I guess the optician was refering to a black pigmentation at the back of the eye as is seen in case of a choroidal nevus
. It is a painless condition and is more often than not detected on routine eye exam. It would have been difficult to be picked up prior to cataract surgery
as the cataract would have hindered with the clear view of the back of the eye. Now that the cataract has been removed, the view is clear and details can easily be seen. It would be better to get her eye examined by the ophthalmologist at this stage so as to confirm whether there is indeed a choroidal nevus present. If present then it needs to be measured and then followed up for any altered appearance or growth ( every 6-12 months).