Degeneration




Vitreous


Vitreous Synchisis and Syneresis


Vitreous degeneration is a physiologic process that occurs with age and may be accelerated in eyes with longer axial length. As the vitreous degenerates, there is liquefaction of the vitreous gel, known as “synchisis,” resulting in small pockets of liquefied vitreous within the firmer vitreous. This leads to destabilization of the vitreous and promotes its collapse, known as “syneresis.” The boundaries between each liquefied pocket and the vitreous gel may form speckled opacifications that may later manifest as symptomatic floaters. These vitreous opacities may become visible to patients and appear as spots, strings, or cobwebs, in the absence of a posterior vitreous detachment (PVD). There are four grades of physiologic vitreous degeneration as documented with swept-source OCT (SS-OCT).




In Grade 0, there is the presence of a premacular bursa (asterisk) with or without a central lacuna (triangle).





In Grade 1, there is the presence of a neighboring shallow space without a connection to the premacular bursa, with increased speckled hyper-reflectivity along the boundaries of this shallow space (arrows).





In Grade 2, there is a connection between these shallow spaces to the premacular bursa.





In Grade 3, there is a connection to a large neighboring space or central lacuna.





Vitreous opacities (circles) may be seen with enhanced vitreous imaging OCT (EVI-OCT) or SS-OCT in patients with symptomatic floaters without a complete PVD.

Images courtesy of Dr. Michael Engelbert




Posterior Vitreous Detachment


Posterior vitreous detachment (PVD) is a common consequence of aging that occurs with vitreous degeneration. As the vitreous body shrinks with syneresis, there is separation of the vitreous cortex or posterior hyaloid from the retina. PVD may also result from traumatic eye injury or inflammatory diseases, or be induced surgically. The process of PVD may occur in stages beginning with perimacular and perifoveal PVD, followed by vitreofoveal separation with or without a break in the posterior wall of the premacular bursa and, finally, separation of the vitreous from the optic disc. Gel liquefaction without concurrent dehiscence at the vitreoretinal interface leads to anomalous PVD and its complications.




Before a PVD occurs, there is complete vitreous attachment (stage 0). EVI-OCT or SS-OCT shows the posterior hyaloid or cortical vitreous attached to the retina in all areas, with visualization of the premacular bursa (asterisk) and pre-optic nerve head space (area of Martegiani). The anterior wall of the premacular bursa may show speckled hyper-reflectivity and should not be misinterpreted as the posterior hyaloid (right).





PVD begins with focal perimacular PVD (stage 1) where the posterior hyaloid (arrows) detaches in one area (left) and progresses to a perifoveal PVD (stage 2) where the posterior hyaloid is detached in both nasal and temporal quadrants, with vitreofoveal adhesion and persistent attachment at the optic disc.





With vitreofoveal separation (stage 3), the posterior wall of the premacular bursa (arrows) may remain intact (stage 3A, left image ) or ruptured (stage 3B, right image ). There is persistent attachment of the vitreous at the optic disc at this stage.





With complete separation of the vitreous at the optic disc (stage 4), the area above the retina appears optically empty and the posterior hyaloid (arrows) may be visible.

Images courtesy of Dr. Michael Engelbert




With complete separation of the vitreous from the optic disc, a Weiss ring corresponding to the site of previous attachment to the optic disc may appear as a symptomatic ring-shaped floater. The Weiss ring may take many forms as shown here or may be fragmented during the process of vitreous separation.




This patient has Weiss rings in both eyes ( arrows ). Standard non-widefield photography focusing on the Weiss ring reveals a “figure of eight” Weiss ring in the right eye and an elliptical Weiss ring in the left eye. The retina is out of focus with non-widefield imaging.





The same patient was imaged with the ultra-widefield system. Notice how ultra-widefield imaging is able to capture the Weiss ring ( arrows ) with the retina still in focus.





This patient has a PVD with a visible Weiss ring ( arrow ) and parts of the separated vitreous seen in the inferior vitreous cavity.




Asteroid Hyalosis


Asteroid hyalosis is a degenerative condition of the vitreous with a prevalence of 1.2% in adults. It is found to be more frequent with aging, with 0.2% prevalence in 43- to 54-year-old and 2.9% in 75- to 86-year-old patients. Multiple small white deposits that typically have a refractile appearance, which resemble stars (or asteroids) shining in the clear night sky, form in the vitreous. The etiology of asteroid hyalosis is still unknown. There may be an association with diabetes mellitus, hyperlipidemia, atherosclerosis, and hypertension. The asteroid bodies are mostly composed of hydroxy­apatite and phospholipids. Asteroid hyalosis is unilateral in 75-90% of cases. Typically, the disorder does not produce symptoms or a reduction in visual acuity. Occasionally, patients may express symptomatic floaters. Treatment is rarely necessary, but, in highly symptomatic cases or when necessary for visualization of the fundus, a vitrectomy may be indicated.




These patients have varying degrees of asteroid hyalosis. Small asteroid bodies are seen in the patient on the left. In the patient on the right, there is a more dense aggregation of the asteroid bodies, which have coalesced into rope-like bands. The asteroid bodies are located in the posterior and mid-vitreous cavity in this case.





This color photograph shows an extensive degree of asteroid bodies filling the vitreous cavity. Visual acuity can be surprisingly good, even with this degree of vitreous opacification. The 3-D OCT image shows reflectance of cords and flecks of asteroid bodies. B-Scan ultrasonography shows intense reflectivity of the asteroid bodies and a characteristic acoustically clear zone anterior to the retina.

Ultrasound image courtesy of Dr. Yale Fisher





Ultra-widefield imaging shows the full extent of asteroid bodies within the vitreous, ranging from scattering of asteroid bodies (top) to dense flecks and cords of asteroid bodies (bottom). The patient on the right has a visual acuity of 20/30.





Asteroid bodies may infrequently prolapse into the anterior chamber after cataract surgery and masquerade as iris metastasis.

Images courtesy of Dr. Carol Shields




Asteroid hyalosis should be differentiated from synchisis scintillans or cholesterosis bulbi, which is an extremely rare accumulation of cholesterol crystals in liquefied vitreous that tend to settle or gravitate inferiorly, causing a snow globe effect. Because synchisis scintillans is an end-stage degenerative condition that occurs in eyes with extensive inflammation, hemorrhage, or trauma, it is usually not visible clinically and more commonly diagnosed after enucleation by the pathologist.




Asteroid bodies are typically adherent to the vitreous framework (left image) , while the cholesterol crystals in synchisis scintillans are not (right image) .





Histopathology of this patient with asteroid bodies shows chalky white spherules with characteristic Maltese cross birefringence under polarized light.

Images courtesy of Dr. Ralph Eagle




Vitreous Amyloidosis


Amyloidosis encompasses a group of disorders characterized by extracellular deposition of amyloid proteins in various organs and tissues of the body. At least 24 different proteins are known to be amyloidogenic; however, the most common forms are immunoglobulin light-chain (AL protein) in primary amyloidosis and serum amyloid A (AA protein) seen in chronic inflammatory diseases. Amyloid proteins consist of insoluble fibrillar aggregates arranged in a characteristic beta-pleated sheet configuration, which is responsible for the ability to bind Congo red and show birefringence in polarized light. Amyloidosis of the vitreous is a rare condition that may be primary, acquired, or familial in nature. It is more often related to familial amyloid polyneuropathy (FAP); however, it may very rarely occur sporadically.




Vitreous amyloidosis may be seen as opacities in the vitreous cavity, retrolental “cobweb” opacities (top right image), or as amyloid deposits causing irregularity at the pupillary border (bottom right image).

Images courtesy of Dr. Stanley Chang (top right) and Dr. Ryuhei Hara (left and bottom right)





Vitreous amyloidosis may be associated with neovascularization and vitreous hemorrhage due to involvement of the retina. In such cases, vitrectomy and pan-retinal photocoagulation are indicated, although recurrence may occur. Post-vitrectomy photograph reveals peripheral yellow-white amyloid deposits around the retinal blood vessels.

Images courtesy of Dr. Anita Agarwal




Familial amyloid polyneuropathies (FAPs) are rare forms of amyloidosis associated with amyloid accumulation in the vitreous. FAPs are inherited in an autosomal dominant fashion with variable penetrance and are caused by mutation in the transthyretin (TTR) gene at locus 18q11.2-q12.1. Involvement of the vitreous is usually seen in association with systemic amyloidosis and clinical features including peripheral neuropathy, renal dysfunction, and cardiomyopathy. Amyloid deposition in the vitreous appears as diffuse whitish gray or yellowish material having a “cobweb” or “cotton-wool” appearance. Other fundus findings include perivascular deposits, superficial retinal gray-white deposits, and small vessel occlusions with associated angiographic filling delays on both fluorescein and indocyanine green angiography. Vitreous amyloidosis should be considered in the differential diagnosis of any vitreous opacification or haze. Diagnosis relies on clinical suspicion and staining of vitreous biopsy specimens with Congo red dye. Vitrectomy remains the treatment of choice for symptomatic vitreous opacification.




This is a 43-year-old healthy male who noted floaters in both eyes. There was obscuration of the fundus with amorphous debris in the vitreous. Fluorescein angiography showed hyperfluorescence from the retinal vasculature (bottom left). Six months later, despite the use of topical and periocular steroids, the vitreous haze progressed to form a “cobweb” appearance (bottom right).





A vitreous biopsy stained with hematoxylin and eosin revealed a large amount of eosinophilic material but no evidence of a cellular infiltration such as lymphocytes (left). The Congo red stain showed the presence of amyloid, which was accentuated on examination with polarization (right).




Vitreous Cyst


Intravitreal cysts are rare ocular curiosities that are usually found incidentally on routine ophthalmological examination. Patients may be asymptomatic or may complain of floaters or transient visual blurring. Vitreous cysts may be classified as congenital or acquired. Congenital cysts are thought to be associated with remnant hyaloid vessels and are usually nonpigmented, smooth, sessile, or pedunculated. Congenital cysts are typically located anterior to the optic disc, and may have limited movement due to vitreous strands attached to the optic disc. Acquired cysts are found in degenerative or inflammatory diseases including retinitis pigmentosa, choroidal atrophy, retinal detachment, retinoschisis, parasitic uveitis, nematode endophthalmitis, and trauma. They are usually pigmented and thought to arise from the degeneration of a ciliary body adenoma breaking into the vitreous cavity or a vitreous reaction to underlying retinal and choroidal degeneration. Vitreous cysts are benign and may be observed without treatment. Symptomatic cysts may be treated with laser photocystotomy or pars plana vitrectomy with cyst excision.




This patient has a free-floating, translucent, smooth, brown-pigmented cyst in the vitreous cavity. Ultrasound shows a spherical hypoechogenic mass with thin hyper-reflective edges that is freely mobile in the posterior vitreous and not attached to any other ocular structures.

Images courtesy of Dr. Noel Padron-Perez





This 50-year-old patient presented with floaters in his right eye. Color photograph shows a smooth, free-floating, vitreous cyst in the inferior fundus. Fluorescein angiography shows a circular area of hypofluorescence due to pre-retinal masking effect and no vascularity of the cyst itself. Ultrasound image shows a free-floating cyst in the posterior vitreous.

Images courtesy of Dr. Yasin Toklu





This patient has a free-floating vitreous cyst with some pigmentation. Spectral-domain OCT shows the cyst located over the macula.

Images courtesy of Dr. Shani Reich






Angioid Streaks


Angioid streaks are visible, irregular crack-like dehiscences in Bruch membrane that are associated with atrophic degeneration of the overlying retinal pigment epithelium. Knapp coined the term “angioid streaks” because their appearance resembles retinal vasculature. Angioid streaks are most commonly associated with pseudoxanthoma elasticum, although they may also be associated with Paget disease of the bone, Ehler–Danlos syndrome, sickle cell or thalassemia hemoglobinopathies, acromegaly, and diabetes mellitus. Patients with angioid streaks are generally asymptomatic, unless they develop complications such as traumatic Bruch membrane rupture or macular choroidal neovascularization (CNV).




This patient with thalassemia has angioid streaks, peau d’orange, and peripapillary CNV. The angioid streaks are best seen with fundus autofluorescence and near-infrared reflectance as radiating dark lines around the disc. The peau d’orange is visualized best with near-infrared reflectance, which allows the transition zone between calcified and noncalcified Bruch membrane to be appreciated. With fluorescein angiography, angioid streaks are seen as bright hyperfluorescent lines around the disc.





This patient with thalassemia has angioid streaks and optic disc drusen. The optic disc drusen are hyperautofluorescent with fundus autofluorescence.

Images courtesy of Dr. Francesca Viola and Dr. Giulio Barteselli






Pseudoxanthoma Elasticum


Pseudoxanthoma elasticum (PXE) is an autosomal recessive multisystem disorder associated with dermatologic, gastrointestinal, cardiovascular, and ocular findings. PXE has been associated with mutations in the ABCC6 gene at chromosome 16p13.1. Characteristic skin changes typically affect the neck, axilla, and other flexural areas. Fundus findings include angioid streaks, a reticular macular dystrophy, a speckled appearance temporal to the macula known as peau d’orange, optic nerve head drusen, comet-like peripheral crystalline bodies, and peripheral RPE atrophic spots. An exudative detachment with yellowish and clear exudate between the ellipsoid zone and the retinal pigment epithelium may produce an acquired vitelliform lesion in PXE. CNV occurs in 72-86% of eyes and is often bilateral. Treatment of CNV in PXE using thermal laser photocoagulation or verteporfin photodynamic therapy is frequently complicated by recurrences and poor visual outcomes. Recently, intravitreal injections of anti-vascular endothelial growth factor drugs have shown promise in treating these patients.




Angioid streaks appear as red, brown, or orange lines representing breaks in Bruch membrane and typically radiate out from the optic nerve in an irregular pattern, which can simulate the appearance of retinal blood vessels. Angioid streaks are not believed to be present at birth but are seen in 90% of PXE patients. Angioid streaks can traverse the macular region, often without a decrease in visual acuity.





These patients have peripapillary atrophy and angioid streaks that emerge from the edge of the atrophy and course radially into the near and midperiphery, sometimes through the fovea itself. Fundus autofluorescence may display angioid streaks as hypoautofluorescent lines that are sometimes undetectable on clinical examination (lower right image).





Peau d’orange or yellow mottling at the level of the retinal pigment epithelium begins in the macular region and, as atrophy ensues, extends more temporally. The macular lesions disappear with aging and are seen more temporally over time. This patient has angioid streaks and temporal peau d’orange that may be accentuated with red free photography (right images).





Ultra-widefield photograph demonstrates the full extent of peau d’orange .





Late phase ICGA demonstrates angioid streaks well and frequently delineates the streaks better than fundus autofluorescence imaging. In this case of PXE, hyperfluorescence is also seen to correlate to sites of peau d’orange in the periphery.





Crystalline bodies with or without comet tails may occur in the peripheral fundus and may represent calcified lesions. These lesions appear as solitary, subretinal, nodular, white bodies with or without a tapering white tail pointing toward the optic disc. There may be atrophic RPE changes and pigmentation at the margin of this finding. Sometimes, a spray of comets may be observed, creating the appearance of a “meteor shower.”

Images courtesy of Dr. Martin Gliem





Focal atrophic RPE lesions, appearing as small, round, yellow, slightly pink or discretely punched-out white scars with varying amounts of pigment, may occur in the peripheral fundus and have been referred to as “salmon spots.”

Images courtesy of Dr. Martin Gliem





The characteristic systemic findings of pseudoxanthoma elasticum include skin changes (plucked chicken-like appearance). Gastrointestinal and cardiac abnormalities may also be associated with this condition.

Images courtesy of Dr. Mark Lebwohl





Optic disc drusen is commonly associated with PXE.

Courtesy of Dr. Martin Gliem




Pattern Dystrophy


A “pattern dystrophy-like” change of the macula may develop bilaterally in approximately 65% of patients with PXE and may manifest as any of the 5 subclasses of pattern dystrophy, including reticular dystrophy, fundus pulverulentus, fundus flavimaculatus, butterfly-shaped dystrophy, and vitelliform dystrophy. The pattern dystrophy-like appearance may be a combination of any of the 5 subclasses and may progress from one type to another over time. Because this condition is unrelated to the autosomal dominantly inherited pattern dystrophy first described by Sjögren, the continued use of the term “pattern dystrophy” in PXE is controversial. Clinically, it is important to recognize that PXE may appear with pattern dystrophy-like changes especially in cases in which angioid streaks are very subtle.




This patient with PXE has no demonstrable streaks on clinical examination, although there is a suggestion of atrophy in the macula. Fundus autofluorescence shows a pattern dystrophy surrounding the posterior pole with peripapillary atrophy and minimal macular atrophy. The inset shows that there is an angioid streak peripheral to the pattern abnormality (arrows). Streaks may not be evident in an eye that has developed diffuse atrophy. PXE in this case is associated with a pattern dystrophy without sparing of the peripapillary area.





The fluorescein angiogram of the same patient shows multifocal areas of hypofluorescence corresponding to the hyperfluorescence seen on fundus autofluorescence (inverse phenomenon). These nummular areas of pigment epithelial hyperplasia are characteristic but not pathognomonic of PXE. The streaks in the posterior pole are more obvious (arrows) with ICG angiography. There is hypoautofluorescence in the central macula of the left eye (right image) where there is a scar evident clinically. The fundus autofluorescence shows a similar pattern abnormality with peripapillary atrophy, as seen in the right eye.





This patient with PXE has atrophy in the posterior pole and a pattern dystrophy-like change on fundus autofluorescence. Note the central as well as peripapillary atrophy in both eyes.





This patient with PXE shows extensive atrophy throughout the posterior pole with hyperpigmentation (left image) . Angioid streaks are evident in the near periphery, anterior to the central atrophy (arrow) . Note the focal area of hyperautofluorescence on the disc. This corresponds to optic nerve head drusen (arrowhead) . Fundus autofluorescence is helpful to detect angioid streaks beyond central atrophy and optic nerve head drusen in PXE.




Subretinal Fluid and Acquired Vitelliform Lesions


Subretinal fluid unrelated to choroidal neovascularization (CNV) may occur in patients with PXE. Subretinal fluid may be found in eyes with no detectable neovascularization or in areas of the fundus remote from neovascular tissue. This form of subretinal fluid is clinically more subtle than the exudation seen with neovascular tissue. The subretinal fluid is thought to accumulate due to RPE dysfunction preceding RPE cell death. It is typically stable over time and shows no change with intravitreal anti-VEGF therapy.




This patient with pattern dystrophy-like changes in the macula, as seen in color photographs and fundus autofluorescence was found to have subretinal fluid on OCT. Fluorescein angiography showed no active leakage and no evidence of CNV.





This color photograph and corresponding fundus autofluorescence shows a localized yellowish material that is hyperautofluorescent. Corresponding OCT shows an acquired vitelliform lesion with fluid accumulating between the ellipsoid zone and the retinal pigment epithelium. PXE is one of the numerous abnormalities that may cause an acquired vitelliform lesion. The acquired vitelliform lesion may occur with or without subretinal fluid and in the absence of CNV. However, there is risk of CNV given the nature of PXE.




Choroidal Neovascularization





Patients with PXE are at high risk for developing CNV. An estimated 72-86% of patients with angioid streaks may develop CNV. The pathologic new vessels are nearly always type 2 (subretinal), and typically originate from the angioid streaks. Their origin from the streaks is not always visible with fluorescein angiography, but it is more apparent with fundus autofluorescence and/or ICG angiography. In this case, there is subfoveal CNV. Treatment with intravitreal anti-vascular endothelial growth factor therapy will lead to consolidation and regression of the CNV.





This patient with PXE has angioid streaks and subretinal exudation secondary to CNV. The late-phase fluorescein study shows focal hyperfluorescence corresponding to type 2 neovascularization (arrow, middle image) . Some irregular areas of hyperfluorescence and hypofluorescence are consistent with RPE abnormalities, but the angioid streaks are not well visualized on the fluorescein study. The late-phase ICG study demonstrates focal leakage corresponding to CNV (arrow, right image) . The radiating irregular hyperfluorescent lines represent the angioid streaks. The CNV is generally noted to occur along the course of one of the angioid streaks.





This histopathological specimen of PXE shows fibrovascular tissue originating from the choroid and extending through defects in the Bruch membrane and the overlying retinal pigment epithelium.




Trauma


Patients with PXE are susceptible to intraocular hemorrhages secondary to traumatic rupture of the RPE, Bruch membrane, and choroid. This could be the result of an intrinsic weakness of the Bruch membrane or an associated clotting abnormality in PXE. Patients may present with subretinal or intraretinal hemorrhages overlying the rupture line, which often develop concentric to the disc or, less frequently, in a radial pattern. In time, the hemorrhages clear and may leave a fibrotic scar. The area with the break in the Bruch membrane is at high risk for CNV.




This patient experienced blunt trauma to the right eye from a tennis ball. OCT reveals no visible break in Bruch membrane or choroid. Note that in addition to subretinal hemorrhages, intraretinal hemorrhages may also occur in the outer nuclear layer.

Images courtesy of Dr. Roberto Gallego-Pinazo





This patient with PXE presented with subretinal hemorrhage in the macular region and around the optic nerve. The blood spontaneously resolved and multiple angioid streaks were revealed. Note that while the peau d’orange appearance could be seen temporal to the macula, the angioid streaks were initially obscured by hemorrhage. Later, residual subretinal blood surrounded a localized area of CNV. The peau d’orange appearance is not seen in areas of atrophy.





This patient experienced blunt ocular trauma. Note the widespread subretinal hemorrhages with foveal involvement. Fluorescein angiography shows hypofluorescence due to blockage from the hemorrhages and hyperfluorescence due to type 2 neovascularization originating from traumatic ruptures in the macula. OCT (top right image) shows hyper-reflective material consistent with type 2 neovascularization and overlying subretinal hemorrhage with a visible break in Bruch membrane. OCT of the same area 3 months later (bottom right image) shows resolution of the subretinal hemorrhage but persistence of fibrovascular tissue.




Fibrous Scarring





These two patients with PXE experienced severe ocular trauma. Note the widespread choroidal ruptures in conjunction with angioid streaks. There is fibrotic scarring, which is seen as staining on the fluorescein angiogram. There is also considerable pigment epithelial hyperplasia, which is characteristic of eyes with increased fundus pigmentation.





In PXE patients, prior to the availability of intravitreal anti-VEGF therapy, disciform scarring commonly occurred in eyes that developed CNV. This patient with multiple angioid streaks shows extensive scarring from CNV (left image) . Another patient with angioid streaks and PXE developed a large disciform scar (right image) . Note that the scarring is more fibrotic inferotemporally. In addition, a small area of active CNV with subretinal hemorrhage is present inferior to an island of fibrosis that connects the two larger areas of scarring ( arrow ).





Severe fibrovascular scarring with pigmentation and atrophy may occur as a result of the natural course of this diffuse neovascular maculopathy.






Pathologic Myopia


Pathologic or degenerative myopia is a leading cause of visual impairment worldwide. It is most common in Asia where the prevalence may be more than 10% in certain populations. Although there is no standardized definition, the commonly used criteria include spherical refractive error in excess of −6 D and axial length of greater than 26.5 mm. This entity has been linked to genetic, environmental, and socioeconomic risk factors.




Histological sections of two globes show the difference in size and shape between a pathologically myopic eye (top left) and an emmetropic eye (top right) . Pathologic myopia may be due to elongation with or without staphylomas (outpouchings of the globe). Ultrasound and pathological specimens of the same eye demonstrate simple elongation (bottom left two images) and elongation with a staphyloma (bottom right two images) . Arrows demarcate the margins of the staphyloma.




Myopic macular degeneration, often associated with a posterior staphyloma, consists of progressive thinning of the retinal pigment epithelium and choroid, fine yellowish-white breaks in Bruch membrane known as lacquer cracks, subretinal hemorrhages, and secondary CNV. Additional ocular findings in pathologic myopia include macular hole, macular retinoschisis, vitreoretinal interface disturbances, premature PVD, peripheral retinal degeneration, retinal detachment, cataract, and normal-tension glaucoma.




The patient on the left has a diffuse staphyloma associated with choroidal thinning and prominent choroidal vessels posteriorly. Fragments of a Weiss ring and vitreous floaters related to a PVD can be seen in the inferior vitreous cavity. The patient on the right is a –34 D myopic male with a well-defined posterior staphyloma associated with chorioretinal atrophy and peripheral pigmentary degeneration.





This patient has a high degree of anisometropia with pathologic myopia in her left eye only. There is pseudoexophthalmos of the left eye due to axial elongation of the globe. Note the differences on the clinical photographs of the posterior segments. The right eye is emmetropic with a normal fundus appearance whereas the left eye has RPE thinning and atrophy in addition to a focal area of hyperpigmentation and fibrous proliferation known as a Fuchs spot. MRI scans show the difference in the size and shape of the globes, normal in the right eye (left image) and elongated in the pathologically myopic left eye (right image).

Images courtesy of Dr. Jerry Sherman





This patient has extreme anisometropia as demonstrated with SD-OCT imaging. Notice the relatively normal choroidal thickness in the right eye and severe choroidal thinning in the left eye, also known as leptochoroid. Leptochoroid, defined as extreme choroidal thinning to less than 20 microns at the subfoveal region, can be compatible with good visual acuity in some patients with high myopia.




Staphyloma


Staphyloma is defined as an outpouching of the ocular wall, the radius of which is less than the surrounding curvature of the globe. The number and location of staphylomas may vary in each eye. Curtin’s original classification of staphyloma subtypes used ophthalmoscopic findings and was based on the morphology of irregularities within the staphyloma. However, the advent of OCT imaging has allowed precise visualization of all staphylomatous irregularities within the globe and has resulted in the formulation of a new classification that is based on the morphology of the outermost border of the staphyloma. Staphylomas are now divided into five subtypes.



Images courtesy of Dr. Ohno Matsui





A staphyloma may also occur more anteriorly in the globe. Note the ultrasound (left image), the pathological specimen (right image), and the schematic drawing (middle image), which illustrate the location of this anterior staphyloma (arrows). Eyes such as these are at risk of penetration during retrobulbar injection if the physician is unaware of the presence of such a staphyloma.





This Type I staphyloma involves the posterior pole (arrows) . The post mortem specimen (right image) is from a patient with pathologic myopia and shows a similar posterior staphyloma.





These images show a Type II staphyloma that begins in the temporal juxtapapillary area and extends through the macula. There is RPE atrophy along the temporal vasculature (top images). Notice the bright myopic ridge seen at areas of atrophy that corresponds to the margin of the staphyloma (middle left image, arrow) . The bright myopic ridge appears as a hyper-reflective line on both near-infrared reflectance and OCT imaging and corresponds to the sharp angulation of the sclera (middle right and bottom images).





These images are a stereo pair showing an eye with pathologic myopia manifesting a Type II staphyloma involving most of the macula. There is a zone of atrophy along the inferior temporal vasculature that may represent a pigment epithelial tear.





These three patients have Type III posterior staphylomas with bulges surrounding the nerve. The bright myopic ridges help to demarcate the edge of the staphyloma (arrows) . The image on the right shows undulating folds within the staphyloma (arrowhead), most probably due to progressive elongation within the bulge of the staphyloma.

Images courtesy of Marian McVicker





This patient is a 68-year-old woman with pathologic myopia involving both eyes. A Type I staphyloma is evident in the right eye and a predominantly Type IV nasal staphyloma is seen in the left eye. Myopic macular degeneration involving the fovea has reduced visual acuity to 20/400 OS. Visual acuity has been preserved at 20/40 OD.





This patient is a 63-year-old female with a Type II staphyloma in the right eye and a Type I staphyloma in the left eye. A lamellar macular hole is evident in the left eye on spectral domain optical coherence tomography imaging. Visual acuity is 20/30 OU.




Radial Tracts and Myopic Staphyloma


A linear or leaf-like emanation that arises from the posterior edge of the staphyloma is seen in approximately 8% of eyes with a myopic posterior staphyloma. As illustrated in the case below, these tracts (yellow arrows) demonstrate clinical features that are comparable to descending tracts in central serous chorioretinopathy; however, they commonly have an anti-gravity orientation. They are proposed to represent sites of previous or existing serous retinal detachment due to RPE injury at the abrupt edge of the staphyloma. The changes in globe curvature are best appreciated on three-dimensional MRI images. OCT images of these regions often demonstrate outer retinal and RPE disruption. (The orientation and site of OCT imaging is represented by the blue arrow.)



Images courtesy of Dr. Ohno Matsui




Dome-Shaped Macula


Dome-shaped macula (DSM) is a morphological feature recently described using OCT. This entity is characterized by an inward convexity of the macula that, in the majority of cases, is associated with high myopia, but can also be found in eyes with hypermetropia, inherited retinal dystrophies, and central serous chorioretinopathy. The cause is unknown although it is postulated to be related to a localized increase in scleral thickness in the area of the DSM and could be due to the process of ocular expansion in myopia. Macular complications of DSM include CNV in 12% of eyes. Localized serous macular detachment without CNV is found in up to 44% of eyes at the top of the DSM, possibly due to choroidal outflow obstruction by a thick sclera and/or abrupt changes in choroidal thickness. Extrafoveal schisis is found in 18%; however, foveal schisis is uncommon suggesting that DSM may be protective against the development of foveal schisis.




OCT imaging with three-dimensional reconstruction shows the macular bulge of DSM and demonstrates that persistence of a nearly normal scleral thickness at the macular region and scleral-choroidal thinning of the surrounding staphyloma cause the inner protrusion of the macula.

Images courtesy Dr. Ohno Matsui





The dome of DSM is most commonly horizontal-oval in shape (left image), but may assume a round (middle image) or vertical-oval shape (right image). The diagnosis may be easily missed if OCT scans are not done in both horizontal and vertical directions.





Serous retinal detachment, without CNV can be associated with DSM (left image). Notice how the choroidal thickness changes abruptly at the borders of the dome (arrows), possibly contributing to choroidal outflow obstruction.





Similar OCT findings may be seen at the superior edge of the inferior staphyloma in the tilted disc syndrome.

Images courtesy of Dr. Suzanne Yzer




Myopic Macular Degeneration


Patients with pathologic myopia may develop severe vision loss from retinal atrophy and CNV. These changes commonly occur in the central macula within a posterior staphyloma. The atrophy progresses insidiously whereas the neovascularization and resulting disciform scarring may produce sudden loss of central vision.




This patient has bilateral pathologic myopia with multifocal atrophy. A disciform scar (left image, arro w ) is seen with surrounding atrophy in the right eye. Diffuse RPE hypopigmentation is apparent in the left eye within the staphyloma (right image, arrows) .





Fundus autofluorescence is useful in delineating the degree of atrophy, as illustrated in this patient. In the right eye there are two islands of preservation in the central macula (arrows), accounting for a slightly better acuity compared to the left eye.





Geographic atrophy in pathologic myopia may be limited to the posterior pole (left and middle images) or diffusely involve the peripapillary area and central macula (right image) . The right image also shows some yellowish discoloration from macular luteal pigment (arrow) and pronounced atrophy of the choriocapillaris and the retinal pigment epithelium.





Progressive atrophy in a patient with pathologic myopia can be monitored with fundus autofluorescence imaging. The top two images show the early stages of atrophy (visual acuity 20/50). Eighteen months later (bottom two images) visual acuity fell to 20/100 due to the progressive enlargement of the areas of atrophy.





This patient with pathologic myopia had a vertical pigment epithelial tear (arrows) through the central macula. Some pigment epithelial hyperplasia has also developed within the defect. There is a peripapillary bulge within a larger, elongated staphyloma (arrowheads) .





This patient has a pigment epithelial tear (arrows) related to a posterior staphyloma. A well-delineated margin of atrophy is seen along the inferior vascular arcade. The tear exposes the choroidal circulation. Tears such as this are probably more common in eyes with pathologic myopia than previously recognized.




Myopic Retinoschisis


Myopic retinoschisis, also known as myopic traction maculopathy, is characterized by retinoschisis of the posterior retina and occurs in 9-34% of highly myopic patients with posterior staphyloma. The pathogenesis is multifactorial involving tangential traction of the inner retina, rigidity of the internal limiting membrane (ILM), thinning of the retina, traction of retinal vessels, and progression of posterior staphyloma. The natural course in a majority of patients can be considered as generally stable with some patients progressing to macular hole formation with or without retinal detachment. Treatment usually involves vitrectomy with ILM peeling and gas tamponade. Although recurrences of myopic retinoschisis may occur, outcomes following repeat vitrectomy can still be favorable.




This patient has pathologic myopia with a posterior staphyloma, a myopic conus, and a tilted optic disc. OCT image shows myopic retinoschisis with an epiretinal membrane but without a full thickness macular hole or retinal detachment.





These two patients have myopic retinoschisis. The right image shows a subfoveal ellipsoid layer defect with subretinal fluid.

Images courtesy of Dr. Stanley Chang





This patient has pathologic myopia with vitreous traction from persistent cortical vitreous (arrows), myopic retinoschisis (arrowheads), and a foveal detachment. Many of these changes are only appreciated on OCT (middle image). The histopathologic specimen (right image) shows a large cystic cavity within the retina and Müller cells delineating less prominent schisis changes. Tractional schisis changes may be seen anywhere in the fundus of the pathologic myopic eye but is most common within the staphyloma.




Lacquer Cracks


Lacquer cracks refer to breaks in the RPE-Bruch membrane complex and have a prevalence of 4-9% in highly myopic eyes. Choroidal and scleral stretching, due to increasing axial length, is the postulated mechanism for these lesions. They are more commonly seen in the posterior pole within the posterior staphyloma, but can also be found in the mid-peripheral or peripheral retina. Lacquer cracks may be precursors to myopic CNV and patchy chorioretinal atrophy. They may also be associated with subretinal hemorrhage, in the absence of CNV, due to bleeding from the choriocapillaris.




Lacquer cracks appear as pale, yellowish-white, radiating lines. Lacquer cracks may be distributed in a pattern that is concentric to the optic nerve, in a random pattern, or in a pattern that is dictated by the morphological structure of the staphyloma. They appear white on red-free photographs (right bottom image).





Lacquer cracks may be difficult to see with fluorescein angiography because of relative preservation of the retinal pigment epithelium. When they do appear, they are hyperfluorescent (middle image, arrows). Lacquer cracks are more evident with ICG angiography (right image) and appear as dark hypofluorescent irregular lines, which distinguish them from bright hyperfluorescent angioid streaks.

Images courtesy of Dr. Irene Pecorella





Lacquer cracks may occur anywhere in the posterior segment in the pathologic myopic eye, but they are usually confined to the posterior staphyloma. If a severely myopic eye is simply elongated without a specific staphyloma or bulge, the cracks may be concentric, surrounding the posterior macular region (arrows top image), or in the peripheral retina (arrows bottom image).




Myopic Stretch Lines


Myopic stretch lines are irregular, branching lines found in the posterior fundus of highly myopic eyes and should be differentiated from lacquer cracks. Myopic stretch lines appear hypofluorescent with ICG angiography similar to lacquer cracks. They can be distinguished however by their pigmented brown appearance on ophthalmoscopy, hyperautofluorescence with fundus autofluorescence, and hypofluorescence on fluorescein angiography. Myopic stretch lines are thought to represent retinal pigment epithelium under stress and may be precursors to lacquer cracks.




In this patient, myopic stretch lines are seen as brown, pigmented lines running along the large choroidal vessels (yellow arrows) . They are most evident on fundus autofluorescence as hyperautofluorescent lines. They appear as hypofluorescent linear lines on both fluorescein and ICG angiography. OCT imaging shows irregular clumping of retinal pigment epithelial cells on and around the large choroidal vessels. (Yellow arrows indicate the site of myopic stretch lines on each imaging modality. Regions imaged with OCT are shown by white arrows on the color picture.)

Images courtesy of Dr. Ohno Matsui




Subretinal Hemorrhages


Patients with pathologic myopia may experience subretinal hemorrhages either from CNV or due to extension of the posterior staphyloma with bleeding from the choriocapillaris. Both types of hemorrhages often coincide with lacquer cracks.




Pathologic myopia and subretinal hemorrhage in three patients. The hemorrhages proved to be non-neovascular in nature in the first two patients (left and middle image) . Hemorrhage in the last patient (right image) was due to a focal area of CNV (arrow) .





Two different patients with pathologic myopia and subretinal hemorrhage that were suspected of having CNV. In the first patient (top row) the fluorescein angiogram shows blocked fluorescence and the ICG angiogram shows lacquer cracks and no CNV. Similar findings were present in the second patient (bottom row). These cases illustrate the usefulness of ICG angiography for excluding CNV when there is an overlying hemorrhage.





Variably sized subretinal hemorrhages may resolve spontaneously in pathologic myopia. They are not always due to CNV, as can be seen here where the hemorrhage resolved without leaving a Fuchs spot.




Choroidal Neovascularization


The prevalence of myopic CNV in pathologic myopia is between 5-11% and is bilateral in approximately 15% of patients. Features associated with an increased risk of myopic CNV include lacquer cracks, patchy atrophy, thinning of the choriocapillaris and choroid, and CNV in the fellow eye. Type 2 neovascularization is the most common manifestation of proliferating choroidal vessels in myopic macular degeneration. The neovascularized membrane is usually pigmented and is often seen in association with a margin of hemorrhage. It usually develops at a discernible lacquer crack, although this is sometimes not evident clinically. As the CNV regresses, a fibrous pigmented scar sometimes referred to as Fuchs spot, or Forster-Fuchs spot, may form and eventually become surrounded by atrophy. Importantly, myopic CNV must be distinguished from other forms of CNV, in particular, multifocal choroiditis or punctate inner choroidopathy, which tend to occur in myopes as well.




These patients have CNV secondary to pathologic myopia. The CNV may appear pigmented (left image) or “dirty gray” (middle image) and is often associated with hemorrhage. Neovascular growth commonly extends into the perfused choriocapillaris area rather than into the region of atrophy (right image).





As the neovascularization evolves, it may be detected as a discrete pigmentary and fibrotic membrane (left and middle images). The pigmentation may take the form of a “ring” surrounding the neovascular tissue and recurrence may occur at the area where the ring is incomplete (right image). Retinal pigment epithelial hyperplasia is responsible for the pigmented appearance surrounding an involuted neovascular membrane, also known as a Fuchs spot.





In this case, a lacquer crack is oriented vertically and there is CNV and hemorrhage at its edges. When the exudative detachment resolves, pigment epithelial hyperplasia is seen bordering the edges (middle image). The histopathological specimen shows the appearance of a Fuchs spot near the fovea with neovascular tissue surrounded by hyperplastic retinal pigment epithelium.





This patient with prominent lacquer cracks developed type 2 neovascularization that showed intense hyperfluorescence on fluorescein angiography. Spectral-domain OCT showed neovascular tissue above the retinal pigment epithelium penetrating through visible cracks in Bruch membrane (arrows).

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Jul 30, 2019 | Posted by in OPHTHALMOLOGY | Comments Off on Degeneration

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