Egyptian Retina Journal

REVIEW ARTICLE
Year
: 2020  |  Volume : 7  |  Issue : 1  |  Page : 1--6

Myopic tractional maculopathy: An overview


Hassan Mortada, Amr Mohamed Abdelaziz Wassef 
 Department of Ophthalmology, Kasr Al Ainy Hospital, Cairo University, Cairo, Egypt

Correspondence Address:
Dr. Amr Mohamed Abdelaziz Wassef
15 Nawal Street, Agouza, Giza 12311
Egypt

Abstract

The concept of splitting of the retinal layers was known since 1958 when first described by Calbert Phillips. However it was not until the advent of Optical Coherence Tomography (OCT) when this pathology was studied with more depth. The term Myopic Foveoschisis was first suggested by Takano in 1999 to describe the separation of retinal layers in patients with degenerative myopia coupled with posterior staphyloma. With the advancement of imaging technology, we have been able to understand more about the forces responsible for the pathology and the risk factors. However, the indications, timing and type of surgical intervention in the spectrum of this macular pathology stays controversial. Our aim in this review article is to present the different options, pros and cons of each.



How to cite this article:
Mortada H, Wassef AM. Myopic tractional maculopathy: An overview.Egypt Retina J 2020;7:1-6


How to cite this URL:
Mortada H, Wassef AM. Myopic tractional maculopathy: An overview. Egypt Retina J [serial online] 2020 [cited 2021 Jan 18 ];7:1-6
Available from: https://www.egyptretinaj.com/text.asp?2020/7/1/1/302994


Full Text



 Introduction



The concept of the splitting of the retinal layers was known since 1958 when first described by Phillips.[1] However, it was not until the advent of optical coherence tomography (OCT) when this pathology was studied with more depth. The term myopic foveoschisis was first suggested by Takano in 1999 to describe the separation of retinal layers in patients with degenerative myopia coupled with posterior staphyloma.[2]

With further advancement in imaging technology and the introduction of spectral-domain OCT which is capable of taking more scans per second and thus much higher resolution, it became more obvious that myopic foveoschisis together with some other macular pathologies that occur in high myopes are a spectrum of the same dynamic process that occurs due to the action of different dragging forces on the macula, and hence the term myopic traction maculopathy (MTM) introduced by Panozzo and Mercanti.[3] The term accurately describes a group of macular disorders that occur in high myopes due to traction forces.

Forces acting on the posterior pole in pathological myopia include [Figure 1]a, [Figure 1]b, [Figure 1]c:{Figure 1}

Adherent, partially detached posterior hyaloid (PH) traction, with or without vitreoschisis (anomalous posterior vitreous detachment [PVD])[4],[5],[6],[7]Altered, rigid internal limiting membrane (ILM)[8],[9]Rigid (potent) retinal arterioles[5],[10],[11]Progression of the posterior staphyloma.[12]

The hypothetical mechanism of myopic retinoschisis is that the rigid layers, namely, the partially adherent PH, epiretinal membranes, ILM, and the inner retinal layers containing the rigid retinal vessels split from the more flexible outer retina, choroid, and retinal pigment epithelium, under the inward traction force of the partially detached PH and the outward force exerted by the backward elongation of the sclera at the posterior staphyloma [Figure 2].{Figure 2}

The Spectrum of Myopic Traction Maculopathy Includes

Myopic macular retinoschisisMyopic macular hole (MMH) without retinal detachmentMMH retinal detachment [Figure 3].{Figure 3}

These three clinical entities are not separate. It is widely agreed now that myopic foveoschisis is the initial stage of the process which can progress to foveal detachment, lamellar hole, or full-thickness MMH all of which are placed under the term MTM[3] [Figure 4].{Figure 4}

Literature does not provide definite answers to the management of different stages of MTM. In fact, the controversy between publications makes it more confusing, there is wide acceptance that there is no standard protocol or procedure for managing MTM and that cases should be regarded individually, the management is either watchful waiting or surgical intervention.[13] However, there are some suggested indications for surgical intervention.

The indications for surgical intervention are [Figure 5] and [Figure 6]a and [Figure 6]b:{Figure 5}{Figure 6}

Progressive diminution of vision, > two lines on Snellen's chart within the past 6 months[3]Metamorphopsia and distorted vision[14]Foveal detachment[15]Full-thickness macular hole (MH).[15]

 Surgical Technique



The basic pars plana vitrectomy is applied, including excision of core vitreous gel, induction of PVD, and excision of PH and shaving of the basal vitreous gel. However, a myriad of variations and extra steps that could be added to the basic procedure exist, owing to the special nature of highly myopic eyes and the surgeries for MTM, those include

Small gauge vitrectomy systems (23 or 25) are advantageous, especially in the presence of thin sclera of high myopes. Furthermore, the rate of complications is much lower with small gauge systems[16]The use of triamcinolone acetate (TA) to highlight the vitreous gel is crucial to ensure complete excision of the vitreous gel, induction of PVD, and complete excision of PH. This has special importance in eyes with pathological myopia and MTM. This is because of the high incidence of vitreoschisis in the eyes with longer axial length and posterior staphyloma. Vitreoschisis means finding a layer of adherent posterior vitreous in the presence of an apparent complete PVD.[17] Hence, staining and even double staining with TA are strongly advisable during pars plana vitrectomy (PPV) for MTM[18] [Figure 7]Strong paravascular vitreoretinal adhesion is not uncommon in the eyes with pathological myopia. Accordingly, the induction of PVD should be done cautiously over retinal vessels to avoid iatrogenic paravascular retinal tears or hemorrhage[19]PVD should be extended to the posterior border of the vitreous base. In high myopia, the latter is usually more posteriorly located than in emmetropic eyes.[20] Hence, PVD should be done under direct visualization and stopped once the circumferential traction line is observed. Failure to do that may result in iatrogenic multiple horseshoe tears or even giant retinal tearThe axial length of highly myopic eyes may be longer than the shaft of regular instruments. This problem may be solved following one or more of the following:{Figure 7}

Tilting the position of the head toward the working fieldTemporary removal of the cannula, introducing regular instruments directly through the sclerotomyUse instruments with long shafts designed for working in highly myopic eyes.[21]

Surgery of ILM: Routine peeling of the ILM, with some modifications, is strongly advocated in all cases of MTM[22] for the following reasons:

In eyes with MTM, the ILM is abnormally tight and thickened.[12] It is considered the most rigid structure over the posterior staphyloma. This results in the failure of the inner retina to comply with the shape of the posterior staphyloma as the outer retina.[8] Accordingly, ILM peeling over the posterior staphyloma, increases the elasticity of the posterior retina allowing it to conform to the concavity of the posterior staphylomaILM peeling ensures complete removal of any adherent cortical vitreous, epimacular membranes thus relieving tangential traction[18]ILM peeling eliminates the scaffold for further cellular proliferation and epimacular reformation.

ILM staining is mandatory in highly myopic eyes with MTM.[23] This enhances the visibility of the ILM in the presence of poor contrast caused by myopic chorioretinal degeneration and atrophy, a common finding in these eyes. Brilliant blue dye is the first choice to stain the ILM during peeling.[24] ILM peeling is particularly challenging in these eyes. Hence, double and sometimes triple staining may be necessary to augment the ILM staining for better visualization and safer peeling.[25]

Surgery on ILM varies according to the pathological entity of MTM: Myopic foveoschisis (MF), MMH without retinal detachment or Myopic macular hole retinal detachment (MMHD):

Myopic Foveoschisis Fovea Sparing Internal Limiting Membrane Peeling

ILM surgery should start just central to the inferior temporal arcade, using either the pinch technique with ILM forceps or first elevating an ILM flap using Tano's scraper, finesse flex loop, or the tissue manipulator. Once a flap or flaps are created, peeling is done using forceps working always toward the fovea so as not to exert any traction on the fovea. ILM peeling should stop 500 um from the fovea. The same is repeated from all directions stopping short of the fovea. At the end, ILM is peeled over the whole area of the posterior staphyloma sparing the fovea. Excess ILM may be excised with the cutter using a low vacuum and low cutting rate. Provided no operative complication is encountered, there is no need for tamponade or fluid/air exchange as it was repeatedly reported not to superior to BSS.[18],[26] It is strongly believed that in symptomatic myopic foveoschesis, PH and ILM peeling across the posterior staphyloma, sparing the fovea, is associated with excellent anatomical and functional results. It may eliminate the risk of postoperative MH formation as well [Figure 8]a, [Figure 8]b, [Figure 8]c.[27],[28]{Figure 8}

Myopic Macular Hole without Retinal Detachment Multi-Layer Internal Limiting Membrane Flap, Envelop Technique

The technique is a modification of the inverted flap technique first described by Michalewska et al. in 2010.[29] Initially, the technique is the same as described in myopic foveoschesis. The ILM peeling is stopped 500 u from the edge of the MH. Under the perfluorocarbon liquid (PFCL) bubble, ILM flaps from all directions, are brought over the macula hole, one over the other, like an envelope. The volume of air injected in these large eyes is sufficient to provide the required tamponade. The patient is instructed to adopt the facedown position for 5 days [Figure 9] and [Figure 10].{Figure 9}{Figure 10}

The inverted flap technique was reported to have a high rate of primary anatomical success in terms of MMH closure.[30] The novel multi-layer (envelop) technique [Figure 9]a, and [Figure 9]b is associated with almost 100% flat closure of the MH., because of the following advantages:

Confirmed placement of the ILM flaps over the MH under PFCL or air, provides scaffolds for Muller cell proliferation and photoreceptor migration to close the holeThe ILM flaps are kept inverted in place. No possibility of displacement or reversion of the flaps.

 Myopic Macular Hole Retinal Detachment: Two Clinical Presentations



Retinal detachment confined to the posterior staphyloma [Figure 11]:{Figure 11}

With a detached retina, ILM peeling is started just nasal to the optic disc, using the latter as an anchor. ILM peeling is carried out toward the MH and stopping as previously described 500 um form the edge of the hole. Under few drops of PFCL, ILM flaps, and peeled from all directions are brought over the MH, one over the other, like an envelope. Finally, fluid and PFCL are exchanged with air. No drainage of the subretinal fluid (SRF) is required as this may jeopardize the ILM flaps. No need to use long-acting gas. The patient is instructed to adopt a facedown position. The SRF usually absorbs in 24 h

Retinal detachment reaching to the periphery [Figure 12]:{Figure 12}

Following proper ILM staining with BB, the retina is attached to PFCL injection. As previously described, ILM peeling is started at the nasal edge of the optic disc and carried out toward the MH and stopping 500 μm from its edge. The ILM flaps are brought over the MH one over each other. A small draining retinotomy is made, with the cutter, at the most peripheral extent of the SRF. More PFCL is injected to achieve complete retinal reattachment, draining the SRF through the peripheral retinotomy. In the absence of proliferative vitreoretinopathy (PVR), air or SF6 is the proper tamponade.[13] Silicone oil is used in more complicated cases with PVR [Figure 13] and [Figure 14].{Figure 13}{Figure 14}

 Summary and Conclusions



In pathological myopia, anomalous PVD, vitreoschisis, rigid ILM, and posterior staphyloma are the main factors contributing to tractional forces acting on the posterior pole and resulting in MTM with a wide range of clinical entitiesThe use of TA to highlight vitreous gel is indispensable for the proper visualization of vitreous layers and cortical vitreous adherent to the retinal surfaceILM is the most rigid structure at the posterior pole. Peeling of brilliant blue stained ILM to the edge of posterior staphyloma is mandatory. It increases the flexibility of the retina and subsequently can conform to the shape of the posterior staphylomaIn myopic foveoschisis, fovea-sparing ILM peeling is associated with excellent anatomical and functional success results. It may eliminate the risk of postoperative MH formationIn MMHs with and without retinal detachment, combined ILM peeling to the edge of the staphyloma and multi-layer ILM flap (envelop) technique is associated with almost 100% flat closure of the hole and retinal reattachmentThe macular buckling technique is rarely needed in MTM.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.

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