The effect of timing of amniotic membrane transplantation on prognosis vision of different degrees of acute ocular surface burn

Abstract

Objective To compare the morphological and functional outcomes of different degrees of ocular burns patients receiving amniotic membrane transplantation (AMT) at different time points after ocular burn. Methods A retrospective analysis was performed.Ninety-two eyes of 76 acute ocular chemical burn patients were enrolled from January 2012 to December 2016 in Henan Eye Hospital.The ocular chemical burns were classified by Dua classifications.According to the operation time of AMT, the patients were divided into within 1 day after injury group, 2-6 days after injury group and more than 6 days after injury group.The best corrected visual acuity and limbal stem cell deficiency score were recorded during the at least one year of follow up.The risk factors affecting limbal stem cell deficiency and visual outcome were analyzed. Results Of all the burned eyes, 29 eyes (31.5%) were result from acid burn, 41 eyes(44.6%) were result from alkaline burns and 22 eyes (23.9%) were result from thermal burn.The average burn severity scores of patients with limbal stem cell deficiency score of 0, 1 and 2 was 1.86±0.54, 3.60±0.94 and 5.35±0.63, respectively, and the overall difference was statistically significant (F=65.532, P<0.01). In mild to moderate ocular surface burn patients, the limbal stem cell deficiency score in more than 6 days after injury group was significantly higher than that in within 1 day after injury group and 2-6 days after injury group (Z=-2.21, P=0.03; Z=-2.33, P=0.02). In severe ocular surface burn patients, there was no significant difference in limbal stem cell deficiency score between the groups (P=0.26). At the last follow-up, the average visual acuity of all eyes was 3.19±1.47.COX regression analysis showed that burn grade and operation timing were the main risk factors for visual prognosis (OR=4.925, 1.368; both at P<0.01). Prognostic visual acuity was linearly correlated with the timing of amniotic membrane occlusion and degree of burn (R2=0.078, 0.685; both at P<0.01), but for the V grade and Ⅵ grade eyes, amniotic membrane timing couldn't improve the score of limbal stem cell deficiency. Conclusions Dua classifications is of great significance in evaluating prognosis of ocular burn patients.AMT is an effective adjunctive treatment in the management of acute ocular chemical burns to support epithelial healing and restore ocular surface integrity with potential to improve vision.AMT can't prevent limbal stem cell deficiency or restore vision in eyes with severe burns. Key words: Ocular burn; Classification; Amnion; Timing of surgery; Outcomes