Good question. Here's the official answer
https://www.canada.ca/en/immigration-refugees-citizenship/corporate/publications-manuals/operational-bulletins-manuals/identity-management/biometrics/conditions.html
Permanent injuries and conditions
Permanent injuries and conditions are any physical state that interferes with fingerprinting or photographing but are not expected to be resolved by the passage of time. Examples include but are not limited to the following:
- missing digits, due to amputation or a birth defect
- conditions that affect the placement of fingers on the collection device, such as severe chronic arthritis
- scarring or other damage to the fingertips that results in extremely poor-quality fingerprints, such as heavy calluses, due to manual labour
- facial scarring, disfigurements or skin conditions that prevent a good-quality photograph from being taken, such as extensive burns
- other physical conditions that prevent a good-quality photograph from being taken, such as tremors that prevent the applicant from remaining still, resulting in a blurry photograph
Instructions for the biometrics enrolment operator at VACs and GAC locations
The biometrics enrolment operator must do all of the following:
- question the applicant regarding the nature of the condition and its cause
- enter a note regarding the nature of the applicant’s injury or condition and its possible cause in CIBIDS
- proceed with biometrics enrolment by capturing the best-quality photograph and fingerprints possible
- advise the applicant that the IRCC office may contact them for further medical information about the injury or condition
Instructions for the IRCC office (inland and overseas)
The officer must do all of the following:
- document the condition or injury in the Global Case Management System
- if no further information is required, process the application, using the available biometric information
- if further information is required, request further information from the applicant about the injury or condition or schedule an interview and collect available biometric information during the interview.
Note: When no fingerprints are recorded, nothing is sent to the Royal Canadian Mounted Police to search against their criminal and immigration databases, so no search response is returned.
Requesting a medical officer or panel physician
IRCC officers may request the assistance of a medical officer or a specialized medical examination with a panel physician if
all the following conditions are met:
- The applicant is unable to provide both a good-quality photograph and a minimum of 5 of the 8 fingerprints other than the little fingers (that is, a minimum of 5 fingerprints of the thumbs and index, middle and ring fingers).
- There are well-founded suspicions of fraud or malfeasance.
- Other attempts to address the situation have not been successful. Examples of this include the following:
- waiting for a temporary injury to improve
- repeatedly collecting biometric information
- requesting that applicants submit pre-existing medical information
- The assistance of the medical officer or specialized medical examination is likely to help with addressing the concerns of the IRCC office.
The basic function of the medical officer and panel physician is to confirm if medical conditions are genuine.
Important: There are certain functions that the medical officer and panel physician should not be requested to provide. These include all of the following:
- confirming the existence of medical conditions that are obvious, even without medical expertise, such as missing or amputated fingers and hands
- determining if medical conditions are natural, the result of an accident or deliberately self‑inflicted in an attempt to commit fraud
- evaluating the quality of the applicant’s fingerprints
If a specialized medical examination is required, the visa office should do all of the following:
- issue a letter advising the applicant of the requirement for the examination
- notify the panel physician directly by email and provide them with information concerning the situation
The applicant is responsible for paying all charges associated with the medical examination.
