Cataract is defined as an opacity or loss of optical clarity of the
crystalline lens. Cataract development follows a continuum extending from
minimal changes in the crystalline lens to the extreme stage of total opacity.
Cataracts may be due to a variety of causes. Age-related cataract (senile
cataract) is the most common type found in adults. Other types are pediatric
(both congenital and acquired), traumatic, toxic and secondary (meaning the
result of another disease process) cataract.  
  
Most cataracts are not visible to the naked eye until they become dense enough
(mature or hypermature) to cause blindness. However, a cataract at any stage
of development can be observed through a sufficiently dilated pupil using a
slit lamp biomicroscope. In settings where this instrument is unavailable
(e.g., skilled nursing facility), a direct ophthalmoscope can be used to
assess the degree to which the fundus reflectivity (red reflex) is impaired by
the ocular media. There is no scientifically proven medical treatment for
cataracts.  
  
In general, cataract surgery is performed to alleviate visual impairments
attributable to lens opacity. There are uncommon situations when lens
extraction becomes medically necessary for anatomic rather than optical
reasons. These include lens induced angle closure (e.g., microspherophakia)
and lens subluxation (e.g., Marfan syndrome). In other situations, cataract
extraction might be medically indicated with relatively less opacity because
of intolerable optical imbalance. Most commonly, this would be due to
surgically induced anisometropia (a significant difference in refractive
errors between the eyes) or aniseikonia (a difference in magnification as a
result of prior lens extraction in the one eye). Some patients may elect lens
removal and replacement primarily for refractive benefits to reduce their
dependence on spectacles. Such elective procedures are not medically necessary
and are called "refractive lens exchanges" to distinguish them from medically
indicated cataract surgery. Finally, advanced cataracts may need to be removed
to properly visualize, treat, and monitor retinal disease, apart from the
patient's visual symptoms and potential.  
  
This policy statement defines the medical necessity for cataract and other
lens extraction in adults, and specifies the required documentation of the
preoperative evaluation necessary to justify the procedure. This A/B Medicare
Administrative Contractor (MAC) encourages but does not require providers to
use the framework of the International Classification of Functioning,
Disability, and Health (ICF) to organize the information related to relevant
structural/functional impairments, activity limitations and/or participation
restrictions, and any environmental factors influencing the decision to
recommend cataract surgery.  
  
 **Medical Necessity**  
  
Medical necessity for cataract surgery is not based solely on the presence of
opacity in the lens(es). Lens extraction is considered medically necessary and
therefore covered by Medicare when 1 (or more) of the following conditions or
circumstances exists:  
  

  1. Cataract causing symptomatic (i.e., causing the patient to seek medical attention) impairment of visual function not correctable with a tolerable change in glasses or contact lenses, lighting, or non-operative means resulting in specific activity limitations and/or participation restrictions including, but not limited to reading, viewing television, driving, or meeting vocational or recreational needs.  
  

  2. Concomitant intraocular disease (e.g., diabetic retinopathy, or intraocular tumor) requiring monitoring or treatment that is prevented by the presence of cataract.  
  

  3. Lens-induced disease threatening vision or ocular health (including, but not limited to, phacomorphic or phacolytic glaucoma).  
  

  4. High probability of accelerating cataract development as a result of a concomitant or subsequent procedure (e.g., pars plana vitrectomy, iridocyclectomy, procedure for ocular trauma) and treatments such as external beam irradiation.  
  

  5. Cataract interfering with the performance of vitreoretinal surgery.  
  

  6. Intolerable anisometropia or aniseikonia uncorrectable with glasses or contact lenses exists as a result of lens extraction in the first eye (despite satisfactorily corrected monocular visual acuity).

  
Medicare will consider coverage of cataract surgery for circumstances not
listed above. Coverage will be based on documentation that supports medical
necessity and is compatible with the accepted standards of medical care.
Medicare coverage extends only to standard non-correcting prosthetic lenses.
Advanced technology prosthetic lenses are not covered.  
  
 **Visual Acuity**  
  
The Snellen chart is frequently used as a screening tool to measure visual
acuity. However, testing using high contrast letters viewed in dark room
conditions, can underestimate the functional impairments caused by some
cataracts in common real-life situations (e.g., glare conditions, poor
contrast environments, reading, halos and starbursts at night, and impaired
optical quality causing monocular diplopia and ghosting). An evaluation of
visual acuity alone can neither rule in nor rule out the need for surgery.
Visual acuity should be recorded and considered in the context of the
patient's visual impairment and other ocular findings.  
  
**Second Eye Surgery**  
  
Surgery is generally not performed in both eyes during the same surgical
session because of the potential for bilateral visual loss. The publication,
Cataract in the Adult Eye, Preferred Practice Pattern, by the American
Academy of Ophthalmology, describes circumstances under which bilateral
cataract surgery might be an option (e.g., a significant cataract in the
second eye).  
  
In the more common situation, where surgery is performed sequentially on
separate days for bilateral visually symptomatic cataracts, the appropriate
interval between the first-eye surgery and second-eye surgery is influenced by
several factors:

  1. The patient's visual needs;  
  

  2. The patient's preferences;  
  

  3. Visual function in the second eye;  
  

  4. The medical and refractive stability of the first eye;  
  

  5. The need to restore binocular vision and resolve anisometropia;  
  

  6. An adequate interval of time has elapsed to evaluate and treat early postoperative complications in first eye, such as endophthalmitis; and/or  
  

  7. Logistical and travel considerations of the patient.