Encouraging results of 25G+ minimally invasive vitrectomy surgery for diabetic tractional retinal detachment

I read with interest the article reporting encouraging results of 25G+ pars plana vitrectomy (PPV) in diabetic tractional retinal detachment (TRD) by Mikhail and colleagues [1]. I humbly want to discuss a few points. During combined cataract surgery with PPV, Mikhail and colleagues make the pars plana ports after the cataract surgery is over and the limbal wound is closed with 10–0 nylon suture. However, the chances of hypotony, a collapse of the anterior chamber, and difficulty in inserting the trocar-cannula can be easily prevented if the 3 part-plana cannulas are inserted prior to the making of corneal wounds for the cataract surgery.

I agree with the authors that the 25G instrumentation provides better control during membrane dissection as the cutter mouth is very near to the cutter tip [2]. The risks of hypotony or endophthalmitis may be reduced by leaving the vitreous cavity under air or gas or silicone oil and beveled entries. With the advent of Chandelier illumination with bimanual surgery, and specific instruments like the microvitreoretinal blade, vertical/horizontal scissors, pick forceps in 25G, the minimally invasive vitrectomy surgery (MIVS) is increasingly becoming the choice for vitreoretinal surgeons for diabetic vitrectomy, even in advanced combined rhegmatogenous-tractional retinal detachment (RTRD) cases. Other advantages of MIVS include better fluidics, maintained intraocular pressure during surgery, better cosmesis, decreased or absent need of suturing of sclerotomy sites, and no clinically significant increase in duration of surgery [2]. The encouraging results of initial retinal reattachment of 91% and final anatomical reattachment of 98% [1] reflect the efficacy of diabetic vitrectomy using MIVS. Only six eyes were noted to develop iatrogenic breaks in this study [1] which may be clinically acceptable given the fact that diabetic vitreous membranes are often very tightly adherent to the retina especially in the area of broad vitreoretinal adhesions and the retina in long-standing TRDs may be thin and fragile. Important factors limiting the visual outcomes in diabetic TRDs despite anatomical reattachment include macular ischemia, pallor of the optic disc, epiretinal membrane and co-existent glaucoma.

Subretinal hemorrhage [3] is not very uncommon in long-standing diabetic retinal detachments. Though a careful search for retinal breaks in such cases is essential, up to 69% cases [3] may not have any clinically detectable break. It would be interesting to know if Mikhail et al. [1] did note subretinal hemorrhage in their series, and the percentage of such patients who had a retinal break. Also, the authors say that nine eyes had proliferative vitreoretinopathy (PVR) (Table 2). The details of the PVR with special reference to subretinal bands would be appreciated.

The cause of failure of retinal reattachment after first surgery in ten eyes may need discussion. Diabetic tractional retinoschisis has been reported in up to 94% of tractional macular elevation in proliferative diabetic retinopathy [4]. How many cases in this series [1] had an evidence of tractional retinoschisis or vitreomacular traction [5] on preoperative optical coherence tomogram?

In Table 3, the significance of the numbers within round brackets in the column ‘number of eyes’ needs elucidation.