This site provides general eye-health education. It cannot replace individual assessment by a registered doctor, and does not offer personal diagnosis, prescriptions, bookings, sales or referrals.
If translations differ or are incomplete, the Traditional Chinese (zh-Hant) text on this site prevails.
Education tool · self-awareness of central vision (macula). A screen version is only a guide and cannot replace a dilated fundus exam. New straight-line distortion or a central dark patch: urgent ophthalmic assessment is needed (usually same day). If vision also drops sharply, there is a curtain, or severe pain with vomiting: go to A&E now.
Illustration / self-check is not a diagnosis; a normal result does not rule out macular or retinal disease, and does not replace dilated fundus exam or OCT.
Suggested viewing distance about 30 cm (not yet calibrated — please calibrate first)
What these findings look like on the grid
Illustration only — not your test result. Cover one eye, look at the centre dot, and compare the four. A normal grid is straight, even, and complete.
Illustration only — not your test result. Cover one eye, look at the centre dot, and compare the four. A normal grid is straight, even, and complete.
A normal demo cannot rule out disease and cannot grade macular degeneration.
1. Match size with an Octopus card or credit card
Screen pixels are not real centimetres. Place an Octopus card or credit card (long edge 85.6 mm) on the rectangle below and drag the slider until the widths match. Align the long edge of the card with the guide. After matching, the grid is near the usual teaching size of about 10 cm (screen error remains — this is not a formal exam).
Card guide (match the long-edge width)
2. Check steps
- Wear the reading glasses you use for newspapers or a phone. Do not wear sunglasses.
- Indoors, steady light, no screen glare. Brightness comfortable — not too dark.
- Gently cover one eye with your palm; do not press the eyeball. Check the better or preferred eye first, then the other.
- With one eye, look at the centre dot. Do not move your eye to “hunt” for lines.
- Ask yourself: can you see all four edges? Any waves, breaks or missing squares? Any central shadow or a vanishing centre dot?
- Repeat with the other eye. Do not use both eyes at once.
On a phone
- Hold it upright, screen facing you; do not tilt sideways.
- After size-matching, hold the phone about 30 cm from your eye (roughly a forearm — near reading distance).
- If the screen is small, the grid will be under 10 cm — hold closer using the distance shown above.
- Turn off auto-rotate and notifications so the screen does not jump mid-check.
- Tap “Start one-eye check” to hide other text and focus more easily.
On a computer screen
- Enlarge the browser window; sit upright with the screen at eye height.
- After matching with a credit card, if the grid is near 10 cm, viewing distance is about 30 cm (reading distance).
- Put a laptop on a desk; do not lie down, or distance will drift.
- An external monitor is steadier than a phone; still match a card — do not assume “a computer is accurate”.
- Close other windows while checking. Wear reading glasses if you use them.
3. Possible abnormal patterns (illustration — not a diagnosis)
The demos above match common education labels: distortion, central blank patch, patch beside centre. Matching is not self-diagnosis or AMD grading; also watch for new change versus yesterday.
- Straight lines look bent or twisted (distortion, metamorphopsia)
- A missing patch in the very centre, or the centre dot vanishes (central scotoma)
- The centre dot remains, but a blank or missing patch sits beside it (paracentral scotoma)
- Self-check at a fixed weekly time for new or worse distortion; self-check does not replace dilated / OCT follow-up your doctor arranged
New or suddenly worse straight-line distortion, or a central or paracentral dark spot: urgent ophthalmic assessment is needed (usually same day). If vision also drops sharply, there is a curtain, or severe pain with vomiting: go to A&E now; do not drive yourself; if you cannot get there: call 999. A normal on-screen Amsler grid does not rule out eye disease.
Illustration / self-check is not a diagnosis; a normal result does not rule out macular or retinal disease, and does not replace dilated fundus exam or OCT.
4. Today’s note (this device only)
No name, nothing uploaded. Compare with yesterday. Taps are a local reminder only — not AMD grading or a diagnosis.
A demonstration is not an examination and cannot replace dilated fundus exam, visual field or OCT. A normal result here does not rule out disease. New changes need prompt review by a registered ophthalmologist; sudden vision loss — go to A&E. This site does not book or refer.