Comment on: The role of posterior vitreous detachment on the efficacy of anti-vascular endothelial growth factor intravitreal injection for treatment of neovascular age-related macular degeneration.

Sir,

We read the article by Neudorfer et al.[1] with great interest. However, we would like to comment upon few points. The authors have mentioned incomplete PVD as their exclusion criteria but patients with VMA on OCT were included in primary analysis as PVD+. This could have resulted in similar outcomes in both groups.

MIVI-TRUST study has shown that intravitreal saline injection can also lead to PVD induction in 10.1% of patients.[2] The authors have included patients with cataract surgery but have not mentioned time duration. A study by Mirshahi et al. reported 1 year incidence of PVD after cataract surgery as 58.6% with 82.4% within 1 month.[3] A study by Sponer et al. termed the word RELEASE for the patients who developed PVD during the follow-up. They reported that RELEASE and VMA groups needed more number of injections.[4] It would have been better if authors also have analyzed this as a separate group.

Fig. 4a shows change in CRT in both groups with time but authors have not mentioned whether increase in CRT from 6 months to 12 month was significant or not. Also the possible reasons for this increase would have been discussed. There is also discrepancy in the graph and its description; PVD- group has lower CRT at 12 months and similar MRT values as compared to PVD+ group. A study by Liu et al. has reported transient regression of CNVM after PPV and recurrence at 12 months. They postulated that vitrectomy may block pathogenic process at preretina level but cannot eliminate the existent, subretinal-level pathologic changes of RPE cells.[5]

The authors have stated that 37 patients were required for the power of 80% but this amount of patients should be in each group to keep this power. Therefore, the power of the study cannot be 80% with a subgroup analysis within 37 patients and, hence, the results should be interpreted with caution.

It would have been better for our understanding if authors have shared the sequential OCT raster scans.

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Conflicts of interest

There are no conflicts of interest.