Spectral domain optical coherence tomography useful for assessing ocular inflammation
Uveitis can be caused by the numerous disorders associated with intraocular inflammation. Some of these have infectious etiologies, and others are caused by systemic diseases, including autoimmune diseases. However, the causes can be unknown or unidentified in many cases. Globally, uveitis is also well known as a disease that potentially leads to blindness. The classification of uveitis based on the degree of inflammation is crucial to evaluate treatment response during follow-up in clinical practice and to ensure standardization of evaluation to maintain the quality of clinical research in different sites.
For management, uveitis is commonly etiologically classified into infectious uveitis (IFU) and nonIFU, followed by clinicopathological classification into granulomatous uveitis vs nongranulomatous uveitis based on ophthalmic examination such as the morphology of keratic precipitates.
In clinical practice, particular characteristics of intraocular cells, such as large cells, small cells, the number of cells, and cell shape, are the key factors that govern this uveitis classification. However, evaluations are made based on subjective examination by physicians, which may depend on their experience, environment, and equipment. Therefore, an objective method to evaluate characteristics of intraocular cells is required.
Recent advances in optical coherence tomography (OCT) have enabled visualization of intraocular inflammatory cells as hyperreflective particles. As the resolution of OCT images has improved, some clinical studies have reported that SD-OCT can capture even subtle intraocular inflammation
This study by Matsumiya et al attempted to elucidate whether the morphological features of vitreal hyperreflective particles on SD-OCT differ among patients with IFU, noninfectious granulomatous uveitis (NIGU), and noninfectious nongranulomatous uveitis (NINGU).
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). Authors 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.
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).
This study demonstrated significant differences in the number of vitreous hyperreflective particles, vitreous particle density, and the length of the largest particle on SD-OCT among the IFU, NIGU, and NINGU groups. In addition, there was a significant correlation between the length of the largest particle and vitreous haze. As a result, the IFU group had larger number of vitreous particles and higher vitreous particle density than NIGU and NINGU groups. The mean length of the largest particle was the longest in the IFU group, followed by that in the NIGU and NINGU groups. There were also significant differences between the IFU vs NINGU and NIGU vs NINGU groups. However, the mean length of the smallest particle did not differ significantly among the three uveitis groups.
To conclude, the number of vitreous particles, vitreous particle density, and length of the largest vitreous particle on OCT differed among the three types of uveitis. The length of the largest vitreous particle on OCT showed a significant correlation with vitreous haze. SD-OCT may be useful for classifying uveitis types and assessing the status of ocular inflammation based on differences in morphological characteristics and the number of vitreous particles.
Source: Matsumiya et al; Clinical Ophthalmology 2023:17 165–174
https://doi.org/10.2147/OPTH.S394441
