By Paul Batson, O.D. Center Director, VisionAmerica of Birmingham John (not his real name) came to see me several months ago for a second opinion. He is truly one of the nicest guys that you could meet but was pretty frustrated. He had undergone cataract surgery at another practice here in town and was not happy for two reasons. First, as a previous -2.50, he was miserable with his loss of near vision. Second, he had this persistent dark shadow he was seeing temporally since his surgery and it wasn't getting any better. As I examined John, everything really looked good. He was 20/20 uncorrected at distance and had a plano refraction. His cornea was clear and he had a well-centered posterior chamber IOL. Upon dilated examination, he was found to have a completely normal retina. So why the shadow? Why was he so unhappy? Let's address the post-op refractive error first. This was clearly a misalignment of the surgical plan and patient expectations. According to the patient, the surgeon never discussed a loss of near vision and didn't discuss possible advanced technology options that would have helped this issue. This could have easily been avoided with a little more discussion and education. Now, the dark shadow. You certainly have to consider retinal detachment in this situation but the timing and symptoms didn't completely match up to me. He didn't have any photopsia's or floaters that preceded his symptom and the fact that it was so acute in onset (right after surgery) and hadn't changed, led me to consider negative dysphotopsia as a probable etiology. Dysphotopsia's as a whole can be somewhat challenging. Fortunately, most of these resolve on their own but according to Kevin M. Miller, MD, Chief of Cataract and Refractive Surgery at the University of California, Los Angeles, approximately 20% of patients undergoing cataract surgery can experience some form of pseudophakic dysphotopsia [1]. As a reminder, dysphotopsia can come in two forms - positive or negative. Positive dysphotopia tends to be the glare, halo's or starburst that patients describe. Most of these tend to be related to the ocular surface and, if aggressively treated, will most often resolve. While you can also see these in patients with advanced technology lenses like multifocals or extended depth of focus lenses, these occur a lot less frequently than first generation multifocal IOL's. Negative dysphotopsias can be more challenging but are fortunately less common. These are the patients that often describe the shadow as horse blinders. It is often a dark shadow that occurs temporally and the patient is usually aware of it pretty early in the post-op period. I've seen doctors tell patients that it may be their eyelid or the corneal incision but in reality, we don't truly know why patients develop this symptom. The most likely cause is an interaction of light at the nasal edge of the IOL and anterior capsule that casts a dark shadow on the nasal retina. The primary diagnostic indicator is that symptoms will almost completely resolve upon pupil dilation. In most cases, whether it's due to neuroadaptation or fibrosis of the anterior capsule, the symptoms will resolve on their own over the first few months. If not, there are a variety of surgical options from repositioning the haptics of the IOL to piggybacking an IOL on top or even IOL exchange. For John, because his symptoms were both refractive in nature (he didn't like being plano) and he was experiencing negative dysphotopsia, the decision was made to exchange the lens for a three-piece IOL with a different power (targeting a -2.0D post op refraction). At his one-day post-op visit, his dark shadow was immediately gone and he was extremely happy to be myopic again. [1]https://www.aao.org/eyenet/article/shedding-light-on-pseudophakic-dysphotopsia
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10/25/2023 02:56:38 am
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