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Acquired Macular Diseases: Pathophysiology, Diagnosis and Management

Lorne B. Yudcovitch, OD, MS, FAAO

College of Optometry, Pacific University

2043 College Way

Forest Grove, OR 97116

 

Contents

 

Macular Hole

Formerly called senile macular hole, these result from a perifoveal focal vitreous cortex contraction that pulls the macular tissue free from the choroid, resulting in a well-delineated round macular defect (Figure 8). The fovea is particularly susceptible to hole formation, due to the fovea being thin, avascular, and with lack of structural support. Hole formation is typically spontaneous and abrupt. It usually is bilateral in only 10 percent of cases.


Figure 8
Figure 8. Above - Macular hole, fundus view. Below – OCT of macular hole.
(Source: http://www.nyee.edu/macular-holes.html)


Etiologies of macular hole include:


Macular hole formation usually occurs in four stages, discussed in Table 2:

Table 2. Stages of macular hole with descriptions.

Stage

Findings

I (Impending Macular Hole)

  1. Decreased or absent foveal depression (Sub-stage IA)
  2. Small round yellow spot/ring in fovea (Sub-stage IB):
  3. Xanthophyll around photoreceptor displacement
  4. Vitreous still adherent to fovea                                           
  5. Macular cyst

II (Early Macular Hole)

  1. Yellow ring enlarges
  2. Tangental tear at one edge of fovea

III (Developed Macular Hole)

  1. Round punched-out area about 1/3 disc diameter (DD)
  2. Halo of retinal detachment surround
  3. Yellow deposits within hole at RPE level
  4. Translucent operculum may be overlying
  5. Visual acuity usually 20/200 or worse

IV (Vintage Macular Hole)

  1. Complete hole
  2. Edematous ‘cuff’ at margins
  3. Complete posterior vitreal detachment (PVD)
  4. Operculum may be more visible

 

Figure 9
I II III IV
Figure 9. Stages of macular hole, fundus view (above) with OCT views (below). (Sources: http://www.rvrc.com/ps_dc_macularhole.cfm, http://www.eyetec.net/group7/ M37S1.htm)

 

Progression from stage I to II usually takes between one week and several months. Usually there is a quick progression from stage II to III hole formation. Visual acuity may improve slightly if the retinal elevation subsides. Eccentric viewing may also improve acuity slightly.

The Watzke-Allen technique (Figure 10) may help in diagnosing and categorizing the macular hole. The method involves moving a vertical slit lamp parallelpiped beam moved over macula using a high plus lens. The patient states if the beam is unaffected, distorts in the middle, or breaks/splits in the middle. These responses usually identify no hole, a partial or impending hole, and a full thickness hole, respectively.


Figure 10
Figure 10. Patient perception of the vertical slit beam while using the Watzke-Allen technique, based on no hole, early macular hole changes, and full thickness hole.

 

Fluorescein angiogram of macular holes shows hyperfluorescence of fluorescein in hole (Figure 11) due to the loss of retinal pigment epithelium (known as an RPE "window defect").


Figure 11
Figure 11. Hyperfluorescence of the macular hole (arrow) during arterial phase of a fluorescein angiogram.

 

Treatment of macular holes involve ILM peeling and vitrectomy. The goals of this surgery are to stimulate glial cell proliferation and migration into the macular area, as well as relieve vitreo-retinal traction in the macular area and posterior pole. The surgical procedure can be enhanced by indocyanine green (ICG) staining (although some surgeons think permanent toxicity to the tissue may occur by using ICG). The peeling and vitrectomy is usually followed by a gas or oil tamponade, which ten requires the patient to be face-down for at least 1 week, to allow proper retinal adhesion (Figure 12).


Figure 12
Figure 12. Patient in face-down position post-gas/oil tamponade retinal surgery.

 

A recent review on macular hole surgery outcomes demonstrated that macular hole closure is expected in over 90 percent of macular holes after one operation, and that closure approaches 100 percent with stage II or early stage III holes. Twenty-five to fifty percent of closed macular holes fail to achieve better than 20/50 acuities, however, and there is about a 20 percent risk of cataracts and retinal tears post-operatively. Despite this, surgery usually has beneficial effect on the patients' quality of life. Currently there are no large randomized clinical trials to establish the risks and benefits of macular hole surgery (1).

 

Macular Pseudohole

 

Macular pseudoholes, as the name implies, have the appearance of macular holes, but are cause vascular tortuosity around the macula. Unlike macular holes, visual acuity is usually good. There may be possible metamorphopsia. The macular tissue still has full thickness, unlike macular holes. Pseudoholes require close monitoring of retina. An ocular coherence tomograph may provide definitive diagnostic differentiation of a macular pseudohole.

 

Figure 13
Figure 13. Left - Macular pseudohole, fundus view. Right – OCT of pseudohole. Note the macular tissue still present (arrow) above the choroid. (Source: http://dro.hs.columbia.edu/pshole2.htm)


Macular Lamellar Hole

 

A macular lamellar hole essentially is a thin layer (lamella) of macular tissue that has lifted from the remaining macular tissue (Figure 14). A lamellar macular hole may be a precursor to a full macular hole. They may also be a 'self-healed' full-thickness macular hole. Lamellar macular holes may also result from macular hole surgery.

 

Figure 14
Figure 14. OCT of macular lamellar hole, which provides definitive diagnosis.
(Source: http://www.retinalphysician.com/article.aspx?article=100221)

 

Cystoid Macular Edema

Cystoid Macular Edema (CME) is an accumulation of fluid within the macula. The layers affected typically are the outer plexiform (Henle's fiber) layer and the inner nuclear layer (Figure 15).

 

Figure 15
Figure 15. CME. Top – histological cross-section. Bottom – OCT cross-section.

 

The breakdown of the inner blood-retinal barrier causes CME. Accumulation is centered around the foveola, with a loss of the foveal depression occurring. Macular thickening occurs with multiple cystic areas, resulting in a 'petaloid' (flower petal-shaped) pattern of edema.

CME is generally benign in short-term (hours-days), but long-standing cases (weeks-months) result in coalescence of the fluid-filled microcysts, which create large cystic spaces. These cystic spaces can create lamellar hole formation at the fovea, ultimately resulting in permanent visual acuity loss (Figure 16). Fluorescein angiogram shows the classic 'petaloid' leakage of dye (hyperfluorescence) in the arterio-venous phase that persists into late phase of the angiogram (Figure 17). Many diverse etiologies can cause CME. The causes are divided according to presence or absence of vascular leakage on fluorescein angiography (Table 3).

Table 3. Causes of CME based on presence or absence of vascular leakage.


CME WITH RETINAL VASCULAR LEAKAGE

CME WITHOUT RETINAL VASCULAR LEAKAGE

Diabetic retinopathy

Certain types of retinitis pigmentosa

Branch retinal vain occlusion

Early stages of macular hole

   Pseudophakia or aphakia

Nicotinic acid maculoipathy

Idiopathic retinal telangiectasia

With choroidal neovascularization

 

Figure 16
Figure 16. OCT macula cross-section showing bullous cysts secondary to CME.
(Source: http://www.nyee.edu/fluid-accumulation.html)


Figure 17
Figure 17. Fluorescein angiogram showing classic 'petaloid' leakage pattern of CME.
(Source: http://dro.hs.columbia.edu/cme.htm)

 

Treatment of CME depends on underlying cause. Laser photocoagulation is used more often when CME is associated with some vascular cases (i.e. retinal vein or arterial occlusions). Systemic carbonic anhydrase inhibitors (i.e. Acetazolamide) are used post-cataract extraction in some cases, and in certain retinitis pigmentosa and intermediate uveitis cases. Steroids and non-steroidal anti-inflammatory drugs (NSAIDs) are sometimes applied topically, orally, by sub-Tenon's injection, or vitreal injection. Triamcinolone is currently a popular injectable steroid used to treat CME (2).

A recent study of 21 eyes that developed post-cataract extraction CME showed that intravitreal triamcinolone 4mg injection improved visual acuities two or more lines in 43 percent of patients and by one or more lines in 86 percent of patients. One-third of eyes injected with triamcinolone developed intraocular pressures (IOPs) of 22mmHg or more (all reduced with topical anti-glaucoma agents), and no other complications were noted (3).

 

Clinically Significant Macular Edema

 

Clinically Significant Macular Edema (CSME) is usually associated with diabetes mellitus (DM). It is the most common cause of visual acuity loss with DM (Figure 18).

 

Figure 18
Figure 18. CSME. Left – fundus view. Right – fluorescein angiogram of same eye
(Source: http://dro.hs.columbia.edu/dme.htm)

 

CSME is defined by using one or more of the following criteria:




Figure 19
Figure 19. OCT image analysis. Left – macular thickening from CSME (note the red central zone of the thickness map). Right – normal macular thickness.
(Source: http://wwwscielo.isciii.es/scielo.php?script=sci_arttext&pid=S0365-66912004 000600008&lng=es&nrm=iso)

 

Treatment of CSME may involve destructive laser burn applications to center of exudate rings. Ideally these ring centers should be 500 to 3000 μm from the fovea, to avoid applying the laser to the foveal area and damaging the fovea. If CSME persists, 300 to 500 μm zone treatment may be necessary if indicated. Grid laser treatment (typically applied in a spiral, concentric pattern) may be needed for diffuse retinal thickening more than 500 μm from fovea and temporal rim of optic disc. Pan-retinal treatment for neovasculoarization may actually induce macular edema, likely due to retinal inflammation from the treatment (Figure 20).

 

Figure 20
Figure 20. Laser treatments for diabetic retinal changes. White spots represent laser burns. Left – focal treatment. Middle – grid treatment. Right – pan-retinal treatment.
(Source: http://www.rochestereyecenter.com/diabetic_retinopathy.asp)


Far Right – fundus image of focal laser burns (scattered arcuate white spots – arrow).

Like CME, CSME treatment may also include intra-vitreal steroid injection (usually triamcinolone). A recent study (on patients with bilateral CSME) evaluated 4mg triamcinolone intravitreal injection on one, with the other eye a control. OCT central macular thickness scans at 1, 3 and 6 months was then performed. Central macular thickness was significantly lowered in injected eyes versus the control eyes, except at 6 months after injection, because of recurrence of macular edema in 9 of 17 injected eyes at that time. The study conclusion was that intravitreal triamcinolone effectively reduces macular thickening in the short term and improves visual acuities in most cases. Long-term effect still remains to be elucidated (4).

 

Central Serous Retinopathy

Central serous retinopathy (CSR), also called central serous chorioretinopathy, is typically a sporadic, unilateral, and self-limiting sensory retinal detachment at macula. Young to middle-aged young males are predominantly affected, with type 'A' personality and stress sometimes associated. It results from a focal break or gap in the RPE, with leakage of sub-retinal fluid through this gap (Figure 21). Fluorescein angiography typically shows a 'smokestack' and 'umbrella' or 'mushroom' hyperfluorescence within the macular detachment occurring during late venous phase (Figure 22).

 

Figure 21
Figure 21. OCT of CSR. Note the elevated retina and small RPE focal detachment.
(Source: http://www.rvscny.com/OCT%20Examples.htm)

 

Figure 22
Figure 22. CSR. Left – fundus appearance. Right – fluorescein angiogram showing classic 'mushroom' hyperfuorescence leakage.
(Source: http://retinalinks.tripod.com/photogallery.html)

 

Fairly sudden visual acuity reduction in one eye may be noted, with 20/40 or better visual acuities typically. A hyperopic refractive shift can occur, due to the shorter axial length to the macular plane. As a result of this hyperopic shift, visual acuity improvement to 20/20 with low plus may be possible. Other symptoms may include s relative scotoma, metamorphopsia, micropsia (smaller image sizes), and impaired dark adaptation. Occasionally the condition can be extrafoveal, and this author has seen a few patients with atypical symptomatic extrafoveal CSR that was revealed via fluorescein angiogram.

CSR usually presents as a shallow, round or oval elevation. The sub-retinal fluid may be clear or turbid, and the detached retina is transparent. Retinal vessels within the CSR area will cast shadows onto the attached RPE and choroid. The distinct smooth border gives a 'glistening' reflex. Sometimes retinal precipitates and RPE detachment may occur. Very rarely a bullous ('bubble') retinal detachment may occur, that shows shifting sub-retinal fluid and exudate.

Fortunately, approximately 80 percent of CSR cases spontaneously resolve, returning to normal or near-normal visual acuity in six months. The remaining 20 percent typically resolve in 1 year. Some mild metamorphopsia can remain, however. Some patients may retain permanent visual acuity reduction or disturbance, usually from a prolonged detachment or recurrent attacks (Figure 23).


Figure 23
Figure 23. Chronic CSR with pigment epithelial changes.
(Source: http://www.cgeye.org/main.asp?url=http://www.cgeye.org/dim.asp?navID=3)

 

Focal laser photocoagulation has been used to obliterate the leakage site of RPE in CSR, and may speed up resolution by a few months. This treatment does not typically improve the visual outcome, however. Argon laser application of two to three low-power intensity burns at 200μm spot size, 0.2 sec duration at leakage point are typically done. A new type of laser for treating patients with CSR, called a selective retina therapy (SRT) laser, is currently being investigated. Its use is for CSR in which associated pigment epithelial detachment has caused sub-retinal fluid formation. The laser selectively treats the RPE yet spares photoreceptors. This leads to outer blood-retina barrier reconstruction. After 1 month of SRT treatment, leakage activity was no longer noted in 80 percent of patients (5).

 

Myopic Macular Degeneration

Myopic macular degeneration is an infrequent but potentially serious finding that typically progresses during young adulthood. It is due to progressive enlargement of the globe, with associated chorioretinal degeneration. Sensory retinal and RPE detachments can also occur. The globe is typically concave, often from posterior staphyloma (elongation of the globe and associated chorioretinal tissue creating an 'outpouching'). Extensive choroidal and retinal thinning results, leading to atrophy of the RPE and choriocapillaris. The sclera may become visible over time due to this atrophy (Figure 24).

 

Figure 24
Figure 24. Myopic degeneration. Left – retinal thinning revealing choroid, with myopic disc. Middle – OCT showing concave globe from posterior staphyloma. (Source: http://www.eyetec.net/group5/M25S1.htm) Right – myopic chorioretinal thinning, exposing the sclera.

 

Lacquer cracks (breaks in Bruch's membrane) are an uncommon finding with extensive myopic degeneration, appearing in about 4 percent of highly myopic eyes (Figure 24). These appear as fine, irregular yellow lines that may branch and crisscross. Lacquer cracks may allow choroidal vessel growth through the breaks, leading to sub-retinal hemorrhages. Secondary pigmentary proliferation from this choroidal vessel growth over time is called a Foster-Fuch's spot. These usually appear as a pigmented lesion in the macular area (Figure 25).

 

Figure 24
Figure 24. Lacquer crack from myopic degeneration, in the macular area (arrow).

 

Figure 25
Figure 25. Foster-Fuch's spots (Left, middle, right) from myopic degeneration.

 

 

 

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