Clinical Trials Logo

Clinical Trial Details — Status: Completed

Administrative data

NCT number NCT01549132
Other study ID # EKHT RETINAL RESEARCH UNIT
Secondary ID
Status Completed
Phase
First received
Last updated
Start date April 2012
Est. completion date March 2014

Study information

Verified date September 2023
Source East Kent Hospitals University NHS Foundation Trust
Contact n/a
Is FDA regulated No
Health authority
Study type Observational

Clinical Trial Summary

The investigators believe that oxygen saturation measurements in the retina may provide more information on how well the retina is working and may detect problems in the retina earlier than the fundus fluorescein angiography (FFA). This may be useful to an ophthalmologist so that they may identify abnormal areas of the retina and commence or change the treatment so that they may prevent irreversible blindness. Most patients with clinically significant macular oedema and/or ischaemic diabetic retinopathy could have either laser or Intravitreal Anti-VEGF injection treatment provided they are counseled about the risks. It is known the Anti-VEGF injections reduce oedema and it is believed that laser treatment of the retina in this condition improves the oxygen supply to the retina and sometimes reverses the damage. It will be useful to take pictures of these treated eyes using the Oxymap spectral retinal camera(s) to see whether the investigators can detect a change in the oxygen saturation in the retina before and after treatment using our oxygen saturation methods.


Description:

WHAT IS SPECTRAL IMAGING? This is a way of studying in detail an area that is being imaged. This can be done because each picture of the same area is taken using different colours of light (wavelength). Different materials in the picture will absorb and reflect the different wavelengths of light from a hyperspectral camera differently. It is then possible to look at each point in the picture and work out what is in the picture. This has been used in satellites and aeroplanes to identify what is on the ground. For example, it can distinguish the different types of trees on the ground based on the different way they absorb and reflect different wavelengths of light. USING SPECTRAL IMAGING IN MEDICINE. Spectral imaging was found to have uses in medicine because of its ability to distinguish one thing from another. A lot of Spectral imaging research has been done to measure the amount of oxygen in the blood. This is because oxygen is important to all living cells in the human body - without it cells would die or stop working. Oxygen is carried to living cells by blood in blood vessels known as arteries and the left over is carried away by veins. Most of the oxygen in the blood is transported by cells in the blood containing a chemical called haemoglobin. There are two main forms of haemoglobin called oxyhaemoglobin (haemoglobin binds to oxygen) and deoxyhaemoglobin (haemoglobin that is not bound to oxygen). The proportion of oxyhaemoglobin to the total amount of haemoglobin (both oxyhaemoglobin and deoxyhaemoglobin) is called the oxygen saturation and is presented as a percentage. The normal saturation in the artery is about 97% because it contains more oxyhaemoglobin and in the vein it is about 75% because it contains less oxyhaemoglobin. Importantly oxyhaemoglobin (HbO2) and deoxyhaemoglobin (Hb) have different spectral characteristics - i.e they absorb light differently at various wavelengths of light. This has been extensively documented in various publications using samples of blood. This property is the basis of pulse oximetry which is the measurement of the oxygen saturation (OS) in the finger tip using a saturation probe which is commonly used in the hospital. The different spectral characteristics of Hb and HbO2 can also be used in spectral imaging to calculate the amount of each in the blood to perform oxygen saturation measurements in certain parts of the body. This has previously been used to study the oxygen supply in the skin and also to look at the oxygen supply in patients with diabetes which is a condition that is caused by a lack of a hormone called insulin causing high amount of sugar in the blood resulting in damage to the blood vessels. Spectral imaging has only recently started to be used in imaging the eye. The main emphasis of Spectral imaging in ophthalmology has been on measuring the oxygen saturations in the retina (the layer at the back of the eye that allows us to see). This is called retinal oximetry. In essence, the principles of retinal oximetry are similar to that of pulse oximetry, i.e using the different spectral characteristics of Hb and HbO2 to calculate the oxygen saturation. In diabetic retinopathy, the only way the investigators can study the blood supply is by performing a Fundus Fluorescein Angiogram (FFA). This is an invasive test which involves the injection of a dye into the arm, this dye is transported by blood to the eye and pictures of the blood vessels are taken with the dye in it. Also, importantly, there are side effects (sometimes life-threatening) to injecting this dye into the arm. If there is a problem with the blood supply in the retina then the dye will not fill up in the blood vessel and is seen in the pictures as a black area. The FFA provides information on the blood supply but not directly on the amount of oxygen in it. Loss of sight from diabetic retinopathy and age-related macular degeneration is believed to be caused by a reduction in the amount oxygen being supplied to the retina by the blood vessels. The investigators believe that oxygen saturation measurements in the retina using spectral imaging could be a more useful test for an ophthalmologist because it may provide more information on how well the retina is working and may detect problems in the retina earlier than the FFA. This may be useful to an ophthalmologist so that they may identify abnormal areas of the retina and commence or change the treatment so that they may prevent irreversible blindness.


Recruitment information / eligibility

Status Completed
Enrollment 45
Est. completion date March 2014
Est. primary completion date March 2013
Accepts healthy volunteers No
Gender All
Age group N/A and older
Eligibility Inclusion Criteria: - Diabetic Retinopathy affecting the central retina (designated maculopathy) - No contraindications to pupil dilation - Ocular media sufficiently clear to enable retinal imaging - Pupils which can be dilated (i.e not using miotic medication) - Willingness to participate with the research study and formal consent obtained. Exclusion Criteria: - Narrow drainage angles or any other contraindication to being dilated. - Dense cataracts or other ocular media opacities inhibiting a good view of the retina on fundoscopy

Study Design


Related Conditions & MeSH terms


Locations

Country Name City State
n/a

Sponsors (1)

Lead Sponsor Collaborator
East Kent Hospitals University NHS Foundation Trust

Outcome

Type Measure Description Time frame Safety issue
Primary Retinal oximetry differences in patients with sight threatening diabetic macular oedema after treatment Does retinal oxygen levels in small blood vessels as measured by spectral imaging photography using the oxymap device at the centre of the retina (macula) differ in diabetic retinopathy in sight threatening disease? 1 year
See also
  Status Clinical Trial Phase
Active, not recruiting NCT00403884 - Selective RPE Laser Treatment (SRT) for Various Macular Diseases N/A
Recruiting NCT03571217 - Shanghai Beixinjing Diabetic Eyes Study
Completed NCT01689090 - Diameter Changes of Retinal Vessels During Hypoxia N/A
Withdrawn NCT04853355 - Non-Responsive Diabetic Macular Edema and Spironolactone Phase 4
Recruiting NCT03750149 - Reading Analysis in Ophthalmologic Patients N/A
Completed NCT00873106 - Retinal Thickness and Volume Estimates Given by Time Domain and Spectral Optical Coherence Tomography N/A
Recruiting NCT05169502 - Discovering Early Biomarkers in Circulating Endothelial Cells for Diabetes Complications by Single Cell RNA Sequencing
Not yet recruiting NCT04699864 - Evaluation of NeoRetina Artificial Intelligence Algorithm for the Screening of Diabetic Retinopathy at the CHUM N/A