AIM:To investigate the influence of posterior capsular opacity(PCO)and its removal on retinal nerve fiber layer(RNFL)thickness measured with spectral domain optical coherence tomography(SD-OCT).

METHODS: Fifty patients underwent RNFL measurements using SD-OCT before and after Nd: YAG laser posterior capsulotomy. The patients were divided into groups according to the value of signal to noise ratio(SNR)measured by SD-OCT as group 1: SNR 3 and 4, group 2: SNR 5 and 6 and group 3: SNR 7 and 8. The other eye served as control(control group).

RESULTS: The mean BCVA, SNR and RNFL measurements significantly increased in eyes underwent Nd: YAG laser capsulotomy. The preoperative and postoperative mean BCVA, SNR and RNFL measurements were significantly different in group 1 and group 2. Although the preoperative and postoperative mean BCVA and SNR were significantly different, the preoperative and postoperative RNFL thickness weren't significantly different in group 3.

DISCUSSION: PCO has an influence on OCT image quality. SNR improved in all cases after removal of the PCO. However, RNFL thickness significantly improved after Nd:YAG laser capsulotomy in patients with preoperative SNR under 7.