Pars Planitis


Article Author:
William Gossman
Krati Chauhan


Article Editor:
Koushik Tripathy


Editors In Chief:
Jasleen Jhajj
Cliff Caudill
Evan Kaufman


Managing Editors:
Avais Raja
Orawan Chaigasame
Carrie Smith
Abdul Waheed
Khalid Alsayouri
Frank Smeeks
Kristina Soman-Faulkner
Trevor Nezwek
Radia Jamil
Patrick Le
Sobhan Daneshfar
Anoosh Zafar Gondal
Saad Nazir
William Gossman
Pritesh Sheth
Hassam Zulfiqar
Navid Mahabadi
Steve Bhimji
John Shell
Matthew Varacallo
Heba Mahdy
Ahmad Malik
Mark Pellegrini
James Hughes
Beata Beatty
Nazia Sadiq
Hajira Basit
Phillip Hynes
Tehmina Warsi


Updated:
7/11/2019 11:26:18 PM

Introduction

Pars planitis is chronic intermediate uveitis for which no systemic disease or associated infection could be found. The term intermediate uveitis describes an intraocular inflammatory process with vitreous as the primary site of inflammation. Inflammation may be present in the anterior vitreous, the vitreous base overlying the peripheral retina-pars plana region. It is characterized by vitreal inflammatory aggregates (snowballs), and whitish exudates on the inferior pars plana (snowbanking). Intermediate uveitis includes posterior cyclitis, pars planitis, and hyalitis.[1]

Pars planitis refers to the subset of intermediate uveitis, characterized by the presence of snowball or snowbank formation, without an underlying infectious or systemic disease.[2]

Etiology

Etiology of pars planitis remains unknown. The most widely accepted hypothesis is that pars planitis represents an autoimmune disorder of the eye. Exposure to an antigen initiates it. The nature of the antigen is not yet known, and this antigen exposure leads to activation of the immune system. The immunogenetic association has been suggested by studies citing association of HLA-B51, HLA-DR2, HLA-DR15,[3] and HLA-DRB1*0802 haplotypes with pars planitis.[2]

Epidemiology

In a prospective epidemiology study of 215 uveitis patients, Vadot et al.[4] found an incidence of 1.4 per 100,000 in France and a prevalence of 5.9 per 100,000. In the United States, Gritz and Wong found an incidence of 1.5 per 100,000 and a prevalence of 4 per 100,000.[5] The disease primarily affects children and adults through the fourth decade. Seventy percent to 90% of cases are bilateral, though most of the time one eye is more symptomatic. There is no sex or race predisposition.

Pathophysiology

The pathogenesis of pars planitis is not completely understood. Pars plana exudates are composed of a loose fibrovascular layer containing occasional fibrocyte-like cells and scattered mononuclear cells.

T cells are the predominant cells present in the vitreous; their percentage varies from 11% to 95%. CD4+ T cells account for 5% to 75% of all the T cells. CD4+ T cells that express CD69,[6] an activation marker, are found in aqueous humor and the blood of the patients with pars planitis. The role of CD8+T cells and B cells in the pathogenesis of pars planitis is not clear. Levels of IL-6 are elevated when compared to other cytokines: IL-1, TNF-alpha, and IL-2.[7] After T cells, macrophages are the second most common cells present.

History and Physical

Patients with pars planitis present with minimal symptoms, for example, floaters or blurry vision. In most cases, there is the absence of photophobia and pain. Occasionally patients may present with sudden loss of vision due to retinal detachment or acute vitreous hemorrhage.

Clinical signs of anterior segment inflammation may be present, mild anterior chamber cells. A characteristic sign of pars planitis is vitreous cell infiltration, ranging from 1+ to 4+. Sometimes the cellular infiltration is so dense that it may obscure the view of the retina. Snowballs, are the yellowish, white vitreal aggregate hallmark and are found in the inferior periphery. Peripheral vasculitis may be seen in 10% to 32% of patients. This may present as venous sheathing which may lead to occlusion and occasionally retinal neovascularization. Cystoid macular edema may be present and is the usual cause of visual decline. There may be complicated cataract (posterior subcapsular cataract).

During the acute phase, white exudates are present, in the later stage, there is collagen production which results in snowbank formation. Snowbanks are mostly located inferiorly, but occasionally they may encompass the entire peripheral retina. 

Evaluation

Diagnosis of pars planitis is based on clinical findings. The presence of more vitreous cells than anterior chamber cells, vitreous snowballs, and the presence of pars plana exudates suggest pars planitis. There may be peripheral vascular sheathing and/or cystoid macular edema/ epiretinal membrane.

Clinical evaluation includes the measurement of visual acuity, intraocular pressure, and slit lamp examination. All patient with pars planitis should be evaluated with a thorough peripheral retinal examination with scleral depression. Chest x-ray or CECT (contrast-enhanced computed tomography) scan of the chest may be done to evaluate for the presence of sarcoidosis and tuberculosis. Serum angiotensin-converting enzyme (ACE) level may be checked. This may be elevated in patients with sarcoidosis.

Other investigations may include complete blood count, erythrocyte sedimentation rate (ESR), venereal disease research laboratory (VDRL) or rapid plasma reagin test, Mantoux,  and serology for human immunodeficiency virus (HIV).

In cases with extensive vitritis, infective causes including toxoplasmosis, acute retinal necrosis, and endophthalmitis must be ruled out before starting steroid therapy.

In very elderly patients with vitritis/vitreous haze and no cystoid macular edema, primary intraocular lymphoma should be ruled out.

Fluorescein angiography will show the extent of vasculitis and show areas of retinal nonperfusion and neovascularization. Optical coherence tomography will show the presence of macular edema, epiretinal membrane, and vitreoretinal traction.

In occasional cases with severe vitreal infiltration, when posterior uveitis, retinitis, endophthalmitis, or tumors are difficult to exclude, a diagnostic vitrectomy may be performed.

Treatment / Management

Treatment decisions are based on the extent of pars plana infiltration, the extent of vasculitis, and coexisting macular edema.

Original Kaplan's four-step ladder approach[2] for pars planitis consisted of:

  1. Regional corticosteroid injections followed by oral prednisolone if the regional/periocular steroid is not effective
  2. Cryotherapy or laser photocoagulation of peripheral retina.
  3. Pars plana vitrectomy (PPV)
  4. If all 3 previous options fail, immunosuppressive steroid-sparing agents were considered. 

However, in current practice, most of the uveitis-specialists use periocular (subtenon)/intraocular and/or oral steroids for pars planitis. Subtenon triamcinolone or intravitreal triamcinolone or other steroid implants (Ozurdex) are usually considered in asymmetrically severe intermediate uveitis with cystoid macular edema. In bilateral cases, one eye may be followed by another periocular or intravitreal steroid which avoids the systemic side effects of steroids. The risk of glaucoma and cataract must be explained to the patient before any intervention with periocular or intraocular steroid.  Topical steroid drop is started only if there are significant anterior chamber cells,

In bilateral cases, unilateral cases not responding to periocular or intraocular steroid, and severe pars planitis, oral prednisolone is started in a dose of 1-1.5mg/kg/day.[2] For rapid action, intravenous pulse methylprednisolone 1g is an option.

Immunomodulatory therapy should be considered as a second step in patients who need longer immunosuppression. Commonly used steroid-sparing immunomodulatory agents include methotrexate, mycophenolate mofetil (MMF), azathioprine, and cyclosporine. 

Anti-tumor necrosis factor agents or biologicals are used as the third step in patients nor responding to conventional immunomodulatory therapy. Adalimumab is the biologic response modifier a tumor necrosis factor (TNF) inhibitor which has been approved for the treatment of noninfectious uveitis. Anti-TNF agents may predispose to demyelination and patients with pars planitis may be at a higher risk of developing multiple sclerosis irrespective of therapy. Thus extreme caution should be used and risk-benefit ratio evaluated before starting a pars planitis patient on an anti-TNF agent. Interferon has also been used successfully in pars planitis, but adverse drug effects include depression and suicidal tendencies.

PPV comprises the 4th step[2] and indications for PPV in pars planitis include vitreous hemorrhage, retinal detachment, severe vitreous opacification, epiretinal membrane (ERM),  and vitreomacular traction (VMT). PPV has the advantage of the removal of the load of inflammatory cytokines in the vitreous and provides an opportunity to remove the mechanical factors causing macular edema including VMT and ERM. The rare risk of PPV includes retinal detachment and recurrence of pars planitis.

Peripheral scatter laser photocoagulation is effective in the treatment of peripheral neovascularization associated with pars planitis. Cryotherapy is another option for peripheral neovascularization, but is painful and may predispose to the development of retinal detachment.

Cataract surgery: Cataract formation is one of the most common complications of pars planitis. Cataract extraction is safe if the intraocular inflammation is controlled with corticosteroids or immunosuppressives for a minimum of three months before surgery.

Complications

Although pars planitis is one of the benign forms of uveitis, severe complications secondary to chronic inflammation may occur.

An important ocular complication is epiretinal membrane formation with a reported incidence of 7% to 36%, the mean duration between onset of pars planitis and epiretinal membrane formation has been reported to be 6.5 to 7.9 years. Cataracts are reported to occur in 14% to 30% of pars planitis cases They may occur as a result of the disease or as a result of treatment with corticosteroids, and it is difficult to distinguish between the two causes. A posterior subcapsular cataract is the most commonly diagnosed cataract. Cystoid macular edema is described as the major cause of vision loss. Other complications include retinal vasculitis, retinal neovascularization, peripheral vitreous traction, and vitreous hemorrhage.

 In a study, the complications of pars planitis 'included macular edema (47.7%), vitreous opacities (38.6%), papillitis (38.6%), vasculitis (36.4%), and cataract (20.5%)'.[8]

Pearls and Other Issues

 

 

Enhancing Healthcare Team Outcomes

The diagnosis and management of pars planitis is best done with a multidisciplinary team that include ophthalmology nurses and pharmacists. Clinicians should note that the diagnosis of pars planitis is based on clinical findings. The presence of more vitreous cells than anterior chamber cells, vitreous snowballs, and the presence of pars plana exudates suggest pars planitis. There may be peripheral vascular sheathing and/or cystoid macular edema/ epiretinal membrane. Clinical evaluation includes the measurement of visual acuity, intraocular pressure, and slit lamp examination. All patient with pars planitis should be evaluated with a thorough peripheral retinal examination with scleral depression. Chest x-ray or CECT (contrast-enhanced computed tomography) scan of the chest may be done to evaluate for the presence of sarcoidosis and tuberculosis. Serum angiotensin-converting enzyme (ACE) level may be checked. 

The treatment depends on the cause but in most cases, high dose corticosteroids and/or biological agents are used. The outcomes depend on the cause and response to treatment.


Interested in Participating?

We are looking for contributors to author, edit, and peer review our vast library of review articles and multiple choice questions. In as little as 2-3 hours you can make a significant contribution to your specialty. In return for a small amount of your time, you will receive free access to all content and you will be published as an author or editor in eBooks, apps, online CME/CE activities, and an online Learning Management System for students, teachers, and program directors that allows access to review materials in over 500 specialties.

Improve Content - Become an Author or Editor

This is an academic project designed to provide inexpensive peer-reviewed Apps, eBooks, and very soon an online CME/CE system to help students identify weaknesses and improve knowledge. We would like you to consider being an author or editor. Please click here to learn more. Thank you for you for your interest, the StatPearls Publishing Editorial Team.

Pars Planitis - Questions

Take a quiz of the questions on this article.

Take Quiz
What is the most common etiology for pars planitis?



Click Your Answer Below


Would you like to access teaching points and more information on this topic?

Improve Content - Become an Author or Editor and get free access to the entire database, free eBooks, as well as free CME/CE as it becomes available. If interested, please click on "Sign Up" to register.

Purchase- Want immediate access to questions, answers, and teaching points? They can be purchased above at Apps and eBooks.


Sign Up
Which is a critical step during diagnostic evaluation of patients with pars planitis?



Click Your Answer Below


Would you like to access teaching points and more information on this topic?

Improve Content - Become an Author or Editor and get free access to the entire database, free eBooks, as well as free CME/CE as it becomes available. If interested, please click on "Sign Up" to register.

Purchase- Want immediate access to questions, answers, and teaching points? They can be purchased above at Apps and eBooks.


Sign Up
A 32-year-old male who is being managed for pars planitis comes for a follow-up appointment after receiving his third intraocular triamcinolone 40 mg injections. At this visit, on fundus examination, he still has inflammatory cells present in the vitreous and continues to complain of blurry vision. What is the best next step in the management of this patient?



Click Your Answer Below


Would you like to access teaching points and more information on this topic?

Improve Content - Become an Author or Editor and get free access to the entire database, free eBooks, as well as free CME/CE as it becomes available. If interested, please click on "Sign Up" to register.

Purchase- Want immediate access to questions, answers, and teaching points? They can be purchased above at Apps and eBooks.


Sign Up
A 29-year-old male presents to the clinic with floaters and visual decline in the right eye. The visual acuity is 20/60 in the right eye and 20/20 in the left eye. Intraocular pressure and anterior segment are normal in both eyes. There are retrolental cells in both eyes. Both fundi reveal inferior snowballs. There are no other retinal or choroidal lesion or retinitis patches. There is cystoid macular edema (CME) in the right eye. The systemic workup is unremarkable. Which of the following is the best initial therapy for this patient?



Click Your Answer Below


Would you like to access teaching points and more information on this topic?

Improve Content - Become an Author or Editor and get free access to the entire database, free eBooks, as well as free CME/CE as it becomes available. If interested, please click on "Sign Up" to register.

Purchase- Want immediate access to questions, answers, and teaching points? They can be purchased above at Apps and eBooks.


Sign Up
A 36-year-old male presents with floaters and visual decline in the right eye. The visual acuity is 20/80 in the right eye and 20/20 in the left eye. Intraocular pressure is normal in both eyes. The lens is clear and there is no anterior chamber cell in both eyes. There are retrolental cells in both eyes. Both fundi reveal inferior snowballs. There are no other retinal or choroidal lesion or retinitis patches. The systemic workup is unremarkable. Which of the following is the most likely cause of the visual decline?



Click Your Answer Below


Would you like to access teaching points and more information on this topic?

Improve Content - Become an Author or Editor and get free access to the entire database, free eBooks, as well as free CME/CE as it becomes available. If interested, please click on "Sign Up" to register.

Purchase- Want immediate access to questions, answers, and teaching points? They can be purchased above at Apps and eBooks.


Sign Up

Pars Planitis - References

References

Pars Planitis: Epidemiology, Clinical Characteristics, Management and Visual Prognosis., Ozdal PC,Berker N,Tugal-Tutkun I,, Journal of ophthalmic & vision research, 2015 Oct-Dec     [PubMed]
Standardization of uveitis nomenclature for reporting clinical data. Results of the First International Workshop., Jabs DA,Nussenblatt RB,Rosenbaum JT,, American journal of ophthalmology, 2005 Sep     [PubMed]
The association of HLA-DR15 and intermediate uveitis., Tang WM,Pulido JS,Eckels DD,Han DP,Mieler WF,Pierce K,, American journal of ophthalmology, 1997 Jan     [PubMed]
Incidence and prevalence of uveitis in Northern California; the Northern California Epidemiology of Uveitis Study., Gritz DC,Wong IG,, Ophthalmology, 2004 Mar     [PubMed]
Epidemiology of intermediate uveitis: a prospective study in Savoy., Vadot E,, Developments in ophthalmology, 1992     [PubMed]
Murphy CC,Duncan L,Forrester JV,Dick AD, Systemic CD4(+) T cell phenotype and activation status in intermediate uveitis. The British journal of ophthalmology. 2004 Mar     [PubMed]
Perez VL,Papaliodis GN,Chu D,Anzaar F,Christen W,Foster CS, Elevated levels of interleukin 6 in the vitreous fluid of patients with pars planitis and posterior uveitis: the Massachusetts eye & ear experience and review of previous studies. Ocular immunology and inflammation. 2004 Sep     [PubMed]
Prieto JF,Dios E,Gutierrez JM,Mayo A,Calonge M,Herreras JM, Pars planitis: epidemiology, treatment, and association with multiple sclerosis. Ocular immunology and inflammation. 2001 Jun     [PubMed]

Disclaimer

The intent of StatPearls is to provide practice questions and explanations to assist you in identifying and resolving knowledge deficits. These questions and explanations are not intended to be a source of the knowledge base of all of medicine, nor is it intended to be a board or certification review of Optometry-Basic Science. The authors or editors do not warrant the information is complete or accurate. The reader is encouraged to verify each answer and explanation in several references. All drug indications and dosages should be verified before administration.

StatPearls offers the most comprehensive database of free multiple-choice questions with explanations and short review chapters ever developed. This system helps physicians, medical students, dentists, nurses, pharmacists, and allied health professionals identify education deficits and learn new concepts. StatPearls is not a board or certification review system for Optometry-Basic Science, it is a learning system that you can use to help improve your knowledge base of medicine for life-long learning. StatPearls will help you identify your weaknesses so that when you are ready to study for a board or certification exam in Optometry-Basic Science, you will already be prepared.

Our content is updated continuously through a multi-step peer review process that will help you be prepared and review for a thorough knowledge of Optometry-Basic Science. When it is time for the Optometry-Basic Science board and certification exam, you will already be ready. Besides online study quizzes, we also publish our peer-reviewed content in eBooks and mobile Apps. We also offer inexpensive CME/CE, so our content can be used to attain education credits while you study Optometry-Basic Science.