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macular translocation surgery procedure types indications complications ophthalmology

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Macular Translocation Surgery

Definition

Macular translocation surgery (MTS) is a vitreoretinal procedure in which the neurosensory retina (specifically the macula/fovea) is surgically detached and shifted to overlie a healthier area of retinal pigment epithelium (RPE) and choriocapillaris, away from a zone of subfoveal choroidal neovascularization (CNV) or RPE damage. This allows subsequent laser photocoagulation of the now extrafoveal CNV without destroying central vision.

Rationale / Principle

In wet (neovascular) AMD, subretinal CNV develops beneath the fovea, making direct laser ablation impossible without sacrificing central vision. MTS relocates the photoreceptor layer so the diseased RPE/CNV complex is no longer under the fovea, enabling treatment of the neovascular membrane and utilization of healthier underlying RPE to support photoreceptor function.

Indications

  • Subfoveal CNV secondary to wet AMD (primary indication)
  • Subfoveal CNV in other conditions: high myopia, presumed ocular histoplasmosis syndrome (POHS), angioid streaks
  • Cases where anti-VEGF therapy has failed or is unavailable
  • Large subfoveal CNV not amenable to PDT alone

Types of Macular Translocation

1. Limited Macular Translocation (LMT)

  • A limited inferior retinotomy (partial/scleral buckling technique) is performed to create a localized retinal detachment
  • The macula is shifted by a small distance (typically 800-1000 µm) using subretinal fluid injection or scleral shortening/imbrication
  • Advantage: lower complication rate, technically simpler
  • Disadvantage: small degree of translocation may not move the fovea sufficiently away from large CNV

2. Full (360-degree) Macular Translocation (MTS-360)

  • A complete 360-degree peripheral retinotomy is performed, allowing the entire retina to rotate freely
  • The retina is detached, rotated by a desired amount, then reattached using laser retinopexy and long-acting gas/silicone oil tamponade
  • Counter-rotation of the globe (by oblique muscle surgery - recession/resection or inferior oblique tenotomy) is required to correct the resulting cyclorotation (torsional diplopia)
  • Advantage: larger translocation possible, suitable for large/extensive CNV
  • Disadvantage: technically demanding, higher complication rate

Surgical Steps (MTS-360)

  1. Pars plana vitrectomy
  2. Induction of total rhegmatogenous retinal detachment (subretinal BSS injection)
  3. 360-degree peripheral retinotomy
  4. Rotation of the detached retina to place the fovea over healthy RPE
  5. Fluid-air exchange and laser retinopexy (photocoagulation of the peripheral retinectomy edge)
  6. Silicone oil or long-acting gas tamponade
  7. Laser photocoagulation of the now-extrafoveal CNV
  8. Oblique muscle surgery (in the same sitting or subsequently) to correct torsion

Outcomes

  • 66% of patients showed improvement in BCVA of 2 lines or more at 21-month follow-up in published series
  • Reading speed improved significantly post-operatively
  • Visual gain is more common in patients with better preoperative acuity and smaller CNV
  • Outcomes are generally inferior to modern anti-VEGF therapy, limiting its current role

Complications

ComplicationApproximate Rate
Proliferative vitreoretinopathy (PVR) retinal detachment19-25%
Cystoid macular oedema41-44%
Torsional diplopia / tilted vision20-25%
Recurrent CNV21-56%
Epiretinal membrane formation23%
RPE atrophy progression11%
Choroidal haemorrhage~4%
Hypotony / elevated IOPOccasional

Current Status

MTS has been largely superseded by intravitreal anti-VEGF therapy (ranibizumab, bevacizumab, aflibercept) which is safer and equally or more effective. Kanski's Clinical Ophthalmology notes that "macular translocation surgery has a high complication rate and has not been successful in improving vision" when placed in the context of modern AMD management. It retains a niche role in:
  • Eyes with large subfoveal CNV unresponsive to anti-VEGF
  • Anti-VEGF-resistant or persistent CNV with good underlying RPE elsewhere
  • Select cases of traumatic CNV in young patients

Key Points Summary

  • MTS moves the fovea from diseased RPE to healthy RPE
  • Two types: Limited (LMT) and Full 360-degree (MTS-360)
  • MTS-360 requires oblique muscle surgery to correct torsion
  • Main complications: PVR retinal detachment, CMO, diplopia, recurrent CNV
  • Largely replaced by anti-VEGF therapy in current practice
  • Still used in select refractory cases
Sources: Kanski's Clinical Ophthalmology (10th ed.); Histology: A Text and Atlas (Pawlina); NICE Interventional Procedures Overview HTG216 (Royal College of Ophthalmologists, 2009)
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