Online Refraction Screener

This screening is provided for patients of the practice. Enter the office access code your doctor's office gave you when your screening was arranged, then tap Continue.

No code? Please call the office and ask for one — the code is given to patients when a screening is booked.

Online Refraction Screener

A subjective refraction screening for one eye at a time: a calibrated letter chart measures your acuity, a red/green (duochrome) task brackets the focus, and a clock-dial task looks for astigmatism. The result is a coarse estimated refraction range — nothing more. Best used on a computer or tablet in even lighting; a phone screen is too small for the letter sizes to mean much.

Screening estimate only — read this first. This page is NOT an autorefractor: a real autorefractor shines infrared light into the eye and measures the reflection from the retina, which no screen or camera can do. It is NOT a prescription, and it is not a substitute for an in-office refraction. Like all subjective testing, the result is only as good as the care and honesty of the person taking it — the screener cross-checks your answers against each other, and if they do not agree it will say UNRELIABLE rather than dress the result up.
Your report is prepared for the office automatically. When you finish this screening — whether you complete it, stop early, or the result is judged unreliable — a report of your attempt is prepared automatically for Dr. Kalish's office, so there is documentation of every attempt. There is nothing for you to approve or send, and no yes/no choice to make. You can also download a PDF copy for yourself at the end.

How to take this screening properly

  1. Take it without glasses or contact lenses. The screener estimates the eye's own focusing error from unaided vision. (If you cannot see even the largest letters, it will tell you so honestly — that itself is useful information for the office.)
  2. One eye at a time. Cover the eye that is not being tested completely — palm, patch, or a tissue over the closed lid. No peeking, and do not press on the eye.
  3. Sit at the exact distance you set below and stay there. Letter sizes are true visual angles only at that distance; leaning in makes the result wrong, not better.
  4. Answer only what you truly see. Guessing letters you cannot read does not help you — the built-in consistency checks will catch disagreement and mark the whole estimate unreliable.
  5. Even, ordinary room lighting. No glare on the screen, screen brightness up, and rest your eyes if they tire — a fatigued screening is a worthless screening.
  6. You will need to respond from your seat — a wireless mouse or keyboard, a tablet on a stand, or a helper who clicks exactly what you say.

You will first do a short guided practice that teaches each of the three tasks — letter reading, red/green comparison, and the clock dial — before anything is scored.

What the result is — and is not

  • Visual acuity per eye, measured line by line on a calibrated chart down to your threshold.
  • An estimated sphere range in coarse half-diopter steps, inferred from how much acuity is lost and which way the duochrome tips. It is always shown as a range, never a single exact-looking number, because that is all this method can honestly support.
  • An astigmatism estimate — axis from the clock dial, and a coarse cylinder range — only when the dial shows one.
  • A confidence statement. One acuity line is repeated later in the run and the duochrome is cross-checked against the acuity; disagreement is reported, with the reason.

Even a clean screening cannot rule refractive error in or out the way an in-office refraction with trial lenses can. Treat the numbers as a reason to book — or not worry — never as a lens order.

Set up the screening

Optional, but please enter it: your name appears on the report as the person who attempted the screening, so the office can file it with the right chart.

Measure from your eyes to the screen, sit there, and stay there for the whole screening. Farther is better: distance is what lets the screen draw the small lines truly.

Drag the slider until the dashed outline is exactly the width of a bank card or driver's licence held against the screen (85.6 mm). This is how the screener sizes letters at true visual angles.

match this width to your card
Chart range: computing…

The practice takes about a minute and is required before the first real run — a refraction task done cold measures the learning curve instead of the eye.

This page is a screening aid prepared for patient education. It is not a medical device, not an autorefractor, and not a prescription, and it does not replace an in-office refraction or eye examination. A screening in the normal range does not rule out refractive error or eye disease; a screening outside it does not establish either. Seek prompt care for any sudden loss of vision, a curtain or shadow across your sight, flashes of light, or a shower of new floaters.

Guided practice
Right eye (OD)
Acuity

Refraction Screening Results

Screening estimate only. These numbers come from a subjective screening on an uncalibrated home screen. They are not an autorefractor reading, not a prescription, and not a substitute for an in-office refraction. Do not order glasses or contact lenses from them.

Screening estimate only — generated by an online screening tool, not a medical device. Not an autorefractor reading, not a prescription, and not a substitute for an in-office refraction or eye examination. Discuss any result — normal, abnormal, or unreliable — with an eye care professional.