Intermediate Uveitis / Pars Planitis

Definition:

Intermediate uveitis refers to inflammation localized to the vitreous and peripheral retina. Intermediate means it is located in the middle part of the eye.

Characteristics of Intermediate Uveitis

• Commonly seen in young adults or teenagers
• Intermediate uveitis may be the first expression of autoimmunity in patients
• Asymmetric disease
• Mostly bilateral
• Clinical duration is the longest of all types of uveitis
• Affects patients of all age groups but is predominantly seen in the third and fourth decade
• Accounts for 10-12% of all uveitis seen in children
• Pars planitis is considered a subset of intermediate uveitis with following characteristic features:
  • Benign condition
  • Autoimmune disorder
  • Presence of white exudates (snowbanks) over the pars plana and ora serrata
  • Aggregation of inflammatory cells in the vitreous (snowballs) in the absence of an infectious etiology

Causes of Intermediate Uveitis

The main cause of intermediate uveitis is not identified but

• It has been identified to be associated with certain diseases as Multiple sclerosis, sarcoidosis, or inflammatory bowel disease. This association suggest an autoimmune component in at least a subset of patients.
• Familial or genetic as it is found to run in families
• Idiopathic
• Infectious causes include
  • Epstein-Barr virus (EBV) infection
  • Lyme disease, human T-cell lympho-trophic virus type1 (HTLV-1) infection
  • Cat scratch disease
  • Hepatitis C

Symptoms of Intermediate uveitis

The patients with uveitis often have very few complaints related to their eyes. Only in the chronic stage or severe cases, patient comes with following symptoms:

• Blurry vision
• Floaters
• Visual loss (in severe cases)
• Systemic symptoms related to associated disorder
• No pain, redness, photophobia
• One eye may be worse than the other

Diagnosis of Intermediate uveitis

Diagnosis of IU requires careful history, ocular and systemic examination together with laboratory studies. In addition to this, following imaging studies may be required to confirm the diagnosis:

• Fluorescein angiography
• B-scan ultrasonography
• Optical coherence tomography (OCT)

Treatment of Intermediate Uveitis

A mild form of IU is self-limiting and does not need much of the treatment as they are asymptomatic. But as the disease becomes chronic, following medical treatment may be required:

• Corticosteroids:
  • Topical therapy with prednisolone acetate 1% or prednisolone sodium phosphate 1%
  • Periocular injections of corticosteroids
  • Oral prednisone
  • Intravitreal triamcinolone acetonide injections
• Immunosuppressive therapy with cyclosporine, tacrolimus, azathioprine, and methotrexate
• Surgical intervention:
  • Cryotherapy
  • Laser photocoagulation
  • Peripheral scatter photocoagulation
  • Pars plana vitrectomy
  • Surgical implantation of a fluocinolone acetonide (Retisert) or dexamethasone (Ozurdex) implant
• Consultation with a gastroenterologist, neurologist, or infectious disease specialist may be necessary, depending on physical findings or pertinent elements of the review of systems.

Complications of Intermediate uveitis

It is a benign form of uveitis that may lead to certain complications in chronic stage or if left untreated. The major complications associated with IU include:

• Glaucoma
• Cataracts
• Macular edema and maculopathy
• Vitreous opacification
• Retinal vasculitis
• Peripheral neovascularization
• Blindness