Dysfunctional lens syndrome paradox

Editor’s Note: Welcome to “Eye Catching: Let's Chat,” a blog series featuring contributions from members of the ophthalmic community. These blogs are an opportunity for ophthalmic bloggers to engage with readers with about a topic that is top of mind, whether it is practice management, experiences with patients, the industry, medicine in general, or healthcare reform. The series continues with this blog by Mark Packer, MD, FACS, CPI. The views expressed in these blogs are those of their respective contributors and do not represent the views of Ophthalmology Times or UBM Advanstar.

The most important question I ask a new patient is this:

“Are you here because you’d like to be able to see just as well without glasses or contact lenses as you do with them, or are you here because the quality of your vision-even with the best glasses or contact lenses-is not satisfactory for performing your activities?” 

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The answer to this question effectively divides those desiring a solely refractive solution from those suffering from decreased functional vision. Of course, the latter may also desire a refractive solution in addition to correction of their diminished function, but their complaint is primarily functional.  In practice, this distinction really matters because it cuts to the heart of our individual customer’s most basic needs and desires.       

Recently, the term dysfunctional lens syndrome (DLS) has been advocated to describe decreased functional vision related to the effects of increasing optical aberrations, as well as subtle age-related opacification of the lens.  DLS has also been defined to include presbyopia, and thus it links what is essentially a refractive condition to a decline in functional vision.  However, while some patients with cataract or DLS may also desire a refractive solution to reduce their dependence on glasses, those who in fact see fine with glasses or contacts, but don’t want to wear them any longer, have purely refractive complaints.  Even in this new hybrid diagnostic category, a distinction between the functional and the refractive applies.

Next: Categorizing DLS

The diagnostic category of DLS was developed as a professional response to the pre-operative diagnostic criteria placed by third party payers on the reimbursement for cataract surgery:  “Characterization of (dysfunctional lens) syndrome came about because patients were describing cataract-like symptoms, but they did not have a diagnosable cataract by Medicare or insurance standards.”[i]

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We should be concerned about this approach because the definition of diagnostic categories should not be allowed to depend on the policies of third party payers-diagnosis depends on the professional authority of ophthalmology.  Careful consideration should be exercised in the development of diagnostic categories if unintended consequences of novel conceptual frameworks are to be avoided.

Let’s reconsider the definition of DSL, starting with its current description: “Recently, the term dysfunctional lens syndrome has been proposed to describe the aspects of the senile crystalline lens, including lens opacities, loss of accommodation, and increase of higher-order aberrations.”[ii]

First of all, lens opacity is cataract by medical definition, regardless of degree.  The clinical threshold for recommending cataract surgery is another matter, and the conditions for coverage of cataract surgery determined by third party payers are yet another.  When I was a resident, the chief would not consider cataract surgery for anyone with better than 20/50 best-corrected acuity.  Over time, his threshold for surgery changed, and, over time, the threshold for surgery promulgated by Medicare carriers and commercial insurers has changed, too.  It will undoubtedly continue to change, as beneficiaries demand better care, as technology improves, and as outcomes continue to demonstrate faster recovery and less morbidity. 

Next: Fundamental distinction

However, the fundamental distinction between refractive lens surgery and functional lens surgery will never change-just as the distinction between aesthetic plastic surgery and reconstructive plastic surgery will never change.  A woman who wants a facelift knows that she does not have a disease, or “rhytidosis syndrome.” She knows that she is seeing the expected effects of aging, and therefore accepts the fact that medical insurance will not cover the procedure she wants.  She understands that the purpose of medical insurance is to protect the financial well being of those who become sick, not to indulge women who can afford greater beauty.

A woman who tells me she “can’t stand to wear these reading glasses any longer” knows that she is fundamentally healthy, that she has no “syndrome.”  She wants to turn back time, to look and feel younger, and she is more than willing to pay for that service herself.  On the other hand, a man who has to give up driving at night because of “changes in his lens” knows that something is wrong, that there is a diagnosis for his ailment, and that something needs fixing.

The line between refractive lens surgery and functional lens surgery is bright.  As a concept, DSL lies mostly on the functional side of the divide, but, like the “God of the Gaps,” a Supreme Being who is acknowledged only in the spaces that science has not yet filled and finds His territory shrinking on a daily basis, DSL is destined to be squeezed.  On the one hand, advancing technology will continue to provide ever more sensitive measurement of minimal levels of lens opacification, expanding the range of lens changes defined as cataract.  Meanwhile, beneficiaries with real visual problems and subtle lens opacities will demand that insurance provide coverage, while those with increasing aberrations will cite the concept of the “wavefront cataract.” On the other hand, patients with purely refractive goals may begin to question whether perhaps they do have a “covered” diagnosis, after all.     

Next: Examining the core

The distinction between refractive lens surgery and functional lens surgery is fundamental.  It lies at the core of the reason why a person came to see a surgeon.  Whether or not cataract surgery is “covered” by a particular third party payer does not change the condition of the eye, or its appropriate diagnosis (although it may change the condition of the eye’s owner’s pocketbook, should he or she decide to proceed with surgery).  The decision to have surgery is multifaceted, after all, and, finally, personal.

The American Academy of Ophthalmology notes in its Preferred Practice Pattern for Cataract in the Adult Eye,“there is no single test or measure that adequately describes the effect of a cataract on a patient’s visual status or functional ability. Therefore, no single test can properly define the threshold for performing cataract surgery. Though various methods of acuity measurement have long been considered the primary determinant for surgical appropriateness, the decision to recommend cataract surgery should not be made solely on this basis. For example, surgery for non-advanced cataract in symptomatic patients with relatively good Snellen acuity often provides significant functional benefits. Standardized evaluation of impairment of visual function and activities of daily living have been shown to correlate with expected improvement and satisfaction after cataract surgery. Several of these validated testing instruments and recent modifications are available for clinical use.”

If an insurance company defines the indication for cataract surgery as, for example, “lens opacity causing a decrease in best-corrected visual acuity, or best-corrected visual acuity with glare, to 20/40 or less,” what becomes of the patient who complains of increasing difficulty driving at night despite 20/20 best-corrected visual acuity with glare, demonstrates a score of 70% on the VF-14 and reveals 0.3 log unit loss of mesopic contrast sensitivity at 6 cycles per degree?  If these findings are demonstrably associated with and reasonably caused by lens opacities-whether discerned on slit lamp exam or with the aid of more sensitive Scheimpflug photography-they are due to cataract, plain and simple, regardless of whether the test results meet any particular pre-specified threshold criteria described by third party payers.  If, on the other hand, there is no lens opacity-but there are sufficient lenticular optical aberrations to explain the functional visual symptoms and clinical findings-then the diagnosis of DLS may be appropriate. 

Next: The paradox

In this regard, DLS becomes a useful designation for the effect of lenticular optical aberrations, primarily spherical aberration, which increasingly reduce the quality of vision throughout life (see ICD10 H53.8, other visual disturbances).  These aberrations are eminently measurable, and may represent an indication for functional lens surgery if correlated with subjective experience, such as difficulty driving at night, regardless of the determination of local Medicare carriers.  Often, the use of a validated questionnaire, contrast sensitivity testing and wavefront aberrometry will provide substantial objective evidence of functional visual impairment in these cases.    

It is an apparent paradox, of course, that corneal higher order aberrations have been traditionally considered a solely refractive concern, particularly since the advent of wavefront-guided LASIK, while lenticular aberrations are considered to be primarily a functional concern.  The resolution of this paradox lies in the observation that lenticular aberrations tend to complement and counterbalance corneal aberrations in youth, enhancing the quality of vision, but increase with age and ultimately magnify corneal aberrations later on.  The discovery of increasing spherical aberration in the lens, and its relationship to decreased functional vision and relatively poorer night driving performance, has driven the development and adoption of aspheric intraocular lenses.[iii]  The increasing aberrations of the aging lens have always been and remain primarily a concern of functional vision.

As opposed to optical aberrations, lens opacities should be diagnosed as cataract, regardless of degree, and are susceptible to digital quantification.  The diagnosis of cataract should be distinguished, however, from the threshold for recommending cataract surgery, which should be in turn independent of any particular third payer’s policy regarding reimbursement.

Next: The 5 procedures

Presbyopia, on the other hand, remains fundamentally a refractive diagnosis, and demands a uniquely refractive solution, as do hyperopia, myopia and astigmatism.

Therefore, in order to remain consistent with our basic understanding of the fundamental differences between refractive lens surgery and functional lens surgery, we have developed five related but distinct procedures: 

1)        Refractive Lens Exchange means that the primary purpose of surgery is to reduce or eliminate the need for eyeglasses. 

2)        Cataract Surgery means that the primary purpose of surgery is to improve functional vision impaired by lenticular opacification.  

3)        Refractive Cataract Surgery means that the primary purpose of surgery is to improve functional vision impaired by lenticular opacification and the secondary purpose of surgery is to reduce or eliminate the need for eyeglasses.  

4)        Dysfunctional Lens Surgery means that the primary purpose of surgery is to improve functional vision impaired by lenticular aberrations.

5)        Refractive Dysfunctional Lens Surgery means that the primary purpose of surgery is to improve functional vision impaired by lenticular aberrations and the secondary purpose of surgery is to reduce or eliminate the need for eyeglasses. 

Next: Leaving third parties out of the picture

Regardless of the apparent complexity involved in the differentiation of these procedures, the fundamental question remains: “Are you here because you’d like to be able to see just as well without glasses or contact lenses as you do with them, or are you here because the quality of your vision-even with the best glasses or contact lenses-is not satisfactory for performing your activities?”  Ask this question first, and the conclusions will follow.   But don’t allow the restrictions of third party payers on reimbursement for cataract surgery to drive your diagnosis or your recommendations for treatment.  Diagnosis and treatment must remain the surgeon’s sole responsibility if our profession is to retain any of its natural inherent authority.   

References

[i] Waring IV, GO.  Diagnosis and Treatment of Dysfunctional Lens Syndrome.  Cataract & Refractive Surgery Today March 2013; http://crstoday.com/2013/03/diagnosis-and-treatment-of-dysfunctional-lens-syndrome/ (Accessed March 4, 2015).

[ii] Waring IV, GO.  Replacement of dysfunctional lens may pose multiple benefits.

Ophthalmology Times, June 14, 2015;  http://ophthalmologytimes.modernmedicine.com/ophthalmologytimes/content/tags/acufocus/replacement-dysfunctional-lens-may-pose-multiple-benefits?page=full (Accessed March 4, 2015).

[iii] Packer, M, Fine, IH, Hoffman, RS.  Wavefront technology in cataract surgery.

Current Opinion in Ophthalmology, 15 (1), pp. 56-60.