Crossed monovision may be as effective as conventional monovision

Certain patients may respond better to the standard technique.

Issue: November 2016

Crossed pseudophakic monovision for patients with a mild degree of anisometropic pseudophakia may work as well as conventional pseudophakic monovision, but crossed pseudophakic monovision has more contraindications and should be avoided if the conventional technique can be performed in most clinical conditions.

IOL monovision is one of the best ways to handle presbyopia in cataract patients. It is a predictable and tolerable procedure, which results in good vision quality at a low cost for the patient, Fuxiang Zhang, MD, told Ocular Surgery News.

Just as effective

However, in a study, Zhang and colleagues showed crossed pseudophakic monovision is as effective as traditional monovision for patients with a mild degree of anisometropic pseudophakia and should be added to the ophthalmology armamentarium.

“Biometry is not perfect, and we all sometimes miss our refractive target. If that happens, crossed monovision may become necessary if the patient still wishes to be glasses-free. For example, if we operate the non-dominant eye first aiming –1 D for near vision but end up as –0.25 D with good distance vision and the patient is happy with the operated eye as the distance vision eye, we can still do the second eye, the dominant eye, aiming at near,” Zhang said.

Additionally, patients sometime want to have the second eye cover what the first eye is not able to see well without glasses. In these types of situations, Zhang said crossed monovision can be an effective technique.

Similar outcomes

After reviewing 7,311 cases of IOL monovision over 14 years, the retrospective, comparative cohort study included 30 patients who underwent crossed IOL monovision and another 30 patients with as many comparable factors as possible to act as control conventional IOL monovision patients. Among 12 items studied, including satisfaction, spectacle freedom, eye-hand coordination, eye-foot coordination or sport-related depth perception, the crossed monovision group did as well as traditional monovision outcomes. In a few items, the crossed group even did better than the conventional group.

Zhang and colleagues also reported the mean anisometropia was 1.19 D in the conventional monovision eyes and 1.12 D in the crossed monovision eyes.

“Knowing that crossed monovision works as well as conventional monovision as long as the anisometropic level is kept at a modest level and as long as contraindications are avoided, we can feel very comfortable and safe to use crossed monovision when the needs arise,” Zhang said.

But, Zhang noted, crossed monovision results are not as predictable as conventional monovision in certain clinical situations, and it is not a good fix when patients are amblyopic, have monofixation syndrome, have a long-standing suppressed eye such as a monocular traumatic cataract, or have a history of strabismus or prism usage.

Traditional IOL is best

Zhang said these cases are not particularly good candidates for conventional monovision either, but crossed monovision will result in more troublesome results.

“In these situations, if we pick the weaker eye, typically the non-dominant eye, as the distance fixation eye, it will result in what is called in literature ‘fixation switch diplopia.’ Typically, the patient will remain symptomatic until the healthy eye is reversed back as the distance fixation eye,” he said.

A traditional monofocal IOL is still the most reliable and predictable technique when it comes to treating patients with a mild to modest degree of anisometropic pseudophakia and one of the best ways to handle presbyopia in cataract patients, including those who have a demanding personality and/or with mild or even moderate ocular comorbidities who are not good candidates for other premium IOLs, Zhang said.

“Backup glasses are very convenient and handy if perfect non-monovision need arises. Our recent 10-year IOL monovision review study, with de-identified survey, demonstrated that 97% of enrolled patients rated it either ‘I like it’ or ‘I really like it,’ 2% [were] neutral and 1% did not like it,” Zhang said. – by Robert Linnehan

Reference:
Zhang F, et al. J Cataract Refract Surg. 2015;doi:10.1016/j.jcrs.2015.10.013.

For more information:
Fuxiang Zhang, MD, can be reached at Downriver OptimEyes Supervision Center-Taylor, 22395 Eureka Road, Taylor, MI 48180; email: fzhang1@hfhs.org.

Disclosure: Zhang reports no relevant financial disclosures.