By Taytum Woest – B.Optom (UJ)

Biomarkers, or biological markers are biological measures of a biological state. Biomarkers are characteristics that can be objectively measured and gives us an indication of normal biological processes, pathogenic processes, or pharmacological response to therapeutic intervention.

Biomarkers should be able to be measured accurately and the results must be reproduceable. 

For medical professionals to be able to make decisions, we need as much information as possible. The information that we gather can fall into two categories:


  • Signs are objective measures that we can observe or measure. This is where the biomarkers come in.

Biomarkers are simply the most objective, quantifiable medical signs modern laboratory science allows us to measure reproducibly.

  • Symptoms refer to what our patients tell us. What are they experiencing? When did it start and how often does it occur? This is a subjective measure because we rely on our patient to give us the information.

There are 4 types of biomarkers:

  1.  Molecular biomarkers can be measured in biological samples such as plasma, serum, and cerebrospinal fluid. An example of a molecular biomarker is blood glucose.

  2. Radiographic biomarkers can be observed and measured through images for example bone mineral density.

  3. Histological biomarkers represent any changes in cells, tissue or fluid, for example grading and staging of cancers.

  4. Physiological biomarkers are obtained by measuring body processes such as blood pressure.

Biomarkers can be useful in early disease detection, disease prevention, determining a patients disease risk and monitoring diseases. They can also be used to measure the safety or toxicity of treatments or environmental exposures.

There are biomarkers for every major system in the body from cardiovascular to respiratory and nervous system.

*** The EYE is no different. Biomarkers are used in early detection of Diabetic retinopathy through imaging of the retina. Biomarkers are also used in early detection of age-related macular degeneration. Recently artificial intelligence has been approved for screening of diabetic retinopathy by using machine learning and deep learning to analyse retinal images and to scan for biomarkers that indicate early diabetic retinopathy.

*** Optometrists are trained to look for biomarkers present in the eye that can indicate possible pathology as well as monitoring ocular diseases. It is therefore very important to have regular eye tests done, not only to make sure you are still seeing clearly, but also to look out for any possible eye diseases.