Ataxia-telangiectasia (AT; Louis-Bar Syndrome) involves primarily the cerebellum, ocular surface, skin, and immune system. Extraocular features are summarized in Table 28-7.
Ocular motor abnormalities are found in many patients with AT and are frequently among the earliest manifestations. Characteristically, there is poor initiation of saccades with preservation of vestibular-ocular movements, as in congenital ocular motor apraxia. Head thrusts are used to compensate for saccades. Strabismus and nystagmus may also be present.
Telangiectasia of the conjunctiva occurs in 91% of patients and develops between the ages of 3 and 5 years. Involvement is initially interpalpebral but away from the limbus (Fig 28-20); it eventually becomes generalized. Similar vessel changes can appear in the skin of the eyelids and other sun-exposed areas.
Table 28-7 Extraocular Features in Ataxia-Telangiectasia
Figure 28-20 Abnormally dilated and tortuous interpalpebral conjunctival vessels in a child with ataxia-telangiectasia, seen only in the interpalpebral fissure.
Individuals with AT are much more sensitive to the tissue-damaging adverse effects of therapeutic radiation and many chemotherapeutic agents. Defective T-cell function in patients with AT is usually associated with hypoplasia of the thymus and decreased levels of circulating immunoglobulin. Recurrent respiratory tract infections and increased susceptibility to malignant tumors are frequent causes of mortality.
Excerpted from BCSC 2020-2021 series: Section 10 - Glaucoma. For more information and to purchase the entire series, please visit https://www.aao.org/bcsc.