What is the ruling for a woman to wear coloured contact lenses?
Alhamdulillah, praise and thanks to Allah for the many countless blessings He has blessed us all with. Blessings and salutations to the Prophet Muhammad PBUH, his wives, his family, companions and all those that follow his teachings to the day of judgement.
According to our analysis, this issue can be concluded as the following:
- There are no differing opinions from the fuqaha regarding the permissibility of wearing coloured or regular contact lenses if it is for medical purposes or a necessity. However, one must consult with an eye specialist or doctor to prevent any complications that could result in vision impairment. 
- There is an opinion that ruled it permissible to wear coloured contact lenses as an adornment, as long as the adornment is not prohibited in the Quran or the hadiths of the Prophet PBUH. This is in accordance with the statement of Allah SWT:
قُلۡ مَنۡ حَرَّمَ زِينَةَ ٱللَّهِ ٱلَّتِيٓ أَخۡرَجَ لِعِبَادِهِۦ وَٱلطَّيِّبَٰتِ مِنَ ٱلرِّزۡقِۚ قُلۡ هِيَ لِلَّذِينَ ءَامَنُواْ فِي ٱلۡحَيَوٰةِ ٱلدُّنۡيَا خَالِصَة يَوۡمَ ٱلۡقِيَٰمَةِۗ كَذَٰلِكَ نُفَصِّلُ ٱلۡأٓيَٰتِ لِقَوۡم يَعۡلَمُونَ
“Say, "Who has forbidden the adornment of Allah which He has produced for His servants and the good [lawful] things of provision?" Say, "They are for those who believe during the worldly life [but] exclusively for them on the Day of Resurrection." Thus, do We detail the verses for a people who know.”
Surah al-A’raaf (32)
Al-Imam al-Syaukani Rahimahullah explains that the adornment in the above verse meant anything that are used as an adornment, whether on the body or the clothes or others, from the permissible natural resources such as diamonds, other precious stones or others. 
Since the above verse uses the general term of adornment, the scholars have concluded that the ruling of wearing coloured or regular contact lenses is permissible on the conditions set by syarak and they are as the following:
- It is not harmful to the wearer.
- There are no elements of deception, or for the purpose of boasting or flaunting the adornment, especially in front of non-mahram men. It is permissible for a wife to wear it, beautifying herself in front of her husband. However, it is prohibited for a woman to wear coloured contact lenses, in order to look beautiful in front of her fiancé, for there is an element of deception.
- Someone is prohibited from spending excessive money (wasting money), for some coloured contact lenses are very expensive.
- The contact lenses should not resemble the eyes of animals, for tasyabbuh (resembling) animals is prohibited in Islam.
According to the above discussion, if the purpose of wearing contact lenses is due to medical purposes or a necessity, then it is permissible whether the contact lenses are coloured or not.
If it is worn as an adornment, the original ruling for it is permissible on the conditions stated above and the ruling could change into a prohibition according to the situation of why it is worn.
Even though the original ruling for it is permissible, we are inclined towards the scholars’ opinion that state that it is best to not wear coloured contact lenses to avoid fitnah, such as deception and excessive spending. Wallahua’lam.