BLEB Grading

  • ·         Indiana Bleb Grading System.

Four parameters are assessed at the slit lamp, using a narrow beam, against a standardized photographic set of blebs.

(1) Bleb height: this describes the maximal vertical elevation of the bleb: flat, low, medium, or high.

(2) Horizontal extent: the maximal horizontal extent is described relative to limbal clock hours: <1 hr, 1–2 hr, >2–<4 hr, and >4 hr.

(3) Vascularity: five simple categories are elaborated: white and avascular, cystic and avascular (with microcysts), mild vascularity, moderate vascularity, and extensive vascularity.

(4) Seidel leakage: in the testing for a bleb leak with a fluorescein strip at the slit lamp, the bleb is categorized as showing no leak, multiple pinpoint leaks without streaming, or brisk streaming within 5 seconds.


  • ·         Moorfields Bleb Grading System.

The bleb is assessed either photographically or at the slit-lamp, and characterized with respect to height and to vascularity in three zones: central bleb, peripheral bleb, and non-bleb. An elaborate photographic set of standards is available, as well as a standardized form for reporting.

(1) Central bleb area: an estimation into five categories of percentages (0%, 25%, 50%, 75%, and 100%) is made of the relative size of the central demarcated area of the bleb relative to the visible conjunctival field superiorly. Often this is confined to the area over the scleral flap; in a uniform bleb, central and peripheral estimations are congruent.

(2) Peripheral bleb area: the maximal extent of the bleb is assessed using a similar scale of five percentage estimations. This parameter assesses the maximal diffusion area of the bleb, as evidenced by slight bogginess or guttering at the edges.

(3) Bleb height: in reference to the standardized photographs, the maximal central bleb height is scaled as flat, low, moderately elevated, or maximally elevated.

(4) Vascularity: considered the most important prognostic parameter for bleb failure, this scale is applied to three areas: the central demarcated bleb, the bleb’s peripheral extent of diffusion, and the surrounding non-bleb conjunctiva. Five grades of vascularity are used: avascular, normal, mild vascularity, moderate vascularity, and severe vascularity. Subconjunctival blood is also notated.



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