The referendum on the Eighth Amendment will see people who are visually impaired casting their vote using a new tactile voting template for the first time.
In previous votes, people with sight loss had to vote with assistance or get help from the presiding officer.
This meant they were denied a secret ballot.
It also meant that they had no way of verifying that the person who had assisted them had marked the ballot paper in the way they requested.
Last year Wexford man Robbie Sinnott, who is visually impaired, won a landmark High Court case.
It found that the Minister for Planning and Local Government had a duty to provide arrangements to guarantee a secret ballot as far as is reasonably practicable.
The minister has made arrangements for voting in Friday's referendum.
A tactile voting device, or tactile ballot template, is placed on top of the ballot paper and includes Braille and embossed numbers.
There is also a cut out square over the slot where the ballot is marked.
The device is then removed from the ballot paper, which is folded and placed in the ballot box.
Free Legal Advice Centre (FLAC) facilitated getting legal support for Mr Sinnott through its Public Interest Law Alliance (PILA).
An example of the new tactile voting system on a sample ballot paper | Image: FLAC
In advance of voting, Mr Sinnott said: "This is a huge moment for people who are blind or vision impaired.
"I've been looking forward to this day for years.
"Previously, when voting I had to compromise my privacy which was never acceptable to me.
"I have a constitutional right to vote in secret and just because I'm visually impaired shouldn't alter this.
"For the first time, I will no longer feel that my entitlement to vote is lesser than somebody else's who just happens to be able to see."
However there are currently no equivalent measures in place for elections where candidates are selected by proportional representations.
FLAC CEO, Eilis Barry, said: "With a general election likely this year and local and European elections scheduled for next year, we're urging the minister to put these arrangements in place as a priority."
Templates are currently in use in Austria, Germany and the UK.
There are over 50,000 people with sight loss in Ireland.
Polls open from 7.00am until 10.00pm on Friday.