Answer:
If the Nystagmus condition this person has is severe enough, then yes they can qualify for Disability benefits. However it is not the simple fact of having Nystagmus that will enable them to receive Disability benefits.
Disability insurance companies and Social Security disability do not look at the specific condition a claimant has, but more so the effect this condition has on the person's ability to work. Disability insurance will only pay benefits when a person is prevented from working due to an illness or injury.
Therefore, if the Nystagmus prevents a person from being able to work, then depending on the Disability insurance policy they have, there is a good chance they can qualify for benefits. If the Nystagmus causes does not prevent the person from being able to work, then they will not be eligible for benefits.