Complications and Comorbidities> Ophthalmology/Otology>

DEFINITION

• A clouding or opacity of the natural crystalline lens of the eye.
• When glucose increases in the lens (as in hyperglycemic states), the sorbitol pathway is activated more than glycolysis; sorbitol accumulates and is retained in the lens.
• Along with sorbitol, fructose also builds up in a lens surrounded by a high glucose environment.
• These two sugars increase the osmotic pressure within the lens, drawing in water.
• The result is swelling of the lens fibers, disruption of the normal cytoskeletal architecture, and ultimately, lens opacification (Andley).

EPIDEMIOLOGY

• Persons with diabetes(DM)  are at increased risk of age-related lens changes indistinguishable from nondiabetic age-related cataracts.
• The lens changes occur at a younger age than in people without DM (Flynn).
• With DM, cortical or posterior subcapsular opacities also occur earlier than in age-matched controls.
• Cataracts present in 20% of patients with type 1 DM, associated with age, history of retina photocoagulation, higher serum creatinine values and hypertension (Esteves).
• The number of cataract cases among adults 40 years or older with DM will likely increase 235% by 2050 (Saaddine).

DIAGNOSIS

• History evaluates if vision is affecting patient's activities of daily living (ADL) (e.g. driving, reading, watching TV).
• Comprehensive eye exam, including visual acuity, slit lamp examination, and a dilated funduscopic examto evaluate the cataract.
• On examination, funduscopic exam may reveal a clouding of the lens and difficult or hazy view of the retina.

SIGNS AND SYMPTOMS

• Cloudy or blurry vision
• Glare (headlights or sunlight may decrease vision); halos around lights
• Poor night vision
• Subdued colors
• Monocular diplopia or multiple images in one eye

CLINICAL TREATMENT

• Symptoms of early cataract may be improved with new eyeglasses, brighter lighting, anti-glare sunglasses, or magnifying lenses.
• If the above measures are not adequate, surgery is only effective treatment, usually cataract extraction with phacoemulisification and intraocular lens implantation.
• Cataract surgery usually recommended only when vision loss interferes with ADLs.
• Other indication for cataract surgery: if the cataract prevents examination or treatment of another eye problem such as diabetic retinopathy or age-related macular degeneration
• Diabetic retinopathy may progress following cataract surgery (Jaffe)
• Therefore, consider laser photocoagulation prior to cataract surgery for patients with CSME, NPDR, or PDR. 

FOLLOW UP

• Reevaluate all patients with preexisting diabetic retinopathy following cataract surgery.
• Patients with DM undergoing phacoemulsification cataract surgery have a doubling of diabetic retinopathy progression 12 months after surgery (Hong).
• This outcome, however, represents less progression than was previously documented with intracapsular and extracapsular cataract surgical techniques (Jaffe).
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EXPERT COMMENTS

• Cataracts usually present bilaterally, however, may have progressed more in one eye.
• Best corrected visual acuity after cataract extraction may be limited secondary to diabetic retinopathy.

REFERENCES