Protective effects of biodegradable collagen implants on thinned sclera after strabismus surgery: a paired-eye study

PURPOSE To determine the efficacy of a biodegradable Ologen (Aeon Astron Europe BV, Leiden, The Netherlands) collagen matrix in reducing the blue color change due to exposed thinned sclera after strabismus surgery. METHODS Fourteen patients with intermittent exotropia undergoing symmetric bilateral lateral rectus recession surgery were included in this prospective, randomized, paired-eye controlled study. In each patient, Ologen was implanted at the original rectus insertion site in one randomly selected eye; the other eye underwent conventional surgery. Ologen was inserted under the conjunctiva without suturing, covering the muscle insertion site. Conjunctival color change was analyzed using computer-based image analysis immediately and 1 week, 1 month, and 3 months postoperatively. Slit-lamp photographs of each eye were evaluated using contrast limited adaptive histogram equalization (CLARE), Canny edge, and the RGB (red-green-blue) model. Secondary outcomes were conjunctival and sclera thickness 3 months postoperatively determined by anterior segment optical coherence tomography. RESULTS Immediately and 1 week postoperatively all color models showed no significant differences between Ologen-implanted and control eyes. Three months postoperatively, Ologenimplanted eyes exhibited significantly lower CLARE (P = 0.041) and RGB model blue color (P = 0.008) values than control eyes. Canny edge (P = 0.061) and RGB model red color (P = 0.152) values did not differ between eyes. Conjunctival stroma and episcleral complex thickness was greater in Ologen-implanted eyes than in controls (P = 0.001). CONCLUSIONS Blue color change was significantly less noticeable in Ologen-implanted eyes than in controls. Thus, Ologen implantation helps prevent visible blue sclera at the original rectus insertion site after lateral rectus recession.