Diagnostic methods for primary vitreoretinal lymphoma: A systematic review.

Primary vitreoretinal lymphoma is a potentially aggressive intraocular malignancy with poor systemic prognosis and sometimes significant diagnostic delays as it may masquerade as chronic uveitis. Despite the variety of diagnostic techniques, it is unclear which modality is most accurate in the diagnosis of PVRL. A systematic literature search was conducted on Ovid MEDLINE, EMBASE and the Cochrane Controlled Register of Trials for studies published between January, 2000, and June, 2023. Randomized controlled trials (RCTs) reporting on the following diagnostic tools used to diagnose patients with PVRL were included: cytology, flow cytometry, MYD88 L265P mutation, CD79B mutation, interleukin 10/interleukin-6 (IL-10/IL-6) ratio, polymerase chain reaction (PCR) for monoclonal immunoglobulin heavy chain (IgH) and immunoglobulin kappa light chain (IgK) rearrangements, and imaging findings. The aggregated sensitivity of each diagnostic modality was reported and compared using the chi-squared (χ2) test. A total of 662 eyes from 29 retrospective studies reporting on patients diagnosed with PVRL were included. An IL-10/IL-6 ratio greater than 1 had the highest sensitivity (89.39%, n = 278/311 eyes, n = 16 studies) for PVRL, where the sensitivity was not significantly different when only vitreous samples were drawn (88.89%, n = 232/261 eyes, n = 13 studies) compared to aqueous samples (83.33%, n = 20/24, n = 2) (p = 0.42). Flow cytometry of vitreous samples gave a positive result in 66/75 eyes (88.00%, n = 6 studies) with PVRL, and monoclonal IgH rearrangements on PCR gave a positive result in 354/416 eyes (85.10%, n = 20 studies) with PVRL. MYD88 L265P and CD79B mutation analysis performed poorly, yielding a positive result in 63/90 eyes (70.00%, n = 8 studies) with PVRL, and 20/57 eyes (35.09%, n = 4 studies) with PVRL, respectively. Overall, our systematic review found that an IL-10/IL-6 ratio greater or equal to one may provide the highest sensitivity in identifying patients with PVRL. Future studies are needed to employ multiple diagnostic tools to aid in the detection of PVRL and to further establish nuanced guidelines when determining the optimal diagnostic tool to use in diverse patient populations.

DIAGNOSTIC YIELD OF IN VITRO VITREOUS BIOPSY FOR INTRAOCULAR LYMPHOMA AT VARIABLE VITREOUS CUTTER SPEEDS USING 25-GAUGE VITRECTOMY.

PURPOSE: Primary vitreoretinal lymphoma is the most common intraocular lymphoproliferative disorder. We evaluated the diagnostic yield of pars plana vitrectomy, specifically using modern high cut rate dual-cycle cutters, on in vitro cell viability and diagnostic yield. METHODS: Human Burkitt lymphoma cell line Namalwa at 2 x 10^5 cells/mL was aspirated by 25-gauge dual-blade guillotine-type vitrectomy at five speeds (500, 1,000, 4,000, 7,500, or 15,000 cuts per minute). Cell viability and diagnostic yield in each subtype group were determined using hemocytometry, viable cell count using Cell Counting Kit-8, and pathologist-guided manual count. RESULTS: No significant deviation in cell count was identified in any cut rate by ANOVA ( P = 0.61), and no trends in the number of viable cells were identified across cut rates (R 2 = 0.188, P = 0.47). Among histologic cell counts per cut-rate, neither linear regression (R = 0.531, P = 0.16) nor ANOVA ( P = 0.096) were statistically significant. CONCLUSION: There was no significant degradation in the number of viable cells with increasing cut speed. These results suggest that in contrast to previous findings using 20g or 23g vitrectomy for diagnostic vitrectomy, modern vitrectomy systems may be used at up to 15,000 cpm without compromising the viability of lymphoma cells.

Vitreous proteomics, a gateway to improved understanding and stratification of diverse uveitis aetiologies.

PURPOSE: The vitreous proteome might provide an attractive gateway to discriminate between various uveitis aetiologies and gain novel insights into the underlying pathophysiological processes. Here, we investigated 180 vitreous proteins to discover novel biomarkers and broaden disease insights by comparing (1). primary vitreoretinal lymphoma ((P)VRL) versus other aetiologies, (2). sarcoid uveitis versus tuberculosis (TB)-associated uveitis and (3). granulomatous (sarcoid and TB) uveitis versus other aetiologies. METHODS: Vitreous protein levels were determined by proximity extension assay in 47 patients with intraocular inflammation and a prestudy diagnosis (cohort 1; training) and 22 patients with a blinded diagnosis (cohort 2; validation). Differentially expressed proteins identified by t-tests on cohort 1 were used to calculate Youden's indices. Pathway and network analysis was performed by ingenuity pathway analysis. A random forest classifier was trained to predict the diagnosis of blinded patients. RESULTS: For (P)VRL stratification, the previously reported combined diagnostic value of IL-10 and IL-6 was confirmed. Additionally, CD70 was identified as potential novel marker for (P)VRL. However, the classifier trained on the entire cohort (cohort 1 and 2) relied primarily on the interleukin score for intraocular lymphoma diagnosis (ISOLD) or IL-10/IL-6 ratio and only showed a supportive role for CD70. Furthermore, sarcoid uveitis displayed increased levels of vitreous CCL17 as compared to TB-associated uveitis. CONCLUSION: We underline the previously reported value of the ISOLD and the IL-10/IL-6 ratio for (P)VRL identification and present CD70 as a potentially valuable target for (P)VRL stratification. Finally, we also show that increased CCL17 levels might help to distinguish sarcoid uveitis from TB-associated uveitis.

CLINICAL FEATURES, DIAGNOSTIC SIGNIFICANCE, AND PROGNOSIS OF VITREORETINAL LYMPHOMA IN YOUNG PATIENTS.

PURPOSE: To investigate the clinical features, diagnostic approaches, and outcomes of young patients with vitreoretinal lymphoma. METHODS: Fifty-one vitreoretinal lymphoma patients (97 eyes) referred to the Eye and ENT Hospital of the Fudan University from 2011 to 2020 were grouped based on their onset age (age ≤50 years and age >50 years). Complete eye examinations, evaluation of systemic conditions, and biological analysis of intraocular fluids were performed. RESULTS: Young patients accounted for 31.4% (n = 16) of the cohort. More eyes had retinal/subretinal pigment epithelial infiltration (20 [64.5%] vs. 23 [34.8%]; P = 0.018) in young patients than in elderly ones. The mutation rate of Myeloid Differentiation Factor 88 gene (MYD88) was significantly lower in young patients than in elderly ones (5 [50%] vs. 21 [91.3%]; P = 0.016). The median time to new onset of central nervous system lymphoma was significantly shorter in young patients (11.7 vs. 36.2 months; P = 0.012). However, mean overall survival did not differ between the 2 groups (64.9 vs. 57.5 months; P = 0.871). CONCLUSION: Early diagnosis and central nervous system evaluation are crucial for young vitreoretinal lymphoma patients with rapid central nervous system involvement. Meanwhile, young vitreoretinal lymphoma patients have some unique features, including more retinal/subretinal pigment epithelial infiltrations and lower MYD88 mutation rates.

Consensus Recommendations for the Diagnosis of Vitreoretinal Lymphoma.

PURPOSE: To provide recommendations for diagnosis of vitreoretinal lymphoma (VRL). METHODS: Literature was reviewed for reports supporting the diagnosis of VRL. A questionnaire (Delphi 1 round) was distributed to 28 participants. In the second round (Delphi 2), items of the questionnaire not reaching consensus (75% agreement) were discussed to finalize the recommendations. RESULTS: Presenting symptoms include floaters and painless loss of vision, vitreous cells organized into sheets or clumps. Retinal lesions are usually multifocal creamy/white in the outer retina. Other findings include retinal lesions with "leopard-skin" appearance and retinal pigment epithelium atrophy. Severe vitreous infiltration without macular edema is the most likely presentation. Diagnostic vitrectomy should be performed. Systemic corticosteroid should be discontinued at least 2 weeks before surgery. An interleukin (IL)-10:IL-6 ratio > 1, positive mutation for the myeloid differentiation primary response 88 gene and monoclonality are indicators of VRL. Multi-modal imaging (optical coherence tomography, fundus autofluorescence) are recommended. CONCLUSIONS: A consensus meeting allowed the establishment of recommendations important for the diagnosis of VRL.

Machine Learning Approach for Intraocular Disease Prediction Based on Aqueous Humor Immune Mediator Profiles.

PURPOSE: Various immune mediators have crucial roles in the pathogenesis of intraocular diseases. Machine learning can be used to automatically select and weigh various predictors to develop models maximizing predictive power. However, these techniques have not yet been applied extensively in studies focused on intraocular diseases. We evaluated whether 5 machine learning algorithms applied to the data of immune-mediator levels in aqueous humor can predict the actual diagnoses of 17 selected intraocular diseases and identified which immune mediators drive the predictive power of a machine learning model. DESIGN: Cross-sectional study. PARTICIPANTS: Five hundred twelve eyes with diagnoses from among 17 intraocular diseases. METHODS: Aqueous humor samples were collected, and the concentrations of 28 immune mediators were determined using a cytometric bead array. Each immune mediator was ranked according to its importance using 5 machine learning algorithms. Stratified k-fold cross-validation was used in evaluation of algorithms with the dataset divided into training and test datasets. MAIN OUTCOME MEASURES: The algorithms were evaluated in terms of precision, recall, accuracy, F-score, area under the receiver operating characteristic curve, area under the precision-recall curve, and mean decrease in Gini index. RESULTS: Among the 5 machine learning models, random forest (RF) yielded the highest classification accuracy in multiclass differentiation of 17 intraocular diseases. The RF prediction models for vitreoretinal lymphoma, acute retinal necrosis, endophthalmitis, rhegmatogenous retinal detachment, and primary open-angle glaucoma achieved the highest classification accuracy, precision, and recall. Random forest recognized vitreoretinal lymphoma, acute retinal necrosis, endophthalmitis, rhegmatogenous retinal detachment, and primary open-angle glaucoma with the top 5 F-scores. The 3 highest-ranking relevant immune mediators were interleukin (IL)-10, interferon-γ-inducible protein (IP)-10, and angiogenin for prediction of vitreoretinal lymphoma; monokine induced by interferon γ, interferon γ, and IP-10 for acute retinal necrosis; and IL-6, granulocyte colony-stimulating factor, and IL-8 for endophthalmitis. CONCLUSIONS: Random forest algorithms based on 28 immune mediators in aqueous humor successfully predicted the diagnosis of vitreoretinal lymphoma, acute retinal necrosis, and endophthalmitis. Overall, the findings of the present study contribute to increased knowledge on new biomarkers that potentially can facilitate diagnosis of intraocular diseases in the future.

Logistic Regression Classification of Primary Vitreoretinal Lymphoma versus Uveitis by Interleukin 6 and Interleukin 10 Levels.

PURPOSE: To assess the diagnostic performance and generalizability of logistic regression in classifying primary vitreoretinal lymphoma (PVRL) versus uveitis from intraocular cytokine levels in a single-center retrospective cohort, comparing a logistic regression model and previously published Interleukin Score for Intraocular Lymphoma Diagnosis (ISOLD) scores against the interleukin 10 (IL-10)-to-interleukin 6 (IL-6) ratio. DESIGN: Retrospective cohort study. PARTICIPANTS: Patient histories, pathology reports, and intraocular cytokine levels from 2339 patient entries in the National Eye Institute Histopathology Core database. METHODS: Patient diagnoses of PVRL versus uveitis and associated aqueous or vitreous IL-6 and IL-10 levels were collected retrospectively. From these data, cytokine levels were compared between diagnoses with the Mann-Whitney U test. A logistic regression model was trained to classify PVRL versus uveitis from aqueous and vitreous IL-6 and IL-10 samples and compared with ISOLD scores and IL-10-to-IL-6 ratios. MAIN OUTCOME MEASURES: Area under the receiver operating characteristic curve (AUC) for each classifier and sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) at the optimal cutoff (maximal Youden index) for each classifier. RESULTS: Seventy-seven lymphoma patients (10 aqueous samples, 67 vitreous samples) and 84 uveitis patients (19 aqueous samples, 65 vitreous samples) treated between October 5, 1999, and September 16, 2015, were included. Interleukin 6 levels were higher and IL-10 levels were lower in uveitis patients compared with lymphoma patients (P < 0.01). For vitreous samples, the logistic regression model, ISOLD score, and IL-10-to-IL-6 ratio achieved AUCs of 98.3%, 97.7%, and 96.3%, respectively. Sensitivity, specificity, PPV, and NPV at the optimal cutoffs for each classifier were 94.2%, 96.9%, 97%, and 94% for the logistic regression model; 92.7%, 100%, 100%, and 92.9% for the ISOLD score; and 94.2%, 95.3%, 95.6%, and 93.9% for the IL-10-to-IL-6 ratio. All models achieved complete separation between uveitis and lymphoma in the aqueous data set. CONCLUSIONS: The accuracy of the logistic regression model and generalizability of the ISOLD score to an independent patient cohort suggest that intraocular cytokine analysis by logistic regression may be a promising adjunct to cytopathologic analysis, the gold standard, for the early diagnosis of primary vitreoretinal lymphoma. Further validation studies are merited.

Are there primary intraocular lymphomas that do not develop into central nervous system lymphomas?

Primary intraocular lymphomas frequently develop into central nervous system lymphomas and vice versa. This study reviewed 22 consecutive patients with primary intraocular lymphoma diagnosed by immunostaining of vitrectomy cell blocks, and examined whether they developed central nervous system lymphoma. Seventeen patients developed central nervous system lymphoma: 3 patients developed intraocular and central nervous system lymphoma simultaneously, 9 patients developed central nervous system lymphoma 1 month to 5 years (median, 3 months) after intraocular lymphoma, and 5 patients developed central nervous system lymphoma preceding the diagnosis of intraocular lymphoma by 3 months to 9 years and 8 months (median, 1.5 years). In contrast, 5 patients did not develop central nervous system lymphoma: 2 patients did not develop local recurrence or central nervous system lymphoma in the follow-up period of 5 years and 11 years, respectively, after vitrectomy alone without additional local or systemic treatment. The remaining 3 patients with intraocular lymphoma had insufficient follow-up periods to determine the prognosis. The results of CD5 immunostaining of vitrectomy specimens were found in pathology reports of 8 patients: 3 patients with CD5-positive large cells and 4 patients with CD5-negative large cells developed central nervous system lymphoma. In summary, only a small number of patients did not develop central nervous system lymphoma based on long-term follow-up after vitrectomy alone. CD5 was not a marker of central nervous system involvement in this study population.

Potential Diagnosis of Vitreoretinal Lymphoma by Detection of MYD88 Mutation in Aqueous Humor With Ultrasensitive Droplet Digital Polymerase Chain Reaction.

Importance: The diagnostic workup of patients suspected of having vitreoretinal lymphoma (VRL) is primarily based on vitreous fluid analysis, including the recently emerging myeloid differentiation primary response gene 88 (MYD88) mutation analysis. Aqueous humor paracentesis is a relatively less invasive and safer procedure than taking vitreous fluid specimens, and aqueous humor-based MYD88 mutation analysis would provide an additional liquid biopsy tool to diagnose and monitor patients with VRL. Objective: To investigate whether the detection of MYD88 L265P by highly sensitive droplet digital polymerase chain reaction (ddPCR) is feasible in the vitreous fluid and aqueous humor of patients with VRL. Design, Setting, and Participants: This cohort study includes aqueous humor and vitreous fluid samples from patients with VRL who were treated at the University Medical Center Utrecht, in Utrecht, the Netherlands, from August 2005 to August 2017. Ocular fluids were randomized and masked before MYD88 L265P analysis, which was performed using an in-house validated ddPCR platform. Patients with uveitis were included as a comparison group. Main Outcomes and Measures: The presence of MYD88 L265P mutation detected by ddPCR in AH and VF. Results: The study included 96 samples from 63 individuals, including 23 patients with VRL (of whom 10 were female and 13 male, with a mean [SD] age of 72 [7.3] years) and 40 individuals with uveitis (of whom 23 were female and 17 male, with a mean [SD] age of 58 [20.9] years). In 17 of 23 patients with VRL (74%), MYD88 L265P was detected; it was not detected in any of the patients with uveitis. It was detectable in both vitreous fluid and aqueous humor samples. In the paired samples, the mutation was detected in 8 of 9 aqueous humor samples (89%) of the MYD88 L265P-positive vitreous fluid samples. In vitreous fluid, the MYD88 ddPCR test showed a sensitivity of 75% (95% CI, 50%-92%) and a positive predictive value of 100%; in aqueous humor, sensitivity was 67% (95% CI, 42%-92%), and positive predictive value was 100%. Specificity was 100% in both fluids. After treatment, the mutation was no longer detectable in any ocular fluids. Conclusions and Relevance: The high concordance between aqueous humor and vitreous fluid samples suggests that use of the easily accessible aqueous humor is nearly as informative as vitreous fluid in the identification of key somatic mutations in patients with VRL. This approach may provide an additional minimally invasive tool for accurate diagnosis, detection of recurrence, and monitoring of treatment.

Metagenomic deep sequencing of aqueous fluid detects intraocular lymphomas.

INTRODUCTION: Currently, the detection of pathogens or mutations associated with intraocular lymphomas heavily relies on prespecified, directed PCRs. With metagenomic deep sequencing (MDS), an unbiased high-throughput sequencing approach, all pathogens as well as all mutations present in the host's genome can be detected in the same small amount of ocular fluid. METHODS: In this cross-sectional case series, aqueous fluid samples from two patients were submitted to MDS to identify pathogens as well as common and rare cancer mutations. RESULTS: MDS of aqueous fluid from the first patient with vitreal lymphoma revealed the presence of both Epstein-Barr virus (HHV-4/EBV) and human herpes virus 8 (HHV-8) RNA. Aqueous fluid from the second patient with intraocular B-cell lymphoma demonstrated a less common mutation in the MYD88 gene associated with B-cell lymphoma. CONCLUSION: MDS detects pathogens that, in some instances, may drive the development of intraocular lymphomas. Moreover, MDS is able to identify both common and rare mutations associated with lymphomas.

Mucosa-associated lymphoid tissue lymphoma with intraocular and orbital involvement: case presentation and review of the literature.

Primary ocular lymphomas are typically confined to either the eye or the orbit. Rarely, in immune-competent patients, lymphomas affect both the eye and the orbit simultaneously. Mucosa-associated lymphoid tissue (MALT) lymphomas are the most common ocular lymphomas. They usually present primarily in the orbit but sometimes can present primarily in intraocular tissue. MALT lymphomas that occur initially in the uvea can sometimes spread to the adjacent orbit. We report a case of progressively enlarging MALT lymphoma in a 62-year-old immune-competent patient causing a severe mass effect in the orbit and simultaneously presenting with intraocular involvement. There was radiographic evidence of lymphoma confined to the orbit with intraocular involvement. The simultaneous presentation makes it difficult to determine if the lymphoma initially presented in the orbit or intraocular tissue, although the orbital component was more impressive. The case also includes a literature review of simultaneous orbital and intraocular MALT lymphomas. The patient responded to systemic chemotherapy with regression in size of the lymphoma, relief of the mass effect seen in the orbit, and the regression of the intraocular involvement.

Cytopathologic findings of cell block materials from the vitreous: Diagnostic distinction between intraocular lymphoma and non-lymphomatous diseases.

Intraocular lymphoma is a rare neoplasm that occurs only in the eyes and/or central nervous system. Diagnosis of intraocular lymphoma is difficult because its clinical manifestations mimic chronic uveitis. Pathological examination of the vitreous is one of the main diagnostic tools for intraocular lymphoma, but this is challenging due to the sparse cellularity and specimen degeneration. Here, we reviewed 33 cell block preparations from vitreous perfusion fluid in order to examine the significance of cytopathological findings for differential diagnosis using vitreous samples. The cases comprised 12 intraocular lymphomas and 21 non-lymphomatous diseases. Cytologically, vitreous samples from non-lymphoma cases showed lower cellularity than the lymphoma cases. Whereas vitreous material from cases with infectious endophthalmitis showed prominent neutrophilic infiltration, material from sarcoidosis cases showed infiltration of small lymphoid cells, especially CD4-positive T cells. On the other hand, lymphoma cases showed higher cellularity, with large, irregular and atypical lymphoid cells, frequent necrotic cells in the background, and less pronounced neutrophil infiltration. Immunocytochemically, 11 of the 12 lymphoma cases were of the B-cell phenotype and the remaining case was of the T/NK-cell phenotype. In conclusion, careful cytopathological examination or immunocytochemistry of vitreous material facilitates appropriate diagnosis of intraocular lymphoma.

High-dose methotrexate following intravitreal methotrexate administration in preventing central nervous system involvement of primary intraocular lymphoma.

In order to prevent central nervous system (CNS) involvement and improve the prognosis of primary intraocular lymphoma (PIOL), we prospectively evaluated the efficacy of combined therapy using intravitreal methotrexate (MTX) and systemic high-dose MTX on treatment-naïve PIOL. Patients with newly diagnosed PIOL whose lymphoma was limited to the eyes were enrolled. The patients were treated with weekly intravitreal MTX until the ocular lesions were resolved, followed by five cycles of systemic high-dose MTX (3.5 g/m2 ) every other week. Ten patients were enrolled in this study and completed the treatment. All patients achieved complete response for their ocular lesions with rapid decrease of intravitreal interleukin-10 concentration. Adverse events of intravitreal and systemic high-dose MTX were mild and tolerable. With a median follow-up of 29.5 months, four patients (40%) experienced the CNS disease development and the mean CNS lymphoma-free survival (CLFS) time was 51.1 months. Two-year CLFS, which was the primary end-point of the study, was 58.3% (95% confidence interval, 23.0-82.1%). In contrast, eight patients were treated with intravitreal MTX alone in our institute, and their 2-year CLFS was 37.5% (95% confidence interval, 8.7-67.4%). In conclusion, systemic high-dose MTX following intravitreal MTX is feasible and might be effective in preventing CNS involvement of PIOL. Further arrangements are worth considering in order to improve the effects. This study was registered with UMIN Clinical Trials Registry (UMIN000003921).

Vitreous evaluation: a diagnostic challenge.

PURPOSE: To categorize vitrectomy cytologic diagnoses and ancillary tests to address appropriate processing of low-volume vitreous samples. DESIGN: Retrospective case series. PARTICIPANTS: Five thousand seven hundred thirty-six vitreous samples. METHODS: Cytologic diagnoses of therapeutic and diagnostic vitrectomy samples and their processing protocols from 3 teaching institutions were reviewed. MAIN OUTCOME MEASURES: Diagnostic results were categorized as negative for malignancy, suspicious for malignancy, and positive for malignancy. All ancillary studies performed were documented, including special stains, immunohistochemistry analysis, cytokine levels, and polymerase chain reaction (PCR) analysis. RESULTS: Of the 5736 vitreous samples analyzed, 4683 (81.64%) were from Tufts Medical Center (TMC), 955 (16.65%) were from Boston Medical Center (BMC), and 98 (1.70%) were from Massachusetts Eye Research and Surgery Institution (MERSI). Cases from TMC and BMC were therapeutic and diagnostic vitrectomies, and MERSI cases were diagnostic vitrectomies. Most vitrectomies showed negative results for malignancy: 99.47% of TMC cases, 99.89% of BMC cases, and 79.6% of MERSI cases. These included vitreous hemorrhage and inflammatory or infectious findings. Ancillary studies performed in this category included Periodic Acid-Schiff staining for fungi, PCR analysis for toxoplasmosis, cytomegalovirus, Epstein-Barr virus (EBV), herpes simplex virus I and II, and vitreous cultures for infections (coagulase-negative Staphylococcus, Candida, Fusarium, and Propionibacterium species). Interleukin (IL) 10-to-IL-6 ratios were performed on 38.7% of cases from MERSI. Fourteen cases from TMC were suspicious for malignancy based on cytologic evaluation. Eleven cases from TMC, 1 case from BMC, and 20 cases from MERSI showed positive results for malignancy and included B-cell lymphoma, retinoblastoma, melanoma, and metastatic adenocarcinoma. The ancillary testing included PCR for heavy chain immunoglobulin gene rearrangements, immunohistochemistry for EBV, in situ hybridization for κ and λ light chains, and cytogenetics. CONCLUSIONS: This is the largest data pool of reported cytologic diagnoses of diagnostic and therapeutic vitrectomy samples. Cytologic evaluation of therapeutic vitrectomy samples provides a valuable baseline of nonpathologic findings that assist in differentiation between malignancy, infections, and inflammatory conditions. Allocation of small-volume vitreous samples to select ancillary testing from the plethora of available diagnostic tests requires preoperative communication between surgeons and pathologists to ensure appropriate and timely treatment methods.