What are the eyesight requirements for a medical certificate in India?
The DGCA's relevant requirements adheres and refers to ICAO Annex 1 (see pages 3 and 4). Here's the relevant text from Annex 1:
Class 1

6.3.3.2 Distant visual acuity with or without correction shall be 6/9 or better in each eye separately, and binocular visual acuity shall be 6/6 or better. No limits apply to uncorrected visual acuity.

Class 2

6.4.3.2 Distant visual acuity with or without correction shall be 6/12 or better in each eye separately, and binocular visual acuity shall be 6/9 or better. No limits apply to uncorrected visual acuity.

(Emphasis mine.)
The above is for the requested uncorrected visual acuity, but it is not the full text, e.g., if the correction is surgical, there is more fine print to read.