A), CNBD (B) and CNFL (C). CNFD and CNFL showed the highest validity to diagnose diabetic peripheral neuropathy with comparable AUCs (no significant difference). Manual CNFD and automated CNFL were associated with the highest odds ratio. 

Automated CNFD and CNFL were consistently associated with the highest sensitivity and specificity to classify patients “with” or without neuropathy.

ACCMetrics installation and Usage Instructions

ACCMetrics installation instructions

Process single CCM image

Process multiple CCM images

Collaborators: Overview

We have helped to establish protocols for IVCCM image acquisition and provided ACCMetrics for clinical trials and research purposes. Collaborators who have used the ACCMetrics are from countries including UK, Canada, Australia, USA, China, Japan, Russia, Germany, Spain and Turkey.

Collaborator Institution Town Country Use of ACCMetrics
Prof. Nathan Efron QUT Brisbane Australia CCM metrics are being compared to other measures of neuropathy in cross sectional and longitudinal studies
Prof. Henri Parson & Prof. Arthur Vinik Eastern Virginia Medical School West Virginia US Differentiate between patients who have received active treatment and those who experience painful diabetic neuropathy
Dr. Gulfidan Bitirgen Meram Faculty of Medicine, Necmettin Erbakan University Konya Turkey Evaluate corneal microstructure in eyes with keratoconus 
Dr. Pablo Villoslada IDIBAPS, Hospital Clinic of Barcelona Barcelona Spain Analyse the dynamics of axonal damage after chemotherapy and identify predictors of neuropathy and nerve regeneration
Dr. Sanjeev Sharma The Ipswich Hospital NHSTrust, Ipswich Surrey UK CCM comparative values as biomarkers to diagnose and assess progression of neuropathy 
Dr. Chenying Yu Department of Ophthalmology, Peking Union Medical College Hospital Beijing China Assess areas affected by refractive surgery and keratopathy. We noticed that some post-LASIK patients' symptoms of dry eye persisted beyond usual recovery period, and we assumed that the regeneration of corneal nerves might play a role in the development and persistence of postoperative dry eye.
Prof. Gagik Galstyan & Dr. Dmitry Atarshchikov Endocrinology Research Center Moscow Russia Identify any associations between lesion in retina and extent of small fiber nerve damage.
Dr. Gordon Smith Division of Neuromuscular Medicine ,University of Utah School of Medicine Utah US CCM metrics are being compared to other measures of neuropathy in cross sectional and longitudinal studies
Dr. Akihiko Ando Jichi Medical University Tochigi Japan Cross-sectional study assess the association between retinal wall thickness and CCM
Dr Daniele Pacaud Alberta Children’s hospital & University of Calgary Calgary Canada Perform CCM on children with T1 diabetes
Dr. Gene Kim Robert Cizik Eye Clinic, Medical School at Houston, University of Texas Houston Study the effects of different corneal wounds caused by cataract surgery and their effects on the corneal nerve moprhology in the pathogenesis and treatment of dry eyes.
Ms. Jasleen Jolly Optometry Department, Oxford Eye Hospital Oxford UK CCM assessments on pancreas and kidney, and islet cells transplant patients before and after transplant
Dr. Marc Schargus University Eye Hospital Bochum Bochum Germany Use CCM to assess patients with neurological and pain related disease.
Dr. Michael Brines Araim Pharmaceuticals  Inc New York US Use CCM to analyse the potential efficacy of ARA 290 on the re-growth of small nerve fibre in patients with diabetes or sarcoidosis
Dr. Chintan Malhotra PGIMER Chandigarh India Use CCM to study nerve fibre alterations in different type of neuropathies (including diabetic neuropathy).
Dr. Szalai Eszter Department  of Ophthalmology, University of Debrecen Debrecen Hungary We are comparing different corneal parameters of young T1DM patients with and without diabetic retinopathy.
Dr. Sonja Puttgen German Diabetes Center at Heinrich Heine University Dusseldorf Germany We use ACCMetrics on a cooperation with Prof. Malik from your university regarding the differences between painful and painless diabetic polyneuropathy in the PROPANE study.
Dr. Mark Stettner  Department of Neurology, Heinrich-Heine-University Heinrich-Heine Germany Study chronic autoimmune inflammatory disorders of the peripheral nervous system
Dr. Stuti Misra (clinician) & Dr. Jason Turuwhenua (Engineer) Department of Optometry and Vision Science, University of Auckland Auckland New Zealand Quantify the phenotypic characteristics of the cornea by CCM in patients with a new diagnosis of keratoconus
Mr Karsten Winter University of Leipzig Leipzig Germany  
Mrs. Milla Rosengård-Bärlund| Folkhälsan Institute of Genetics, Biomedicum Helsinki Helsinki Finland Study the significance of low baroreflex sensitivity as a marker of autonomic dysfunction on a 10-year follow-up visit of 140 patients.
Mr. Kirwan Asselineau LSMU, Eiveniu gatve Kaunas Lithuania A 3 year research study which aim is to establish a baseline in a healthy population of sub-basal nerve plexus characteristics 
Prof. Antonio Miguel Morgado Department of Physics, University of Coimbra Coimbra Portugal Analyse CCM images of the sub-basal nerve plexus and use that analysis as a reference in the development of peripheral diabetic neuropathy assessment methods based on image texture analysis. 

What collaborators say about the performance of the ACCMetrics

“We have applied the ACCMetrics to quantify nerve fibre morphology in the sub-basal nerve plexus to assess neuropathy in patients undergoing chemotherapy and patients with fibromyalgia. ACCMetrics is very easy to use and provides very useful information” Dr Pablo Villoslada
The August Pi i Sunyer Biomedical Research Institute
“We have applied the ACCMetrics to quantify nerve fibre morphology in patients with keratoconus. The new version of ACCMetrics works perfectly and quantifies the nerve fibers and branches excluding the dendritic cells; which, in my opinion, is the most significant improvement comparing with the previous version” Dr Gulfidan Bitirgen Meram
Necmettin Erbakan University
“We have used the ACCMetrics to compare CCM with modified LDIflare to determine their comparative values as biomarkers to diagnose and assess progression of small fibre neuropathy” Dr Sanjeev Sharma
The Ipswich Hospital NHS Trust