Is it permissible for a woman to uncover her eyes unnecessarily?

Firstly: 

What the woman must do is cover her face because of a great
deal of shar‘i evidence which indicates that it is obligatory for the woman
to cover her face in front of non-mahram men. And she has two ways in which
she can cover: 

Either she may lower down on her face something that will
cover it completely and not let anything of it show, and she can see through
that cover

or she may wear the niqab (face veil) which is that which
covers the face but leaves the eyes uncovered. 

In Saheeh al-Bukhaari (1838) it says: “The woman in
ihram should not wear niqab or gloves.” The fact that the woman in ihram is
forbidden to wear niqab indicates that it is permissible to wear it when not
in ihram. 

Hence the fuqaha’ and scholars said that it is permissible
for a woman to wear niqab, but that is on condition that she does not go to
extremes in uncovering the eye socket or show too much of the cheeks. 

Imam al-Ramli ash-Shaafa‘i (may Allah have mercy on him)
said: 

It is haraam to look at a woman in niqab of whom nothing can
be seen except her eyes, especially if she is beautiful. How much fitnah may
be caused by looking at a woman’s eyes. End quote from Nihaayat
al-Muhtaaj, 6/188 

It says in Fataawa al-Lajnah ad-Daa’imah: With regard
to the niqaab: Abu ‘Ubayd said, describing the niqab according to the Arabs:
it is that from which the eye appears.  It was known by other names,
including “burqa‘”. As for the ruling on it, it is permissible. 

The source for that is the hadeeth narrated from Ibn ‘Umar
(may Allah be pleased with him), according to which the Prophet (blessings
and peace of Allah be upon him) said: “The woman in ihram should not wear
niqab or gloves.” Narrated by al-Bukhaari. The fact that he (blessings and
peace of Allah be upon him) forbade the woman in ihram to wear niqab
indicates that it is permissible when not in ihram. End quote from
Fataawa al-Lajnah ad-Daa’imah (vol. 1, 17/171). 

Shaykh ‘Abd al-‘Azeez ibn Baz, Shaykh ‘Abd ar-Razaaq ‘Afeefi,
Shaykh ‘Abdullah ibn Ghadyaan, Shaykh ‘Abdullah ibn Qa‘ood. 

This has been
stated previously in the following answers:
1496,
8540,
21134 and
100719 

Secondly: 

Once the above becomes clear, we will realise that there is
nothing wrong with a woman wearing a niqaab from which only her eyes appear
through a narrow opening which does not uncover anything more than what is
needed in order to see. The ruling that this is permissible is not dependent
upon there being any need; rather it is generally applicable and it is
permissible for her to wear the niqab whether the woman needs to see where
she is going or not, and whether she is sitting in a car or walking down the
street. The evidence quoted above which indicates that it is permissible to
wear the niqab was narrated in a hadeeth of the Prophet (blessings and peace
of Allah be upon him), and the tafseer of Ibn ‘Abbaas is general in
application and is not restricted to cases of necessity. 

And Allah knows best.