A woman who could not see out of her right eye suffered a two-month delay to get treatment after an optometrist failed to investigate a "floater" in her right eye.

An eye surgeon who helped advocate for the woman said it was likely the delay in treatment worsened her sight.

"If I hadn't bothered to get another check done by my own optometrist, and been fortunate enough to have [health] insurance so I was able to proceed with my fast-tracked surgery, another patient in my position may have been left with severely impaired sight," the woman said in a Health and Disability Commission report published today.

An HDC investigation found the optometrist in breach of the Code of Health and Disability Services Consumers' Rights for the failure and has been ordered to audit all his clinical assessments to ensure they were documented correctly.

The woman - whose name is not being published for privacy reasons - was away on holiday when the floater suddenly appeared in her right eye.

Floaters are spots in a person's vision which are often harmless but can sometimes be a symptom of a developing eye condition or underlying health issue.

She contacted her usual optometrist, after the floater was still there five days later, who told her to not to wait until she returned from holiday and advised she get it checked immediately.

She was seen by an optometrist in the area where she was holidaying who although he undertook several tests showing "significant reduced vision", did not document all assessment findings and instead ticked a box reporting no change in her vision.

Two months later, the woman went to her usual optometrist when she was still unable to see objects in the middle of her right eye.

It was there she was diagnosed with a macular hole caused by the floater and made an urgent referral to see a ophthalmologist (a surgical eye specialist).

The macula provides the sharp, central vision needed for reading, driving, and seeing fine detail. A macular hole can cause blurred and distorted central vision.

Her usual optometrist wrote a letter to the surgeon saying: "It is extremely disappointing that the optometrist she [Mrs A] saw [while on holiday] didn't action any further investigation for the fact that the vision on the right eye got so bad."

In a clinic letter, the surgeon said that the macular hole had closed, but that as a result of the delay in having it treated, "it may be that that delay is what's causing the poor sight".

He noted "a bit of a cataract" and suggested that cataract surgery might need to be done "sooner rather than later" to try to improve the women's vision.

The optometrist at fault's lawyer said in the report: "She is disappointed and regretful that she missed this [full thickness macular hole] diagnosis. Since the complaint was made, she has spent significant time reflecting on the case, both personally and with her colleagues, and now understands that she should have carried out further investigations, given the results of the visual acuity test. She accepts that by not doing so, her actions fell short of best practice."

Deputy Health and Disability Commissioner Kevin Allan criticised the optometrist, saying she should have taken further diagnostic steps to investigate the cause of the woman's reduced vision.

"As a result [of the failure to investigate], the cause of [the woman's] symptoms were not identified, and surgery to address her degenerating sight was delayed," Allan said.

Allan was also critical of the fact that that the optometrist did not fully document her assessment findings or method of examination.

He recommended that the optometrist undertake a documentation audit to confirm that all clinical assessments have been documented fully, and provide a written apology to the woman.

Allan also recommended that the Optometrists and Dispensing Opticians Board of New Zealand consider whether a review of the optometrist's competence is warranted.