In vivo confocal microscopy of trachoma in relation to normal tarsal conjunctiva

Abstract

Objective: To describe the in vivo confocal microscopy (IVCM) appearances of the tarsal conjunctiva in trachoma compared with the appearance of healthy conjunctiva and to develop grading systems for IVCM examination of the tarsal conjunctiva for use in future studies on trachoma and other conjunctival diseases.

Design: Prospective observational study.

Participants: In vivo confocal microscopy examination was performed on 302 clinically normal adults, 16 clinically normal children, 750 adults with trachomatous conjunctival scarring, and 25 children with active trachoma.

Methods: Clinical evaluation was performed with ×2.5 loupes, and IVCM examination of the upper tarsal conjunctiva was carried out with a Heidelberg Retina Tomograph 3 with the Rostock Cornea Module (Heidelberg Engineering GmbH, Dossenheim, Germany).

Main outcome measures: In vivo confocal microscopy images were analyzed for cellular and tissue changes associated with trachomatous inflammation and scarring compared with healthy subjects.

Results: Trachomatous subjects with follicular and papillary inflammation had an increased inflammatory cellular infiltrate, including dendritiform cells, discrete follicular and papillary structures, and cystic lacunae suggestive of tissue edema. Trachomatous conjunctival scarring was seen with IVCM as organization of the subepithelial connective tissue into bands/sheets. Grading systems for inflammatory changes and scarring were developed, with the system for scarring showing good interobserver agreement with an intraclass coefficient of 0.88.

Conclusions: In vivo confocal microscopy provides a powerful tool for examining the ocular surface. Numerous cellular and tissue changes were observed in subjects with trachoma, the first time IVCM has been applied to this disease. These changes both complement and add to previous histologic analyses. In vivo confocal microscopy promises to provide new insights into the pathogenesis of trachoma and other conjunctival diseases.

Figure 1

Normal tarsal conjunctiva. Images are 400×400 μm with the bar representing 50 μm. A, Superficial epithelial cell nuclei. B, Inflammatory cell nuclei; note heterogeneity in size and shape (arrow). C, Dendritic cells (arrow). D, Superficial blood vessels.

Figure 4

Active disease in adults with conjunctival scarring. Images are 400×400μm with the bar representing 50 μm. A, Increased inflammatory cell infiltrate. B, Follicular structure. C, Activated DCs. D, Cystic lacunae. DC = dendritiform cells.

Figure 6

Conjunctival connective tissue organization/scarring grading system for IVCM. Images are 400×400 μm. A, Normal: homogenous, amorphous appearance with occasional fine, wispy strand. B, Grade 1: Heterogeneous appearance with poorly defined clumps or bands present. C, Grade 2: clearly defined bands of tissue that constitute <50% of the area of the scan. D, Grade 3: clearly defined bands or sheets of tissue that constitute ≥50% of the area of the scan and in which striations are visible. If different grades of scarring are seen within a particular volume scan, then the highest grade is recorded. The connective tissue that is graded needs to be separate from that associated with the vascular tissue; if this is not possible then the scan is considered ungradable. IVCM = in vivo confocal microscopy.