Pterygium versus pseudo-pterygium in black and white

Pterygium is a triangular fibrovascular overgrowth of the subconjunctival tissue encroaching on to the cornea due to UV radiation-induced p53 mutation, resulting in insufficient limbal stem cells and fibroblast invasion [Fig. 1a].[1,2] Pseudo-pterygium is bulbar conjunctival growth on the cornea secondary to limbal damage from trauma, burns, or previous surgery, where the epithelium extends around the fibrovascular mass.Figure 1: a, b, and c—Clinical photographs of pterygium, pseudo-pterygium, and recurrent pterygium respectivelyPseudo-pterygium is inflammatory, stationary, and is not attached to the underlying cornea throughout its full length, while true pterygium is a progressive ocular surface disease [Fig. 1b].[3] Recurrent pterygia due to various intrinsic and extrinsic risk factors are more difficult to remove because of the scarring from the previous surgery [Fig. 1c].[4] Therefore, it is important to discern the features to meliorate surgical techniques. Anterior segment optical coherence tomography (AS-OCT) is a valuable and objective method for differentiating these corneal invasions. Discussion AS-OCT of pterygium shows a wedge-shaped mass that causes an elevation of the corneal epithelium and its separation from wavy destroyed Bowman's layer. Immediately central to the cap of the pterygium the epithelium, Bowman's membrane and corneal stroma appear normal [Fig. 2a]. In contrast, AS-OCT in pseudo-pterygium shows an overgrowing membrane actually attached to the underlying cornea and a real plane of cleavage exists between the pseudo-pterygium and the underlying corneal epithelium. The central point of attachment to the cornea shows invasion beneath the epithelium and destruction of Bowman's membrane [Fig. 2b]. In recurrent pterygium, wedge-shaped masses of tissue are found between the corneal epithelium and the underlying partly destroyed Bowman's membrane. The central tip of these wedges was found to be more advanced and creeping beneath the corneal epithelium as opposed to the primary pterygium [Fig. 2c].[5]Figure 2: a—AS-OCT image of pterygium; yellow arrows depict elevated corneal epithelium and red arrows mark wavy destroyed Bowman's layer. b—AS-OCT image of pseudo-pterygium; yellow arrows show the overgrowing membrane not attached to the cornea, and red arrows show the plane of cleavage. c—AS-OCT image of recurrent pterygium; yellow arrows show the corneal epithelium and red arrows depict partly destroyed Bowman's layer with the central tip creeping forwardThus, AS-OCT aids in understanding these fibrovascular corneal invasions prior to surgery adding to the clinical diagnosis. Financial support and sponsorship Nil. Conflicts of interest There are no conflicts of interest.