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Cho, Kwan Hyuk, MD*,†,‡; Park, Sang Jun, MD*; Woo, Se Joon, MD, PhD*; Park, Kyu Hyung, MD, PhD*

doi: 10.1097/IAE.0000000000001875
Original Study

Purpose: To investigate correlations between the inner-retinal irregularity index and interdigitation zone (IZ) defects preidiopathic and postidiopathic epiretinal membrane (ERM) surgery.

Methods: The authors retrospectively assessed ophthalmic parameters in 89 eyes of 89 patients with ERM. They divided patients into the no-IZ defect (51, 57%) and IZ defect (38, 43%) groups. The IZ defect group was subdivided into recovered (22, 58%) and remaining IZ defect (16, 42%) subgroups, according to IZ recovery status at final examination. The inner-retinal irregularity index of each group was measured before and 1-, 3-, and 6-month postsurgery.

Results: Clinical characteristics were similar in both groups. The IZ defect group had a statistically significant higher inner-retinal irregularity index than the no-IZ defect group before (P = 0.023), but not after ERM surgery. The inner-retinal irregularity index of the recovered and remaining IZ defect subgroups was similar before surgery, but differed markedly 6 months after surgery (P = 0.048). Changes in the inner-retinal irregularity index quantitatively correlated with IZ defect size before and after ERM surgery (P < 0.001).

Conclusion: The inner-retinal irregularity index differed significantly according to the IZ status and also correlated with the IZ defect before and after ERM surgery. The inner-retinal irregularity index may reflect the outer-retinal damage in ERM.

The inner-retinal irregularity index shows significant degree-dependent correlation with interdigitation zone defects before and after epiretinal membrane (ERM) surgery. It may provide a basis for explaining the development of outer-retinal damage, as well as acting as a predictive prognostic marker in ERM.

*Department of Ophthalmology, Seoul National University College of Medicine, Seoul National University Bundang Hospital, Seongnam, South Korea;

Department of Retina Center, HanGil Eye Hospital, Incheon, South Korea; and

Department of Ophthalmology, Catholic Kwandong University College of Medicine, Incheon, South Korea.

Reprint requests: Kyu Hyung Park, MD, PhD, Department of Ophthalmology, Seoul National University Bundang Hospital, #300 Gumi-dong, Bundang-gu, Seongnam, Gyeonggi-do 463-707, Korea; e-mail:

Supported by the National Research Foundation of Korea (NRF) Grant funded by the Korean government (MSIP) (2013R1A2A2A04015829) and an SK Telecom Grant funded by the Seoul National University Bundang Hospital (06-2014-160). The sponsor or funding organization had no role in the design or conduct of this research.

None of the authors have any conflicting interests to disclose.

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© 2018 by Ophthalmic Communications Society, Inc.