Tissue banks are in constant research and development worldwide nowadays. Such is the case of amniotic membrane (AM) applications in ophthalmology, which have experimented an important increase lately by means of different preservation approaches as lyophilized AM or even as AM extract eye drops [1], [2], [3].

Pterygium is a common ocular surface disease with surgery as usual treatment. Most accepted surgical techniques include the implant of a tissue barrier – most frequently conjunctiva or AM – to decrease the risk of pterygium recurrence [4], [5].

Pterygium is essentially an inflammatory process of the corneal limbus as a result of uncontrolled cellular proliferation with overexpression of p53 protein and Ki-67 nuclear protein, among other alterations. With the decrease of the apoptosis, there is an increase on the concentration of transforming growth factor beta (TGF-β), collagenases and therefore subconjunctival proliferation rises [6], [7].

AM grafts used as tissue barriers are an effective alternative to conjunctival autografts (CAG) because of its anti-inflammatory properties and to spare healthy conjunctiva [8]. AM exerts anti-inflammatory, antifibrotic, and antimutagenic properties and pain-relieving effects, being a source of growth factors and cytokines. AM can be implanted as a fresh graft or be stored under various conditions such as cryopreserved or lyophilized [4],[9]. The Barcelona Tissue Bank (Banc de Sang i Teixits, Barcelona, Spain) has been providing the cryopreserved amniotic membrane (CAM) for a long time. Since 2019, it also provides lyophilized amniotic membrane (LAM).

CAM allows a better preservation of proteins and growth factors compared to lyophilization. However, a special equipment is required for its maintenance at –80 °C. It is necessary to keep the cold chain and its storage cannot exceed several months. On the other hand, LAM samples can be stored for several years at room temperature and, moreover, treatment with trehalose before lyophilization can even improve its quality [4], [9].

This study compares CAM versus LAM grafts in pterygium surgery regarding clinical outcomes, cosmetic results, disease symptoms index and recurrences.