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Refractive Surgery | Oct 2014

Identification and Treatment of DLS

Replacement of the dysfunctional crystalline lens offers a permanent solution for baby boomer patients seeking LASIK correction.

Patients in their mid-50s to 60s often present for a LASIK evaluation because they no longer want to use glasses for both distance and reading. These baby boomer patients have difficulty seeing at distance due to congenital ametropia and at near due to their progressive presbyopia. They do not come in stating that they cannot drive at night due to glare; instead, they are seeking an elective procedure to provide spectacle independence. For many years, we performed LASIK in these types of patients. However, they would frequently come back over time complaining that their LASIK had worn off.

We began paying attention to the source of the issue for these patients: the aging of the crystalline lens. There is a constellation of ways that the crystalline lens progressively becomes dysfunctional due to aging, including opacification and loss of accommodation. Additionally, higher-order aberrations increase in the aging lens and exacerbation of narrow angles may also occur.1

DYSFUNCTIONAL LENS SYNDROME

Using an advanced ocular analysis including a digital lens-centric exam, we often find that baby boomer patients presenting for LASIK do not have clear lenses; they have dysfunctional lens syndrome (DLS), a clinical entity that has been overlooked and inadequately characterized for years.2

The term dysfunctional lens syndrome characterizes a syndrome of the dysfunctionality of the lens as a spectrum of changes that occur ubiquitously with age. Part of the rationale behind the terminology is to avoid the use of the terms very early cataract or precataract. These terms are dismissive and imply that the patient’s only option is to wait for that very early cataract to ripen or for that precataract to become a cataract, delaying surgery by 5 to 10 years.

Daniel S. Durrie, MD, recently proposed a series of stages of lens dysfunctionality. According to this grading scale, a stage 3 dysfunctional lens is a cataract that affects a patient’s daily activities and meets insurance-based criteria for diagnosis of a cataract.

By 2020, there will be more than 2 billion presbyopes worldwide; currently half of Asia is presbyopic.3,4 One thing we have learned from working with new technologies around the world is that presbyopia can manifest in the early to mid 40s in certain geographic areas, significantly affecting people’s quality of life. Many patients could benefit from the identification and treatment of DLS.

DYSFUNCTIONAL LENS REPLACEMENT

As I explain to patients with DLS, their situation is similar to looking through two dirty windshields, one in front of the other. We can clean (focus) the outer windshield (the cornea) with LASIK, but the inner windshield (the crystalline lens) is still dirty. Therefore, in patients with DLS, it makes more sense to exchange the aging crystalline lens for an appropriately selected IOL rather than performing LASIK now and cataract surgery years later. Although we do perform clear lens exchange in younger patients with large amounts of hyperopia, dysfunctional lenses are not clear, hence the use of the term dysfunctional lens replacement.

Dysfunctional lens replacement for DLS has become a big part of my practice. Patients respond well to this treatment option because we educate them appropriately. Combining the use of dilated Scheimpflug imaging and associated densitometry with the the AcuTarget HD double-pass wavefront diagnostic device (AcuFocus), we take patients on a digital tour of their eyes, showing them their dysfunctional lens and the resulting light scatter. The AcuTarget HD generates an ocular scatter index (OSI), which gives patients a score for their quality of vision. Snellen described visual acuity in 1863, but things have changed since then: We now have advanced diagnostics, and these measure functional vision—or quality of vision. A patient may have 20/20 visual acuity but have clinically relevant light scatter. Showing patients the light scatter (point-spread function) and increased OSI helps them understand the value of addressing the source of the problem—the aging crystalline lens—and doing so with a single procedure while preventing future cataract formation.

We recommend that dysfunctional lens replacement incorporate the use of the femtosecond laser because of its advanced capabilities for creating limbal relaxing incisions and capsulotomies, which may lead to better outcomes with advanced-technology IOLs. Furthermore, we feel that visual recovery is often quicker with use of the femtosecond laser due to greatly reduced phaco energy, and, as a result, we can truly deliver refractive results with lens replacement.

During the refractive consultation, we emphasize to all patients that DLS is a normal part of the aging process and that no action is required. For patients who wish to pursue surgery to treat presbyopia, dysfunctional lens replacement is presented as an option. As with all surgical procedures, we outline the relative risks and benefits of each technique. We are careful to point out that lens surgery is more invasive than LASIK, as the former is an intraocular procedure and, thus, carries different surgical risks.

In my community, patients are hearing about this treatment and seeking it out. Occasionally I advise these patients that they may be better candidates for a corneabased procedure due to the clarity of their lens. The paradigm is certainly changing.

CASE PRESENTATIONS

Case No. 1. An architect in his 50s with a stage 1 dysfunctional lens presented for LASIK. He would have been a fine candidate; however, careful examination of the lens revealed subtle anterior and posterior cortical opacities, which were confirmed on Scheimpflug images and densitometry (Figure 1). I showed the patient these findings and told him I could perform either LASIK or dysfunctional lens replacement, the latter being a permanent solution that would prevent future development of cataracts and, thus, avoid a second surgery.

Case No. 2. A woman in her 50s presented requesting LASIK, desiring freedom from her reading glasses. The patient, an owner of a hormone replacement clinic, was taking hormones. Her right eye appeared fairly straightforward, but subtle asymmetry of opacity was noted in her left lens, which is clearly seen in the dilated Scheimpflug image (Figure 2). This patient did not come in complaining of glare; she just wanted out of her reading glasses. I opted to perform dysfunctional lens replacement in this case.

Case No. 3. A 58-year-old patient presented for LASIK. Due to the presence of stage 2 dysfunctional lenses, we performed dysfunctional lens replacement first on her left eye. Notice the differences in the point-spread function, OSI, and densitometry between the treated and untreated eye (Figure 3).

SUMMARY

The take-home message is that many patients in their late 50s and 60s requesting LASIK do not have clear lenses. Advanced diagnostics such as the AcuTarget HD, which performs double-pass wavefront analysis and provides OSI, dilated Scheimpflug imaging, and lens densitometry, help us to better understand patients’ quality of vision and to refine dysfunctional lens replacement.

Dysfunctional lens replacement is an all-in-one solution. In a way, this procedure may end up being LASIK for the baby boomers. To quote John Marshall, PhD, “Why should the cornea suffer for the crimes of the lens?”5

George O. Waring IV, MD, FACS, is the Director of Refractive Surgery and an Assistant Professor of Ophthalmology at the Storm Eye Institute, Medical University of South Carolina. He is also the Medical Director of the Magill Vision Center in Mt. Pleasant, South Carolina. He disclosed a financial interest related to the material discussed herein. Dr. Waring may be reached at e-mail: waringg@musc.edu.

  1. Rocha KM, Nosé W, Bottós K, Bottós J, Morimoto L, Soriano E. Higher-order aberrations of age-related cataract. J Cataract Refract Surg. 2007;33(8):1442-1446.
  2. Waring GO IV. Diagnosis and treatment of dysfunctional lens syndrome. Cataract & Refractive Surgery Today. 2013;13(3):36-38.
  3. CIA World Factbook. https://www.cia.gov/library/publications/the-world-factbook/geos/ch.html. Accessed September 19, 2014.
  4. Global Presbyopia-Correcting Surgery Market Report. Market Scope. April 2012.
  5. Marshall J. Are we getting closer? A commentary to the keynote address. Paper presented at: the 2013 AECOS European Symposium; June 29, 2013; Cannes, France.

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