To review the etiology and presentation of pars
To review traditional and modern management
strategies for controlling inflammation in patients with pars planitis
To review some common statistical terms such as
incidence, prevalence, median, mean, and mode
A 22 year old female presents for an annual follow-up visit. On questioning, she says that over the last several months she has noticed mildly decreased vision with occasional “spots” in her visual field. At first the symptoms occurred only in the left eye, but she says she is starting to notice them in her right eye as well. Apart from being a contact lens wearer of 5 years, her ocular and medical history is unremarkable. She takes only birth control pills and has no allergies. She has no significant family history, and reports no recent illnesses, tick bites, or travel. She is sexually active in a monogamous relationship and engages in no high-risk activities such as illicit drugs.
On examination, the patient’s best-corrected visual acuities are 20/25 in the right eye and 20/40 in the left eye. Intraocular pressures and visual fields are within normal limits. There is 1+ cell in the anterior chamber of the left eye. On dilated exam, several “clumps” of whitish material are seen in the vitreous of the left and (to a lesser extent) right eye.
What is the most likely diagnosis?
• Anterior uveitis
Anterior uveitis, or iritis, is characterized by anterior chamber inflammation with patients commonly complaining of red eye, pain, and decreased vision. Although the patient described does have anterior chamber inflammation, the fundoscopy findings cannot be explained solely by anterior uveitis.
• Posterior vitreous detachment
Although posterior vitreous detachment can cause floaters, even in a young patient, the other symptoms and findings make the diagnosis less likely. In a patient with posterior vitreous detachment, visual acuity should be relatively unaffected (assuming no retinal tears or detachments), and glial tissue (rather than vitreous inflammation) can be seen on fundoscopy.
• Lyme disease
Lyme disease is a tick-borne disease that can produce uveitis in addition to other symptoms such as rash and arthralgias. The absence of a tick bite or rash makes the diagnosis unlikely.
• Pars planitis
Pars planitis is a subset of intermediate uveitis characterized by pars plana exudates (“snowbanks”) and vitreous condensations (“snowballs”) occurring in the setting of only minimal anterior chamber involvement. 1, 2 In 2005, the Standardization of Uveitis Nomenclature Working Group clarified the definition of pars planitis to account only for such inflammation occurring in the absence of an infection (e.g. Lyme disease) or systemic disease (e.g. sarcoidosis), with the term “intermediate uveitis” being used for the latter two cases.2
The prevalence of pars planitis has not been extensively studied however its incidence has been noted at approximately 1.5-2.1 per 100,000 per year3, 4 and it accounts for 2.4-15.4% of uveitis referrals.5, 6 In pediatric patients, pars planitis accounts for a relatively greater proportion of uveitis cases and is behind only juvenile idiopathic arthritis and idiopathic uveitis.7