This is a double-masked randomized controlled trial which aims to assess the effects of precision tinted spectacle lenses on visual stress symptoms within an undergraduate University student population.

The participants will be recruited from the undergraduate Ulster University student population. Those students who have been identified as potentially having visual stress will be invited to undergo screening tests to assess their eligibility to participate in the randomized controlled trial.

Visit 1:

Each consenting participant will undergo tests to assess their eligibility to participate in this study.

Provided the participant meets the inclusion criteria then they will undergo a baseline eye examination and reading tests including the Wilkins Rate of Reading test (WRRT).

The participant will then undergo colorimetry testing using the Intuitive colorimeter (Cerium TM) using the established procedure to individually measure the optimum chromaticity which alleviates visual stress symptoms for each participant. This will be the 'experimental' colour. A second colour will be measured at which visual stress symptoms will be present, this colour will not be aversive to the participant and will be as close to the 'experimental' colour as possible to aid masking. This will be the 'control' colour and it will be individually determined for each participant. Participants and researchers will be masked to which spectacles are 'control' and 'experimental' throughout the course of the trial.

Visit 2 & 3:

The participant will be invited to return to collect one pair of spectacle with coloured lenses. Reading speed will be assessed using the Wilkins Rate of Reading Test (WRRT) and visual stress will be assessed using a symptom questionnaire and Pattern Glare Test (PGT) with and without the coloured spectacles. The participant will be asked to take the spectacles away and will be advised to wear the spectacles for concentrated tasks, including reading. The participant is free to choose when they wish to wear the spectacles. The participant will keep the spectacles for a minimum of six weeks, after this time they will be invited to return the spectacles and repeat measures of reading speed and visual stress will be assessed. Participants will be asked to document reading symptoms in an online diary and note the length of spectacle wear-time at the start and end of the 6-week wear period.

There will be a time lapse between visit 3 and visit 4 where the participant will have no coloured spectacles.

Visit 4 & 5

The participant will return to collect the other pair of spectacles. Reading speed and visual stress will be assessed as in visit 2 & 3. They will keep the spectacles for the same time period. They will be invited to return, at the end of visit 5 the participant will be able to chose their preferred pair of coloured spectacles to take away with them to keep.

Three months later the participant will be contacted to check if they are still wearing the coloured spectacles.

Inclusion Criteria:

• All consenting undergraduate University students, studying at Ulster University who have visual stress symptoms.

Exclusion Criteria:

• Reduced visual acuity
• Uncorrected spectacle prescription
• Decompensating heterophoria
• Heterotropia
• Accommodative insufficiency
• Convergence insufficiency
• Ocular health abnormality
• Any participant currently using precision tinted lenses

The researcher will perform colorimetry testing to measure the chromaticity of the 'experimental' and 'control' coloured lenses.The 'experimental' and 'control' colour will be as similar in chromaticity as possible. The details of the 'experimental' and 'control' colour will be given to an external person who will randomly assign the order in which the spectacles will be collected by the participant. There is a significant time lapse between the colorimetry assessment where the 'experimental' and 'control' colours are measured and the collection of the first pair of spectacles.