Vitreomacular Traction Syndrome

Description

Vitreomacular traction (VMT) syndrome is a condition where the posterior hyaloid face of the vitreous is abnormally adherent to the macula and exerts traction anteriorly. The traction results from a partial posterior vitreous detachment (PVD), with persistent attachment of the posterior hyaloid to the retinal internal limiting membrane at the macula.

VMT is an entity that is similar to a stage 1 macular hole, except that a broader area of retina is affected by traction. VMT also shares some similarities to idiopathic epiretinal membranes, such as the presence of fibrocellular tissue at the macula. However, epiretinal membranes differ from VMT in that even in the presence of a complete PVD, the membrane may exert lateral traction on the macula due to the effects of contractile elements. If VMT occurs in association with an epiretinal membrane, then multiple adhesions of the vitreous are more likely, exerting a broader area of traction.

Symptoms

VMT can cause reduced vision, metamorphopsia, photopsia or micropsia.

Signs

Visual acuity can range from 20/30 (6/9) to 20/400 (6/120). There will be signs of a partial posterior vitreous detachment, with the posterior hyaloid still attached centrally at the fovea. On stereoscopic examination the fovea may appear elevated, with retinal thickening and cystic changes. Diagnosis in some cases may be difficult with biomicroscope and fundus lens alone; however, ocular coherence tomography (OCT) usually enables definitive diagnosis (see below under Additional Investigations).

Prevalence

Rare (1/10,000) overall, although in populations with posterior vitreous detachment uncommon (approximately 1/1,000).

Significance

Traction on the fovea can cause significant visual disturbance due to retinal thickening and cystoid macular edema, and there is a risk of the development of a macular hole or more rarely a tractional retinal detachment at the macula.

Differential Diagnosis

Epiretinal membrane, Macular hole

See Also

Macular edema, Posterior vitreous detachment

Management

Additional Investigations

• The Amsler grid will often show subjective distortion of central vision and may be used to qualitatively monitor progression or treatment.
• OCT enables assessment of the vitreous face and the macula:
  • The mean thickness at the macula may be compared to normative data with the instrument, using measurements from multiple line scans in a radial spoke pattern. Macular thickness in the central 1mm zone for VMT may be 400 to 800 microns or more, whereas in the normal eye it is usually 300 microns or less.
  • Ultrastructural changes in the retina are assessed using high resolution scans, including foveal elevation and/or cystic changes. A thickened posterior hyaloid will be attached at the foveal/perifoveal area. A single line scan may show
• Fluorescein angiography may show cystoid macular edema.
• B-scan ultrasonography can be used to evaluate vitreous adhesion to the optic nerve and macula. Although it has lower resolution than OCT it can be used in a dynamic mode to assess the mobility of the vitreous

Advice

Occasionally the vitreous may spontaneously detach from the macula, resolving the retinal traction and leading to an improvement in visual acuity. Observation of the patient for up to 3 months may be considered to allow for this possibility.

Incisional Surgery

Significant visual loss or distortion from persistent vitreous traction may require pars plana vitrectomy and peel of the internal limiting membrane at the fovea. Surgery is intended to allow the macula to flatten and any cystic changes to resolve. Visual acuity is usually improved after surgery. OCT will show resolution of traction and reduction in macula thickening.