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Decreasing efficacy of repeated intravitreal triamcinolone injections in diabetic macular oedema

C K M Chan^1,2, S Mohamed^1,2, M P Shanmugam^1,2, C-W Tsang^1,2, T Y Y Lai^1,2 and D S C Lam^1,2

¹ Department of Ophthalmology and Visual Sciences, The Chinese University of Hong Kong, Hong Kong
² Hong Kong Eye Hospital, 147K Argyle Street, Kowloon, Hong Kong

Correspondence to:
Correspondence to:
Professor Dennis S C Lam
Department of Ophthalmology and Visual Sciences, The Chinese University of Hong Kong, University Eye Center, Hong Kong Eye Hospital, 147K, Argyle Street, Hong Kong; dennislam_pub{at}cuhk.edu.hk

Background/aim: Intravitreal triamcinolone (IVTA) results in transient improvements in diabetic macular oedema (DMO), necessitating repeated injections. The authors report a case series of 10 eyes of 10 patients with DMO, who received a repeat injection of 4 mg IVTA, at least 26 weeks after the first injection of the same dose.

Method: Pre-injection and at 2, 4, 9, and 17 weeks post-injection, best corrected visual acuity (BCVA) and central foveal thickness (CFT) on optical coherence tomography, after the first and repeat injections, were compared using paired t test. Side effects were monitored.

Results: BCVA, CFT, intraocular pressure (IOP), and cataract scores were not significantly different before initial and repeat injections (given at 32.5 (SD 3.5) weeks after the first injection). Transient improvements of BCVA and CFT were achieved after both injections. However, after the repeat injection, the BCVA was significantly worse at all time points (p<0.05) and so were the best achieved CFT and the CFT at 4 weeks post-injection (p = 0.034 and 0.011 respectively), compared with the initial injection. Post-injection maximum IOPs and increase in cataract scores were not significantly different between the two injections.

Conclusion: A repeat injection of 4 mg of IVTA may not be as effective as an initial injection for the treatment of DMO.

Abbreviations: BCVA, best corrected visual acuity; CFT, central foveal thickness; CSMO, clinically significant macular oedema; DMO, diabetic macular oedema; ETDRS, Early Treatment of Diabetic Retinopathy Study; IOP, intraocular pressure; IVTA, intravitreal triamcinolone; LOCS, Lens Opacity Classification System; OCT, optical coherence tomography; VEGF, vascular endothelial growth factor

Keywords: diabetic macular oedema; triamcinolone acetonide; dose-response relation

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