Defining dysfunctional lens syndrome

Rose is a rose is a rose is a rose--a line written (1913) by Gertrude Stein and its variations in a famous quotation are often interpreted as meaning “things are what they are--makes a statement of the law of identity, and in the post-factum age is ever more meaningful.

An ophthalmologist could as well write: “Cataract is a cataract is a cataract is a cataract,” ICD-10 Code H25.0 for the diagnosis “Cataracta senilis incipiens” in its earliest stage and notably with a surgical history of more than 2,500 years.

Couching was already known to the Babylonian civilisation. In spite of progress to surgical techniques in many countries during the past decade, cataract remains the leading cause of visual impairment (47.9%, according to WHO) in the world, except for developed countries.

Usually, the medical procedures phacoemulsification and IOL implantation are covered by private or public health insurances when visual acuity drops below 20/40 (0,5). Patients have funded upgrading options themselves if refractive optimisation of pseudophakic presbyopia is the goal.
 

Enter DLS

What is dysfunctional lens syndrome (DLS) all about then? In refractive surgery, presbyopia correction remains the holy grail. The demand is increasing along with the aging of the population. Procedures that target the cornea or sclera have failed to turn into blockbusters, such as LASIK. The refractive surgeon is reluctant to propose LASIK in an individual older than 45 to 55 years for many reasons: insufficient presbyopia correction with monovision; increased dry eye problems; and most commonly, instability of refraction and increasing visual symptoms due to the aging of the crystalline lens.

DLS characterises a spectrum of changes that occur with age, including presbyopia, opacification, loss of image quality, and higher-order aberrations. Actually, reduction of quality of vision is coded as well (ICD-10 H53.8 other visual disturbances).

Rational behind DLS

Part of the rationale behind the DLS terminology is to avoid the use of others, such as very early cataract or pre-cataract. These terms can seem dismissive, implying that a patient’s only option is to wait for the early cataract to ripen or for a pre-cataract to become a cataract, delaying surgery by 5 to 10 years.

Prof George O Waring IV, of the University of South Carolina, USA, defines three stages of DLS:

Stage 1 is defined by the onset of presbyopia and the subsequent progressive loss of accommodation.

Stage 2 includes some opacification of the lens with the onset of aberrations or change of refraction.

In stage 3, DLS is advanced--not yet meeting the insurance-based criteria for a cataract--but influencing the daily life of the patient. In stages 2 and 3, a lens-based procedure should be preferred to LASIK if the patient is demanding refractive surgical intervention.

Cataract is a cataract, and DLS is a clinical entity that has been overlooked and inadequately characterised. In the perspective of the refractive surgeon, this new entity is important since it gives objective measures to decide between a cornea-based LASIK or a lens-based procedure, such as refractive lens exchange.

Stein’s famous quotation might simplify things. There are always two sides to every story, and it is a question of perspective to reveal the tru behind what is called a fact.