Lamellar Macular Hole

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Article initiated by:

Mélanie Hébert MD MSc, Yosra Er-reguyeg

All contributors:

Yosra Er-reguyeg, Leo A. Kim, MD, PhD, Mélanie Hébert MD MSc, Amir Hajrasouliha, MD

Assigned editor:

Amir Hajrasouliha, MD

Review:

Assigned status Up to Date

 by Amir Hajrasouliha, MD on April 18, 2024.

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Contributing Editors:	add

Disease Entity

Lamellar macular hole (LMH) is a retinal disorder that affects the macula involving a loss of tissue in the inner layers of the retina.

Etiology and Risk Factors

The majority of LMH cases are idiopathic. However, LMH has been linked to conditions causing cystoid macular edema (CME) (e.g., Irvine-Gass syndrome, diabetic macular edema, retinal vein occlusions), as patients presenting such conditions may experience spontaneous rupture of the roof of a cystoid space. Conditions involving tractional forces applied to the retina, such as presence of tractitional epiretinal membranes (ERM) or a vitreomacular tractions (VMT), are also considered risk factors.

General Pathology

Though the understanding of LMH has evolved with new optical coherence tomography (OCT) findings, it remains unclear whether all LMH form through tractional forces exerted on the fovea or through degeneration of the inner layers of the retina. While initially described as a complication of CME, subsequent research identified conditions leading to the formation of LMH. Partial or complete posterior vitreous detachment (PVD) causing traction on the fovea can potentially lead to the formation of intraretinal cysts/schisis or ERM (i.e., contractile preretinal proliferation of myofibroblasts with an extracellular matrix). LMH may also be the consequence of an aborted FTMH formation process. On the other hand, certain LMH do not exhibit apparent signs of traction. Instead, they are rather associated to an epiretinal proliferation (ERP) of hyalocytes, fibroblasts, and glial cells lacking contractile properties and degeneration of the inner layers of the fovea; suggesting another subtype of LMH. However, recent findings suggest that both the tractional and degenerative forms of LMH initially stem from a tractional force exerted onto retinal tissue.

Pathophysiology

Recent OCT studies identified four pathways for the development of idiopathic LMH, all of which were tractional:

• Type 1: disruption of a foveal cyst from VMT;
• Type 2: rupture of parafoveal cysts or schisis mainly from ERM;
• Type 3: central intraretinal cyst formed under a tight ERM with subsequent cyst roof dehiscence;
• Type 4: gradual loss of foveal tissue without cystic lesions, initiated by ERM traction.

Indeed, both the “degenerative” and “tractional” phenotypes of LMH could begin with a tractional event that damages the Müller cells or its connections to the foveal walls, resulting in a schisis between the outer plexiform layer (OPL) and Henle fiber layer (HFL). Over time, this tractional event would cause gradual degeneration of Henle fibers, leading to the emergence and enlargement of the foveal cavitation. If combined with a secondary event, such as choroidal ischemia, this chronic HFL degeneration may cause loss of the retinal outer layers and ultimately lead to death of central photoreceptors and retrograde degradation of bipolar and horizontal cells. Thus, the ERP that characterizes “degenerative” LMH could represent a reparation process resulting from an initial tractional insult.

If present, preretinal proliferation may correlate with visual acuity, with ERP leading to poorer visual acuity compared to ERM. Degenerative LMH configuration is also associated with higher rates of photoreceptor layer defects and lower residual foveal thickness.

Primary prevention

As most LMH cases are idiopathic, there are no preventative measures to stop the disease from occurring.

Diagnosis

History

LMH primarily affects individuals from 50–70 years of age, with an overall prevalence ranging from 1.1% to 3.6% in the general population according to population-based cohort studies.

Physical examination

Dilated fundus examination can indicate the presence of a macular hole, which can later be best confirmed as being lamellar with OCT or fundus autofluorescence.

Signs

OCT imaging showing the partial loss of inner foveal tissue is diagnostic. Fundus autofluorescence can also show hyperautofluorescence due to a window defect in the macular area from the loss of foveal tissue.

Symptoms

LMH symptoms, akin to other vitreoretinal interface syndromes, include reduced visual acuity, metamorphopsia, and central scotoma. While symptoms may be subtle initially, they tend to progress gradually.

Clinical diagnosis

OCT diagnostic criteria for LMH have undergone multiple changes over time. The most widely used 2006 criteria adopted by the International Vitreomacular Traction Study Group included:

1. An irregular foveal contour;
2. A break in the inner fovea;
3. Dehiscence of the inner foveal retina from the outer retina;
4. The absence of a full-thickness foveal defect with intact foveal photoreceptors.

Govetto et al. subsequently divided LMH into “tractional” and “degenerative” categories with a minimum of 3/5 diagnostic criteria for each type (see table). If it fails to correspond to either category, the lesion is classified as “mixed”.

"Degenerative" LMH features	"Tractional" LMH features
An inner/outer retinal layer ratio of more than 1:2 Ellipsoid zone defect(s) Round-edged cavitation Foveal bump(s) Epiretinal proliferation (ERP)	An inner/outer diameter ratio of less than 1:2 An intact ellipsoid zone (EZ) Sharp-edged split(s) Intraretinal cystoid spaces An epiretinal membrane (ERM)

The newest consensus made by Hubschmann et al. distinguishes LMH presenting with tractional, contractile ERM by identifying them as ERM foveoschisis (ERMF). LMH presenting with degenerative configuration are simply referred to as LMH.

Criteria	ERMF	LMH
Mandatory criteria	The presence of a contractile ERM; Schisis at the level of the Henle’s fiber layer	An irregular foveal contour A foveal cavity with undermined edges The apparent loss of foveal tissue
Optional anatomical features	Microcystoid spaces in the inner nuclear layer (INL) An increase in retinal thickness The presence of retinal wrinkling	Presence of a central foveal bump Epiretinal proliferation (ERP) Disruption of the ellipsoid zone
OCT imaging	Figure 1: Case of epiretinal membrane foveoschisis (ERMF). Can be recognized by the presence of foveoschisis in the outer retinal layers (between the outer plexiform and the outer nuclear layer). A hyperreflective contractile epiretinal membrane can also be observed.	Case of “true” LMH. Can be recognized by its hat-like shape and the presence of epiretinal proliferation above the ganglion cell and nerve fiber layers.

This new classification suggests that LMH and ERM foveoschisis are two distinct entities. However, this definition may change as recent findings propose that both ERMF and LMH result from a tractional event; they would essentially represent the same condition at different stages of development.

Diagnostic procedures

OCT is the gold standard for diagnosing and managing LMH with findings as described above. Fundus autofluorescence can also be performed which shows hyperautofluorescence through loss of foveal tissue leading to a window defect.

Laboratory test

Laboratory investigations are not warranted for idiopathic LMH cases.

Differential diagnosis

Macular pseudohole (MPH)

MPH can have a very similar appearance to LMH. However, they differ in that, contrary to LMH, MPH does not involve loss of foveal tissue. The abnormal, hollow foveal contour found in MPH is rather due to contraction of an ERM against the foveal walls. Mandatory diagnostic criteria for MPH are ERM sparing foveal walls, retinal thickening, and verticalized or steepened foveal profile. Minor diagnostic criteria include near normal central foveal thickness. These characteristics are not typical of LMH and can help differentiate the two conditions.

Vitreomacular traction (VMT)

VMT occurs during PVD when part of the vitreous remains attached to the retina, causing traction which can potentially damage the macula. This can lead to schisis of foveal tissue layers, which may mimic the aspect of LMH. Metamorphopsia can be experienced with both diseases. On OCT, VMT presents an attachment of the vitreous cortex to the macula and a distortion of the foveal surface. Unlike LMH, the layer of retinal tissue pulled by the vitreous is still connected to the rest of the fovea via its edges. However, VMT can lead to the formation of LMH.

Full-thickness macular hole (FTMH)

FTMH presents like LMH with loss of VA, metamorphopsia, and central scotoma. However, the lesion in this case is more severe than an LMH, with the fovea presenting a full-thickness defect. Stage 1 or stage 2 macular holes may be mistaken for LMH.

Management

General treatment

As most LMH remain stable over time, no treatment is indicated in idiopathic, asymptomatic cases. The treatment is surgical and consists of pars plana vitrectomy (PPV) which may involve the removal of preretinal tissue (ERM/ERP) and/or of the internal limiting membrane (ILM).

Medical therapy

As of today, no therapeutic modalities/drugs are indicated for the treatment of idiopathic LMH. Patients are simply monitored until spontaneous closure occurs in certain cases or symptoms develop warranting surgical management.

Medical follow up

Regular follow-up of LMH is essential to track the progression of the disease and consider surgical intervention if the LMH deteriorates over time, as they can progress to FTMH.

Surgery

Surgical treatment of LMH using PPV is usually indicated for patients with progressive deterioration of the foveal profile or symptomatic visual loss associated with metamorphopsia and/or central scotoma. It remains that the decision to intervene surgically is made on a case-by-case basis, weighing risks and benefits for the patient. PPV helps release vitreomacular adhesions by removing ERM/ERP and ILM, facilitating the restoration of a regular foveal profile. Tamponade with air or gas may be used, but longer duration gas is not critical for the surgery to succeed. In those cases, patients are usually instructed to maintain prone positioning postoperatively. Removal of the ERM/ERP and ILM has been shown to induce closure of the LMH, notably by releasing tractional forces. However, peeling may be sometimes laborious, particularly with ERP which has a fluffy texture making it more difficult to peel. Getting rid of the membrane around the LMH walls can lead to iatrogenic damage and the formation of FTMH postoperatively. Alternative techniques include the use of platelet rich plasma during surgery, the fovea-sparing ILM peel, as well as the embedding of the peeled ILM into the LMH. These approaches show promising results, as the articles in which they were described reported no cases of postoperative FTMH.

Surgical follow up

Regular surgical follow-ups are essential to assess for anatomical and functional success, as well as manage potential complications.

Complications

The most common surgical complication following PPV is cataract. Non-closure of LMH and FTMH development are also reported. Other complications include intraoperative retinal breaks, postoperative ocular hypertension or hypotension, and/or acute postoperative endophtalmitis.

Prognosis

Patients with LMH have a favorable prognosis, as most remain stable over time, with no significant visual acuity decline. While not necessary, surgical treatment is effective with most studies reporting a statistically significant improvement in visual acuity postoperatively.