The Skin Pathology assessment with Optical Technologies (SPOT) study aims to assess the feasibility of recently developed light-based skin imaging tools such as Optical Coherence Tomography (OCT) for the study of eczema (dermatitis [AD]).

Tools such as OCT have enabled us to see beneath the skin surface, allowing us to see changes in our skin which are hidden and impossible to assess by eye, simply by shining harmless light into the skin. The investigators want to understand what these changes represent in the broader context of eczema.

To do this, the investigators would like to recruit 60 volunteers who have a range of different eczema severities. The investigators would also like to recruit 20 healthy volunteers, who have never suffered from eczema. All volunteers would be aged between 11 and 60.

The study is based at the Royal Hallamshire Hospital in Sheffield, with consent and sample-collection taking place at either the hospital's Clinical Research Facility or the Sheffield Children's Hospital. The study consists of a single main visit, which is expected to take approximately 3 hours, and a short follow up visit 2-4 weeks later.

During the main study visit, the investigators will collect a range of measurements from the inner elbows and cheeks using harmless topical probes (Including OCT). These measurements include information about the skin's layers, blood flow, composition, water loss, acidity and redness. The investigators will also collect some samples, including tape-strips, a saliva sample and blood samples. For adult participants the investigators will also collect 2-4 skin biopsies from the inner elbows, which involves removing small pieces of skin under a local anaesthetic.

It is our hope that by demonstrating the advantages of new harmless imaging techniques, the investigators can reduce the need for invasive procedures in the future. Long term, this may help us to improve the way healthcare professionals monitor and treat eczema.

A total of 80 participants will be recruited for the study spread equally across 4 cohorts, those with healthy skin, and those with a mild/moderate/severe eczema/dermatitis [AD] lesion on their inner elbow.

Our first point of contact with the participant involves providing them with a copy of the age-appropriate PIS and completing an expression of interest (EOI) form through phone/email/post. The EOI form contains questions for pre- screening purposes so that the likelihood of suitability can be estimated in order to avoid wasting the time of people who clearly don't meet the basic entry criteria (severity will need to be assessed during the screening visit). For volunteers who meet the basic entry criteria as outlined on the EOI form, the investigators will make it clear that the next step will be for a researcher on our team to contact them to arrange a screening/informed consent session at our test facility.

A member of the team will then contact interested volunteers to arrange their visit, at least 24 hours following the provision of the PIS. The bulk of the study consists of a single visit, which contains the full screening process, informed consent and the study protocol (A second short follow up visit 2-3 weeks later is also required for those providing biopsies).

When the participant arrives at either the Sheffield Children's Hospital (For adolescents) or the Royal Hallamshire Hospital Clinical Research Facility (Adults), a nurse will talk the participant through the study and what it involves. They will also be asked some basic questions about their skin and current medication. Their skin will be inspected visually by eye to assess eligibility and cohort allocation. If the participant is eligible, then they will be required to fill in an informed consent form (11-15 year olds will complete an assent form, with their legal guardian completing a consent form).

Following consent, the participants will be taken to the Royal Hallamshire Hospital Skin Research room. They will be asked to roll up their sleeves such that their elbows are able to acclimatise for 20 minutes. While waiting, the scan sites will be marked on the participants elbows using a washable ink (Scan sites on the cheeks will not be marked with ink) and a skin questionnaire will be conducted which asks basic questions about the history of eczema at each scan site. When ready, images will be collected from the scan sites using handheld probes which gently contact the skin surface. All of the images collected are completely harmless, and simply involve shining light into the skin. The following measurements will be collected in order: Clinical Photographs (From elbows and cheeks), Trans-epidermal water loss measurements (From elbows and cheeks), skin redness (From elbows and cheeks), FTIR spectra (From elbows and cheeks), Optical Coherence Tomography (From elbows and cheeks), Laser doppler images (From elbows), Polarisation-sensitive Optical Coherence Tomography (From elbows) and skin pH (From elbows and cheeks).

Once the images are collected, some samples will be collected from the participant. These include a buccal (Saliva) sample collected from the cheek and tape-strip/FIBROTX samples collected from the elbows. Both of the latter sampling methods involve sticking a patch onto the skin and gently peeling it off, which collects just the molecules/cells at the surface of the skin.

Following this sample collection, the participants will be taken back to the Sheffield Children's Hospital (For adolescents) or the Royal Hallamshire Hospital Clinical Research Facility (Adults) and a total of three 5ml blood samples will be collected from their arm. Adult participants will be required to provide at least 2 biopsies from their elbow at this point, this involves small pieces of skin being removed under local anaesthetic so that they can be viewed under a microscope. A further 2 biopsies are optional depending on consent.

As mentioned above, participants that provided biopsies will be required to attend a follow-up visit 2-4 weeks later in order to remove any stitches and check the health of the biopsy site.

All research data collected in the pursuit of this study, will be collected in pseudo-anonymised form. For the purposes of this study, "pseudo-anonymised research data" is data that has had all personal identifiable information (such as name, initials and date of birth) replaced by the subject identifier (unique study number), and so protects the identities on the participants whilst still enabling the information to be traced back by the direct study team (who will have access to the study number allocation).

Following the study visit, the pseudo-anonymised electronic data will be stored on a secure Sheffield Corporate Information and Computing Services (CICS) managed server with access limited to study delegates only. Any paper records will be stored in locked cabinets in the study rooms/offices. Patch samples will be sent to FIBROTX for analysis - any remaining samples will be sent to a biobank where consent has been explicitly provided. The two required biopsies will be gifted to Leo Pharma who will undertake study specific analysis, any remaining tissue will be entered into a biobank hosted by BioStorage Technologies GmbH on behalf of Leo Pharma. The optional biopsies will be analysed by researchers at the University of Sheffield, any remaining tissue will be entered into the University Of Sheffield Biobank so that it can be made available for use on future research studies. The first blood sample will be processed by Laboratory Medicine at the Northern General Hospital in Sheffield, the second will be gifted to Leo Pharma, and stored in a biobank hosted by BioStorage Technologies GmbH where it will be available to LEO Pharma and their research partners, the third will be stored in the University of Sheffield Biobank. Extracted DNA (from the saliva samples) will be kept for a maximum of 10 years by the University of Sheffield in the care of the Principal Investigator, so that it may be used to support future genetic studies.

Electronic data from the study will be analysed at Sheffield following the study completion. Information from this study will be used to write scientific reports and publications, but they will not include any information which makes it possible for participants to be identified. A summary of findings will be distributed to all participants at the close of the study.

Inclusion Criteria:

Healthy subjects and AD patients

1. Male or female
2. Aged between 11-60 years
3. Volunteer understands the purpose, modalities and potential risk of the trial
4. Volunteers able to read and understand English
5. Volunteers willing to sign the informed consent

AD patients:

1. Volunteers with AD defined according to the UK working party diagnostic criteria
2. Must have an AD lesion present at either the right or left forearm (Proximal end).
3. For 10 participants in each AD group: visible AD lesion present on either the right or left cheek.
4. For 10 participants in each AD group: Global severity score (EASI) that matches their cohort allocation (Mild/Moderate/Severe).

According to the UK working party diagnostic criteria, eczema is defined as exhibiting an itchy skin condition plus 3 or more of:

• History of involvement of the skin creases
• Personal history of asthma or hay fever
• History of generally dry skin in past year
• Visible flexural dermatitis
• Onset below age 2

Instructions to participants 1. Do not ingest caffeine (e.g Coffee) or take anti-inflammatory drugs (e.g Ibuprofen) on the imaging day (until after imaging).

Exclusion Criteria:

1. Treatment with the following medications within 4 weeks: systemic immunosuppressive/immunomodulating drugs (e.g. methotrexate, cyclosporine, azathioprine, mycophenolate-mofetil, Janus kinase inhibitors, etc.), systemic corticosteroids.
2. Three or more bleach baths during any week within 4 weeks.
3. Treatment with biologics within 5 half-lives (if known) or 12 weeks.
4. Treatment with the following medications within 2 weeks if mild/moderate global severity or 1 week if severe global severity: topical corticosteroids, topical calcineurin inhibitors.
5. Treatment with any topical leave-on product on the test areas 7 days prior to participation if healthy/mild and 24 hours prior to participation if moderate/severe global severity.
6. Volunteers with acne, suntan, birth marks, multiple nevi, tattoos, blemishes or dense body hair that obstruct the test areas.
7. Volunteers with a condition that in the opinion of the investigator contradicts participation in the study.
8. Volunteer is incapable of giving fully informed consent.
9. Volunteers judged by the PI to be inappropriate for the trial.

Patient with atopic dermatitis/atopic eczema and Healthy Controls