Fig. 2.1
Left congenital anophthalmia. (a) Axial CT scan shows that the left orbital cavity becomes smaller with no normal eyeball, where irregular nodular soft tissue can be seen. In addition, medial rectus, lateral rectus, and optic nerve are slender. The right eyeball becomes bigger with fronted lens and shallow anterior chamber. (b) Axial CT scan is the upper section of the (a), which shows smaller left orbital cavity and irregular soft tissue in the portion of absent eyeball
Fig. 2.2
Right congenital anophthalmia. (a) Coronal CT scan shows that the right orbital cavity becomes smaller with irregular hyper-dense soft tissue in the portion of absent eyeball. In addition, the extraocular muscles become slender. (b) 3D CT scan shows no palpebral fissure deformity on the right side and slightly sunken eye fossa
2.1.4 Evaluation
The clinical symptoms of patients with congenital anophthalmia are obvious and diagnosis can be easily made after clinical examination. In order to have a more detailed understanding of the disease, ultrasound or CT examinations can be further performed. If the density of soft tissue in the orbit is heterogeneous and its boundary with surrounding structures is not clear, MRI examination should be further performed to exclude neoplastic lesions.
2.2 Congenital Microphthalmia
There are three types of microphthalmia: deficient microphthalmia, concurrent microphthalmia, and simple microphthalmia. Simple microphthalmia means that the volume of the eyeball is smaller but with no other significant ocular deformities. Deficient microphthalmia refers to the congenital defect of ocular tissue in embryonic stage. Concurrent microphthalmia means small eyeball with other ocular malformations, in which a persistent hyperplasia of the primary vitreous (PHPV) is most common.
2.2.1 Pathological Features
- 1.
Simple microphthalmia manifests as slightly smaller eyeball, resulting from growth stagnation in late embryo.
- 2.
The internal structure of the eyeball is generally normal; the orbital volume decreases slightly and the lens accounts for 3–4% of the volume of the eyeball.
2.2.2 The Selection of Examination Order
- 1.
CT: It is the optimal method for this lesion, which may show the size and shape of eyeball whether normal or not.
- 2.
MRI: It can be used to accurately measure the length of the eyeball, the size of the lens, and the thickness of the choroid and sclera to provide important information for clinical treatment.
2.2.3 Imaging Performance
- 1.
CT performance: The eyeball and the orbital volume become smaller; the lens is larger with obtuse margin; the vitreum is normal; the extraocular muscles and optic nerve are slender (Fig. 2.3).
- 2.
MRI performance: On the ipsilateral side of microphthalmia, the extraocular muscles are slender (Fig. 2.4). The optic nerve may be slender or absent. The subarachnoid space around the optic nerve becomes wider. The anterior atrium of the eyeball deepens when small eyeball is accompanied with concomitant glaucoma.
Fig. 2.3
Left simple microphthalmia. (a) Axial CT scan shows that the left eyeball is significantly smaller with normal shape; the lens is visible but moves forward; anterior atrium becomes shallow; the optic nerve and extraocular muscles are slender. (b) Sagittal CT scan shows that the left eyeball is smaller with normal shape; the lens moves forward; anterior atrium becomes shallow; the density of the vitreum is homogeneous
Fig. 2.4
Right simple microphthalmia. (a) Axial scan of T1WI shows that the right orbital cavity becomes smaller; the eyeball becomes significantly smaller with normal shape; the lens is visible but moves forward; the anterior atrium becomes shallow and the superior rectus is slender. (b) Axial scan of T2WI shows that the volume of the right eyeball becomes significantly smaller; the lens becomes larger in size and lower in signal and it moves anteriorly resulting in a shallower anterior atrium. (c) Coronal scan of T1WI shows that the right optic nerve is absent and the extraocular muscles are more slender compared with that of the contralateral side. (d) Sagittal scan of T1WI shows smaller right orbit cavity without normal optic nerve
2.2.4 Evaluation
CT examination has unique advantages in the imaging of congenital microphthalmia as it is not affected by the opacity of the refractive media. Thus, it can clearly show the changes of the eyeball, internal cyst, optic nerve, ocular muscle, and orbital bone. It can not only identify the diagnosis and classification of microphthalmia, but also make accurate quantitative evaluation of the orbital volume, thus providing valuable information for the treatment of microphthalmia.
MRI is beneficial to more clearly observe other accompanying abnormalities, including some subtle lesions such as underdevelopment or detachment of the retina.
2.3 Optic Disc Defect and Retrobulbar Cyst
Defective microphthalmia includes congenital microphthalmos with optic disc defect and cyst, and congenital microphthalmos with orbital cyst. An eyeball with small cyst and normal shape and size usually has partial function, while an underdeveloped eyeball with obvious defect and large cyst is nonfunctional. The shape of the eyeball may be normal or unable to retain. The lens may not develop or dislocate.
2.3.1 Pathological Features
With complete or partial defect of disc, usually accompanied by the defects of iris or choroid.
2.3.2 Imaging Examination
- 1.
Ultrasonic: Optimal method for this lesion.
- 2.
CT: It shows whether the shape or internal structure of the affected eyeball is normal, such as calcification.
- 3.
MRI: It shows the lesion more clearly, which is helpful to differentiate from other lesions.
2.3.3 Imaging Performance
- 1.
Ultrasound performance: Simple optic disc defect manifests as defected choroid sclera expanding back out with clear boundary and usually accompanied by the retinal detachment. Morning glory syndrome manifests as that the optic disc and the surrounding areas move back and sag. The posterior pole bulges with clear boundary. Irregular weak echo may be shown in the area of depression.
- 2.
CT performance: Simple optic disc defect manifests as incomplete eye ring with defect at the connecting part of optic nerve and eyeball; elliptic or irregular cystic low-density area with clear boundary can be seen if a cyst is formed, which is connected or adjacent to incomplete eyeball, generally locating below the eyeball and behind the eyelid (Fig. 2.5). Morning glory syndrome manifests as a V bulges in the optic disc. The connection of the optic nerve and the eyeball is in expanding funnel shape and the depression is filled with hypo-dense tissue (Fei et al. 2013).
- 3.
MRI performance: Retrobulbar cyst is hypo-intense on T1WI and hyper-intense on T2WI. When retinal detachment occurs, “V”-shape signal with iso-intense on T1WI and hyper-intense on T2WI can be seen at the posterior part of eyeball. Morning glory syndrome manifests as a funnel expansion area with iso-intense on T1WI and hyper-intense on T2WI (Fig. 2.6).
Fig. 2.5
Bilateral optic disc defect and posterior cyst of left eyeball. (a) The axial CT scan shows that the bilateral eyeballs become obviously small and flat; the lens becomes more hyper-dense and distorted; a cystic hunch can be seen behind the left eyeball. (b) The sagittal CT scan shows that the left eyeball is irregularly lobulated; the density of the lens increases and an oval cystic hunch can be seen at the posterior of the eyeball
Fig. 2.6
Left optic disc defect and retrobulbar cyst. (a) The axial scan of T1W1 shows that the left eyeball becomes slightly smaller; the lens moves anteriorly. An iso-intense hunch can be seen at the optic disc of posterior of eyeball; and arc iso-intense signal can be seen at the posterior of eyeball. (b) The axial scan of T2W1 shows arc hyper-intensity at the posterior of the left eyeball and cystic hyper-intensity at the optic disc
2.3.4 Evaluation
CT may show the abnormal changes of the defected small eyeball and concomitant cyst, but some other lesions, such as congenital cystic eyeball, sclera staphyloma of posterior eyeball, dermoid cyst, cystic degeneration of optic nerve glioma, meningocele, and hemangioma, should be distinguished.
Congenital cystic eyeball means that the optic vesicle does not sag, resulting in one or more capsules being formed. Intraocular structures are usually absent while lens can be visible sometimes. Sclera staphyloma of posterior eyeball refers to any congenital or acquired focal expansion of eyeball wall. The expansion is not confined to the optic disc. The bulging part and the eyeball are at obtuse angle and the size of eyeball is usually normal.
MRI can show the abnormal signs of the orbit, which is useful to distinguish from other orbital lesions.
2.4 Permanent Primordial Vitreous Hyperplasia
2.4.1 Pathological Features
- 1.
The mass behind the lens is composed of vascular loose connective tissues, including hyperplasia of fiber blood tissues and vitreous artery remnants.
- 2.
The mass is connected forward with the posterior surface of the lens.
- 3.
The vitreous artery covered by retina is connected backward with the optic disc.
- 4.
Cartilage and bony tissues can be seen in the tumor.
2.4.2 Imaging Examination
- 1.
CT: It is optimal for this lesion, which may show the lesion’s location and shape as well as calcification.
- 2.
MRI: It may show more detailed lesions and surrounding abnormalities, thus providing more information for differential diagnosis.
2.4.3 Imaging Performance
- 1.
- 2.
MRI performance: The signal of vitreum increases on both T1WI and T2WI. Tubular soft tissues with clear boundary are connected from posterior lens to front retinal optic disc. In addition, a triangle or “wine cup”-shaped or irregular mass behind the lens can be seen, which is iso- or slightly hypo-intense on both T1WI and T2WI. The vitreous artery and fibrous vessel membrane enhance, while the proliferated fibrous connective tissues do not (Fig. 2.8c, d).
Fig. 2.7
Left permanent primordial vitreous hyperplasia. The axial scan of non-contrast CT shows slightly hyper-dense banded soft tissue posterior to left lens, connecting backward to the optic disc
Fig. 2.8
Right permanent primordial vitreous hyperplasia. (a) The axial scan of non-contrast CT shows smaller eyeball and lens as well as shallow anterior chamber on the right side. In addition, banded soft tissue (white arrow) can be found to connect from posterior lens to the optic disc. (b) The axial scan of non-contrast T1W1 shows that right eyeball becomes smaller. Slight hypo-intense banded soft tissue (black arrow) in the hyper-intense vitreum can be found to connect from posterior lens to the optic disc. (c) The axial scan of T2W1 shows that slight hyper-intense banded soft tissue (black arrow) in the hyper-intense vitreum can be found to connect from posterior lens to the optic disc. (d) The axial scan of contrast fat-suppressing MRI shows that the banded soft tissue does not enhance
2.4.4 Evaluation
MRI has a higher sensitivity and specificity to show lesions in the eyeball with leukokoria than CT. CT and MRI both can show the shape of soft tissue in the vitreum clearly. CT is more sensitive for calcification, which is beneficial to distinguish from other lesions in eyeball. However, CT is not as sensitive as MRI in the assessment of detailed information in the lesion. Therefore, both CT and MRI are recommended to assess the lesion in the eyeball, if possible.
2.5 Coats Disease
The diagnostic criteria of coats disease is the idiopathic retinal capillary expansion, accompanied by infiltration of the retina and frequent exudative retinal detachment. The characteristics of this disease are as follows: male, school-aged children and juveniles, monocular lesions, no calcification, normal size of eyeball, and crescent-shaped hyper-dense soft tissue in the posterior eyeball. Patients with this disease mostly complain with decreased vision, strabismus, and white reflection in pupil area (Grosso et al. 2015).
2.5.1 Pathological Features
- 1.
Retinal lipid exudation in the early period.
- 2.
Lots of protein effusion and bleeding with part or entire detachment of retina in the middle period.
- 3.
The exudation replaced by connective tissue in the late period, accompanied by inflammation or atrophy of the eyeball.
2.5.2 Imaging Examination
- 1.
Ultrasound: It is the optimal examination for this disease.
- 2.
CT: It may identify whether calcification occurs or not.
- 3.
MRI: It is helpful to distinguish from other lesions as it may show more detailed characteristics of the lesion.
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