Vitrectomy for center-involved diabetic macular edema

Abstract

Purpose: To determine the effect of vitrectomy for center-involved diabetic macular edema (CI-DME).

Methods: This was a retrospective study of 53 eyes of 45 patients who had vitrectomy for CI-DME and were followed up for at least 12 months. Charts were reviewed for visual acuity (VA), central subfield mean thickness measured by optical coherence tomography, presurgical and postsurgical interventions for CI-DME, and number of office visits in the first 12 months after surgery. Preoperative spectral domain optical coherence tomography was performed on 38 patients, and they were graded for ellipsoid zone (EZ) intactness by three independent graders with assessment of agreement between graders using intraclass correlation coefficients and Bland-Altman analysis.

Results: The median VA improved from 20/100 (interquartile range [IQR], 20/63-20/200) at baseline to 20/63 (IQR, 20/32-20/125) at 12 months. The median central subfield mean thickness improved from 505 μm (IQR, 389-597 μm) at baseline to 279 μm (IQR, 246-339 μm) at 12 months. Intergrader agreement for EZ intactness was moderate (intraclass correlation coefficients 0.4294-0.6356). There was no relationship between preoperative intactness of the EZ and the 12-month change in VA.

Conclusion: Vitrectomy consistently thins the macula in CI-DME and, on average, leads to clinically significant improvement in VA comparable in size to that reported with serial intravitreal anti-vascular endothelial growth factor injections. A large, comparative, prospective, randomized clinical trial of these two treatments is needed to determine which is more effective and cost-effective.

Keywords: center-involved diabetic macular edema; diabetic macular edema; spectral domain OCT; vitrectomy.

Figure 1

Time course of response of the logMAR VA after vitrectomy for diabetic macular edema. Abbreviations: % ile, percentile; logMAR, logarithm of the minimum angle of resolution; VA, visual acuity.

Figure 2

Time course of response of the CSMT after vitrectomy for diabetic macular edema. Abbreviations: % ile, percentile; CSMT, central subfield mean thickness.

Figure 3

Graph of 12-month change in logMAR VA after vitrectomy for diabetic macular edema versus the intactness of the EZ assessed as the average of three scores by independent graders. Notes: The black line is the least-squares regression line. The slope does not differ from zero to a statistically significant extent (P=0.5641). Abbreviations: logMAR, logarithm of the minimum angle of resolution; VA, visual acuity; EZ, ellipsoid zone.

Figure 4

Multimodal imaging of patient described in case 1. Notes: (A) Monochromatic fundus photograph of the right eye of the patient described in case 1. (B) Late phase frame of the fluorescein angiogram of the right eye of the patient described in case 1. The yellow arrow indicates neovascularization elsewhere. The blue arrow indicates neovascularization of the disc. The pink arrow indicates preretinal hemorrhage. (C) Preoperative SD-OCT of the right eye of the patient described in case 1. White arrow indicates submacular fluid. Green arrow indicates the photoreceptor layer with an absent EZ line. (D) 12-month postvitrectomy SD-OCT. The red arrow indicates an absent EZ line. Abbreviations: SD-OCT, spectral domain optical coherence tomography; EZ, ellipsoid zone.

Figure 5

Multimodal imaging of patient described in case 2. Notes: (A) Monochromatic fundus photograph of the left eye of the patient described in case 2. (B) Late phase frame of the fluorescein angiogram. The green arrow indicates profuse leakage of fluorescein throughout the macula. (C) Preoperative SD-OCT scan of the left eye. The turquoise arrow indicates the photoreceptor layer with an absent EZ line. (D) 12-month postvitrectomy SD-OCT. The red arrow indicates an absent EZ line. The yellow arrow indicates a nasal ERM that does not cover the fovea. Abbreviations: SD-OCT, spectral domain optical coherence tomography; EZ, ellipsoid zone; ERM, epiretinal membrane.