Objective Quantification of Posterior Segment Inflammation: Measuring Vitreous Cells and Haze Using Optical Coherence Tomography

Anterior Vitreous Objective Assessment in Uveitis: An Anterior Segment Swept Source Optical Coherence Tomography Study

PURPOSE

To assess inflammatory changes in the anterior vitreous (AV) using a swept source anterior segment optical coherence tomography (SS-ASOCT) and to correlate them with uveitis features and clinical grading of intraocular inflammation.

METHODS

140 eyes from 96 patients were included in this observational, cross-sectional study: 40 ACTIVE uveitis, 40 INACTIVE uveitis and 60 CONTROLS. All eyes underwent intraocular inflammation clinical grading (anterior chamber (AC) cells counting and vitreous haze evaluation) and AV imaging with SS-ASOCT. Cells seen in the AV on OCT were manually counted using imageJ. Vitreous reflectivity variation was indirectly measured by calculating the vitreous/iris pigment epithelium (VIT/IPE) relative intensity. These OCT-based parameters were compared across the groups and correlated with inflammation clinical grading.

RESULTS

The mean [SD] number of AV OCT cells was significantly higher (both p < 0.001) in ACTIVE uveitis (12[9.8]) compared to INACTIVE uveitis (4.5[3.5]) and CONTROLS (4[3.1]). In ACTIVE uveitis the number of AV OCT cells was significantly and positively correlated with the AC cells (p = 0.04), the VIT/IPE relative intensity (p = 0.0002), the uveitis anatomical classification (INTERMEDIATE UVEITIS, p = 0.02) and the vitreous haze clinical grading (p < 0.0001). The mean[SD] VIT/IPE relative intensity of the AV increased from CONTROLS (0.12[0.01]) to INACTIVE uveitis (0.15[0.01]) to ACTIVE uveitis (0.17[0.02]), but with no statistically significant differences.

CONCLUSIONS

We were able to visualize and objectively evaluate changes occurring in the AV in eyes with uveitis by means of a commercially available SS-ASOCT. OCT-cells in the AV could represent an adjunctive tool in the objective evaluation of intraocular inflammation.

Insights into the diagnosis and management of sarcoid uveitis: A review

Sarcoidosis is a leading cause of non-infectious uveitis that commonly affects middle-aged individuals and has a female preponderance. The disease demonstrates age, sex and ethnic differences in clinical manifestations. A diagnosis of sarcoidosis is made based on a compatible clinical presentation, supporting investigations and histologic evidence of non-caseating granulomas, although biopsy is not always possible. Multimodal imaging with widefield fundus photography, optical coherence tomography and angiography can help in the diagnosis of sarcoid uveitis and in the monitoring of treatment response. Corticosteroid remains the mainstay of treatment; chronic inflammation requires steroid-sparing immunosuppression. Features on multimodal imaging such as vascular leakage may provide prognostic indicators of outcome. Female gender, prolonged and severe uveitis, and posterior involving uveitis are associated with poorer visual outcomes.

Are intravitreal hyperreflective particles alike in eyes with acute toxoplasma chorioretinitis and non-infectious uveitis?

BACKGROUND

To compare distinctive features of hyperreflective particles observed on spectral-domain optical coherence tomography (OCT) sections in eyes with acute toxoplasma chorioretinitis (TC) and non-infectious uveitis (NIU).

METHODS

Medical records and the spectral-domain OCT images of the patients with TC and NIU were retrospectively reviewed. The TC and NIU groups were compared in terms of age, sex, mean OCT image quality, mean central macular thickness (CMT), presence of intraretinal fluid (IRF), presence of subretinal fluid (SRF), number of hyperreflective particles in the posterior vitreous area and mean particle measurement in the posterior vitreous area.

RESULTS

Non-infectious uveitis group included nine patients (60 %) with Behcet's uveitis, five patients (33.3 %) with idiopathic posterior uveitis or panuveitis, and the remaining patient (6.7 %) with HLA-B27 associated uveitis. Comparison of the mean age, sex distribution, mean OCT image quality, mean CMT, presence of IRF, presence of SRF and the mean number of hyperreflective particles in the posterior vitreous area between the two groups showed no statistically significant differences (p = 0.085, p = 0.051, p = 0.748, p = 0.431, p = 0.109, p = 0.080 and p = 0.152, respectively). However, the mean length of the hyperreflective particles in the posterior vitreous area was 27.22 ± 8.60 μm in the TC group, and 21.91 ± 3.58 μm in the NIU group, with a significant difference between the two groups (p = 0.036).

CONCLUSION

This pilot study aimed to assess the hyperreflective particles in the posterior vitreous area using spectral-domain OCT images and image processing software. Despite its limitations, such as the small sample size, limited understanding of the nature of hyperreflective particles, and the absence of differentiation between acute and chronic uveitis, our study points out the potential role of the measurement of the hyperreflective particle length located in the posterior vitreous in differentiating the acute infectious versus non-infectious uveitis as the hyperreflective particles tend to be larger in infectious cases.

Automated quantification of uveitic keratic precipitates by use of anterior segment optical coherence tomography

BACKGROUND

Evaluation of ocular inflammation via common imaging modalities like optical coherence tomography (OCT) has emphasised cell visualisation, but automated detection of uveitic keratic precipitates (KPs) remains unexplored.

METHODS

Anterior segment (AS)-OCT dense volumes of the corneas of patients with uveitic KPs were collected at three timepoints: with active (T0), clinically improving (T1), and resolved (T2) inflammation. At each visit, visual acuity and clinical grading of the anterior chamber cells were assessed. A bespoke algorithm was used to create an en face rendering of the KPs and to calculate their volume and a ratio of the volume of precipitates over the analysed area. The variation of AS-OCT-derived measurements over time was assessed, and compared with clinical grading.

RESULTS

Twenty eyes from 20 patients (13 females, mean age 39 years) were studied. At T0, the mean volume of the corneal KPs was 0.1727 mm3 , and it significantly reduced to 0.1111 mm3 (p = 0.03) only at T2. The ratio between the volume of the KPs and the corneal area decreased from T0 (0.007) to T1 (0.006; p = 0.2) and T2 (0.004; p = 0.009). There was a statistically significant correlation between the AC cell count and the AS-OCT volume measurements of the KPs at the three time points.

CONCLUSIONS

AS-OCT can image uveitic KPs and through a bespoke algorithm we were able to create an en face rendering allowing us to extrapolate their volume. We found that objective quantification of KPs correlated with inflammatory cell counts in the anterior chamber.

Artificial Intelligence-Assisted Processing of Anterior Segment OCT Images in the Diagnosis of Vitreoretinal Lymphoma

Anterior segment optical coherence tomography (AS-OCT) allows the explore not only the anterior chamber but also the front part of the vitreous cavity. Our cross-sectional single-centre study investigated whether AS-OCT can distinguish between vitreous involvement due to vitreoretinal lymphoma (VRL) and vitritis in uveitis. We studied AS-OCT images from 28 patients (11 with biopsy-proven VRL and 17 with differential diagnosis uveitis) using publicly available radiomics software written in MATLAB. Patients were divided into two balanced groups: training and testing. Overall, 3260/3705 (88%) AS-OCT images met our defined quality criteria, making them eligible for analysis. We studied five different sets of grey-level samplings (16, 32, 64, 128, and 256 levels), finding that 128 grey levels performed the best. We selected the five most effective radiomic features ranked by the ability to predict the class (VRL or uveitis). We built a classification model using the xgboost python function; through our model, 87% of eyes were correctly diagnosed as VRL or uveitis, regardless of exam technique or lens status. Areas under the receiver operating characteristic curves (AUC) in the 128 grey-level model were 0.95 [CI 0.94, 0.96] and 0.84 for training and testing datasets, respectively. This preliminary retrospective study highlights how AS-OCT can support ophthalmologists when there is clinical suspicion of VRL.

Characteristics of Cellular Infiltration into Posterior Vitreous in Eyes with Uveitis on the Classification Basis Assessed Using Optical Coherence Tomography

Purpose

To evaluate the characteristics of posterior vitreous cells in patients with uveitis on the classification basis using spectral domain optical coherence tomography (SD-OCT).

Methods

In this retrospective chart review, all eyes were classified into three groups: infectious uveitis (IFU, n=7), noninfectious granulomatous uveitis (NIGU, n=13), and noninfectious nongranulomatous uveitis (NINGU, n=13). We measured the size, number, and density of vitreous hyperreflective particles in the posterior vitreous area that was defined as the space between the vitreous top and the internal limiting membrane on OCT. The correlations between vitreous haze and vitreous particles were also evaluated.

Results

Thirty-three eyes from 23 patients with active posterior uveitis were included. IFU had significantly more particles than NIGU and NINGU (P=0.03 and P<0.001, respectively). The vitreous particle density was higher in IFU than in NIGU and NINGU (P=0.03 and P=0.003, respectively). The mean largest particle size was greater in IFU and NIGU than in NINGU (P=0.01 and P=0.03, respectively). The median vitreous haze of 2+ in IFU, 1+ in NIGU and NINGU showed no significant difference among three groups (P=0.21). Conversely, the correlation of the largest particle size with vitreous haze was significant at ρ= 0.44 (P=0.01).

Conclusion

SD-OCT may be useful for assessing ocular inflammation based on morphological characteristics of vitreous particles on the uveitis classification basis.