Sir,

Myelinated nerve fibres (MNF) can be a rare cause of recurrent vitreous haemorrhage.

Case report

A 26-year-old lady with no previous medical problems presented with a 6-year history of left recurrent vitreous haemorrhages that resolved spontaneously. The left eye was amblyopic due to myopic anisometropia with vision of 1/60. Anterior segment examination showed a posterior subcapsular cataract and no rubeosis. Fundoscopy showed extensive MNF associated with telangiectasia (Figure 1a). The right eye examination was normal with visual acuity of 6/6.

Figure 1
figure 1

Myelinated nerve fibres and retinal vascular abnormalities. (a) Colour fundus photograph showing the telangiectasia and abnormal retinal vasculature (arrows) in association with the myelinated nerve fibres. (b) Fluorescein angiography (FFA) revealed large areas of retinal capillary closure and collateral circulation. (c) FFA (late films)—the disc neovascularisation (NVD) and telangiectasia (arrows) were more evident.

Full size image

Fluorescein angiography revealed large areas of retinal capillary closure, collateral circulation, disc neovascularisation (NVD), and telangiectasia, which appeared as bulb-like/saccular dilatations in the region affected by the MNF (Figure 1b and c). Argon laser panretinal photocoagulation was performed due to the repeated vitreous haemorrhages and presence of NVD angiographically. Serial yearly fundus photos showed the appearance of new telangiectasia and progressive changes in the vasculature, regardless of ongoing laser treatment (Figure 2). Despite several PRPs, the NVD have minimally regressed and the recurrent haemorrhages persist. The patient remains under review.

Figure 2
figure 2

Serial yearly colour fundus photographs and FFA of the left eye. (a) Initial fundus photo showed a small telangiectasia adjacent to the myelinated nerve fibres (MNF) (arrows). (b) Progressive vascular changes (arrows) are evident but more striking on FFA (c), even after several laser sessions (d, e). (f) Peripheral fundus photograph shows the extent of panretinal photocoagulation. No laser marks are seen in the peripapillary region due to poor uptake of laser by the retinal pigment epithelium underneath the feathery partially translucent MNF.

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Comment

MNF are generally considered benign lesions1, 2, 3 and are reported in 0.98% of the population.1, 2 However, occasionally they have been reported with other ocular problems including strabismus, nystagmus, coloboma, macular aplasia, amblyopia, keratoconus,1, 2 and epiretinal membranes.4 Other associations are neurofibromatosis, Down's and Gorlin's syndromes, Marcus Gunn pupil,1, 2 and autosomal dominant vitreoretinopathy with skeletal malformations.3, 5

MNF can rarely be associated with retinal vascular abnormalities.1, 2, 3, 4, 5 The mechanism why MNF lead to retinal ischaemia and secondary vascular changes is not known.1, 2 Theories of mechanical disruption of the retinal vasculature by the surrounding myelin2 or a localised ischaemic process as a result of the excess cells in the area of myelination1 have been suggested. Myelination of the retinal nerve fibres, on account of their increased diameter and enhanced metabolic activity, compete for available oxygen in the tissue producing relative ischaemia. Once the inner retinal ischaemia occurs, the mechanism of neovascular activity behaves the same as in proliferative diabetic retinopathy, other vaso-occlusive disorders (eg, branch retinal vein occlusion, sickle cell disease) and other telangiectactic conditions (eg, Coat's disease), possibly due to the local release of angiogenic factors like vascular endothelial growth factor (VEGF). A review of the literature1, 2, 3, 4, 5 highlights the following common characteristics in patients presenting with vitreous haemorrhage in association with MNF:

  1. a)

    age less than 50 years

  2. b)

    invariable presence of NVD angiographically

  3. c)

    widespread MNF extending over several disc areas

  4. d)

    no retinal vascular abnormality in the fellow eye and

  5. e)

    unremarkable medical history.

Generally, the vitreous haemorrhages were self-limiting and cleared spontaneously on most occasions. Rubeosis was not a reported complication.

As this condition is rare, experience with laser photocoagulation is limited. Only few of the reported symptomatic patients had laser treatment.1, 2, 3 In some patients, this seemed to control the vitreous haemorrhage with2 or without1 regression of the NVD, while in others recurrent vitreous haemorrhages persisted despite multiple laser treatments.3 Only one patient required vitrectomy to clear the dense haemorrhage.3 The role of anti-VEGF treatment in this condition has not been explored yet.

Our patient was examined regularly as a child as she was undergoing occlusion therapy. Although the MNF were noted, the microvascular abnormalities were absent then. This case illustrates that the vascular abnormalities are not necessarily present at birth or childhood but can gradually evolve at a later stage. It is important to be familiar with the rare association of MNF and vitreous haemorrhage to lessen the risk of misdiagnosis1, 2 and to avoid unnecessary investigations especially since symptomatic patients tend to present at a young age.