Pathological myopia and Posterior staphyloma

POSTERIOR STAPHYLOMA OF MACULA

POSTERIOR STAPHYLOMA IN HIGH MYOPE +22D

Pathological myopia:

-incidence 2 % in US

-more in chinese , japanese, arab, jewish.

-blacks virtually free of this.

Pathological myopes may present with decreased visual acuity, an unusually large exophoria, strabismus (typically exotropia), open angle glaucoma, premature lenticular opacification and increased axial length (26.5 33.5mm).

Dilated fundus examination may unveil any of these signs:

flat, obliquely inserted discs,

posterior staphyloma,

myopic crescent,

patchy choroidal atrophy within the posterior pole,

vitreous syneresis,

breaks in Bruch's membrane with accompanying choroidal atrophy known as lacquer cracks,

subretinal neovascular membrane with overlying retinal pigment epithelial hyperplasia (Fuch's spot),

subretinal neovascularization without Fuch's spot (subretinal scarring, bleeding, exudate),

retinal breaks or detachments.

Patho-logical myopia has two stages, developmental and degenerative.

Damage in the developmental stage results from axial lengthening, followed by damage from vascular alterations. Elongation of the globe, known as posterior staphyloma, occurs in stages and results from scleral thinning. This progressive scleral ectasia can form in the posterior pole (disc and macula), inferiorly, nasally or in multiple, complex patterns. Breaks in Bruch's membrane with accompany- ing choroidal atrophy create lesions known as lacquer cracks. These dehiscences are associated with increased risk for choroidal neovascularization.

Progressive myopia is associated with systemic diseases such as Marfan's syndrome, retinopathy of prematurity, Ehler's-Danlos syndrome, Stickler's syndrome and albinism

Posterior staphyloma in degenerative myopia

1.Subretinal hemorrhage from choroidal neovascular membrane in degenerative myopia. (Courtesy Dr. Arnie Patrick)

2.Subretinal hemorrhage and Fuch's spot from choroidal neovascular membrane in degenerative myopia. (Courtesy Dr. Arnie Patrick)

Management:

Anytime you detect a posterior staphyloma, lacquer crack or Fuch's spot in the fundus, fluorescein angiography is appropriate. A- and B-scan ultrasonography can confirm the presence of increased axial length and posterior staphyloma.

Annual DFE to monitor:

1. Development of choroidal neovascular membrane

2. Retinal detachment

Currently no effective treatment to halt the progression of pathological myopia. Refractive error treat with contact lens and spectacles.

Because pathological myopia results from stretching of the globe, it compromises ocular stability and strength. Counsel patients to avoid dangerous circumstances and activities. Contact sports or activities that jolt the body increase the risk for retinal detachment.

Clinical Pearls:

• Don't rely on refractive error alone to make the diagnosis of pathologic myopia. Many patients with myopia
  >10.00D never show signs of myopic progression or pathologically related tissue alteration.
• Suspect pathological myopia if the myopia continues to progress beyond the pubescent years.
• Lacquer cracks usually manifest in young males.
• Extrafoveal CNVMs seem to respond best to laser treatment.
• Differential diagnoses include histoplasmosis, congenital staphyloma, coloboma, gyrate atrophy, age-related choroidal atrophy, age-related macular degeneration, angioid streaks and tilted discs.

source:http://legacy.revoptom.com/handbook/oct02_sec5_3.htm