Here you see into the RRB 2019 form different Medical Standards.

So, basically standards description for different Medical classification is:
·
A-1 Physically fit in all respects. Visual Standards —Distance
Vision: 6/6,6/6 without glasses. Near Vision: Sn: 0.6,0.6 without glasses (must
clear fogging test) and must pass test for Colour Vision, Binocular Vision, Field
of Vision & Night Vision.
·
A-2 Physically fit in all respects. Visual Standards—Distance
vision: 6/9,6/9 without glasses. Near Vision: Sn: 0.6, 0.6 without glasses and
must pass test for Colour Vision, Binocular Vision, Field of Vision & Night
Vision.
·
A-3 Physically fit in all respects. Visual Standards—Distance
Vision: 6/9,6/9 with or without glasses (power of lenses not to exceed 2D).
Near Vision: Sn: 0.6, 0.6 with or without glasses and must pass test for Colour
Vision, Binocular Vision, Field of Vision & Night Vision.
·
B-1 Physically fit in all respects. Visual Standards —
Distance Vision: 6/9,6/12 with or without glasses (power of lenses not to
exceed 4D). Near Vision: Sn: 0.6, 0.6 with or without glasses when reading or
close work is required and must pass test for Colour Vision, Binocular Vision,
Field of Vision & Night Vision.
·
B-2 Physically fit in all respects. Visual Standards —
Distance Vision: 6/9,6/12 with or without glasses (power not to exceed 4D).
Near Vision: Sn: 0.6, 0.6 with or without glasses when reading or close work is
required and must pass test for Field of Vision.
·
C-1 Physically fit in all respects. Visual Standards —
Distance Vision: 6/12, 6/18 with or without glasses. Near Vision: Sn: 0.6, 0.6
with or without glasses when reading or close work is required.
·
C-2 Physically fit in all respects. Visual Standards —
Distance Vision: 6/12, Nil with or without glasses. Near Vision, Sn: 0.6
combined with or without glasses when reading or close work is required.
Also, in the previous year (2018) Medical Standards are as follows:
(keep in mind that Railway Requirement rules are hardly changed, so in simple words these are almost same as usually)
MEDICAL STANDARDS FOR
ALP/Technician:

Some Important
Points:
- Candidates who have undergone Lasik surgery or any other surgical procedure to correct refractory error are not eligible for the post having Medical Standards A1, B1 and B2.
- Different Medical standards shall apply to Ex-Servicemen of Indian Railway.
- For ALP Post: Stringent medical standard and hence they are specifically advised to ensure that their fitness both in terms of vision as well as physical standards is as per the prescribed requirements detailed in the medical manual indicated above.
MEDICAL STANDARDS FOR
Group-D:

- Those who are opting for A2 medical standard posts may note that these posts have stringent medical standard and hence they are specifically advised to ensure that their fitness both in terms of vision as well as physical standards is as per the prescribed requirements in the medical manual indicated above.
- The persons with disabilities are exempted from appearing for PET. However, after qualifying in the CBT, such candidates will have to pass the medical examination prescribed for Persons with Disabilities.
For PWD Candidates
ALP/Technician & Group-D Posts
Definitions of
Disabilities: Definitions of categories of disabilities for the
purpose of recruitment are given below -
(a) Blindness: 'Blindness' refers to a condition where a person suffers from any of the following conditions, namely: Total absence of sight; or Visual acuity not exceeding 6/60 or 20/200 (snellen) in the better eye with correcting lens; Limitation of the field of vision subtending an angle of 20 degrees or worse;
(b) Low Vision: "Person with Low Vision" means a person with impairment of visual functioning even after treatment or standard refractive correction but who uses or is potentially capable of using vision for the planning or execution of a task with appropriate assistive device.
(c) Hearing impairment means loss of sixty decibels or more in the better ear in the conversational range of frequencies. It will also include persons who are deaf and dumb.
(d) Loco Motor Disability: "Loco Motor Disability" means disability of the bones, joints or muscles leading to substantial restriction of the movement of the limbs or any form of cerebral palsy.
(e) Cerebral Palsy: "Cerebral Palsy” means a group of non-progressive conditions of a person characterized by abnormal motor control posture resulting from brain insult or injuries occurring in the pre-natal, peri-natal or infant period of development.
(f) All the cases of orthopedically handicapped persons would be covered under the category of "Loco Motor Disability or Cerebral Palsy."
Important Note: All one eyed candidates and candidates whose visual degree of disability is less than 40% shall not be considered as Visually Handicapped persons and the provision for engaging Scribe shall not be applicable to them.