Surgeons theorize dysfunctional lens syndrome to be root cause of visual dysfunction in baby boomers
Dysfunctional lens replacement may be the most appropriate treatment for the source of visual dysfunction.
Presbyopia is ubiquitous, affecting virtually everyone in middle age. Existing treatments for presbyopia include monovision, multifocal ablation, corneal inlays and refractive lens exchange.
Because refractive lens exchange, also known as dysfunctional lens replacement (DLR), is not covered by insurance, younger patients who are unable or unwilling to pay out-of-pocket may forego treatment. Some ophthalmologists use the term “dysfunctional lens syndrome” to show these patients why their vision is deteriorating and why DLR is a viable alternative to LASIK.
Some surgeons recommend that patients undergo DLR early, rather than have LASIK early and cataract surgery later. One procedure is better than two, according to George O. Waring IV, MD.
For patients who come into his office complaining that their LASIK “wore off,” Waring informs them that it did not; rather, their aging lens continued to become more dysfunctional.
The root cause of presbyopia is the lens, not the cornea, he said, so exchanging the lens gives the patient a permanent solution.
Furthermore, lens-based surgery is a better option than LASIK for many patients who have age-related dry eye that may worsen after LASIK, Waring said.
Disease definition and progression
Waring prefers the term “dysfunctional lens syndrome” as an alternative to “pre-cataract” because pre-cataract suggests that the condition is not serious and does not merit treatment just because it is not a cataract.
“Anytime you have multiple dysfunctions, it’s basically a syndrome,” he said. “Here we have multiple characteristic age-related changes of the lens.”
“It’s not OK because we commonly get these patients who are in their early 60s and they don’t qualify for cataract surgery, and they stopped driving at night years ago because of their dysfunctional lens,” Waring said. “They had been told that their cataracts weren’t ripe or that they had a pre-cataract. So, they didn’t really think that they had an option to do anything … That’s one subset of patients whom we can help by educating them to show them that they just have a dysfunctional lens and that we can help them.”
Dysfunctional lens syndrome is an age-related degenerative cascade that runs the gamut from lens stiffening and loss of accommodation to visually significant cataract. It is multifaceted. First, nuclear sclerosis and subtle cortical changes cause forward light scatter, loss of contrast sensitivity and glare. Then, the lens becomes stiffer and loses the ability to accommodate. Finally, changes induce spherical aberrations that reduce quality of vision, Waring said.
Diagnostics and patient education
To educate patients about the clinical value of DLR, Waring said he uses an analogy of two dirty windshields.
“The cornea is dirty because it’s out of focus because of their congenital refractive disorder. And then they’re looking through an inner windshield that is dirty, which is their nuclear sclerosis with all of the light scatter,” he said. “I could clean the outer windshield — perform laser vision correction — but then they’re still going to be looking through a dirty windshield on the inside with the aged dysfunctional lens. So, if you’re looking through one clean windshield and one dirty one, or vice versa, you’re still not going to see well.”
Therefore, from a quality of vision standpoint, it makes more sense to go forward with performing a lens replacement than it does to do LASIK, according to Waring.
Additionally, advanced diagnostic devices can be used to show patients some of the anatomic and optical signs of dysfunctional lens syndrome.
The Optical Quality Analysis System (HD Analyzer, Visiometrics) is a double-pass wavefront device that measures light scatter, Waring said.
“It does a simulation of what the vision would look like,” he said. “You can actually objectively show the patient the light scattering as it falls on the retina. They can see that it’s not a crystal-clear ray of light falling on the retina.”
Dilated slit lamp photography enables the surgeon to show the patient age-related nuclear and cortical changes in the lens. Dilated Scheimpflug photography has a densitometer that measures the density of lens opacities that cause light scatter, Waring said.
“It’s another objective measurement,” he said. “It’s like a giant CT scan or image of their dysfunctional lens. You take a patient on a digital tour of the eye.”
Diagnostic images help patients understand why DLR is preferable to LASIK, Waring said.
“All of a sudden, they have an ‘a-ha’ moment when you first show them with these advanced diagnostic techniques and devices why they’re not seeing well and why it makes sense to go straight to the source and do a dysfunctional lensectomy,” he said. – by Matt Hasson