Cylindrical error and CDVA significantly improve after Nd: YAG capsulotomy in Pseudophakic Eyes
Posterior capsular opacification (PCO), also known as secondary cataract, is one of the most common complications seen after cataract surgery. PCO can be attributed to the postoperative wound healing response resulting from controlled trauma to the eye during cataract surgery. PCOs result from residual lens epithelial cells (LECs) after cataract surgery where LECs proliferate over the anterior capsule spreading to other surfaces, most importantly the posterior capsule. Once the cells begin covering the posterior capsule, they eventually reach the visual axis. Although a thin layer of LECs may not markedly impact the light path, significant growth of LECs may cause light scatter. PCO formation is multifactorial, including surgical technique, intraocular lens (IOL) material, and IOL design; however, the individual influence of these factors on PCO formation is difficult to distinguish clinically.
Treatment for PCO involves YAG capsulotomy using a neodymium: yttrium-aluminum-garnet (Nd:YAG) laser directed beyond the implanted lens and focused on the posterior, opacified portion of the capsule. The laser creates an opening in the capsule, allowing light to reach the retina unimpeded, thus removing the opacity. The study by Moshirfar et al aimed to compare the differences in sphere, cylinder, spherical equivalent (SE), axis, and corrected distance visual acuity (CDVA) prior to and after YAG capsulotomy to determine whether patients need to be refracted after the procedure.
Patients who underwent Nd:YAG capsulotomy after cataract surgery from January 2013 to April 2022 were included in this retrospective study. Sphere, cylinder, spherical equivalent (SE), axis, and corrected distance visual acuity (CDVA) were compared pre- and postoperatively in 683 eyes of 548 patients at one month (n = 605 eyes) and one year (n = 211 eyes). Patients with both one-month and one-year follow-ups (n = 133) were also compared. Eyes were stratified into single-piece (n = 330), three piece (n = 30), and light adjustable lenses (LALs) (n = 16). Pre- and postoperative measurements were analyzed within each group.
Cylinder was significantly decreased at one-month (p = 0.006) and one-year (p = 0.003) compared to preoperative measurements. No significant change in sphere or axis was observed at follow-up visits (p > 0.05). CDVA significantly improved at both time points (p < 0.05). No significant change in any parameters between the one month and one-year groups was observed (p > 0.05). There was significant improvement in CDVA in the single and three-piece lens groups (p < 0.0001 and p = 0.026, respectively), with no change in the LAL group (p > 0.05).
This study evaluated the effect of YAG capsulotomy on refraction, SE, and CDVA in a large sample of patients based on pre- and postoperative assessments. Authors found no change in sphere or axis at either one-month or one-year follow-up visits when compared to preoperative values. CDVA was significantly improved from baseline at both time intervals, as expected, given the nature of the YAG procedure. Interestingly, there was also a statistically significant reduction in cylinder one month and one year postoperatively compared to preoperative values (differences of 0.042±0.448 D and 0.101±0.455 D, respectively). Upon stratification of cylinder, postoperative values demonstrated an improvement in the distribution of cylindrical power compared to preoperative values, confirming that cylinder improves after YAG capsulotomy. Although the exact cause for this difference is unclear, it may be due to a potential shift in lens position with time or a larger capsulotomy.
This study highlighted the expected improvement in CDVA at both one month and one year follow-ups as well as in single and three-piece lenses. Study results show that Nd:YAG capsulotomies appear to cause a statistically significant, but arguably clinically negligible, decrease in cylinder magnitude. The type of lens does not alter the change in postoperative refractive measurements. Due to the increasing incidence of cataract surgery, the rise of IOL placement will increase the risk of PCO formation and the need for Nd:YAG capsulotomy.
Despite lack of clinical change in refractive error and SE after the YAG capsulotomy, we suggest that patients be refracted after the procedure due to their improvement in CDVA.
Source: Moshirfar et al; Clinical Ophthalmology 2023:17
