Iris scanning is a way of securely keeping the contents of your phone from prying eyes, first introduced on the Galaxy S8 and S8+. It uses the biometric information of your irises to identify you. And because virtually no two irises are alike as well as being almost impossible to replicate, scanning your irises is a fool-proof method of mobile security. But there's an issue with this Iris scanner, I get some sharp pain around the nerve behind my eyes. watery eyes and serious headache using the iris scanner.

That was my personal experience , I did some findings online and found out exactly what i thought might be the cause of the pains around my head / the watery eyes. In 2017, daily mail Uk released an article titled

"Is the Galaxy S8 hazardous to your eyesight? Samsung users claim iris scanner is causing eye discomfort"


Multiple Galaxy S8 users have complained about pain after using the iris scanner

Some noted they felt dizzy and other said the pain happened after the first use 

Experts noted that eyes are sensitive to infrared radiation and damage can occur

It was meant to be Samsung’s ‘saving grace’, but users have found an issue just two months after the Galaxy S8 has hit the market.

Multiple owners of the handset have reported feeling sharp pains and dizziness after using the iris scanner since purchasing the device – and it is so profound that some have reverted back to the fingerprint scanner.

Although the South Korean firm has deemed the technology safe, studies have found that the protein found in the lens of the eye is very sensitive to the infrared radiation used in the biometric and when exposed, can lead to cataract.

DANGERS OF INFRARED RADIATION 

Researches had discovered that the longer a subject was exposed to infrared radiation, the more enzyme activity was found to decrease.

The team had concluded that the technology does have the ability to cause corneal opacity, burns on the retina, breakdown of blood-aqueous barrier and delayed cataract.

And the decrease of total lens proteins was more pronounced in the group consisting of animals which were decapitated after 1 hour of exposure, which may be due to cataract formation.

Researchers also explained that when IR radiation is incident on the eye, it is absorbed by the cornea and converted into heat which is then conducted to the lens and induces cataract.

According to Janet Voke with Nova Southeastern University, IR raises the temperature of the anterior eye.

The lens is only able to absorb a small amount of the radiation and for it to cause damage, ‘the overall exposure level would need to be high’

Voke also noted that damage could occurs as the ‘result of smaller repeated doses’ - which may be similar to the amount your eyes are exposed to while opening your smartphone

You can read the full article here

https://www.dailymail.co.uk/sciencetech/article-4597594/Samsung-users-say-iris-scanner-causing-eye-discomfort.html

Here are some precautions to take when you want to use the Iris scanner.

1. To protect your eyes, keep the screen at least 20cm away from your face.

2. Do not attach unofficial screen protector or tempared glass to your phone.

3. Do not use the Iris scanner with infant's

4 Do not use when you have these : Dizziness,Seizures,loss of awareness ,blackouts or other symptoms link to epileptic conditions.


Though samsung released a statement that denies the Iris damage issue. Which says

"If eyes are exposed to IR within the distance of 2cm for more than 10 seconds, it might be harmful to your eyes. However, Iris scanning of S8/S8+ devices operates at a distance of 20cm~35cm within 1 second.
 
If you look at the iris recognition LED for more than 10 seconds or you are too close to it, the device will automatically stop iris recognition to protect your eyes.
There is no harm for human eyes.
In addition, IR LED of the Iris scanner of S8/S8+ achieved safety certification of the highest level “Exempt” based on the international standard IEC 62471. (IEC: International Electronical Commission).".

https://www.samsung.com/hk_en/support/mobile-devices/galaxy-s8-is-it-harmful-being-ir-irradiated-on-the-eyes-for-authentication/

Does anyone here have had the same issue? If yes i will advise you to stick with the following. Pattern recognition, fingerprint, Pin or face Id to avoid story that touch. With my experience with the Iris scanner , i will never use it again...

@lalasticlala

My phone also has this feature buh I never thought of using it cos I didn't really famz it
Lol thank God I'm most definitely NOT gonna ever use it