All content on Eyewiki is protected by copyright law and the Terms of Service. This content may not be reproduced, copied, or put into any artificial intelligence program, including large language and generative AI models, without permission from the Academy.

Ultra widefield fundus photo with snowballs

Disease Entity

Intermediate uveitis (IU) is a chronic, relapsing disease of insidious onset. According to the Standardization of Uveitis Nomenclature (SUN) working group criteria, IU is defined as an intraocular inflammation mainly focused on the vitreous and peripheral retina. It incorporates pars planitis, posterior cyclitis, and hyalitis.

IU accounts for 1.4 to 31% of all uveitis patients, and up to 20% of cases of pediatric uveitis.

Epidemiology

IU is a rare disease, with an estimated incidence of 1.4-2.0 /100,000. In 2004, a large-scale study tracking incidence and prevalence of uveitis in Northern California showed that in intermediate uveitis, there was an incidence of 1.5/100,000 person-years and a period prevalence of 4.0/100,000 persons. These values were notably higher in patients aged 45 to 64 years, with lower incidence and prevalence in pediatric patients and females.

The annual incidence of par planitis was 2.077 per 100,000 individuals in a 20-year study evaluating patients in Olmsted County, Minnesota. Within various pediatric populations, pars planitis is responsible for 5 to 26.7% of uveitis cases.

However, the epidemiology of IU seems to have geographical differences, possibly due to different etiologies. Whereas in Europe, the United States and China IU is usually idiopathic, in other parts of the world, such as India, infectious causes, particularly tuberculosis, are more frequent.

Risk Factors:

Race and ethnicity: Non-Hispanic, white
Approximately equal gender distribution in pediatric populations; slight female preponderance in older cases
Median age of onset: 8-11 years
Genetics: HLA-DR2 and its split antigen HLA-DR15

Etiology

General IU may have a number of causes. However, the exact pathophysiology of pars planitis remains unclear. It appears to be an immunologically mediated condition involving a CD4+ T-cell mediated response to an endogenous antigen of unknown origin. This reaction leads to inflammation in the vitreous and peripheral vasculitis. Analysis of aqueous humor and peripheral blood in pars planitis patients has shown that CD4+ T cells expressing the activation marker CD69 are present. Elevated IL-6 levels have been observed in the vitreous of patients with active intermediate and posterior uveitis, supporting the involvement of autoimmunity in the manifestation of the disease.

Infectious causes

Tuberculosis
Leprosy
Lyme disease
Syphilis
Toxocariasis
Whipple disease.

Noninfectious causes

Sarcoidosis – about 25% of patients with sarcoidosis develop IU, and 2% to 10% of patients with IU develop sarcoid disease
Blau syndrome
Multiple sclerosis (MS) – the proportion of MS in IU patients varies from 7% to 30.4%, and 3% to 27% of patients with MS develop IU. IU in children is rarely related to MS, but children with IU may develop MS later in life. Retinal periphlebitis at the time of diagnosis increased the risk of MS and/or optic neuritis. Associations identified between the condition and HLA‑DR2, ‑DR15, ‑B51, and ‑DRB1 × 0802 haplotypes suggest an immunogenetic predisposition.
Inflammatory bowel disease
Lymphoma – 66% of intraocular lymphomas are a manifestation of a primary central nervous system lymphomas (PCNSL), and 10%-20% of them may present as vitreous or retinal infiltrates mimicking uveitis.
Tubulointerstitial nephritis and uveitis (TINU) syndrome
Sjögren syndrome

Pars Planitis (Idiopathic IU)

Pars planitis is an idiopathic subtype of intermediate uveitis characterized by fibroinflammatory aggregates at the pars plana (“snowbanks”) and peripheral retina (“snowballs”). It is a diagnosis of exclusion that most commonly affects the pediatric patient population. The condition is typically bilateral, yet asymmetric, with more severe cases observed in those with an earlier age of onset. Common findings include mild to moderate anterior segment inflammation, diffuse vitreous cells, vitreous haze, sheathing of peripheral retinal venules, and retinoschisis.

General Pathology

Histologic studies show condensed vitreous, fibroblasts, lymphocytes, and lymphocyte cuffing of the peripheral retinal veins. Snowbanks and snowballs consist of a fibrovascular layer containing mononuclear leukocytes and fibrocyte-like cells, as well as vitreous collagen, Müller cells and fibrous astrocytes.

Histologic examination of eye tissue affected by pars planitis reveal condensed vitreous, fibroblasts, lymphocytes, and lymphocyte cuffing around the peripheral retinal veins. The formations known as snowbanks and snowballs are composed of a fibrovascular layer containing mononuclear leukocytes and fibrocyte-like cells, in addition to vitreous collagen, Müller cells, and fibrous astrocytes.

Pathophysiology

The exact pathophysiology of intermediate uveitis in general remains unclear. However, it appears to be an immunologically mediated condition involving a CD4+ T-cell mediated response to an endogenous antigen of unknown origin; these cells account for up to 95% of all cell types in the vitreous of patients with IU. This reaction leads to inflammation in the vitreous and peripheral vasculitis. Analysis of aqueous humor and peripheral blood in pars planitis patients has shown that CD4+ T cells expressing the activation marker CD69 are present. Elevated IL-6 levels have been observed in the vitreous of patients with active intermediate and posterior uveitis, supporting the involvement of autoimmunity in the manifestation of the disease.

Genetic factors also play a role in pars planitis pathogenesis. Associations identified between the condition and HLA‑DR2, ‑DR15, ‑B51, and ‑DRB1 × 0802 haplotypes suggest an immunogenetic predisposition. Other HLA‑DR15-related disorders include multiple sclerosis, optic neuritis, and narcolepsy, indicating a shared genetic background with pars planitis. HLA-DR is the most significant, occurring in 67%-72% of patients.

Clinical Manifestations

History

IU classically affects younger patients, aged 15 to 40 years. Reported symptoms of pars planitis are usually unilateral, with gradual onset beginning with mild vision blurring and floaters. Severe vitreous inflammation in pars planitis is often associated with uveitic macular edema, which may lead to decreased vision. Rarely, intravitreous hemorrhage due to neovascularization may impair vision in patients with intermediate uveitis. Ocular symptoms may be mild or absent, with intermediate uveitis being incidentally noted on routine examination.

Symptoms

Painless floaters
Decreased/blurred vision
Pain, photophobia and red eye are rare symptoms

Physical Examination

Anterior Segment Findings

Common examination findings in patients with pars planitis include:

Anterior chamber cells:
- Grade 0: 19.5%
- Grade ½+: 11.9%
- Grade 1+: 8.4%
- Grade 2+: 4.0%
- Grade 3+: 0.4%

Anterior chamber flare:
- Grade 0: 33.2%
- Grade 1+: 9.3%
- Grade 2+: 1.3%
- Grade 3+: 0.4%

Small keratic precipitates:
- None: 36.7%
- Fine: 6.6%
- Round: 0.9%

Posterior synechiae, particularly involving the inferior iris: 5.3%

Peripheral corneal endotheliopathy (Figure 1), evidenced by opacification of the posterior cornea in the inferior region: 17.7%

Other anterior segment findings:

Linearly arranged keratic precipitates at the junction of the edematous and nonedematous cornea suggest an underlying autoimmune disease, akin to the phenomenon of corneal allograft rejection.

Band keratopathy, a deposition of calcium in the cornea, has been documented in children with IU, a condition that may arise in various chronic pediatric uveitis cases. Possible inferior posterior corneal haze may be present on fundoscopic examination due to inflammatory endotheliopathy.

Figure 1: Slit lamp photograph shows posterior synechiae and peripheral corneal endotheliopathy in a child with pars planitis. Copyright: Journal of Ophthalmic and Vision Research

Posterior Segment Findings

Table 1: Vitreous haze grading criteria. Adapted from Nussenblatt R, Palestine A, Chan C, Roberge F. (1985). Ophthalmology, 92(4), 467–471. doi.org/10.1016/s0161-6420(85)34001-0

Figure 2a: Visual representation of vitreous haze scoring criteria. Source: R.B. Nussenblatt, A.G. Palestine, C.C. Chan, F. Roberge. (1985). Standardization of vitreal inflammatory activity in intermediate and posterior uveitis. Ophthalmology, 92(467-471). doi:10.1016/S0161-6420(85)34001-0

Figure 2b: Photographic images simulating vitreous haze scoring criteria using the SPOTS system. Source: Eaton, J.S. & Miller, P.E. (2017). The SPOTS System: An Ocular Scoring System Optimized for Use in Modern Preclinical Drug Development and Toxicology, 33(10):718-734. doi:10.1089/jop.2017.0108
Pars planitis is a subtype of intermediate uveitis. Intermediate uveitis is characterized by inflammation of the vitreous, which manifests with vitreous cells and vitreous haze. Intermediate uveitis activity grading is based on vitreous haze, utilizing the Nussenblatt scale (Table 1, Figure 2a; additional reference of vitreous haze in Figure 2b). In severe cases of pars planitis, the density of vitreous inflammation may obscure the retina, posing challenges in excluding a diagnosis of posterior uveitis
Figure 3: Vitreous snowballs appear as globular yellow-white inflammatory clusters most commonly found in the mid vitreous and inferior periphery.
Vitreous snowballs, recognizable as globular yellow-white inflammatory clusters, are commonly found in the mid vitreous and inferior periphery (Figure 3). While situated close to the retina, they do not make direct contact and have been reported in up to 100% of eyes affected with pars planitis.
Snowbanking is the distinctive hallmark of pars planitis (Figure 4). These white or yellowish-white formations typically span the pars plana, originating inferiorly and progressing superiorly.
Degenerative changes in the vitreous, marked by fiber-like cylindric condensations of coarse vitreous strands, may be observed.
Figure 3: Vitreous snowballs appear as globular yellow-white inflammatory clusters most commonly found in the mid vitreous and inferior periphery.
Peripheral retinal vascular sheathing, primarily affecting venules, is a frequent occurrence, seen in 10%–32% of patients (Figure 4).

Peripheral periphlebitis is a common finding (16%-36%), particularly in patients with MS.
Younger patients may present with vitreous hemorrhage.

Diagnosis

IU is typically a clinical diagnosis and requires exclusion of infectious and associated systemic inflammatory disease. Evaluation for exclusion involves testing for infectious etiologies such as tuberculosis, syphilis, and Lyme disease, as well as autoimmune-mediated etiologies such as sarcoidosis, multiple sclerosis, and Behçet disease.

Notably, malignancy should be considered and investigated in elderly patients, as primary intraocular lymphoma may present with diffuse vitritis mimicking IU. Along with severe vitritis, chorioretinal lesions and poor or partial response to therapy should raise suspicion for lymphoma.

The Standardization of Uveitis Nomenclature (SUN) Working Group has provided classification criteria for distinct uveitides including pars planitis for research as well as clinical use (Table 2).

Table 2. SUN II Classification of pars planitis.

Name

Etiology

Classification

Exclusion

Pars planitis

Eye-Limited

Evidence of intermediate uveitis:
1. Vitreous cells AND/OR vitreous haze
2. If anterior chamber cells are present, anterior chamber inflammation severity less than vitreous severity
3. No evidence of retinitis or choroiditis
4. No retinal vascular occlusion in posterior pole and midperiphery

AND

Evidence of pars planitis
1. Vitreous snowballs OR
2. Pars plana snowbanks

Multiple sclerosis, defined by the McDonald criteria
Positive serology test result for syphilis using a treponemal test
Evidence of sarcoidosis (either bilateral hilar adenopathy on chest imaging or tissue biopsy demonstrating non-caseating granulomata)
Positive serology for Lyme disease, either IgG or IgM (eg, positive ELISA AND Western blot with requisite number of bands for assay used)

Adapted from EyeWiki: https://eyewiki.org/SUN_II_Classification_of_Uveitides#SUN_II_Classification_of_Uveitides

Laboratory studies

Complete blood cell (CBC) count
Erythrocyte sedimentation rate (ESR) and or C-reactive protein (CRP)
Angiotensin-converting enzyme (ACE)
Lysozyme
Nontreponemal and treponemal testing (RPR or VDRL and FTA-ABS)
Interferon gamma release assay (IGRA)
Tuberculin skin test

Imaging

Chest radiograph and/or chest computerized tomography (CT)
Brain, orbit, and spinal magnetic resonance imaging (MRI)

Ocular imaging

Digital color fundus photography

In patients with IU, fundus photographs allow documentation of baseline appearance of retinal lesions, and they help to assess progression of the condition and response to treatment during follow-up. Peripheral retinal pathologies such as snowbanking, retinoschisis, and peripheral tractional membranes, and macular complications such as macular edema, epiretinal membranes, atrophy, and scars can be documented by color fundus photography.

Optical coherence tomography (OCT)

OCT imaging is very useful in evaluating the macula for CMO, ERM, macular hole, and atrophy. It can be a useful tool for the follow-up of these patients, and it allows monitoring the response to treatment. Visual potential and prognostic factors can also be determined by OCT: Correlations have been shown between:

vision and foveal thickness
IS/OS junction abnormalities and poorer visual prognosis
CMO with healthy IS/OS junction and better visual prognosis with aggressive treatment

Intravenous fluorescein angiography (IVFA)

IVFA is beneficial to show the activity of retinal vascular inflammation in IU. It allows the detection of CMO, and it helps detect retinal vasculitis in the posterior segment (Figure 5) and may demonstrate areas of retinal nonperfusion and neovascularization.

Figure 5: Fluorescein angiography of retinal vasculitis in pars planitis

Indocyanine green angiography (ICGA)

ICGA has not demonstrated any clinical usefulness in cases of IU.

Ultrasonography (US)

US imaging may be helpful in cases where media opacities (band keratopathy, cataract, or significant vitreous inflammation) preclude adequate visualization of the fundus and do not allow for OCT imaging. US at 20- and 50-Hz frequencies can detect snowbanking in IU, and a 20-Hz probe may be more useful to detect the presence of CMO.

Ultrasound biomicroscopy

Ultrasound biomicroscopy (UBM) supplements ocular examination and can be used to evaluate patients with IU. UBM utilizes frequencies between 35–100 MHz, and it offers detailed images of the pars plana region, detecting features such as snowbanking, cyclitic membranes, peripheral vitreous membranes, and vitreoretinal traction. It also serves as a valuable tool for monitoring treatment response.

Diagnostic Procedures

Diagnostic vitrectomy

Diagnostic vitrectomy may be necessary in:

Suspicion of malignancy
Cases where retinitis or endophthalmitis cannot be excluded
Cases refractory to medical therapy

Samples can be obtained by vitreous aspiration, vitreous biopsy, or chorioretinal biopsy.

Vitreous aspiration (0.2-0.5 cc are aspirated using a 23—gauge needle) is associated with more traction at the vitreous base, and increased risk of hypotony and retinal detachment.
Vitreous biopsy (1 cc of vitreous is collected directly from the vitrectomy bag) is associated with lesser vitreous traction and can be combined with therapeutic vitrectomy.
Chorioretinal biopsies are highly invasive, and they are only indicated in cases where other techniques have failed and disease is bilateral and rapidly progressive. It is usually performed in the worst-seeing eye, and it can be done via a scleral flap or by pars plana vitrectomy.

Differential Diagnosis

Other intermediate uveitides include:
- Syphilitic uveitis
- Ocular tuberculosis
- Toxocariasis
- Lyme-associated uveitis
- Sarcoidosis
- Multiple sclerosis
- Behçet uveitis
- Fuchs uveitis

Masquerades include:
- Vitreoretinal lymphoma
- Retinoblastoma

Management

Treatment for pars planitis is warranted in cases of reduced vision, substantial vitreous opacities, macular edema, retinal vasculitis, or other uveitic complications. Various approaches include the use of topical, periocular, systemic, and intravitreal corticosteroids. In instances of multiple recurrences in the affected eye(s), chronic uveitis, steroid-induced ocular hypertension/glaucoma, or corticosteroid-refractory inflammation, treatment escalation is advised. Options for treatment escalation most commonly involve steroid-sparing immunomodulatory therapy, but they also may include peripheral retinal cryopexy, indirect laser photocoagulation, or pars plana vitrectomy. Malignancy and infection must be ruled out before commencing nonspecific anti-inflammatory therapy.

Mild vitreous cells in the absence of symptoms or vision loss may be observed. However, little consensus exists as to what threshold to adopt in these cases
Treat vision-threatening complications (CMO, vitritis) in symptomatic patients with active disease.

Some 25% to 35% of patients with pars planitis have mild disease, no macular edema or other complications, and good vision, and do not need treatment; these patients maintain good vision with up to 10 years of follow-up.

However, when treatment is needed, the goal is complete suppression of the inflammation (ie, to “grade 0” inflammation).

A stepladder approach has been the most widely adopted strategy in the treatment of IU, with CS therapy being the mainstay of treatment/

Corticosteroids

Periocular CS

Periocular CS (eg, subtenon injection of 0.5-1.0 mL of triamcinolone acetonide 40 mg/mL) are beneficial in patients with unilateral or asymmetric involvement and in the presence of macular edema. Injections can be repeated every 6 to 8 weeks until the vision and CMO have stabilized; at least 2 or 3 injections are suggested before considering this modality ineffective.

Intravitreal steroids (IVS)

Triamcinolone acetonide (IVTA)

IVTA is associated with high rates of complications, and thus many authors consider it an emergency procedure when essential structures such as the macula have to be rescued immediately, to allow time to organize the long-term management.

Slow-release intravitreal implants

Slow-release dexamethasone 0.7 mg intravitreal implant (Ozurdex®; Allergan, Irvine, CA, USA)

Ozurdex has been approved for treatment of intermediate and posterior uveitis, after having shown in case series to significantly improve retinal thickness and visual acuity and to delay and reduce recurrence of uveitic CMO.

Sustained-release fluocinolone acetonide 0.19 mg (Iluvien®, Alimera) or 0.59 mg intravitreal implant Retisert®, Bausch and Lomb)

The MUST trial: compared systemic anti-inflammatory therapy vs. fluocinolone acetonide intraocular implant for intermediate uveitis, posterior uveitis, and panuveitis. No difference was observed in the rates of improvement in macular edema; however, subjects treated with fluocinolone implant had greater quantitative improvement in macular thickness over the follow-up period. A few studies have shown implanted eyes have improved CMO (Pavesio et al, Callanan et al). The use of fluocinolone implants has been limited by the high rate of complications, including cataract formation, ocular hypertension, and hypotony.

Systemic CS

Patients with bilateral disease, severe ocular inflammation, or unilateral disease unresponsive to periocular steroids should be treated systemically, for example with prednisone 1.0-1.5 mg/ kq body weight/day per os for 4-6 weeks, with gradual tapering according to patient’s response.

Steroid-sparing immunosuppressive therapy

Immunosuppressants are considered a second step in patients for long-term treatment. Indications for commencing systemic immunomodulatory therapy are:

Ocular and anatomical

Acute, vision-threatening disease
Chronic, persistent disease
Exudative RD
Macular involvement
Bilateral, vision-threatening disease

Therapeutic failure

Failure of local steroid therapy

Failure of systemic steroid therapy

Active uveitis with doses of prednisone 30 mg or 0.5 mg/kg/day
Recurrence of uveitis after tapering oral CS to less than 7-10 mg/day
Intolerance to oral CS
Need for steroid sparing

The choice of immunosuppressive agent is dependent on the patient’s clinical findings and comorbidities, and on the ophthalmologist’s preference and experience. Methotrexate is the most widely used first‐line immunosuppressive agent in children with chronic noninfectious uveitis because of its long-term safety record and well tolerance. Cyclosporine has also been reported effective. Other drugs used include mycophenolate mofetil, azathioprine, leflunomide, tacrolimus, and rituximab.

Anti-tumor necrosis factor- α (Anti-TNF-α) agents

This class of agents includes adalimumab and infliximab. Anti-TNF-α agents may be used successfully as the third step in patients who are not responding to conventional immunosuppressive agents, although no study exists directly addressing the use of these drugs in noninfectious IU.

However, since pars planitis is associated with increased risk for MS development, anti-TNF-α agents should be employed with extreme caution, as they may potentiate demyelinating disease.

Interferon α may help improve macular edema in noninfectious IU, and interferon β has shown success in the treatment of IU-related CMO. However, to date no study has directly compared Interferon α versus interferon β for this indication.

Pars plana vitrectomy (PPV)

For cases unresponsive to medical intervention, surgical options should be considered for further treatment. In cases where complications such as vitreous condensation, vitreous hemorrhage, retinal detachment, and issues with epiretinal membranes causing retinal traction or macular hole, pars plana vitrectomy (PPV) is a viable surgical intervention. PPV has been used in the following clinical scenarios:

Vitreous condensations
Vitreous hemorrhage
Retinal detachment
ERM causing retinal traction
Ciliary traction causing hypotony
Active inflammation and CMO refractory to medical treatment.

Vitrectomy promotes mechanical clearance of inflammatory mediators and debris, and anatomical correction of vitreoretinal traction. In addition, it may be used for diagnostic purposes.

Cryotherapy and laser photocoagulation

Although cryotherapy was used to induce regression of vitreous-base neovascularization and to stabilize inflammation, it has now fallen out of favor, as it might aggravate blood-ocular-barrier disruption and possibly accelerate the rate of retinal detachment.

Laser photocoagulation is currently considered as an adjunctive approach to other treatment modalities, especially in cases associated with peripheral neovascularization, retinal traction, or retinoschisis.

Medical follow up

In the acute phase, patients are reevaluated every 1 to 4 weeks, depending on disease severity.

In the chronic phase, reexamination is performed every 3 to 6 months.

Complications

IU can lead to blindness due to complications and permanent damage to ocular structures, especially if the diagnosis is delayed. Children are at high risk of amblyopia.

Neovascularization in the peripheral retina (6.5%), usually associated with snowbanking
Neovascularization in the optic nerve head
Band keratopathy (in up to 45% of eyes)
Optic disc swelling (3 to 7.4%)
Cystoid macular edema (CMO) is a common complication of IU, occurring in up to 50% of patients, and it is the major cause of impaired vision in these patients. The risk of CMO increases with disease severity and duration.
Epiretinal membrane (ERM) formation is common, occurring in approximately 35% of eyes
Cataract formation in 15%-50% of eyes, usually PSC or anterior subcapsular

Cataract surgery in patients with IU should only be performed after inflammation has cleared, ideally with no further inflammation for at least 3 months. Some authors advocate starting oral prednisone 1 mg/kg body weight/day for 5 days before surgery, with tapering over the following month.

An adequate preoperative control of inflammation, a meticulous surgical technique, a foldable hydrophobic acrylic intraocular lens implanted in the capsular bag, and good postoperative inflammation control are crucial for successful cataract surgery in pars planitis patients. A combined pars plana vitrectomy may be considered in cases with significant vitreous opacity.

Studies have shown good clinical outcomes after cataract surgery in patients with IU, with 90% of patients obtaining at least some improvement in vision, and 88% of patients achieving visual acuity above 20/40.

Uveitic glaucoma occurs in 7.6% of acute uveitis cases and in 11.1% of patients with chronic IU at 5 years.
Retinal detachment (RD, 2.2%-51% of eyes): all forms of RD may occur, including exudative RD secondary to inflammation, tractional RD due to vitreous traction, and rhegmatogenous RD secondary to vitreous traction, leading to peripheral hole formation.
Inferior peripheral retinoschisis is a complication that occurs almost exclusively in children.

Prognosis

The natural history of IU is variable. Although generally considered a benign disease, many cases show a prolonged course with exacerbations, and only 10% of patients may have a self-limited course of disease. In addition, many patients develop complications that may lead to visual loss. Adequate control of inflammation and prompt detection and treatment of associated complications are thus essential in improving the overall prognosis of the patient.

Overall, the visual prognosis of pars planitis in children is reported to be favorable if adequate treatment is implemented early in the disease course. In a study conducted by Donaldson and colleagues, of 24 patient eyes, 75% maintained a visual acuity of 20/40 or better after 10 years of follow-up.

Severe visual loss is uncommon, but there is a high incidence of ocular complications, such as optic disc edema leading to optic atrophy and macular edema, which are associated with visual impairment. Long-term follow-up suggests that although optic disc edema may indicate a risk for macular edema, it is noted that not all patients with optic disc edema develop substantial visual loss.

Factors associated with better outcomes in pars planitis include older age of disease onset and prompt initiation of systemic steroid-sparing IMT. Ongoing monitoring is advised to assess for uveitic and steroid-induced complications, such as cataracts or glaucoma.

References

1. Brad Bowling. Kanski's Clinical Ophthalmology - A Systematic Approach, 8th edition. Elsevier, 2015.

2. Myron Yanoff, Jay S. Duker. Ophthalmology, 4th edition. Elsevier, 2014.

3. Nika Bagheri, Brynn N. Wajda. Will's Eye Manual - Office and Emergency Room Diagnosis and Treatment of Eye Disease, 7th edition Wolters Kluwer. 2017.

4. Ozdal PC, Berker N, Tugal-Tutkun I. Pars Planitis: Epidemiology, Clinical Characteristics, Management and Visual Prognosis. J Ophthalmic Vis Res. 2015 Oct-Dec;10(4):469-80. doi: 10.4103/2008-322X.176897. PMID: 27051493; PMCID: PMC4795398.

5. Ness T, Boehringer D, Heinzelmann S. Intermediate uveitis: pattern of etiology, complications, treatment and outcome in a tertiary academic center. Orphanet J Rare Dis. 2017 Apr 27;12(1):81. doi: 10.1186/s13023-017-0638-9. PMID: 28449695; PMCID: PMC5408401.

6. Babu BM, Rathinam SR. Intermediate uveitis. Indian J Ophthalmol. 2010 Jan-Feb;58(1):21-7. doi: 10.4103/0301-4738.58469. PMID: 20029143; PMCID: PMC2841370.

7. Jabs DA. Immunosuppression for the Uveitides. Ophthalmology. 2018 Feb;125(2):193-202. doi: 10.1016/j.ophtha.2017.08.007. Epub 2017 Sep 20. PMID: 28942074; PMCID: PMC5794515.

8. Gritz DC, Wong IG. Incidence and prevalence of uveitis in Northern California; the Northern California Epidemiology of Uveitis Study. Ophthalmology. 2004 Mar;111(3):491-500; discussion 500. doi: 10.1016/j.ophtha.2003.06.014. PMID: 15019324.

9. Donaldson MJ, Pulido JS, Herman DC, Diehl N, Hodge D. Pars planitis: a 20-year study of incidence, clinical features, and outcomes. Am J Ophthalmol. 2007 Dec;144(6):812-817. doi: 10.1016/j.ajo.2007.08.023. PMID: 18036872.

10. Nguyen AT, Koné-Paut I, Dusser P. Diagnosis and Management of Non-Infectious Uveitis in Pediatric Patients. Paediatr Drugs. 2024 Jan;26(1):31-47. doi: 10.1007/s40272-023-00596-5. Epub 2023 Oct 4. PMID: 37792254.

11. Khochtali S, Ozdal P, AlBloushi AF, Nabi W, Khairallah M. Pediatric Pars Planitis: A Review. Ocul Immunol Inflamm. 2023 Dec;31(10):1915-1929. doi: 10.1080/09273948.2023.2279683. Epub 2023 Dec 14. PMID: 37976519.

12. Standardization of Uveitis Nomenclature (SUN) Working Group. Classification Criteria For Pars Planitis. Am J Ophthalmol. 2021 Aug;228:268-274. doi: 10.1016/j.ajo.2021.03.045. Epub 2021 Apr 15. PMID: 33845006; PMCID: PMC8634775.

13. Hunchangsith, Boonsiri. Pars Planitis. Uveitis: A quick guide to essential diagnosis. 2021. 49-52. doi:10.1007/978-3-030-52974-1_11.

14. Ozdemir HB, Ozdal PC. Clinical characteristics and treatment of pars planitis: an adalimumab experience. Graefes Arch Clin Exp Ophthalmol. 2022 Feb;260(2):561-569. doi: 10.1007/s00417-021-05398-4. Epub 2021 Sep 27. PMID: 34568953.

15. Navarrete A, Koriat A, Amer R. Implications of pars planitis-associated cystoid macular edema on visual outcome and management in children. Graefes Arch Clin Exp Ophthalmol. 2020 Aug;258(8):1803-1811. doi: 10.1007/s00417-020-04696-7. Epub 2020 Apr 28. PMID: 32346784.

16. Kosmaczewska A, Przeździecka-Dołyk J, Turno-Kręcicka A, Ciszak L, Szteblich A, Węgrzyn A, Frydecka I, Misiuk-Hojło M. Imbalance in PB IL-17-Secreting and Regulatory Cells in Pars Planitis Is Associated with Dysregulation of IFN-γ-Secreting Cells, Especially in Patients with Clinical Complications. Mediators Inflamm. 2020 Jul 31;2020:9175083. doi: 10.1155/2020/9175083. PMID: 32801998; PMCID: PMC7415078.

17. Agarwal A, Aggarwal K, Gupta V. Pars Planitis (Idiopathic Intermediate Uveitis of the Pars Planitis Type). The Uveitis Atlas. 2019. 475-478. doi:10.1007/978-81-322-2410-5_88.

18. Chauhan K, Tripathy K. Pars Planitis. StatPearls. 2023. https://www.ncbi.nlm.nih.gov/books/NBK436019/

19. Bahar M. Pars Planitis Epidemiology, Diagnosis, Follow-Up And Prognosis. CMJ. 2023;45(4):8-16. doi:10.7197/cmj.1386749.

20. Arellanes García L, Ortiz-Ponce G, Recillas-Gispert C. Peripheral corneal endotheliopathy and pars planitis. Ocul Immunol Inflamm. 1996;4(3):135-8. doi: 10.3109/09273949609079646. PMID: 22823324.

21. Thomas AS, Ali A, Arepalli S, Suhler EB. Inferior Corneal Haze and Inflammatory Endotheliopathy Related to Pars Planitis. Ocul Immunol Inflamm. 2020 Jul 3;28(5):798-801. doi: 10.1080/09273948.2019.1629603. Epub 2019 Oct 1. PMID: 31573365.

22. Standardization of Uveitis Nomenclature (SUN) Working Group. Classification Criteria For Pars Planitis. Am J Ophthalmol. 2021 Aug;228:268-274. doi: 10.1016/j.ajo.2021.03.045. Epub 2021 Apr 15. PMID: 33845006; PMCID: PMC8634775.

23. Concha Del Río LE, Duarte González GA, Mayorquín Ruiz M, Arellanes-García L. Characterization of cyclitic membranes by ultrabiomicroscopy in patients with pars planitis. J Ophthalmic Inflamm Infect. 2020 Jan 27;10(1):7. doi: 10.1186/s12348-020-0194-7. PMID: 31997032; PMCID: PMC6989698.

24. Yalçındağ FN, Temel E, Özgür EG. Spectral domain optical coherence tomography findings of patients with pars planitis and risk factors affecting visual acuity. Int Ophthalmol. 2021 May;41(5):1753-1761. doi: 10.1007/s10792-021-01734-z. Epub 2021 Feb 9. PMID: 33559832.

25. Faia LJ. Pars Planitis in Children. In: Özdek, Ş., Berrocal, A., Spandau, U. (eds) Pediatric Vitreoretinal Surgery. Springer, Cham. https://doi.org/10.1007/978-3-031-14506-3_53.

26. Ozer MD, Batur M. Anti-tumor necrosis factor-alpha treatment in pediatric patients with pars planitis: a single-center experience from Turkey. Int Ophthalmol. 2023 Jan;43(1):155-166. doi: 10.1007/s10792-022-02398-z. Epub 2022 Jul 3. PMID: 35780435.

27. Rosenbaum JT, Bodaghi B, Couto C, Zierhut M, Acharya N, Pavesio C, Tay-Kearney ML, Neri P, Douglas K, Pathai S, Song AP, Kron M, Foster CS. New observations and emerging ideas in diagnosis and management of non-infectious uveitis: A review. Semin Arthritis Rheum. 2019 Dec;49(3):438-445. doi: 10.1016/j.semarthrit.2019.06.004. Epub 2019 Jun 10. PMID: 31301816.

28. de Boer J, Berendschot TT, van der Does P, Rothova A. Long-term follow-up of intermediate uveitis in children. Am J Ophthalmol. 2006 Apr;141(4):616-21. doi: 10.1016/j.ajo.2005.09.035. PMID: 16564794.