Mrs Maria Lim was due to see her doctor this month - a follow-up for her knee replacement surgery done a year ago and her osteoporosis condition - but the appointment has been postponed to July.

The 80-year-old, who also has hypertension and arthritis, will have her medications delivered to her doorstep by the polyclinic, at no additional cost.

This is to minimise the need for her to leave the house.

Mr Eddy, 61, has had his gastric bypass surgery postponed indefinitely. The surgery, to help him lower his cholesterol and sugar levels, as well as lose weight, had been scheduled for March 23.

"The surgery has been postponed till the next available period as I will need to take a full month of medical leave," said Mr Eddy, who takes medication twice a day to control his blood sugar levels and has to be mindful of his diet. He declined to give his full name.

Elective procedures and non-essential follow-ups have been postponed for most patients at public and private clinics and hospitals as Singapore battles the coronavirus pandemic, but doctors make the call on necessary procedures.

A patient suffering from gastric pain was told his endoscopy check-up at Ng Teng Fong General Hospital on April 24 would proceed, despite the circuit breaker. The 20-year-old, who gave his name only as Mr Cai, said: "It was done in around 10 to 15 minutes and my next appointment is in October."

Another instance was when a scheduled emergency cataract surgery was done on May 8 for Ms Adriana Tan, 41.

"My cataract was aggressive and I had lost vision in my left eye. It was so bad that if you stood in front of me and did not move, I could not see you. I could see only light and shadows," said Ms Tan, who works in the real estate industry.

With just over two weeks till the circuit breaker is set to be lifted on June 1, doctors who have postponed the bulk of their non-urgent cases will soon have to deal with the backlog.

Dr Lee Hung Ming, senior consultant from Asia-Pacific Eye Centre at Gleneagles Hospital, has reduced the number of procedures he does a month by around 90 per cent since the tightened circuit breaker measures came into effect.

All Lasik and most cataract procedures have been postponed to after June 1.

The eye surgeon told The Straits Times: "We operate only if both eyes are badly affected or if there might be potential complications if not treated. This is especially since most of our cataract patients are elderly and they should stay at home."

Cardiologist Chuang Hsuan-Hung, who practises at the Asian Heart & Vascular Centre, has postponed more than half of his patients' non-urgent treatments since late February. Most patients requested to have their operations postponed so as not to risk virus exposure.

"We mostly operate on patients that come in via A&E (accident and emergency), when it is life threatening. Otherwise, if they are asymptomatic and their condition is manageable, then surgery can be postponed," Dr Chuang said.

Both doctors said their backlogs are likely to still be manageable after the circuit breaker due to the absence of foreign patients.

Said Dr Chuang: "For the next two to three months after the circuit breaker, we will be treating only Singaporeans. The additional 20 to 30 per cent of foreign patient load is likely to return only later, depending on the global situation."

He intends to extend his clinic operating hours if need be.

Dr Lee is also confident that his clinic should be able to clear the backlog within one to two months.

"Without foreign patients, we should have enough capacity, while also implementing added precautions such as safe distancing and spacing out of consultations to prevent patients who are waiting, (having) to crowd inside or outside the clinic," he said.