Early DMO: a predictor of poor outcomes following cataract surgery in diabetic patients. The DICAT-II study

Abstract

Background: The prospective DIabetes and CATaract Study II (DICAT II) was performed to characterise the risks of cataract surgery to the retinae of patients with early diabetic macular oedema (E-DMO).

Methods: DICAT II was a prospective, comparative, multicentre, observational study involving six Italian clinics. Patients were aged ≥55 years, had type 1 or 2 diabetes with spectral-domain optical coherence tomography evidence of ESASO classification Early DMO. Group 1 eyes (78 eyes, 78 patients) underwent phacoemulsification-based cataract surgery. Group 2 eyes (65 eyes, 65 patients) had E-DMO and either clear media or had undergone uncomplicated cataract surgery ≥1 year previously. Central subfield thickness (CST) and best-corrected visual acuity (BCVA) were assessed in both groups.

Results: The negative impact of surgery on CST was evident after the first postoperative week; CST peaked during the first month, then rapidly decreased. CST worsening ≥10 µm was observed in 63/78 eyes (80.7%) and 29/65 eyes (44.6%) in Groups 1 and 2, respectively (p < 0.0001). CST worsening of ≥50 µm was observed in 51 eyes (65.4%) and 10 eyes (15.4%) in Groups 1 and 2, respectively (p < 0.0001). Mean CST worsening was lower in Group 2 than in Group 1 (38.6 ± 30.4 µm vs 85.5 ± 55.3 µm, p < 0.0001) with a lower BCVA loss (-2.6 ± 3.5 letters vs -8.2 ± 6.2 letters, p < 0.0001). Higher glycaemic levels and HBA1c levels were significantly associated with the risk of >50 μm CST worsening in eyes from both groups.

Conclusion: Early DMO is associated with poorer outcomes after cataract surgery and requires close pre- and postoperative monitoring.

Conflict of interest statement

The authors declare no competing interests.

© 2021. The Author(s), under exclusive licence to The Royal College of Ophthalmologists.

Figures

Fig. 1. The ESASO Classification standard.

Early DMO (E-DMO) is defined as small intraretinal cysts associated with well-recognisable and normal retinal segmentation (inner retinal layers, ellipsoid zone and external limiting membrane) and with an increase in central subfield thickness (CST) less than 30% of maximum normal values. A–C represent three levels of progression still considered E-DMO.

Fig. 2. Amount and timing of worsening of BCVA and CST after cataract surgery in eyes with E-DMO.

Compared to natural history (Gr 2) cataract surgery (Gr 1) determined a marked increase in CST and decrease in BCVA peaked at 15-30 days postop. A Correlation between worsening of postoperative BCVA and CST in Group 1 (line) and distribution of CST worsening among the two groups during follow-up, divided in six progressive classes (bar chart). Most of the eyes in Group 2 (follow-up) evidenced a minimal or mild CST worsening, less than 50 microns in 84% of eyes, while 65.4% of eyes of Group 1 (surgery) evidenced a CST worsening higher than 50 microns (p < 0.0001). B Comparison of worsening of BCVA in the two groups during follow-up. In Group 1 worsening was calculated relative to the first postoperative measurement at 1 week. C Percentage of eyes in Group 1 with CST worsening ≥50 µm according to time of postoperative follow-up. The vast majority of eyes (78.4%) worsened during the first postoperative month.

Fig. 3. Worsening of minimal E-DMO after cataract surgery.

A Preoperative oedema, CST 378 µm, BCVA 52 letters. B Two weeks after surgery: CST 630 µm and BCVA 39 letters (−13).