PTERYGIUM PROGRESSION DETECTED BY IN VIVO CONFOCAL MICROSCOPY Martone Gianluca, Malandrini Alex, Balestrazzi Angelo, Tosi Gian Marco, Pichierri Patrizia, Caporossi Aldo Department of Ophthalmology University of Siena, Italy Department of Ophthalmology University of Siena, Italy

No author has a financial or proprietary interest in any material or method mentioned

Introduction Pterygium is a benign growth of the conjunctiva from the nasal side of the sclera towards the centre of the cornea. It is associated with, and thought to be caused by ultraviolet-light exposure. The pathogenesis is still debated (1). The histopathology is characterized by basophilic degenerative fibrovascular tissue invading the superficial cornea with destruction of the underlying Bowman’s membrane. IVCM is becoming a useful diagnostic tool for ocular surface imaging to describe limbus and corneal diseases (2). It can provide details of ocular structures at the cellular level. In some studies, IVCM was used to examine the typical structure of pterygium (3-4).

To perform a qualitative assessment of anatomical and pathological changes in the cornea and conjunctiva of patients affected by pterygium and to describe the typical components of progressive and not-progressive pterygium by IVCM. Purpose

40 eyes of 32 patients with primary pterygium was examined by slit lamp examination and IVCM in a prospective randomized double blind study. IVCM (Heidelberg Retina Tomograph II with the Rostock Cornea Module) analysis was performed in two different corneal areas, in the central and peripheral pterygium zone. The IVCM images (400 µm x 400 µm) were acquired from the periphery to central pterygium areas. During the examination, all subjects were asked to fixate external light target in order to good visualization of the pterygium. All eyes were evaluated at baseline, after 6 and 12 months. After 12 months they were classified in two groups: progressive and non-progressive group. Methods

Results: Progressive group Irregular corneal epithelium adjacent to the pterygium head and not well defined transfer zone Actvated keratocytes and stromal edema at body of pterygium Many capillaries and an important infiltration of dendritic cells in pterygium head Cloudy and hyperreflective margin of the apex head Hyperreflective formations as scars that could be Bowman’s membrane breaks

Irregular epithelium morphology adjacent to the head of the pterygium but the margins are well defined Results: Not progressive group Many irregular hypereflective areas were also present between the head of pterygium and adjacent cornea (Fuchs' dots) Bright intracellular inclusions in the basal epithelial cell layer (Stoker’ s line) and the surrounding epithelium appears absolutely normal Reduction of stromal edema with low activated keratocytes and low inflammatory cells and vessels

Discussion In this study, IVCM was used to examine the typical structure of primary pterygium. The body and the head of the pterygium and the corneal epithelium and stroma adjacent to the pterygium head were characterized by the presence of different findings between the progressive and not-progressive groups. Significant correlations were found between clinical progression of the pterygium and IVCM parameters. Furthermore, the findings obtained by IVCM suggest that it may be helpful as a non-invasive and uncomplicated method to study the anatomical structural corneal and conjunctival changes in patients with pterygium and understanding its condition of progression. Larger studies should be carried out to understand further the changes at the level of the cornea induced by the pterygium and correlate them with signs of clinical progression to plan the surgery.

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