Signs of uveitis in the intermediate portion of the eye include
inflammatory cells in vitreous
vitreous haze (Fig 5-7)
snowballs (clumped vitreous cells)
snowbanks (exudate over pars plana)
ciliary body detachment
vitreous strands or traction band
The hallmark of intermediate uveitis is vitreous cell and haze. Cells may be clumped or individual. The cells make up vitreous haze when viewed in combination with proteinaceous vitreous debris.
Figure 5-7 Grading scale for vitreous haze: representative standard images. Grade 4: Dense opacity obscuring optic nerve head. Grade 3: Optic nerve visible, borders blurred, no retinal vessels seen. Grade 2: Significant blurring of optic nerve and retinal vessels but still visible. Grade 1: Few opacities, mild blurring of optic nerve and retinal vessels. Trace (0.5+): Trace. Grade 0: Clear.
(Courtesy of NEI, originally published in Nussenblatt RB, Palestine AG, Chan CC, et al. Standardization of vitreal inflammatory activity in intermediate and posterior uveitis. Ophthalmology. 1985;92(4):467–471.)
Figure 5-8 Slit-lamp technique for viewing anterior vitreous cells and opacity, demonstrated in a patient with amyloidosis.
(Courtesy of Emilio M. Dodds, MD.)
Table 5-9 Grading Scheme for Vitreous Chamber Cells and Haze
The physician typically grades vitreous cells on a 0–4 numeric scale by observing the retrolental space in a dilated eye using the slit-lamp biomicroscope and a 1 × 0.5 mm beam (Fig 5-8). The consensus is that cells in the vitreous strands are old, and cells in the syneretic areas are likely new. The SUN system does not specify a grading system for vitreous cells. Table 5-9 shows the vitreous cell grading scale used in the Multicenter Uveitis Steroid Treatment Trial (MUST).
Vitreous haze may be a better indicator of disease activity than cell counts alone. The grading of vitreous haze is based on the clarity of view of the posterior segment on funduscopic examination. The National Institutes of Health grading system for vitreous haze, which the SUN system adopted, employs a standardized set of fundus photographs that defines vitreous haze on a 0–4 scale (see Fig 5-7). Vitreous haze has been used in inclusion criteria in clinical trials for uveitis, and a 2-step improvement has been used as a principal outcome measure.
Additional signs of inflammation in the vitreous include snowball opacities (clumps of inflammatory cells in the vitreous) and snowbanks (exudates over the pars plana, especially prominent inferiorly). Active snowbanks have a fluffy or shaggy appearance. As pars planitis becomes inactive, the pars plana appears gliotic or fibrotic and smooth; thus, these changes are not referred to as snowbanks. Vitreal strands and snowballs may vary in clinical appearance by disease type. Chronic intermediate uveitis may be associated with cyclitic membrane formation, secondary ciliary body detachment, and hypotony.
Excerpted from BCSC 2020-2021 series: Section 9 - Uveitis and Ocular Inflammation. For more information and to purchase the entire series, please visit https://www.aao.org/bcsc.