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Letter to the Editor

Diabetic retinopathy

New proposed classification

Rao, Prasan M MS, FRCSEd

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Indian Journal of Ophthalmology: Sep–Oct 2008 - Volume 56 - Issue 5 - p 440-441
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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.

1. Dubey AK, Nagpal P, Chawla S, Dubey B. A proposed new classification for diabetic retinopathy: The concept of primary and secondary vitreopathy Indian J Ophthalmol. 2008;56:23–9
2. Lincoff H, Kreissig I. Patterns of non-rhegmatogenous elevations of the retina Br J Ophthalmol. 1974;58:899–906
3. Imai M, Iijima H, Hanada N. Optical coherence tomography of tractional macular elevations in eyes with proliferative diabetic retinopathy Am J Ophthalmol. 2001;132:458–61
4. Faulborn J, Ardjomand N. Tractional retinoschisis in proliferative diabetic retinopathy: A histopathological study Grafes Arch Clin Exp Ophthalmol. 2000;238:40–4
© 2008 Indian Journal of Ophthalmology | Published by Wolters Kluwer – Medknow