Boy found to have decreased vision during school screening

OCT of the affected right eye revealed mild macular thickening without cystoid macular edema.

Catherine A. Cox

Jordana F. Goren

A 10-year-old boy was referred to the Lahey Clinic for decreased vision in the right eye noted during a school vision screening. The patient had not previously reported any decrease in vision; however, when probed about his symptoms, he reported that his right eye might have been blurry for a few months. Otherwise, he denied flashes, floaters, pain, redness or photophobia. A complete review of systems was negative.

History

The patient’s ocular history was unremarkable. Medical history was notable for Lyme disease 4 years ago, which was treated with antibiotics. There was no family history of strabismus, amblyopia or childhood blindness. The patient’s family had no pets, and there was no history of recent travel or sick contacts.

Examination

On examination, best corrected visual acuity was 20/200 in the right eye and 20/20 in the left eye without improvement with refraction. Pupils were reactive without afferent pupillary defect. Ishihara color plate testing was normal in both eyes. Extraocular movements were full, IOPs were 17 mm Hg in the right eye and 16 mm Hg in the left eye, and visual fields were full to confrontation. There were 1+ cells in the anterior chamber of the right eye, and dilated fundus exam demonstrated 3+ vitreous cells with faint exudation in the pars plana. There was no evidence of vasculitis or retinitis. The left eye was normal without anterior or posterior chamber cells. Optical coherence tomography of the right eye revealed mild macular thickening without cystoid macular edema. OCT of the left eye was normal (Figures 1a to 1c).

Figure 1a. OCT of the right eye. Note the vitreous opacities causing retinal shadowing and mild retinal thickening without cystoid macular edema. Images: Bartolini CE, Soukiasian SH

Figure 1b. Normal OCT of the left eye.

Figure 1c. OCT retinal thickness map on presentation.

What is your diagnosis?

Intermediate uveitis

The differential diagnosis of a child with unilateral intermediate uveitis includes infectious etiologies such as syphilis, Lyme disease, toxocariasis, cat scratch disease, human T-cell lymphoma virus (HTLV-1) and tuberculosis. Noninfectious causes such as sarcoidosis, inflammatory bowel disease, tubulointerstitial nephritis, intraocular foreign body and infiltrating retinoblastoma would also be on the differential diagnosis. If the aforementioned causes are ruled out, the most likely diagnosis for a child with vitritis and pars plana exudates is idiopathic pars planitis. In an older patient, additional diagnoses such as multiple sclerosis and intraocular lymphoma would be more likely.

Given that there was no history of surgery or trauma, an intraocular foreign body was considered unlikely. Although diffuse infiltrating retinoblastoma can be mistaken as intermediate uveitis, there was no obvious mass or ill-defined thickening of the retina in our patient. Similarly, inflammatory diseases should be considered but are less likely without associated systemic symptoms. Although Toxocara granulomas can mimic unilateral pars plana exudates, the granulomas tend to be temporal and anterior to the equator; the appearance and inferior location of the exudates in this case made Toxocara unlikely. HTLV-1 was extremely unlikely given that the patient was not from an endemic area.

Follow-up

Complete blood count, ACE levels, Lyme antibody, FTA-Abs, RPR and lysozyme levels were normal. A chest radiograph was also unremarkable. Given the characteristic appearance and negative work-up, the patient was diagnosed with idiopathic pars planitis and treated with a sub-Tenon injection of triamcinolone acetonide. Two weeks later, the patient returned to clinic with symptomatic improvement in the affected eye and improvement in visual acuity to 20/125. The anterior chamber was quiet, and there was decreased vitritis. On dilated fundus exam of the right eye, the peripheral exudates had disappeared.

Discussion

Uveitis is characterized by the primary anatomical location of inflammation rather than on structural complications, such as macular edema, peripheral vascular sheathing or neovascularization. Ocular inflammation that primarily involves the vitreous, pars plana and peripheral retina is called intermediate uveitis. The majority of patients with intermediate uveitis have no associated infection or systemic disease. This idiopathic form of intermediate uveitis is termed pars planitis.

Pars planitis is a fairly common form of unilateral, but more commonly bilateral, uveitis, accounting for 15% of all cases in referral uveitis clinics. In children, the percentage is 25%. Patients are typically between the ages of 5 and 40 years; however, there is a bimodal age distribution (5 to 15 years and 20 to 40 years). There is no predilection for gender or race. The etiology of pars planitis is unknown. HLA-DR15 is found in 64% to 72% of patients, an allele also associated with multiple sclerosis, suggesting a possible autoimmune component.

Patients with pars planitis usually present insidiously with blurred vision, floaters and distortion of central vision but rarely have pain or photophobia. Bilateral disease occurs in 70% to 90% of cases, and one-third of patients with unilateral disease initially will develop bilateral disease. Children often do not complain of their symptoms, which may account for the delay in diagnosis in comparison to adults.

The most characteristic findings on exam are vitreous cells, pars plana exudates and snowballs (aggregates of vitreous cells), often found in the inferior periphery. Peripheral vascular changes such as perivascular sheathing are common, especially in HTLV-1 associated intermediate uveitis. Anterior segment involvement is minimal in adults and usually occurs as a result of spillover from the vitreous. By contrast, children tend to present with more significant anterior segment inflammation.

Cystoid macular edema is the major cause of vision loss in patients with pars planitis, affecting up to 50% of patients and becoming chronic and refractory in 10% of cases. Other complications include cataract, glaucoma, epiretinal membrane, posterior synechiae, band keratopathy and retinal detachment. Optic disc edema occurs in 50% of children. Peripheral retinal neovascularization can lead to vitreous hemorrhage, which is also more common in children than adults (28% vs. 6%).

The diagnosis of intermediate uveitis/pars planitis is based on the patient’s history and clinical findings. Diagnostic testing should be performed to rule out other causes of intermediate uveitis such as sarcoidosis, tuberculosis, Lyme disease, syphilis, systemic malignancy or inflammatory disease. A gallium scan is recommended if there is a high suspicion for sarcoidosis and MRI if there is a high suspicion for multiple sclerosis. Lumbar puncture and vitreous sampling may be needed to rule out large cell lymphoma in older patients.

Intermediate uveitis requires treatment if there are vision-threatening complications in symptomatic patients with active disease. Mild vitreous cell in the absence of symptoms or vision loss may be observed. Periocular depot corticosteroids or systemic corticosteroids are considered first-line treatment. Periocular steroids are usually administered every 6 to 8 weeks and have the advantage of minimal systemic complications. If the uveitis is bilateral, however, systemic steroids are often preferred. Transscleral cryotherapy to the area of snowbanking should be considered in patients who fail to respond to either oral or sub-Tenon corticosteroids or in patients with a history of vitreous hemorrhage and peripheral neovascularization. Pars plana vitrectomy may be useful in refractory causes. Concurrent systemic immunomodulatory medications such as methotrexate, azathioprine, cyclosporine and mycophenolate mofetil can be used in patients with recalcitrant disease or to reduce the need for corticosteroids.

The clinical course in intermediate uveitis/pars planitis may be self-limited in 10% of cases, relapsing and remitting in 30%, or persistent and prolonged in 60%. In most cases, however, the disease “burns out” after 5 to 15 years. Visual potential can be optimized by good control of inflammation and proper treatment of complications. Children typically have a worse visual prognosis, which may be related to delay in diagnosis or decreased use of aggressive treatments such as systemic steroids and immunosuppressive therapy.

References:

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• Claudia E. Bartolini, MD, and Sarkis H. Soukiasian, MD, can be reached at New England Eye Center, Tufts University School of Medicine, 750 Washington St., Box 450, Boston, MA 02111; 617-636-4219; fax: 617-636-4866; website: www.neec.com.

• Edited by Catherine A. Cox, MD, and Jordana F. Goren MD, MS. Drs. Cox and Goren can be reached at New England Eye Center, Tufts University School of Medicine, 750 Washington St., Box 450, Boston, MA 02111; 617-636-4219; fax: 617-636-4866; website: www.neec.com.