eMedicine Specialties > Ophthalmology > Dermatologic Disorders

Psoriasis

Robert Arffa, MD, Clinical Assistant Professor, University of Pittsburgh School of Medicine
Contributor Information and Disclosures

Updated: Dec 11, 2008

Introduction

Background

Psoriasis is a common skin disease. Ocular signs occur in approximately 10% of patients, and they are more common in men than in women. Patients with ocular findings almost always have psoriatic skin disease; however, it is rare for the eye to become involved before the skin.^{1, 2, 3}

Pathophysiology

Psoriasis involves hyperproliferation of the keratinocytes in the epidermis. The cause of the loss of control of keratinocyte turnover is unknown. However, environmental, genetic, and immunologic factors appear to play a role. Psoriasis is associated with certain human leukocyte antigen (HLA) alleles, particularly human leukocyte antigen Cw6 (HLA-Cw6). In some families, psoriasis is an autosomal dominant trait.

Disease exacerbations can be triggered by trauma, stress, alcohol, medications, and infection (eg, staphylococcal, streptococcal, human immunodeficiency virus). The epidermis is infiltrated by a large number of activated T cells, which appear to be capable of inducing keratinocyte proliferation. Conjunctival impression cytology demonstrated a higher incidence of squamous metaplasia, neutrophil clumping, and nuclear chromatin changes in patients with psoriasis.^{4, 5}

Frequency

United States

This condition affects 1-2% of the population. Approximately 6.4 million Americans have psoriasis.

International

Internationally, the incidence of psoriasis varies dramatically. A study of 26,000 South American Indians did not reveal a single case of psoriasis. In the Faeroe Islands, an incidence of 2.8% was observed.

Sex

Psoriasis appears to be slightly more prevalent among women than among men; however, men are thought to be more likely to experience the ocular disease.

Age

• Psoriasis can begin at any age. The median age of onset is 28 years.
• About 10-15% patients have onset of psoriasis before age 10 years.

Clinical

History

• The skin almost always is affected before the eyes. Ocular findings occur in approximately 10% of patients.
• The nonocular symptoms are related to rash and psoriatic arthritis.
  • The rash can be uncomfortable or even painful.
  • Psoriatic arthritis can cause stiffness, pain, throbbing, swelling, or tenderness of the joints. The distal joints, such as the fingers, toes, wrists, knees, and ankles, are most often affected.
• The most common ocular symptoms are redness and tearing due to conjunctivitis or blepharitis.

Physical

• Ocular manifestations^{6, 7}
  • Eyelid: Blepharitis is the most common ocular finding in psoriasis. Erythema, edema, and psoriatic plaques may develop, and they can result in madarosis, cicatricial ectropion, trichiasis, and even loss of the lid tissue.
  • Conjunctiva
    • A chronic nonspecific conjunctivitis is fairly common. It usually occurs in association with eyelid margin involvement. Psoriatic plaques can extend from the lid onto the conjunctiva.
    • Chronic conjunctivitis can lead to symblepharon, keratoconjunctivitis sicca, and trichiasis.
    • Nodular episcleritis and limbal lesions resembling phlyctenules also can be seen.
  • Corneal involvement
    • Corneal disease is relatively rare. Most often, it is secondary to lid or conjunctival complications, such as dryness, trichiasis, or exposure.
    • The most common finding is punctate keratitis. Filaments, epithelial thickening, recurrent erosions, vascularization, ulceration, and scarring can occur. The vascularization tends to be superficial, peripheral, and interpalpebral or inferior.
    • Rarely, peripheral infiltration and melting can occur in the absence of trichiasis and exposure.⁸
  • Lacrimal sac: In one case, recurrent nasolacrimal duct occlusion was observed, presumably caused by washing of the scales into the lacrimal sac.
  • Uvea: Usually, anterior uveitis can be seen in association with psoriatic arthritis. Acute psoriatic uveitis tends to be bilateral, prolonged, and more severe than nonpsoriatic cases.^{9, 10}
• Complications of psoriasis treatment
  • Retinoids have been reported to cause dry eye, blepharitis, corneal opacities, cataracts, and decreased night vision.^{11, 12}
  • Psoralen-ultraviolet A (PUVA) treatment results in conjunctival hyperemia and dry eye, particularly if sun protection is not used. There does not appear to be a risk of cataract.
• The most common skin manifestations are scaling erythematous macules, papules, and plaques. Typically, the macules are seen first, and these progress to maculopapules and ultimately well-demarcated, noncoherent, silvery plaques overlying a glossy homogeneous erythema. The area of skin involvement varies with the form of psoriasis.
• The most common type of psoriasis is chronic stationary psoriasis (psoriasis vulgaris). This involves the scalp, extensor surfaces, genitals, umbilicus, and lumbosacral and retroauricular regions.
  • Psoriasis inversa: It involves flexural surfaces and intertriginous areas, and it is not associated with scaling.
  • Eruptive psoriasis: It involves the upper trunk and upper extremities. Most often, it is seen in younger patients.
  • Other forms: Psoriatic erythroderma is a generalized form. Various pustular forms also exist.

Causes

• The pathogenesis of psoriasis is poorly understood. A genetic tendency seems to exist.
• Many factors have been observed to trigger exacerbations, including cold, trauma, infections (eg, streptococcal, human immunodeficiency virus), stress, alcohol, and drugs (eg, iodides, steroid withdrawal, aspirin, lithium, beta-blockers, botulinum A, antimalarials).
• Hot weather, sunlight, and pregnancy may be beneficial.

References

• Blepharitis, Adult
• Dry Eye Syndrome
• Keratoconjunctivitis, Atopic
• Keratoconjunctivitis, Sicca

• Psoriasis Center
• Psoriasis Overview
• Psoriasis Causes
• Psoriasis Symptoms
• Psoriasis Treatment
• What Is Psoriasis - Overview
• Types of Psoriasis Overview
• Understanding Psoriasis Medications