MACULAR HOLE

Idiopathic macular holes are full-thickness defects that arise in the macula in less than 1% of the population. They are most prevalent in the 50to 80-year age group, and appear to be more common in women. Approximately 10% of patients develop bilateral macular holes.

Macular holes also may arise in association with trauma, myopia, and chronic cystoid macular edema. Rarely, tangential traction from an epiretinal membrane may cause a full-thickness macular hole. Most apparent macular holes arising within epiretinal membranes are not full thickness and are classified as macular pseudoholes.

Symptoms

Patients present with a variable degree of visual loss depending on the size of the hole, the location of the hole relative to the foveola, and the size of any associated neurosensory retinal detachment. Associated symptoms include central scotoma and metamorphopsia. The visual loss may be noted incidentally on covering the fellow eye.

Clinical Features

The clinical features vary depending on the stage of the macular hole at presentation. The macular findings are appreciated best with the use of a fundus contact lens. In patients with a stage 1 macular hole, a yellow spot (stage 1A) or yellow ring (stage 1B) is visualized in the center of the fovea. Stage 2 macular holes are characterized by a full-thickness macular hole less than 400 µm in diameter. Fine retinal striae radiating from the hole may be visualized. Stage 3 macular holes are larger than 400 µm in diameter and may have an associated cuff of subretinal fluid. Stage 4 macular holes are similar to stage

3 holes except that a total posterior vitreous detachment (PVD) is present. The base of the hole may contain yellow-white deposits on the retinal pigment epithelium (RPE). Eyes with a vitreofoveolar separation often have an operculum overlying the macular hole.

Differentiating a true macular hole from a pseudohole is performed with a slit beam or laser aiming beam test. A slit beam centered over the macular hole is perceived as being bent, pinched, or interrupted in the location of the macular hole. A 50-µm laser aiming beam will “disappear” when projected into the hole.

Ancillary Testing

Macular holes are diagnosed by clinical examination. Ancillary testing may provide insight into pathogenesis but rarely affects management decisions. B-scan ultrasonography may demonstrate the vitreoretinal

relationship that contributes to hole formation. Macular holes and the posterior hyaloid membrane also may be imaged with optical coherence tomography (OCT).

Fluorescein angiography may reveal a central hyperfluorescent transmission or “window” defect as a result of xanthophyll pigment displacement and retinal pigment epithelial atrophy in long-standing cases.

Pathology/Pathogenesis

The precise pathogenesis of macular holes is becoming better understood. Imaging with OCT and ultrasonography suggests that localized perifoveal vitreous detachment (an early stage of age-related PVD) results in static and dynamic tractional forces that lead to a full-thick- ness foveolar dehiscence.

In pathologic sections macular holes are full-thick- ness retinal defects. Glial cells extend across the retinal surface along the margins of the hole. These are often continuous with an adjacent epiretinal membrane. The parafoveal retina demonstrates cystic changes in the outer plexiform layer. The retinal pigment epithelial cells in the area of the hole are distended with lipofuscin and lose their apical microvillous processes.

Treatment/Prognosis

Stage 1 holes are estimated to have a 50% to 60% rate of progression to full-thickness macular hole. Some stage

1 holes are relatively asymptomatic; therefore, the true rate of progression in the general population may be lower. Stage 2, stage 3, and stage 4 holes have been demonstrated to have a better visual outcome with vitrectomy compared to observation. Vitrectomy involves complete removal of the core vitreous and the posterior hyaloid membrane, including all epiretinal tissue. Removal of the internal limiting membrane may be employed in some cases. The use of adjuvant therapies such as autologous serum and growth factors is controversial. Following vitrectomy, a fluid-gas exchange is performed followed by tamponade with the patient in a face-down position.

The rate of hole closure with surgery approaches 80% to 90%. Visual recovery is variable, with holes of shorter duration and holes less than 500 µm in diameter experiencing the greatest benefit. Complications of surgery include retinal detachment, cataract progression, and visual field defects.

Systemic Evaluation

Macular holes are not associated with systemic disease.

Stage 1A macular hole is characterized by a central yellow spot without retinal dehiscence. The central yellow spot results from the loss of the normal foveal depression.

Stage 2 macular hole in this patient with 20/200 visual acuity exhibits eccentric retinal dehiscence. Stage 2 macular holes are small, full-thickness macular holes less than 400 µm in diameter.

A yellow ring without retinal dehiscence is the characteristic finding in patients with stage 1B macular holes. Approximately 50% of stage 1 macular holes resolve spontaneously.

Stage 3 macular holes are full-thickness macular holes greater than 400 µm in diameter without a posterior vitreous detachment (PVD). Stage 4 macular holes are similar to stage 3 macular holes except that a total PVD is present.

Fundus photograph of woman with a stage 2 macular hole with eccentric retinal dehiscence and 20/200 visual acuity.

This photograph of the same patient demonstrates resolution of the macular hole after pars plana vitrectomy with membrane peeling and gas tamponade. Her visual acuity improved to 20/30.

MYOPIC DEGENERATION

Simple myopia is one of the most common ocular disorders encountered, with a prevalence estimated at 10% to 30% of the population. Degenerative myopia is a less common condition associated with greater visual disability.

Symptoms

Patients with degenerative myopia may present with progressive visual loss associated with progressive myopic changes. Central visual impairment may result from lacquer cracks, atrophic maculopathy, choroidal neovascularization (CNV), or macular hole formation.

Clinical Features

The clinical features of degenerative myopia are the result of slowly progressive enlargement of the globe. Stretching of the posterior pole results in drag of the choroid and the retinal pigment epithelium (RPE) from the optic nerve, leaving an atrophic temporal crescent. Extensive ectasia of the sclera in the posterior segment leads to formation of a staphyloma with posterior herniation of the retina and choroid. Enlargement of the globe leads to thinning of the RPE and choriocapillaris, resulting in a “tigroid” appearance of the fundus and more pronounced visualization of the larger choroidal vessels.

Macular examination may demonstrate atrophic areas resulting from loss of the RPE and choriocapillaris. Lacquer cracks represent spontaneous ruptures of Bruch’s membrane. Lacquer cracks appear as irregular yellow or whitish lines and are typically located in the base of a staphyloma. The acute development of a lacquer crack may be heralded by a subretinal hemorrhage.

The most significant visual complications of degenerative myopia are CNV, macular hole formation, and macular atrophy. Choroidal neovascularization has been estimated to occur in 5% to 10% of patients whose axial length is greater than 26.5 mm. In this setting, CNV is typically small and often has an associated pigmented rim. Subretinal fluid and hemorrhage may be present. The CNV may be associated with a lacquer crack.

Spontaneous involution of a CNV in degenerative myopia may leave a pigment clump referred to as Fuchs’ spot. Macular hole in degenerative myopia may be associated with a posterior retinal detachment.

Ancillary Testing

Fluorescein angiography is useful in the evaluation of patients with degenerative myopia. Lacquer cracks

appear as early hyperfluorescent lines that remain hyperfluorescent in the late phases of the angiogram without leakage. Lacquer cracks that were not visible with

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clinical examination may be evident on angiography. Angiography is important in the evaluation of CNV. Typical early hyperfluorescence with late leakage is present. Late leakage tends to be more localized than that observed with CNV associated with age-related macular degeneration (AMD).

Pathology/Pathogenesis

The pathogenesis of degenerative myopia remains unclear. The clinical features appear to result from progressive enlargement of the globe with stretching and subsequent damage to the ocular tissues.

Treatment/Prognosis

Macular holes and associated retinal detachments are generally repaired with pars plana vitrectomy and gas tamponade. In cases of extreme posterior staphyloma, an external approach with a scleral buckle applied to the macular region has been used.

The optimal management of CNV associated with myopia remains unclear. Some CNVs may resolve spontaneously without treatment, with relative stabilization of visual acuity. A small, randomized trial of laser photocoagulation of CNV located outside the fovea demonstrated a beneficial effect of laser therapy at 2 years’ follow-up in terms of visual acuity. No significant benefit was noted at 5 years, and a significant number of recurrences were noted. Laser treatment of CNV in myopia is further marred by progressive expansion of laser scars with longer follow-up.

Photodynamic therapy is capable of stabilization of visual acuity with a limited number of patients regaining significant amounts of vision. Subretinal surgery for the removal of CNV in degenerative myopia has been limited, but early results show a low rate of visual improvement and a significant recurrence rate. Limited macular translocation has been used successfully in small case series of CNV associated with myopia.

Systemic Evaluation

Degenerative myopia may be observed in systemic conditions including Marfan’s syndrome, Ehlers-Danlos syndrome, Stickler’s syndrome, and Down’s syndrome.

Myopic degeneration is characterized by peripapillary atrophy, straightening of the retinal vessels, and macular abnormalities. This patient had a prominent posterior staphyloma with marked peripapillary atrophy.

Lacquer cracks represent spontaneous ruptures of Bruch’s membrane. The development of a new lacquer crack may be associated with subretinal hemorrhage.

Macular abnormalities include mild, nonspecific retinal pigment epithelial alterations, lacquer cracks, atrophy, choroidal neovascularization (CNV), Fuchs’ spots, and macular holes. This patient had a pigmented Fuchs’ spot following spontaneous resolution of CNV.

The finding of subretinal hemorrhage usually indicates the presence of choroidal neovascularization (CNV). The CNV associated with myopic degeneration is often small and pigmented. Fluorescein angiography typically reveals a classic pattern of new vessels.

Fundus photograph of a patient with a myopic fundus revealing subretinal hemorrhage and a pigmented choroidal neovascular membrane.

Fluorescein angiogram of the same patient demonstrates classic choroidal neovascularization with a well-defined pattern of hyperfluorescence. The surrounding hypofluorescence results from hemorrhage and retinal pigment epithelial hyperplasia.