Slowly progressive visual loss or blurring, usually over months to years, affecting one or both eyes. Glare, especially in bright sun or from oncoming headlights while driving at night, and altered color perception may occur, but not to the same degree as in optic neuropathies. Characteristics of the cataract determine specific symptoms.

(See Figure 13.1.1.)

Figure 13.1.1: Cataract with early cortical changes and nuclear sclerosis.

Critical

Opacification or discoloration of the normally clear crystalline lens.

Other

Blurred view of the retina with dimming or disruption of the red reflex on retinoscopy. Myopic shift from nuclear sclerosis may cause increased near vision—so-called “second sight.” Cataract alone does not cause a relative afferent pupillary defect (RAPD).

• Age-related: Most common. Advanced forms include mature, hypermature, and Morgagnian.

• Trauma: Penetrating, concussion (Vossius ring), and electric shock.

• Toxic: Steroids in any form (including intravitreal injections), miotics, antipsychotics (e.g., phenothiazines), and others.

• Secondary.

  • Chronic anterior uveitis. See 12.1, Anterior Uveitis (Iritis/Iridocyclitis).

  • History of vitrectomy.

  • Repeated intravitreal injections (if trauma to lens occurs during a procedure).

  • Ionizing radiation.

  • Tumor.

  • Acute angle-closure glaucoma: May have glaukomflecken. See 9.4, Acute Angle Closure Attack.

  • Degenerative ocular disease: Retinitis pigmentosa, Leber congenital amaurosis, gyrate atrophy, Wagner and Stickler syndromes associated with posterior subcapsular cataracts, and others.

• Endocrine/metabolic/chromosomal.

  • Diabetes: Juvenile form characterized by rapidly progressing white “snowflake” opacities in the anterior and posterior subcapsular locations. Age-related cataracts form earlier than in nondiabetics.

  • Hypocalcemia: Small, white, iridescent cortical changes, usually seen in the presence of tetany.

  • Wilson disease: Red-brown pigment deposition in the cortex beneath the anterior capsule (a “sunflower” cataract). See 13.9, Wilson Disease. 

  • Myotonic dystrophy: Multicolored birefringent opacities, “Christmas-tree” cataract behind the anterior capsule.

  • Others: Down syndrome, neurofibromatosis type 2 (posterior subcapsular cataract), atopic dermatitis (anterior subcapsular), etc.

Types

1. Nuclear: Yellow or brown discoloration of the central lens. Typically blurs distance vision more than near (myopic shift).

2. Posterior subcapsular: Plaque-like opacity near the posterior aspect of the lens. Best seen with retroillumination as a dark shadow against the red reflex. Glare and difficulty reading are common complaints. Symptoms may improve postdilation. Associated with ocular inflammation, steroid use, diabetes, trauma, radiation, or excessive alcohol use. Classically occurs in patients <50 years of age. Typically, more rapid onset.

3. Cortical: Vacuoles and radial or spoke-like opacities in the periphery that expand to involve the anterior and posterior lens. Glare is the most common complaint. Often asymptomatic until central changes develop.

NOTE Traditionally, a mature cataract is defined as lenticular changes sufficiently dense to totally obscure the view of the posterior lens and posterior segment of the eye. No iris shadow is seen on oblique illumination at the pupillary margin. Rarely, the cortex may liquefy, and the nucleus becomes free floating within the capsule; this is known as a hypermature or Morgagnian cataract. If the liquefied cortex leaks through the intact capsule, wrinkling of the lens capsule may be seen and phacolytic glaucoma may develop. See 9.11.1, Phacolytic Glaucoma. A visually significant cataract is one which subjectively causes bothersome visual symptoms.

Determine the etiology, whether the cataract is responsible for the decreased vision, and whether surgical removal would improve vision.

1. History: Medications (e.g., tamsulosin and other drugs used for urinary retention [alpha-1 antagonists] strongly associated with intraoperative floppy iris syndrome)? Systemic diseases? Trauma? Ocular disease or poor vision before the cataract?

2. Complete ocular examination, including distance and near vision, pupillary examination, and refraction. When best-corrected acuity is 20/30 or better, glare testing is helpful to demonstrate decreased vision. A dilated slit-lamp examination using both direct and retroillumination techniques is required to view the cataract properly. Fundus examination, concentrating on the macula, is essential in ruling out other causes of decreased vision.

3. For preoperative planning, note the degree of pupil dilation, density of the cataract, and presence or absence of pseudoexfoliation, phacodonesis (quivering of the lens indicating zonular damage or weakness), or corneal guttae.

4. B-scan ultrasound (US) if the fundus is not visible to rule out detectable posterior segment disease.

5. The potential acuity meter (PAM) or laser interferometry can be used to estimate the visual potential when cataract extraction is considered in an eye with posterior segment disease.

   NOTE PAM and laser interferometry often overestimate the eye’s visual potential in the presence of macular holes or macular pigment epithelial detachments. Interferometry also overestimates visual potential in cases of amblyopia. Near vision is often the most accurate manner of evaluating macular function if the cataract is not too dense. Nonetheless, both PAM and laser interferometry are useful clinical tools.

6. Keratometry readings and measurement of axial length are required for determining the power of the desired intraocular lens (IOL). Corneal pachymetry or endothelial cell density is occasionally helpful if corneal guttae are present.

1. Cataract surgery may be performed for the following reasons:

   • To improve visual function in patients with symptomatic visual disability.

   • As surgical therapy for ocular disease (e.g., lens-related glaucoma or uveitis).

   • To facilitate management of ocular disease (e.g., to allow a fundus view to monitor or treat diabetic retinopathy or glaucoma).

    

2. Correct any refractive error (e.g., prescription of corrective lenses) if the patient declines cataract surgery.

3. A trial of mydriasis (e.g., cyclopentolate 1% b.i.d. to t.i.d.) may be used successfully in some patients who desire nonsurgical treatment. The benefits of this therapy are only temporary. Most useful for posterior subcapsular cataracts.

Unless there is a secondary complication from the cataract (e.g., glaucoma), a cataract itself does not require urgent action. If a patient requires bilateral cataract extraction, surgery is typically first performed on the more advanced cataract. Patients who decline surgical removal are reexamined annually or sooner if symptoms worsen.

If congenital, see 8.12, Pediatric Cataract.