Some patients have SLOT XO suffered "significant" sight loss due to delays caused by Covid, a doctor has warned.
More than 32,250 people across Wales have waited over nine months for treatment, according to the latest data.
Consultant ophthalmologist Andrew Feyi-Waboso said the issue was a "huge problem".
The Welsh government said "essential and urgent" eye care had continued during the pandemic.
Mr Feyi-Waboso, who works at the Royal Glamorgan Hospital in Llantrisant, has started a pilot scheme to identify people with worsening glaucoma.
The eye condition, which affects the optic nerve, can cause irreversible damage to vision if it is not treated.
Some people are born with it, while for others it develops later in life, according to the NHS.
It has emerged that attendances at the glaucoma clinic at the Rhondda Cynon Taf hospital were reduced by as much as 90% during the worst of the pandemic, with only a skeleton team seeing the most urgent patients.