Ординатура / Офтальмология / Английские материалы / Oxford American Handbook of Ophthalmology_Tsai, Denniston, Murray_2011

RETINAL ARTERY OCCLUSION (2) 447

Figure 13.12 Hollenhorst plaque (arrow) lodged in a peripheral retinal artery. See insert for color version.

.

HYPERTENSIVE RETINOPATHY 449

Ophthalmic

•Scotoma, diplopia, photopsia, dVA.

•Retinopathy: focal arteriolar narrowing, CWS, flame hemorrhages.

•Choroidopathy: infarcts that may be focal (Elschnig’s spots) or linear along choroidal arteries (Siegrist’s streaks), serous retinal detachments.

•Optic neuropathy: disc swelling ± macular star.

Investigation and treatment

Refer to a medical team for admission and cautious lowering of blood pressure; too rapid a reduction may be deleterious (e.g., stroke).

Table 13.17 Adult hypertension clinical guidelines

Table 13.18 Common antihypertensives

450 CHAPTER 13 Medical retina

Hematological disease

Hemoglobinopathies

Normal adult hemoglobin (HbA) comprises two A- and two B-globin chains associated with a heme ring. In sickle hemoglobinopathies, there is a mutant hemoglobin, such as HbS (B-chain residue 6 Glu lVal), which behaves abnormally in response to hypoxia or acidosis. This causes “sickling” and hemolysis of red blood cells.

Many other mutant hemoglobins have been described, the most common one being HbC. In thalassemias the problem is one of inadequate production of one or more of the A- or B-chains.

Although systemic disease is most severe in sickle-cell disease (HbSS), ocular disease is most severe in HbSC and HbS-Thal disease. Sickle hemoglobinopathies are seen in Africans and their descendents (Table 13.19); thalassemias are mainly seen in Africans and in Mediterranean countries.

HEMATOLOGICAL DISEASE 451

Investigation

• Hb electrophoresis, CBC.

Some patients with HbSC or HbS-Thal may be unaware of their disease.

Treatment

•Observation.

•Consider laser photocoagulation in proliferative sickle retinopathy. Its use is controversial, as most sea-fans spontaneously regress. The rationale is to remove the drive to neovascularization by ablating the ischemic retina.

•Consider vitreoretinal surgery for persistent vitreous hemorrhage (e.g., >6 months) and tractional retinal detachment, although the results are generally disappointing, and specialist perioperative care is required.

Anemia

Retinal findings increase with severity of anemia, particularly in the presence of thrombocytopenia. The retinopathy is usually an incidental finding, thus investigation and treatment should already be under way with the hematologist.

Clinical features

•Retinopathy: usually asymptomatic; hemorrhages, cotton wool spots, venous tortuosity.

•Other: subconjunctival hemorrhages, optic neuropathy (if dB12).

.

Leukemia

Retinal findings are more common with acute rather than chronic leukemias. Leukemic complications may be due to direct infiltration or secondary anemia and hyperviscosity.

Clinical features

•Retinopathy: usually asymptomatic; hemorrhages, CWS, venous tortuosity, pigment epitheliopathy (“leopard spot” from choroidal infiltration), neovascularization (rare).

•Other: spontaneous hemorrhage (subconjunctival or hyphema), infiltration (iris lanterior uveitis ± hypopyon; orbit proptosis; optic nerve loptic neuropathy ± disc swelling).

Hyperviscosity

Hyperviscosity arises from abnormally high levels of blood constituents, either cells (e.g., primary or secondary polycythemia, leukemias) or protein levels (e.g., multiple myeloma, Waldenstrom’s macroglobulinemia).

Clinical features

•Retinopathy: usually asymptomatic; hemorrhages, CWS, venous tortuosity, and dilation.

•Other: optic disc swelling in polycythemia and multiple myeloma, conjunctival/corneal crystals, iris/ciliary body cysts in multiple myeloma.

452 CHAPTER 13 Medical retina

Vascular anomalies

Retinal telangiectasias

Retinal telangiectasia describes abnormalities of the retinal vasculature, usually with irregular dilation of the capillary bed, and segmental dilation of neighboring venules and arterioles. Most commonly, they are acquired secondary to another retinal disorder (e.g., CRVO).

Congenital forms represent a spectrum of disease from the severe and early onset of Coats’ disease to the more limited and later onset of idiopathic juxtafoveal telangiectasia (see Table 13.21).

Coats’ disease

This uncommon condition is the most severe of the telangiectasias. It affects mainly males (M:F 3:1) and the young, although up to a third may be asymptomatic until their 30s. Although often considered a unilateral disease, around 10% cases are bilateral.

Clinical features

•May be asymptomatic; dVA, strabismus, leukocoria.

•Telangiectatic vessels, “light bulb” aneurysms, capillary dropout, exudation (may be massive), scarring.

•Complications: exudative retinal detachment, neovascularization, vitreous hemorrhage, rubeosis, glaucoma, cataract.

.

Investigations

FA highlights abnormal vessels, leakage, and areas of capillary dropout.

Treatment

Consider laser photocoagulation (or cryotherapy) of leaking vessels; treat directly rather than with a scatter approach. Anti-VEGF therapy may decrease vascular leakage and reduce the degree of exudation and subretinal fluid. Scleral buckling with drainage of subretinal fluid may be performed for significant exudative detachment but carries a guarded prognosis.

Table 13.21 Causes of retinal telangiectasias

454 CHAPTER 13 Medical retina

Figure 13.13 Retinal macroaneurysm surrounded by an area of retinal hemorrhage. See insert for color version.

.

Figure 13.14 Fluorescein angiogram demonstrates a small area hyperfluorescence in the location of the dilated retinal macroaneurysm. The surrounding area is

hypofluorescent due to blockage by the retinal hemorrhage. See insert for color version.

The underlying abnormality is of polypoidal aneurysmal dilation of abnormal choroidal vasculature usually around the posterior pole. These result in the clinical picture of recurrent multiple serous or hemorrhagic detachments of retina/RPE in the absence of features suggestive of AMD (e.g., drusen) or intraocular inflammation.

The choroidal aneurysms can be confirmed on ICG, assisting differentiation from AMD or other neovascular processes. Prognosis is variable.

RADIATION RETINOPATHY 455

Radiation retinopathy

Irradiation of the globe, orbit, sinuses, or nasopharynx may lead to retinal damage. This usually occurs after a delay of 6 months to 3 years, which is thought to be the turnover time for endothelial cells of the retinal vasculature.

Risk of retinopathy increases with radiation dose: 90% of brachytherapy patients receiving a macular dose of 7500 rad developed maculopathy; over 50% of patients receiving orbital/nasopharyngeal irradiation may develop retinopathy. Retinopathy is unlikely following doses of 2500 rad given in fractions of 200 rad.

Clinical features

Treatment

Consider focal photocoagulation for macular exudation and panretinal photocoagulation for proliferative radiation retinopathy, although less intensive treatment is usually required than in diabetic retinopathy.