Dear Editor,We read with interest the article on the newer classification of
diabetic retinopathy by Dubey et al.1 and would like to share
our views regarding the concept of vitreoretinal traction
in diabetic retinopathy. The authors should be praised for
adding a new dimension to the classification of diabetic
retinopathy.The authors have mentioned that progressive vitreoretinal
traction can produce tractional retinal detachment, secondary
rhegmatogenous retinal detachment, persistent macular edema
and various types of vitreous hemorrhage. These findings have
been classified in the group ″secondary diabetic vitreopathy″.
However, the authors have not included tractional schisis
(either macular or non-macular in location) secondary to
vitreous contraction in the classification.Lincoff et al., have described the entity of ″tractional schisis″
resulting from splitting of the inner retina and causing an
elevation of the retina similar to tractional retinal detachment.2
Differentiating between the two conditions is important, as
the indications of surgery and prognosis may differ between
them. The features of schisis are symmetrical elevation below
the point of traction, slow progression, absence of pigment
demarcation line, failure to spread rapidly in the presence of
a tear. Vitrectomy in these eyes is less risky, because of lack
of rapid progression of retinal detachment in the event of
iatrogenic retinal breaks. In eyes with longstanding tractional
schisis, the vessels in the elevated layer get obliterated; the
elevated layer disintegrates and resembles a large partial-
thickness retinal hole.Tractional retinoschisis with or without retinal detachment
was the most frequent pattern of tractional macular elevation
in eyes with proliferative diabetic retinopathy and observed
in 94% of eyes as reported by Imai et al.3 Optical coherence
tomography (OCT) imaging in eyes with relatively clear
overlying vitreous can be useful in differentiating between
schisis and detachment. The splitting plane is thought to be the
outer plexiform layer.4 Visual recovery after vitrectomy may
be greater in eyes with tractional macular detachment rather
than eyes with schisis involving the macula.Dubey′s classification of diabetic retinopathy prognosticates
the various manifestations of the disease process. Thus, we
hope that the authors would also include non-macular and
macular tractional schisis in their classification, not only for
the sake of completion, but also as differentiating schisis
from tractional detachment is useful for the management and
prediction of possible recovery of central vision.