in case of blind person, in normal circumstances and till modern technology and the facilities are made available to the blind person as well as to the court, question of execution of affidavit of such person would not arise and it will be necessary for examination of such person before the court or the commissioner. In case of blind person therefore, question of adhering to Rule 4 of Order XVIII would not arise either in appealable cases as well as in non appealable cases and the court will have to follow the procedure prescribed under Rule 5 in case of appealable case or under Rule 13 in case of non appealable cases even in case of recording of examination in chief of the witnesses. Similarly, in case of illiterate person the court can insist for examination of such person by adhering to provision of Rule 5 in appealable cases and Rule 13 in non appealable cases, irrespective of the fact that parties have produced affidavit in terms of Rule 4 or not. It will be entirely in the discretion of the Court to pass an appropriate order and insist for oral testimony of such witness irrespective of affidavit of such person being filed.
https://www.lawweb.in/2012/04/procedure-for-recording-evidence-of.html