This is a phrase used by the Arabs even before Islam.
It has two implications;
1- Tears of Happiness
2- Refuge (i.e. A traveller in the desert in a sandstorm – when the traveller finds a safe cave)
You want your family to be; Happiness for you and Refuge.
It’s Opposite is; Heat of the eyes – عين حارّة. i.e. “May Allah heat your eyes.” = Sorrow etc.
وَالَّذِينَ يَقُولُونَ رَبَّنَا هَبْلَنَا مِنْ أَزْوَاجِنَا وَذُرِّيَّاتِنَا قُرَّةَأَعْيُنٍ وَاجْعَلْنَا لِلْمُتَّقِينَ إِمَامً
And who say, “Our Lord, Bestow [hab-laNaa] upon Us from our spouses and offsprings comfort of the eyes, (Literally: the coolness (when)the eyes settle down) and make us an îmam (Leader) of the pious.” [Furqan 25:74]
hiba – to give a huge gift.
إِذْ تَمْشِي أُخْتُكَ فَتَقُولُ هَلْ أَدُلُّكُمْ عَلَىٰ مَن يَكْفُلُهُ ۖ فَرَجَعْنَاكَ إِلَىٰ أُمِّكَ كَيْ تَقَرَّ عَيْنُهَا وَلَا تَحْزَن
[And We favored you (O Moses)] when your sister went and said, ‘Shall I direct you to someone who will be responsible for him?’ So We restored you to your mother thather Eyes cool (she might be content) and not grieve.
When Moses speaks to Allah;
his eyes become cool
when speaking to Pharoah;
his eyes become warm.
Allah’s Messenger, Muhammad (sal Allah alayhi wasalam) said;
جعلت قرة عيني في الصلاة
Ju’illat Qurrata ‘ayni Fis-salah (the Coolness of my eyes is in the prayer)
The Messenger of Allah, Muhammad (sal Allah alayhi wasalam) gets insulted alot by the disbelievers, his eyes become warm. His eyes become cool in the salaah [prayer]. He becomes relaxed and re-strengthened.