Sir,

Megalocornea is a corneal abnormality1 and occurs in three patterns: simple megalocornea unassociated with other ocular abnormalities; megalophthalmos anterior with megalocornea, iris and angle abnormalities as well as buphthalmos in infantile glaucoma.2 Megalophthalmos anterior is a rare, most X-linked recessive, nonprogressive bilaterally symmetrical condition.3,4 In comparison to simple megalocornea, eyes with megalophthalmos anterior have enlargement of the iris-lens diaphragm and ciliary ring in addition to the cornea.3 The megalophthalmos anterior patients present a very deep anterior chamber depth (AC depth) and a vitreous index (vitreous length/axial length × 100) below 69%.5

The pathogenesis of simple megalocornea and megalophthalmos anterior is unknown. There may be a large cornea (keratodysgenesis), iris and angle abnormalities (iridogoniodysgenesis), or a combination of these.2

The differentiation between simple megalocornea, megalophthalmos anterior and primary infantile glaucoma is often difficult, but very important, as in the latter case surgical treatment prevents blindness.5

We describe a case of megalophthalmos anterior with ciliary body dysplasia, diagnosed using ultrasound biomicroscopy.

Case report

A 23-year-old, healthy man was seen in our outpatient department with bilateral symmetric megalocornea (vertical diameter 14.0 mm). His dead grandfather on the mother’s side had a known megalophthalmos anterior.

Visual acuity with glasses was 20/16 in both eyes. The myopic refraction was 6.0 D in the right eye and 5.0 D in the left eye. Corneal curvature was normal (K-readings: right eye 41.50/42.75 × 8; left eye 41.25/42.50 × 10). Slit-lamp examination showed a clear cornea, an enlargement of the complete anterior segment of the eye and peripheral iris transillumination defects. There was no lento- or iridodonesis and no Krukenberg’s spindle. Gonioscopy revealed a wide open angle with excessive mesenchymal tissue. Intraocular pressure was 10 mmHg in both eyes. Signs of glaucoma were absent. The optic nerve heads did not show any pathological findings and computed perimetry was normal.

Biometrically measured anterior chamber depth was increased to 5.3 mm in the right and 5.2 mm in the left eye. Lens thickness was 3.8 mm and vitreous index 66% in both eyes.

We perform an ultrasound biomicroscopy examination in both eyes with radial and transverse sections of the globe at the 3, 6, 9 and 12 o’clock position. In both eyes ultrasound biomicroscopy shows a cornea with normal thickness, open angle (62 degree), thinning of the root of the iris and insertion of ciliary processes on the posterior surface of the peripheral iris. The distance between ciliary processes and iris root was 1309 mm. Ciliary processes were absent in the normal region of ciliary body (Figure 1).

Figure 1
figure 1

Ultrasound biomicrocopy in radial (a) and transverse (b) sections of the globe shows open angle, thinning of the root of the iris and insertion of ciliary processes on the posterior surface of peripheral iris (arrows). Dotted line: plane of transducer motion.

Full size image

Megalophthalmos anterior with ciliary body dysplasia was diagnosed.

Comment

Our case of megalophthalmos anterior demonstrates that the enlargement of the iris-lens diaphragm and ciliary ring during eye development (keratodysgenesis and iridociliarygoniodysgenesis) can result in an insertion of ciliary processes on the posterior surface of peripheral iris.

Arcus lipoides, mosaic corneal dystrophy, pigment dispersion, cataract and lens dislocation are associated ocular anomalies.6 To our knowledge, ciliary body dysplasia in megalophthalmos anterior has not yet been described.

In a case of buphthalmos due to infantile glaucoma, normal insertion with a prolongation of ciliary processes has been seen by ultrasound biomicroscopy.7 However, ultrasound biomicroscopy examinations of ciliary body in megalophthalmos anterior have not yet been performed.

We emphasize that in cases with megalocornea, ultrasound biomicroscopy is a helpful, additional tool for examination of the ciliary body. Perhaps ciliary body dysplasia may be a further feature for distinguishing megalophthalmos anterior from buphthalmos.