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8 Noninflammatory Diseases of the Sclera

The most frequent ocular manifestation in

Senile Scleral Hyaline Plaques

hyperparathyroidism is band keratopathy, a bilat-

Senile scleral plaques, occurring in individuals

eral and symmetrical peripheral corneal calcifi-

over 60 years (either sex), appear as a dark oval

cation with tiny Swiss cheese-like holes and a

nonprogressive patch about 2 mm in diameter

clear interval between the band and the limbus

surrounded by a dense calcareous yellowish ring;

[53, 54]. Extension of the band keratopathy may

the center of the patch appears translucent, allow-

involve the conjunctiva and the sclera.

ing the underlying uvea to be seen [38, 65–72].

Conjunctival calcification is described as white

The lesion, usually bilateral and symmetrical, is

flecks or glass-like crystals near the limbus.

localized to the interpalpebral region, anterior to

Scleral calcification appears as white translucent

the insertion of the horizontal recti muscles. The

plaques [38].

central translucent area can be transilluminated

by directing the light through the pupil, but

8.1.4.2 Other Causes of Hypercalcemia

although the sclera is thinned (from 0.6 to 0.3 mm)

Other diseases which may cause calcium depo-

[71], the wall is resistant, with no tendency to per-

sition in the sclera are hypervitaminosis D [50,

foration. Histologically, plaques show decreased

56, 57], idiopathic hypercalcemia of infancy

cellularity, replacement of the superficial layers

[54], Boeck’s sarcoidosis, and hypophosphatasia

of the sclera by large masses of hyaline degenera-

[49, 50].

tion, loss of birefringence, deposition of calcium,

Hypophosphatasia is a rare inborn metabolic-

and fragmentation of sclera fibers; the latter may

borne disease characterized by hypercalcemia,

account for the scleral weakness. The location of

low serum, and tissue alkaline phosphatase con-

the plaque therefore may be determined by the

centrations, and increased blood and urine levels

maximal stresses of the muscles. Differential

of phosphoethanolamine and inorganic pyro-

diagnosis of senile scleral hyaline plaques should

phosphate [51]. In hypophosphatasia bone matu-

include scleromalacia perforans, since both

ration is prevented because osteoblasts cannot

lesions have loss of scleral substance, lack of

incorporate calcium into otherwise normal bone

inflammatory reaction, and painless development

matrix. Abnormalities in bone maturation lead to

[73–75]. Unlike in scleromalacia perforans, in

rickets in children and osteomalacia in adults.

senile scleral plaques there is no evidence of

The disease may be classified as infantile, child-

rheumatoid arthritis, there is no progression,

hood, or adult forms. Ocular manifestations are

males are affected as often as females, there is no

uncommon and are present only in the infantile

histopathologic necrosis, and prognosis is good

and childhood forms. They include band keratop-

without treatment (Table 4.11).

athy, conjunctival calcification, cataracts, harle-

Calcium deposition in sclera also may occur

quin orbits, papilledema, optic atrophy, retinitis

following severe scleral inflammation at any age

pigmentosa, and blue sclerae [58–62].

[38, 39].