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Small gauge vitrectomy may not protect against nuclear sclerotic cataract progression
The many benefits of small-gauge vitrectomy may not include decreasing the progression of nuclear sclerotic cataract, according to a study.
A prospective study of patients undergoing 20-gauge, 23-gauge or 25-gauge vitrectomy found no detectable differences in cataract progression.
“This was not a surprise finding,” study co-author Nancy M. Holekamp, MD, director of Retina Services at Pepose Vision Institute in Chesterfield, Mo., said. “That was our hypothesis all along because we engage in cataract research. We know that vitrectomy surgery in anyone over the age of 50 causes a rapid acceleration of nuclear sclerotic cataract simply because the vitreous gel is being removed. The vitreous protects the eye from nuclear sclerotic cataract.”
Some of the ophthalmic literature proposes that one of the advantages of small-gauge surgery may be the prevention of post-vitrectomy cataract.
“Based on our research, we knew this was not true, but we needed to prove it,” Dr. Holekamp told OSN Retina.
The study was published in Retina.
Study results
Of the 42 study eyes of 39 patients analyzed, 20-gauge vitrectomy was performed in 11 eyes, 23-gauge vitrectomy was performed in 22 eyes and 25-gauge vitrectomy was performed in nine eyes.
The study’s primary endpoint was nuclear sclerotic cataract progression at 6 months and 12 months, as measured by Scheimpflug lens photography. Because some eyes were lost to follow-up or had cataract surgery, at 6 months only 28 eyes were photographed, and at 1 year only 11 eyes were photographed.
“Scheimpflug technology is so highly sensitive because it quantifies the degree of opacity into pixels, and therefore you can assign a numeric value to the degree of cloudiness of the lens, then perform statistics,” Dr. Holekamp said. “This allows us to achieve statistical significance despite the small number of eyes.”
At 1 year, no statistically significant difference was seen between the 20-gauge and 23-gauge groups. The 25-gauge vitrectomy group was excluded from analysis because only one patient remained in the group at 1 year.
“The power of our study is using Scheimpflug technology and following these eyes prospectively,” said Dr. Holekamp, who advocates that cataract research incorporate such technology because it is quantitative.
“A lot of people have proposed that the trauma of the vitrectomy surgery is what causes cataract. And although we cannot rule that out completely, it does not fit with the mechanism of nuclear sclerotic cataract,” Dr. Holekamp said.
The mechanism of nuclear sclerotic cataract is oxidative damage.
“The oxygen comes from the retina, and a formed vitreous gel will consume that oxygen and protect the lens,” she said. “However, by removing the vitreous gel with any gauge vitrectomy surgery, you will end up with progressive cataract in any patient over the age of 50. But under the age of 50, the lens has the ability to protect itself from oxidative damage and the time to nuclear sclerotic cataract development is longer.”
The study confirmed that people older than 50 years develop rapidly progressive nuclear sclerotic cataract after vitrectomy surgery, according to Dr. Holekamp.
“Therefore, this should be part of the informed consent process for everyone undergoing vitrectomy surgery,” she said.
Nearly half of the study participants had cataract surgery within 1 year.
“So, I tell my patients who are phakic at baseline that they will likely require not one but two operations to visually rehabilitate the eye,” Dr. Holekamp said.
Dr. Holekamp, who performs small-gauge vitrectomy, said advantages of small-gauge surgery include smaller incisions, fewer sutures and increased postoperative comfort. She is researching how to prevent post-vitrectomy nuclear sclerotic cataract altogether.
“If we can prevent post-vitrectomy cataract, we can probably prevent age-related cataract in general,” she said. – by Bob Kronemyer
Reference:
- Almony A, Holekamp NM, Bai F, Shui YB, Beebe D. Small-gauge vitrectomy does not protect against nuclear sclerotic cataract. Retina. 2012;32(3):499-505.
For more information:
- Nancy M. Holekamp, MD, can be reached at Pepose Vision Institute, 1815 Clarkson Road, Chesterfield, MO 63017; 636-728-0111; email: nholekamp@gmail.com.
- Disclosure: Dr. Holekamp has no relevant financial disclosures.