Intermediate Uveitis

Intermediate uveitis is inflammation predominantly of the vitreous base, pars plana and peripheral retina. Pars planitis is the idiopathic subtype, with snowbank formation and no associated infection or systemic disease.

• Bimodal onset: children and young adults (5 to 30 years) and a second smaller peak in the fourth decade; bilateral in up to 80 percent, often asymmetric.
• Associations: multiple sclerosis (about 5 to 15 percent of patients, especially adults), sarcoidosis, tuberculosis, syphilis, Lyme disease, Bartonella, and rarely lymphoma (older patients with bilateral vitritis).
• Complications: cystoid macular oedema (commonest cause of vision loss), cataract, glaucoma, vitreous haemorrhage, peripheral neovascularisation, tractional and rhegmatogenous retinal detachment, epiretinal membrane.

• Floaters and gradual blurring, usually without pain, redness or photophobia; strabismus and leukocoria in some children.
• Vitreous cells and haze; snowballs (white vitreous aggregates, inferior); snowbanking (white fibrovascular plaque over the inferior pars plana and peripheral retina); peripheral retinal vasculitis (periphlebitis).
• Mild anterior chamber cells in some, posterior subcapsular cataract, band keratopathy in children.
• Macular oedema and optic disc oedema.
• Neurological symptoms (numbness, weakness, optic neuritis history) suggesting multiple sclerosis.

• Slit lamp and dilated indirect ophthalmoscopy with scleral indentation (to examine the pars plana and peripheral retina).
• Optical coherence tomography for macular oedema; widefield fluorescein angiography for vasculitis, disc leakage and peripheral neovascularisation.
• Exclude infection and systemic disease: syphilis serology, interferon gamma release assay, chest X-ray or CT, ACE, Lyme serology, and MRI brain and spine with contrast when multiple sclerosis is suspected.
• Diagnostic vitrectomy for vitreous cytology and polymerase chain reaction if poor steroid response or older patient with bilateral vitritis (lymphoma).

• Observation alone if vision is 6/9 or better and no macular oedema.
• Treat when vision is reduced by macular oedema or active vasculitis:
  • Sub-Tenon (posterior) triamcinolone acetonide 40 mg, repeated every 3 months if effective.
  • Oral prednisolone 1 mg/kg daily (maximum 60 mg) for 2 to 4 weeks, then taper; avoid prolonged use in children (growth suppression, cataract, glaucoma).
  • Intravitreal dexamethasone implant 0.7 mg (every 4 to 6 months) or fluocinolone implant 0.18 mg for chronic bilateral disease.
  • Topical steroid for anterior component only.
• Steroid sparing therapy for persistent or steroid dependent disease: methotrexate 15 to 25 mg weekly (children 10 to 15 mg/m2 weekly), mycophenolate, azathioprine, and adalimumab 40 mg every 2 weeks (80 mg loading), with infliximab in refractory cases. Anti-TNF agents (adalimumab, infliximab) may precipitate or worsen demyelination and should be avoided when multiple sclerosis is present; prefer methotrexate, mycophenolate or interferon beta, with neurology input.
• Peripheral ablation (cryotherapy or indirect laser) for persistent snowbank with neovascularisation or vitreous haemorrhage.
• Pars plana vitrectomy for non-clearing vitreous haemorrhage or opacities, epiretinal membrane, tractional detachment, and refractory macular oedema.
• Cataract surgery after at least 3 months of quiet inflammation, with perioperative steroid (oral prednisolone 0.5 to 1 mg/kg for 1 week before and after).
• Monitoring: every 1 to 3 months, then every 3 to 6 months; the disease often burns out after years in the young.