Sir,

We report the clinical efficacy and safety of intravitreal Iluvien implant in vitrectomised eyes of chronic diabetic macular oedema (DMO), irrespective of the timing of vitrectomy procedure.

Case reports

Case 1 A 50-year-old diabetic female received multiple intravitreal anti-VEGF and triamcinolone (IVT) injections for chronic DMO (Figure 1), and subsequent vitrectomy for severe macular traction. Post-vitrectomy DMO was still present despite additional intravitreal therapies. She received Iluvien implant 7 months post vitrectomy. Post-Iluvien DMO resolved with no further adjunctive therapy up to 1 year.

Figure 1
figure 1

Case 1: Left eye OCTs (a–d). (a) Severe vitreo-macular traction on chronic diabetic DM0. (b) Post-vitrectomy (pre-Iluvien) showed recurrent mild diffuse DMO persisting. (c) Partial resolution of DMO 1 week post Iluvien. (d) No evidence of recurrence after 1 year, without further adjunctive therapy. Abbreviations: CRT, central retinal thickness; OCT, optical coherence tomography; VA, visual acuity.

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Case 2 A 48-year-old diabetic male with bilateral proliferative retinopathy and DMO received many laser and anti-VEGF therapies (Figure 2), but responded best to repeated IVT injections over a 9-year period. The right eye underwent vitrectomy for recurrent vitreous haemorrhage 3 years before bilateral Iluvien implantations. The right DMO resolved gradually over 1 year without adjunctive therapy; left eye DMO responded only briefly before recurring significantly. Vitrectomy (with the Iluvien implant preserved in situ) for the left eye was carried out a year later, and achieved DMO resolution post-vitrectomy.

Figure 2
figure 2

Case 2: Right eye OCTs (a–d), left eye OCTs (e–h). (a) Recurrent vitreous haemorrhage and gross DMO before vitrectomy. (b) Recurrent persistent DMO, 3 years post vitrectomy (4 months post last triamcinolone injection). (c) Partial resolution of DMO 1 week post Iluvien. (d) DMO resolution was complete after 1 year, without further adjunctive therapy. (e) Pre-Iluvien left eye showed refractory gross DMO. (f) Incomplete resolution of DMO 1 month post Iluvien. (g) Recurrence was evident within few months. (h) Improved DMO 2 weeks post vitrectomy. Abbreviations: CRT, central retinal thickness; OCT, optical coherence tomography; VA, visual acuity.

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Comment

Intravitreal steroids and anti-VEGF therapies were known to be effective and may have complementary effects on reducing retinal vascular permeability.1 Surgical intervention as a means to treat unresponsive DMO however, showed inconclusive benefit in the absence of tractional DMO.2 Study on non-diabetic rabbits suggested no differences in pharmacokinetics/concentration of short-term intravitreal steroid in vitrectomised vs non-vitrectomised eyes,3 contradicting the positive results of clinical studies on diabetic patients.4, 5

Given that patient 2 had a dramatic result in a previously vitrectomised eye and then a similar effect in other eye post-vitrectomy, concomitant systemic influence is unlikely to contribute to the positive outcomes. Both patients had good risk-factor control and experienced no adverse effects. Our cases demonstrated that intravitreal Iluvien could achieve desirable anatomical improvement in chronic DMO in vitrectomised eyes, in the first year without adjunctive therapy. It also raised an interesting concept that vitrectomy, indicated for varied clinical reasons, may enhance the performance of Iluvien implant when performed at any stage. Larger controlled studies nevertheless are needed to further evaluate the concept.