BASICS

DESCRIPTION

• Intermediate uveitis (IU) is inflammation primarily, of the anterior vitreous, ciliary body, and peripheral retina.

• Pars planitis is a subset of IU for which there is no associated infection or systemic disease.

EPIDEMIOLOGY

• IU comprises ∼15% of all cases of uveitis

• No gender predisposition

• Bilateral in 70–90% of cases, but can be asymmetric

• Pars planitis accounts for 85–90% of intermediate uveitis

– It has a bimodal distribution; the younger age group is 5–15 years, and older age group is 20–40 years

RISK FACTORS

Genetics

Pars planitis has been shown to be associated with HLA-DR15 and HLA-DR51

PATHOPHYSIOLOGY

• The pathophysiology of IU/pars planitis is not well understood

– It is probably an autoimmune reaction against an ocular antigen

• Peripheral retinal veins are the primary foci for inflammation

COMMONLY ASSOCIATED CONDITIONS

• Sarcoidosis

• Multiple sclerosis

• Infectious conditions

– Syphilis

– Tuberculosis

– Lyme’s disease

– Toxocariasis

– HTLV-1

– Bartonella

• Pars planitis has no associated systemic condition

DIAGNOSIS

HISTORY

• Patients present with floaters and decreased vision

• Usually a white, quiet eye, but patients can experience redness and photophobia (more commonly in children).

PHYSICAL EXAM

• Anterior vitreous cellular reaction

• Snowballs, which are aggregates of vitreous cells

• Snowbanks, which are inflammatory pars plana exudates, typically found inferiorly

– Tends to indicate more severe disease

• Vascular tortuosity and peripheral retinal phlebitis

Pediatric Considerations

In children, IU tends to cause greater anterior chamber inflammation

DIAGNOSTIC TESTS & INTERPRETATION

Lab

• Complete blood count (CBC) with differential count

• Erythrocyte sedimentation rate (ESR)

• Purified protein derivative (PPD) skin test

• Angiotensin-converting enzyme (ACE) level, which can be elevated in sarcoidosis

• Consider serologic testing for Lyme’s, syphilis, and Bartonella

Imaging

• Chest X-ray to assess for sarcoidosis and tuberculosis

– If chest X-ray is negative, consider gallium scan or computed tomography (CT) to rule out sarcoidosis if clinical suspicion is high

Diagnostic Procedures/Other

• Fluorescein angiography is helpful in determining presence of cystoid macular edema (CME), retinal phlebitis, and neovascularization.

• Ultrasound biomicroscopy (UBM) can demonstrate pars plana exudates and vitreitis in cases with small pupil

• Diagnostic vitrectomy may be needed in cases where there is suspicion of intraocular lymphoma, endophthalmitis, or in cases refractory to medical therapy

Pathological Findings

• Histologic findings show lymphocytic infiltration of retinal veins

• Pars plana exudates consist of fibroglial tissue with inflammatory cells

DIFFERENTIAL DIAGNOSIS

• Primary central nervous system lymphoma

• Endophthalmitis

• Other uveitic conditions, including Vogt–Koyanagi–Harada disease and Fuch’s heterochromic cyclitis

TREATMENT

MEDICATION

First Line

• Treat underlying cause of disease if infectious etiology is present

• For other cases, corticosteroids are indicated if patient is symptomatic or has vision loss.

– Periocular corticosteroids are first line

– Oral corticosteroids is indicated if local therapy is ineffective, or if there is bilateral severe disease

– Intravitreal injection for refractory cases

Second Line

• Immunomodulatory therapy if corticosteroids fail or side effects cannot be tolerated

– Methotrexate

– Cyclosporine

– Azathioprine

– Mycophenolate mofetil

– Tacrolimus

SURGERY/OTHER PROCEDURES

• If drug therapy fails, cryotherapy and laser photocoagulation can be performed to peripheral retina for ablation of pars plana exudates and neovascularization

• Pars plana vitrectomy (PPV) for chronic inflammation or structural complications such as retinal detachment

– PPV is helpful in reducing CME

ONGOING CARE

FOLLOW-UP RECOMMENDATIONS

• Ophthalmology

• Rheumatology or infectious disease specialist, depending on etiology

PROGNOSIS

• IU generally has a chronic course with exacerbations and remissions, although a small subset of patients have self-limiting disease

– Of all subsets of uveitis, IU tends to have the longest duration, most cases last for 5–15 years but can be longer

• Visual outcome is related to severity of disease and presence of CME

– Pars plana exudate indicates poorer prognosis

• Pars planitis has an overall favorable visual prognosis

COMPLICATIONS

• Chronic inflammation from IU can lead to CME.

• Cataracts result from both chronic inflammation and corticosteroid therapy

– Perioperative use of corticosteroids is needed to control inflammation.

• Glaucoma, both angle closure and open angle

• Band keratopathy

• Peripheral retinal neovascularization

• Vitreous hemorrhage

• Retinal detachment

ADDITIONAL READING

• Bloch-Michel E, Nussenblatt RB. International Uveitis Study Group recommendations for the evaluation of intraocular inflammatory disease. Am J Ophthalmol 1987;103:234–235.

• Jabs DA, Nusenblatt RB, Rosenbaum JT. Standardization of Uveitis nomenclature (SUN) working group. Standardization of uveitis nomenclature for reporting clinical data. Results of the First International Workshop. Am J Ophthalmol 2005;140:509–516.

CODES

ICD9

• 363.21 Pars planitis

• 364.3 Unspecified iridocyclitis

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