The influence of mild posterior capsular opacification on spectral domain optical coherence tomography retinal nerve fiber layer thickness.

Abstract

Τo investigate whether Yag laser capsulotomy, in addition to restoring ocular media transparency, may also significantly alter retinal nerve fiber layer (RNFL) thickness analysis and spectral domain optical coherence tomography (SD OCT) indices and quality parameters, such as signal strength (SS), in patients with mild, diffuse posterior capsular opacification (PCO). Prospective interventional case series study which enrolled 28 patients with mild PCO and good baseline best-corrected visual acuity (BCVA). All patients underwent a complete ophthalmologic examination, including SD OCT RNFL thickness measurement prior to Yag laser capsulotomy. Following laser intervention, all patients repeated the same complete ophthalmic examination and results were recorded and analysed. Mean RNFL thickness showed a significant postoperative increase from 89.6 to 94.1μm (p = 0.01), which was also confirmed for superior (p = 0.041), nasal (p = 0.011) and inferior quadrants (p = 0.032). SS and BCVA were also significantly increased after laser treatment (p < 0.01). A significant positive correlation was observed between SS and mean RNFL thickness postoperatively (p = 0.043) but not preoperatively (p = 0.059). Similarly, a significant relationship was found between BCVA and average RNFL thickness after (p = 0.017) but not before (p = 0.457) laser intervention. Our study suggests that the presence of even mild PCO may alter the sensitivity of SD-OCT acquisition and lead to inadvertent RNFL thickness underestimation. Clinicians should be alerted to this contingency and take it into consideration when evaluating various optic neuropathies with SD OCT, in pseudophakic eyes.