Visual function parameters measured after protocol refraction will include: Photopic and mesopic visual acuity and contrast sensitivity using City Occupational acuity-plus software17, near visual acuity, reading speed and SKILL card18, MAIA microperimetry and cone dark adaptation.19 Intra-ocular scatter will be assessed using the Oculus C-quant to assess the extent to which ocular factors are degrading vision.20 Three-point vernier acuity will also be measured as this is thought to stay stable throughout life.15 Time will be taken to ensure participants receive sufficient training to produce reliable thresholds.