Anterior segment surgeons already do many things to ensure their patients have a good experience during their cataract surgery operation, including multiple steps designed to get as close to the intended refractive target as possible.
In recent years, the addition of femtosecond laser to cataract surgery has helped make lens ablation easier, streamlined making incisions, and has helped ensure a consistent capsulorrhexis is made in each surgery. But the addition of laser is only one example of how ophthalmology has embraced high technology to help make the entire process more accurate and predictable. One could easily look at the variety of diagnostic tools used during the preoperative evaluation to help guide decision making and surgical planning for any number of examples.
In fact, the successful integration of technology into cataract surgery during the perioperative period has allowed surgeons to do a better job meeting (and often exceeding) patients’ expectations. We are moving ever closer to realizing the true meaning of “refractive cataract surgery.”
Still, even though we go to great lengths to lock down the refractive outcome for our patients, there is one testing modality in particular that seems to be greatly underutilized for what it can add to the evaluation. In my practice, the discretionary use of Light Induced Visual-response (LIV) testing is often a deciding factor in whether to perform surgery, and if so, what kind of lens would be suitable for a patient’s visual system.
In the end, patients want us to make a recommendation for the IOL that will help achieve their postoperative vision goals. That responsibility should motivate us to seek out every piece of data that will give us the confidence in the lens options we present to patients.
Why Light Induced Visual-response (LIV)™?
The name LIV describes exactly what this test is, while also suggesting why it can unveil critical information. Technically speaking, a LIV test records the electrical response of cells that have been targeted with a light-based stimulus. What that means, though, is that the test records objective information about how the cells along the visual pathway are functioning—it helps tell us whether they are healthy, sick, dying, or dead.
That kind of data can be crucial in a number of contexts. First, in patients with dense cataracts that prohibit an inspection of the retina, and when you cannot image with OCT, a LIV test will provide valuable information about the health of the retina. Knowing about the viability of the visual system may ultimately determine whether removing the cataract will be of any benefit.
To be clear, cataract surgery is one of the safest operations in modern medicine. At the same time, very dense cataracts often occur in older individuals who may be on medications or have other complications that suggest a risk for undergoing any surgery.
I had a cataract consultation with an elderly patient recently who was 20/400 with no view of the retina preop by exam or OCT imaging; his aftercare would have required a lot of help from family, including requiring them to take time off from work. They were all concerned whether having the operation would have been worth it given that it would require making special arrangements for care, even in the short-term.
The LIV test we performed in this patient suggested that the retina was healthy. We eventually did cataract surgery with IOL placement in each eye and he wound up achieving 20/30 vision. More importantly, though, he is extremely happy, as is his entire family and support system.
LIV-ing and Premium IOLs
All cataract surgeries require careful planning and execution to achieve the desired outcome. For those patients who are seeking either a multifocal or toric IOL, the expectations for the final vision are heightened because we are asking them to pay extra, and often out of pocket, for the chance to achieve improved quality of postsurgical vision.
Several tests have become almost necessary for patients thinking about a premium lens. For example, we use OCT to determine if any pathology is present that may suggest a less than optimal outcome with a multifocal IOL. Yet, while it is objective, OCT only captures the retina structure at one given time, which may or may not correlate with function. Whereas LIV testing—because it provides insight into the viability of retina cells, and because a change in signal indicates change in the health of those cells—is often a critical factor in making a decision in borderline cases, such as mild epiretinal membranes. Some of these latter patients may benefit from premium IOL technology if so desired by them as long as LIV testing reveals normal function.
There is an analogous situation that ophthalmologists may be familiar with in evaluating patients with suspect glaucoma. There are often several factors we have to consider before starting treatment. We may look to visual field testing, but that is both subjective and often inconclusive on its own. In those cases, we look to additional pieces of information, like family history, to help break the tie. Coincidentally, there are also different kinds of LIV testing that can be used with patients with suspected glaucoma that provide vital information for guiding treatment decisions.
The bottom line is that we use data in the clinic to support the decisions we make with and for patients every day. As we look to achieve greater confidence in making a lens recommendation, LIV testing becomes yet another meaningful way we can help insure and ensure the final outcome.
This article represents the experiences and opinions of Mitchell A. Jackson, M.D. Physicians should make medical decisions based on the individual facts and history of each patient.