To investigate the outcomes of quantitative lens nuclear opalescence change after pars plana vitrectomy and intravitreal gas injection in patients with idiopathic epiretinal membrane and macular hole.

All patients were divided into two group according to the kinds of injected gases, either Group 1 (fluid/air exchange) or Group 2 (20% SF₆ gas injection). Lens nuclear opalescence according to the classification of Lens Opacities Classification System (LOCS) III, mean nuclear density and maximal nuclear density of Pentacam® scheimpflug image changed by image J, besides refractive errors were evaluated before surgery and 1, 2, 4, 6, and 12 months after surgery.

Out of 40 eyes of 40 patients included in the analysis, 21 received only fluid/air exchange (Group 1) and 19 received 20% SF₆ gas injection (Group 2). There were significant changes in lens nuclear opalescence between the study and control (unaffected) eyes. In both groups, the study eyes experienced significant progression of cataract compared with the control eyes, in terms of mean nuclear density, maximal nuclear density and LOCS III. In comparison according to the kinds of injected gases, there was a significant difference in mean nuclear density after 4 months, maximal nuclear density after 2 months and 4 months, LOCS after 2 months and 4 months, and refractive error after 1, 2, 4, and 6 months between both groups ( p = 0.003).

After vitrectomy and intravitreal gas injection, changes in postoperative lens nuclear opalescence of the study eyes progressed more rapidly compared with the control eyes. This study identified that lens nuclear opalescence of Group 2 progressed rapidly, but after 12 months there was no significant difference of lens opacity between the kinds of injected gases.