Cataracts are opacities of the crystalline lens (eFigure 7–35) and are usually bilateral. They are the leading cause of blindness worldwide. Age-related cataract is by far the most common cause (eFigure 7–36). Other causes include (1) congenital (owing to intrauterine infections, such as rubella and CMV, or inborn errors of metabolism, such as galactosemia); (2) traumatic; (3) secondary to systemic disease (diabetes mellitus, myotonic dystrophy, atopic dermatitis); (4) topical, systemic, or inhaled corticosteroid treatment; (5) uveitis; or (6) radiation exposure. Most persons over age 60 have some degree of lens opacity. Cigarette smoking increases the risk of cataract formation. Multivitamin/mineral supplements and high dietary antioxidants may prevent the development of age-related cataract.
Dense cataract viewed through dilated pupil with slit-lamp beam.
Age-related cataract. A and B: “Coronary” type cortical cataract (frontal and cross-sectional views): club-shaped peripheral opacities with clear central lens; slowly progressive. C: “Cuneiform” type cortical cataract: peripheral spicules and central clear lens; slowly progressive. D: Nuclear sclerotic cataract: diffuse opacity principally affecting nucleus; slowly progressive. E: Posterior subcapsular cataract: plaque of granular opacity on posterior capsule; may be rapidly progressive. F: “Morgagnian” type (hypermature lens): the entire lens is opaque, and the lens nucleus has fallen inferiorly. (Reproduced, with permission, from Riordan-Eva P, Augsburger JJ. Vaughan & Asbury’s General Ophthalmology, 19th ed. McGraw-Hill, 2018.)
The predominant symptom is progressive blurring of vision. Glare, especially in bright light or when driving at night; change of focusing, particularly development of nearsightedness; and monocular double vision may also occur.
Even in its early stages, a cataract can be seen through a dilated pupil with an ophthalmoscope or slit lamp. As the cataract matures, the retina will become increasingly difficult to visualize, until finally the fundus reflection is absent and the pupil is white.
Functional visual impairment, specifically its effect on daily activities such as increased falls, is the prime criterion for surgery. The cataract is usually removed by one of the techniques in which the posterior lens capsule remains (extracapsular), thus providing support for a prosthetic intraocular lens. Ultrasonic fragmentation (phacoemulsification) of the lens nucleus and foldable intraocular lenses allow cataract surgery to be performed through a small incision without the need for sutures, thus reducing the postoperative complication rate and accelerating visual rehabilitation. The standard monofocal prosthetic intraocular lens can correct near or far vision. Multifocal, ...