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Clinical protocol

Clinical protocol for the identification and management of Visual Stress 

The Visual Stress assessment and the Intuitive Colorimeter™ assessment follow a strict protocol and use a defined list of diagnostic criteria. The assessments are designed to help individuals gain a better understanding of:

  • how various triggers in the visual environment can lead to discomfort and difficulties; 

  • how to identify, manage and reduce triggers; and 

  • which assistive tools and technologies are available. 

This clinical protocol was initially outlined by the College of Optometrists in the United Kingdom, supported by the International Institute of Colorimetry, and published in 1995 in the Journal of Ophthalmic & Physiological Optics. A further study published in 2016 identified practical diagnostic guidelines for identifying Visual Stress. 


The clinical protocol, strictly followed by Opticalm and their provider network, was used as the framework for the development of the Visual Stress and Intuitive Colorimeter™ assessments. The assessments were designed to assist individuals with visual systems that are hypersensitive and/or compromised. These individuals are pre-qualified using diagnostic criteria, including the diagnosis of specific neurological and conditions and the experience of any particular set of sensitivities and difficulties. 

assessment with patient and clipboard

1. Eye examination

When an individual experiences problems with their vision, including reading difficulties, blurriness, eyestrain, or headaches, following a visual task, they should start by consulting with an optometrist. Opticalm’s provider network includes eye care professionals who offer comprehensive vision assessments, investigating eye health, refractive error, and other vision-related conditions that may be contributing to their symptoms.

Individuals should fill their new prescriptions before booking a Visual Stress assessment. 

The five (5) steps of the clinical protocol

2. Screening for Visual Stress using diagnostic criteria 

Opticalm has developed screening tools to help individuals and their healthcare providers identify if Visual Stress may be contributing to symptoms and difficulties.

  • The free pre-screening test explains the diagnostic criteria using informative videos and material to assist individuals in completing the screening. At the end of the test, the system produces a report, provides resources to address symptom management and reduction, and elaborates on the next possible steps.

  • Healthcare practitioners use the referral form to screen patients before referring them for Visual Stress and Intuitive Colorimeter™ assessments with an Opticalm provider.

  • Providers have access to a more detailed diagnostic indicator form that the patient completes before attending the initial Visual Stress assessment. 

3. Visual Stress assessment

Once a pre-screening has been completed, the Visual Stress assessment is the next step. It includes several tests to establish the existence of Visual Stress and to identify the impact of colour. Independent tests for pattern sensitivity, perceptual distortions, and rate of reading improvement are performed to confirm the diagnosis of Visual Stress, identify visual triggers, and capture their perceptual distortions. During the assessment, visual environmental modifications and accommodations are identified and recommended, and a report is produced.

4. Intuitive Colorimeter™ assessment

The Intuitive Colorimeter™ is a medical instrument that systematically and independently samples hue (360 degrees of colour), saturation (50 degrees of saturation), and luminance (4 levels of brightness) to arrive at a precise colour that could reduce the sensitivities and difficulties related to a patient’s Visual Stress. During the assessment, several additional steps are taken, such as:

  • the optimal filter lens is trialed under different lighting conditions, environments, & tasks; 

  • other filter lens specifics are identified (refraction prescription/frame details);  

  • additional modifications and accommodations are identified and recommended; and 

  • a comprehensive report is produced. 

This testing process effectively identifies the presence of Visual Stress and its triggers.

5. Tint update assessment

Whether precision tinted lenses were prescribed to help manage post-concussion sensitivities, anxiety, headaches, or to help with learning-related reading and concentration issues, over time, the brain may adapt, causing changes in the effectiveness of the lens tint.

The tint update assessment works towards reducing the need for accommodations. In other words, reducing the grey levels and saturation of the filter hue as the individual’s brain becomes more tolerant of the visual triggers causing symptoms. Note that this is not the case for every individual, as some related conditions may influence the rate of recovery.

When any vision change is noticed, a complete vision assessment by an optometrist is highly recommended to investigate eye health or refractive error needs before a tint update assessment. 

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