Alex V. Levin
Thomas W. Wilson
Many diseases have both ocular and renal abnormalities. Metabolic disorders including cystinosis (Chapter 20: Metabolic, Figs. 20.1 and20.2) and Fabry disease %(Chapter XX:, Figure XX.X) result in accumulation of intracellular materials within the eye and kidney tissue. Diabetes mellitus (Chapter 16: Endocrine, Figs. 16. 1 and 16.2) commonly causes damage to the peripheral blood vessels and results in retinopathy, nephropathy, and neuropathy. Hypertension also targets the eyes and kidneys.
Renal and perirenal tumors are associated with specific eye diseases. The phakomatoses (Chapter 23: Phakomatoses) have an association with ocular abnormalities and renal tumors, including renal cysts (tuberous sclerosis), pheochromocytoma (neurofibromatosis type I), and renal cell carcinoma (von Hippel-Lindau). There is also a strong association between sporadic aniridia and Wilms tumor.
Pigmentary retinopathy has been associated with other systemic syndromes including Senior-Loken syndrome (nephronophthisis and retinitis pigmentosa [Chapter 8: Retina and Vitreous]), Bardet-Biedl syndrome, and Cockayne syndrome (Chapter 29: Syndromes). The oculocerebrorenal syndrome of Lowe has the combination of ocular and renal tubular abnormalities (Chapter 20: Metabolic, Fig. 20.12). Cryptophthalmus in Fraser syndrome will often have an associated renal hypoplasia (Chapter 2: Lids and Adnexa, Fig. 2.1).
Figure 26.1 Alport Syndrome— Anterior Lenticonus
Alport syndrome is due to abnormal collagen type 4. It may be inherited as an autosomal dominant, autosomal recessive, or X-linked recessive disorder depending on which of the three collagen strands in the collagen fibril triple helix is affected. Renal manifestations include hemorrhagic nephritis leading to hematuria, which is the most common presenting sign. Anterior lenticonus, as shown here, is a forward bowing out of the lens centrally with or without lens opacity. This is caused by abnormal type 4 collagen within the lens capsule. The collagen weakness within the anterior lens capsule allows the cortical material to become displaced anteriorly, which forms the characteristic anterior lenticonus with or without subcapsular opacification.
Figure 26.2 Alport Syndrome—Retina
The fundus will often contain white flecks or larger white coalescent opacities at the level of the retinal pigment epithelium. They are concentrated within the macula and midperiphery, but typically spare the central fovea. The retinal function remains normal and the vision and electroretinogram are typically normal. Retinal blood vessels are not attenuated and there is no disc pallor, as seen in the retinal degenerations.
Figure 26.3 Renal-Coloboma Syndrome
Renal-coloboma syndrome (also known as papillorenal syndrome) is due to mutation in the pax2 gene. This developmental homeobox gene is responsible for ensuring development of an optic stalk on each side of the anterior neuropore (neural tube). The optic nerve malformation is not a classic optic nerve coloboma, but rather often appears as an enlarged optic nerve head with surrounding peripapillary atrophy and possibly an enlarged cup. A wide variety of renal abnormalities may be seen.