Macular Holes

Synonyms: macular cyst, retinal hole, retinal perforation

Macular hole is a round, full-thickness defect of retinal tissue in the foveal retina, leading to loss of central vision, metamorphopsia and a central scotoma. The condition mainly affects elderly patients. Since the early 1990s surgical repair of macular holes has evolved, changing the prognosis dramatically.

Most macular holes (around 90%) are unilateral. The hole evolves through a series of stages, starting with an impending hole. About half of impending holes regress spontaneously. The rest progress to full-thickness holes. These run from the internal limiting membrane to the outer segment of the photoreceptor layer. As this involves the fovea, central visual acuity is affected.

If a macular hole is found in one eye, the risk of developing a hole in the other eye is around 2% if the vitreous is detached. However, the risk is around 15% if it is still attached and 50% if there is already an impending hole in the other eye.

Epidemiology

Prevalence is estimated at around 0.8% in several studies and incidence at around 8 per 100,000 per year.^{[1, 2, 3]}

Around 10% of macular holes are bilateral at diagnosis.^[3]

Women are more commonly affected than men. Peak incidence for idiopathic macular hole formation is around 70 years, although patients with non-idiopathic holes tend to be younger.^[3]

Although most macular holes are seen in elderly patients, they have been described in children, where they are rare and usually attributable to trauma. Isolated cases of idiopathic macular hole have been described in a child.^[4]

Aetiology^[5]

Around 90% of macular holes are idiopathic.

It is thought that age-related degeneration of inner retinal layers at the central fovea may predispose the eye to macular hole formation. The hole may be initiated by incidental tractional forces from the vitreous, leading to foveal detachment and subsequent hole formation.^[6]

Risk factors include cystoid macular oedema, retinal detachment, retinal surgery, laser injury, hypertension, very high myopia and diabetic retinopathy.

Presentation

Symptoms appear gradually over days/weeks:

• Distorted vision.
• Visual acuity reduction will depend on the site of the hole: small eccentric holes may have little effect on acuity. Holes that are not full-thickness also have less effect on acuity.
• Look for a tiny well-defined 'punched out' area of the macula, which can be hard to detect. There may be yellow-white deposits at the base with a grey margin around it representing oedema.
• Slit-lamp examination will show 'a round excavation with well-defined borders' interrupting the beam of the slit lamp.
• Most patients also have a semi-translucent tissue over the hole, which may be surrounded by a grey halo caused by detachment of the retina.
• Macular hole may (rarely) be an incidental finding.

Macular holes are classified by size and degree: classification relates to prognosis.

Gass Biomicroscopic Classification^[7]

• Stage 1a: yellow spot. This is not specific for macular hole and may also represent central serous chorioretinopathy, cystoid macular oedema and solar maculopathy.
• Stage 1b: occult hole - doughnut shaped yellow ring (200-300 μm) centred on the foveola. Around 50% will progress to stage 2.
• Stage 2: full-thickness macular hole (<400 μm). Pre-foveolar cortex usually separates eccentrically, creating a semi-transparent opacity (often larger than the hole) and the yellow ring disappears. Progression to stage 3 is usual.
• Stage 3: holes >400 μm associated with partial vitreomacular separation.
• Stage 4: complete vitreous separation from the entire macula and optic disc.

Investigations

Diagnosis is usually made clinically; however, the following may be helpful:

• Optical coherence tomography: this technique provides high-resolution cross-sectional imaging of the retina and is useful in predicting prognosis.^[8]
• Fluorescein angiography may be useful in differentiating macular holes from cystoid macular oedema and choroidal neovascularisation. It typically shows a window defect early in the angiogram that does not expand with time, with no leakage or accumulation of dye.
• There may be Amsler grid abnormalities, although plotting small central scotomas is often difficult.

Management

Referral to ophthalmology is required. The patient will need to be seen by a vitreoretinal surgeon. Not all units have one, so patients referred locally may be transferred on to tertiary referral centres for investigation and management.

Treatment^[5]

Classic macular hole surgery consists of vitrectomy, posterior vitreous cortex separation and intraocular gas tamponade. However, more recently there has been a move towards internal limiting membrane peeling as adjuvant therapy for increasing closure rates.^[9]

Surgery is successful in preserving/improving vision in around 90% of cases of full-thickness hole. The chosen surgery depends on the staging of the hole:

• Surgical closure is considered up until stage 3 or 4 associated with a visual acuity of 6/18 or worse.
• Pars plana vitrectomy relieves traction on the edge of the hole. The vitreous is removed and a long-acting gas bubble is introduced to tamponade the macula back into position. The development of micro-invasive techniques has improved the rate of recovery following surgery.
• In selected patients (particularly with larger holes) short periods of postoperative face-down positioning are used to encourage hole closure.^{[10, 11, 12]}
• Most patients' visual acuity improves by two lines of the Snellen chart. Success is still possible if the hole is long-standing (6 months-2 years) or if the patient is aged >80 years.^{[13, 14]}
• Occasionally more than one operation is required to close the hole.
• The internal limiting membrane (ILM) is a thin, transparent acellular membrane on the surface of the retina which may participate in the pathogenesis of maculopathies including macular hole. ILM peeling can improve the hole closure rate. Identification of the ILM is a challenging step in surgery. Therefore, staining the ILM is essential and may also decrease surgical trauma to the retina during ILM removal. ILM peeling is performed in selected patients. Patient selection is still the subject of discussion.^[15]
• ILM flap formation, where the ILM is partially peeled then inverted and used to cover the hole. This technique is reserved for larger holes.^[16]
• Zinc and beta-carotene replacement have been advocated (Ocuvite®). These are of unproven benefit and are contra-indicated in patients with actively bleeding ulcers.^{[5, 17]}
• Ocriplasmin (Jetrea®) is a recombinant protease with activity against fibronectin and laminin, both components of the vitreoretinal interface. It is used (as an intraocular injection) to treat symptomatic vitreomacular adhesion (approved in the USA in 2012). It dissolves the links from the vitreous to the macula, aiding detachment. It may be an alternative to surgery in some patients.^{[5, 18, 17]}
• For those patients who have a condition that precludes surgery, visual rehabilitation may be the only option. Referral to low vision clinics may be helpful.

Complications

Many patients develop cataracts. 76% of cases require cataract extraction within two years of macular surgery.

Other problems include:

• Retinal detachment.
• Iatrogenic retinal tears.
• Macular retinal pigment epithelium changes.
• Enlargement of the hole.
• Macular light toxicity.
• Postoperative intraocular pressure spikes.
• Endophthalmitis.
• Late reopening of an initially successfully closed hole.
• Retinal pigment epithelial abnormalities.
• Retinal detachment (less than 5%).

Prognosis^[19]

Several factors affect outcomes. These include stage and size of the hole, duration of the symptoms, pre-operative visual acuity and other technical parameters that can be measured by optical coherence tomography (OCT) including the Macular Hole Index (MHI) - the ratio of the hole height to its basal diameter, with a higher ratio predicting a better outcome.

• Stage 1 holes spontaneously resolve in 50% of cases.
• Stage 2 holes almost always progress without surgery.
• If the macular hole has been present for 1-3 years then surgery is likely to be successful. If it has been present for 5 years or longer, then outcomes are more variable.
• With surgery, early stage 2 holes show anatomical closure in >90% of cases and a two or more line improvement on the Snellen chart in 80% of cases. NB: successful anatomical repair and visual acuity not necessarily correlated.
• 10% stay the same and 10% lose some visual acuity.
• There is a 12% chance (20% if other risk factors are present) of a similar hole developing in the other eye.
• Visual acuity of 20/50 or better results in around half of patients whose symptoms are of recent onset.

Dr Mary Lowth is an author or the original author of this leaflet.