Eye health and OCT
An OCT scan is an ultrasound made of light: it images the layers under the retinal surface at a few microns of resolution, so it shows change that a photograph of the surface cannot. It takes about four seconds an eye and it is in the test fee.
The scan's value is comparative. One scan is a picture; two scans five years apart are a measurement.
Glaucoma
Glaucoma takes peripheral field first and painlessly, which is why it is usually found by someone looking rather than by the person who has it. We measure pressures, image the nerve head, and run a field screen on anyone over 40, anyone with a family history, and anyone whose scan asks the question.
Macular change, cataract, diabetes
Distortion in straight lines is the symptom to ring about the same day. Cataract is graded and referred when it stops you driving or reading, not when it first appears. Diabetic patients are screened here as well as by the national programme, because two looks a year is better than one.
What a pinhole tells us before any of that
If acuity improves through a pinhole, the fault is refractive and lenses fix it. If it does not, the fault is behind the optics and we go looking. That single card is what separates an order from a referral letter, and it is the reason nobody here sells you a stronger prescription to chase a symptom.
Referrals go to the Sheffield hospital eye service, urgent ones by phone the same day, and we tell you what we have written.