Effect of Cataract Grade according to Wide-Field Fundus Images on Measurement of Macular Thickness in Cataract Patients

PURPOSE: To investigate the effects of cataract grade based on wide-field fundus imaging on macular thickness measured by spectral domain optical coherence tomography (SD-OCT) and its signal-to-noise ratio (SNR). METHODS: Two hundred cataract patients (200 eyes) with preoperative measurements by wide-field fundus imaging and macular SD-OCT were enrolled. Cataract severity was graded from 1 to 4 according to the degree of macular obscuring by cataract artifact in fundus photo images. Cataract grade based on wide-field fundus image, the Lens Opacity Classification System III, macular thickness, and SD-OCT SNR were compared. All SD-OCT B-scan images were evaluated to detect errors in retinal layer segmentation. RESULTS: Cataract grade based on wide-field fundus imaging was positively correlated with grade of posterior subcapsular cataracts (rho = 0.486, p < 0.001), but not with nuclear opalescence or cortical cataract using the Lens Opacity Classification System III. Cataract grade was negatively correlated with total macular thickness (rho = −0.509, p < 0.001) and SD-OCT SNR (rho = −0.568, p < 0.001). SD-OCT SNR was positively correlated with total macular thickness (rho = 0.571, p < 0.001). Of 200 eyes, 97 (48.5%) had segmentation errors on SD-OCT. As cataract grade increased and SD-OCT SNR decreased, the percentage of eyes with segmentation errors on SD-OCT increased. All measurements of macular thickness in eyes without segmentation errors were significantly greater than those of eyes with segmentation errors. CONCLUSIONS: Posterior subcapsular cataracts had profound effects on cataract grade based on wide-field fundus imaging. As cataract grade based on wide-field fundus image increased, macular thickness tended to be underestimated due to segmentation errors in SD-OCT images. Segmentation errors in SD-OCT should be considered when evaluating macular thickness in eyes with cataracts.

Cataract Change after Vitrectomy and Gas Injection in Patients with Epiretinal Membrane and Macular Hole

PURPOSE: 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. METHODS: 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. RESULTS: 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). CONCLUSIONS: 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.