Ordinary prescription glasses and contact lenses let visible light through, so you can use a SAD lamp with either; sunglasses, strongly tinted lenses and "blue-blocking" coatings reduce the dose and defeat the point. After laser or cataract surgery, and with any diagnosed eye condition, the NHS advice applies: speak to a GP, or the clinic that treated you, before starting. This guide sets out what is known, and where the line between general information and medical advice falls.
How does a SAD lamp work through the eyes?
Light therapy is not a skin treatment and the light does not need to hit any particular part of the eye directly. Bright light entering the eye reaches specialised cells in the retina that report light levels to the body clock; a lamp rated at 10,000 lux at its stated distance provides the morning signal that a dark UK winter does not. You do not look at the panel; you sit with it slightly above eye level and a little to one side while you eat or read, and glance at it now and then. How does a light therapy lamp work? explains the mechanism, and are SAD lamps safe? covers UV, eye strain and who should check first.
Glasses
Standard prescription lenses are made to transmit visible light, and the dose reaching the retina is not meaningfully reduced by them. Two things can reduce it. Photochromic lenses, the ones that darken in sunlight, are triggered mainly by ultraviolet, so a UV-free lamp should not darken them much, but some newer types respond to visible light too and will cut the dose if they do. Blue-light filtering coatings and tinted lenses deliberately remove part of the spectrum the body clock is most sensitive to; they are a poor match for a lamp session, and it is better to take them off for the 20 to 30 minutes if your eyesight allows. Reading glasses, varifocals and clear anti-reflective coatings are all fine.
Contact lenses
Ordinary soft and rigid contact lenses transmit visible light and can be worn during a session. Some lenses now include a UV filter, which is irrelevant to a UV-free lamp, and a small number are tinted or blue-filtering, which matters as above. If your eyes feel dry during a session, the cause is usually the room, the screen you are reading or blinking less while you concentrate, rather than the lamp; blink, look away and use drops if you normally would. If dryness or discomfort persists, stop and see an optician.
After laser eye surgery
This is where general information stops. Laser procedures such as LASIK and LASEK involve a healing period during which many people are advised to avoid bright light and are sensitive to glare, and the timing differs between procedures and between patients. The clinic that carried out your surgery will have given you written aftercare guidance on light exposure; follow it, and ask them directly whether and when a 10,000 lux lamp is appropriate for you. Once you have been discharged from aftercare with no restrictions, there is no general reason a UV-free lamp should be treated differently from a bright day, but that is a question for your surgeon, not for a lamp manufacturer.
After cataract surgery
The natural lens of the eye yellows with age and filters some blue light. A replacement lens implant may transmit more of the shorter wavelengths, which is one reason some people notice colours look brighter after cataract surgery. That change is not a reason to avoid daylight, and most implants are designed with it in mind, but it is a reason to check with your ophthalmologist before adding a bright lamp to your mornings, particularly in the weeks after surgery. Light therapy lamps for older adults covers the wider picture.
Eye conditions and medicines
The NHS is specific: light therapy might not be suitable for people with certain eye conditions, or who take medicines that increase sensitivity to light, and you should speak to a GP before trying it. Conditions that affect the retina, such as macular degeneration or diabetic eye disease, are the usual reason for caution; some antibiotics, acne treatments and other medicines list photosensitivity as a side effect, which you can check on the patient leaflet or with a pharmacist. None of this means a lamp is off limits; it means the decision belongs with someone who knows your eyes.
| Situation | Usual position |
|---|---|
| Clear prescription glasses, varifocals, readers | Fine; no reduction in dose worth worrying about |
| Tinted, blue-filtering or photochromic lenses | Reduce the dose; take them off for the session if you can |
| Ordinary contact lenses | Fine; blink and use drops if dry |
| Recent laser eye surgery | Follow your clinic's aftercare guidance; ask them first |
| Cataract surgery | Check with your ophthalmologist, especially early on |
| Diagnosed retinal or other eye condition | Speak to a GP or eye specialist before starting |
| Medicines that increase light sensitivity | Check the leaflet, ask a pharmacist or GP first |
Frequently asked questions
Do I need special glasses to use a SAD lamp?
No. There is no protective eyewear for a UV-free lamp used as directed, and anything tinted reduces the effect. Sit at the rated distance and do not stare at the panel.
Can the lamp damage my eyes?
The early 10,000 lux trials reported no eye changes over two to six weeks, and a UV-free LED panel at the rated distance is dimmer than a bright day outdoors. Glare, headache and eye strain do happen, usually when the lamp is too close or too bright for you; light therapy lamp side effects explains how to adjust. Any change in your vision is a reason to stop and see an optician.
Can I use a lamp if I have had an eye test that found nothing wrong?
A normal eye test removes the most common reasons for caution. The NHS advice to speak to a GP first still stands if you take medicines that increase light sensitivity or have a condition affected by bright light.
Where does this leave you?
Glasses and contacts are not a barrier; tints and coatings are a small one; surgery and eye conditions are a question for the people who treat you. If you are cleared to try a routine, choose a UV-free lamp with a stated lux at a stated distance and sit at that distance. How to choose a SAD lamp in the UK lists what to look for, and the choose your light page compares DAYARC Rise and Mini.
About DAYARC
DAYARC is a new UK circadian rhythm startup. We make two bright-light lamps for the morning: DAYARC Rise (£199), a full-size lamp rated at 10,000 lux at approximately 30–36 cm, with four brightness settings, a 15 to 60-minute timer and adjustable height and angle; and DAYARC Mini (£49.99), a compact lamp rated at 10,000 lux at approximately 25 cm, with a folding stand that doubles as its cover. Both use UV-free LEDs and run from the mains. We publish plain specifications with the measuring distance, we do not make medical claims, and we write the DAYARC Journal to help people build a simple morning light routine around their own daily rhythm. You can read more about how we think on our approach page or compare the two lamps.
This article is general information, not medical advice. Check with a GP or qualified healthcare professional before using bright light if you have an eye condition, a condition affected by bright light such as bipolar disorder, or take medicines that increase your sensitivity to light. If you have persistent low mood or think you may have depression, speak to your GP. If you need urgent help, contact NHS 111, or call 999 in an emergency.