For minor eye problems, you can see an advanced optometrist via the MECS scheme. These are eyecare professionals who go through extra training to be able to deal with most eye problems and is accessed free via the NHS, usually within a few days. The nearest opticians to here, which are part of this scheme are Eye Emporium on Roman Road, or Specsavers in Bethnal Green.
Please see the MECS website here or the different leaflets linked below
(leaflet available at that web address in English, Bengali and Sylheti)