The Effect of Changing Colours on Central Crowding Reading

Abdullah Alsalhi1, 2, Nadia Northway1, Abd Elaziz Mohamed Elmadina2, *
1 Department of Vision Sciences, Glasgow Caledonian University, Glasgow, UK
2 Department of Optometry, Qassim University, Qassim, Saudi Arabia.

© 2021 Alsalhi et al.

open-access license: This is an open access article distributed under the terms of the Creative Commons Attribution 4.0 International Public License (CC-BY 4.0), a copy of which is available at: This license permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

* Address correspondence to this author at Department of Optometry, Qassim University, Qassim, Saudi Arabia; E-mail:



Crowding can be defined as the impaired recognition of closely spaced objects. Changing colour and lighting enhance visual comfort and perceptual troubles that influence impaired vision reading.


The current study was aimed to investigate the impact of changing the flanker distance and unflanked targets with colours on central crowding reading for subjects with their distant best correction (BCVA) equal to or greater than 6/6.


Six native English speakers (age: 18–38) who participated in a cross-section intervention study were asked to identify the orientation of the letter E (flanked or unflanked) in different directions around the central target in different colours (red, green, blue and black) on a white background.


Different colours affect central crowding (p<0.05). However, the central crowding reading of red was not affected by changing flankers (P > 0.05).


Central reading crowding is visual crowding. Different colours affect central crowding. However, the central crowding reading in red was not affected by changes in flankers.

Keywords: Central crowding reading, Flanked letter E, Unflanked letter E, Color changing, Vision, BCVA.