Hypertensive Retinopathy

“Albuminuric retinitis” was initially noted by Leibreich in 1859 [2], and Marcus Gunn published detailed case descriptions in 1892 [3]. Hypertensive retinopathy is the most common ophthalmic manifestation of hypertension [4], with a reported prevalence of 2–14% in nondiabetic adults over age 40 years [5]. Detection of hypertensive retinopathy is important to preserve vision and to guide treatment of the underlying systemic disease [1].

Multiple clinical grading systems have been published. The four-stage Keith-Wagener-Barker classification was described in 1939 [6], and the five-stage Scheie classification was described in 1953 [7]. More recently, a simpler three-stage classification has been proposed (Table 22.1) [8]. Regardless of the classification scheme, the progression of the disease generally follows the known pathophysiology [9]. Initially, retinal arteriolar constriction occurs as part of an autoregulatory mechanism [10]. With continued disease, breakdown of the inner blood-retinal barrier occurs, with subsequent hemorrhages and exudates, followed by retinal edema (Fig. 22.1a, b). In advanced cases, optic nerve edema (hypertensive optic neuropathy) may ensue, which is caused by ischemia leading to axonal edema [11] (Fig. 22.2a, b).

The differential diagnosis of hypertensive retinopathy is listed in Table 22.2 [12]. Selected reported risk factors for hypertensive retinopathy are listed in Table 22.3.

Table 22.1 Classification of hypertensive retinopathy (Adapted from [8])

Hypertensive retinopathy is typically bilateral, although unilateral disease has been reported in the setting of contralateral carotid disease [13]. Optical coherence tomography of advanced cases typically may demonstrate cystoid macular edema and subretinal fluid [14, 15].

Hypertensive retinopathy may predict increased risks of systemic morbidity and mortality. Large population-based studies have documented statistically significant associations between worsening degrees of hypertensive retinopathy and risks of stroke [16], cognitive impairment [17], and cardiovascular death [18].

Hypertensive Choroidopathy

Hypertensive choroidopathy is more common in younger patients, whose retinal vessels are not yet sclerotic from exposure to chronic hypertension [9]. Although there is no formal grading system for hypertensive choroidopathy, the clinical manifestations follow the histopathology [19]. Initial ischemia is followed by chronic choroidal vascular occlusion and ultimately recanalization of the choroidal vessels.

Clinically, choroidal infarcts may manifest as Elschnig spots [20] (Fig. 22.3a, b, c) or less commonly as Siegrist’s streaks. If the choroidopathy involves the macula, permanent visual loss may result [21]. Continued ischemia of the retinal pigment epithelium may lead to exudative (serous) retinal detachment (Fig. 22.4). In severe cases, massive suprachoroidal hemorrhage may occur, with associated anterior displacement of the lens-iris diaphragm and nonpupillary block angle closure [22].

Indirect Effects

Hypertension is a risk factor for a variety of retinal and choroidal diseases, summarized in Table 22.4 (Fig. 22.5a, b, c). For many of these diseases, an association is well documented, while for others, an association is suspected but has not been conclusively demonstrated [5].

Fig. 22.1 (a) Color photograph of hypertensive patient depicting features of moderate hypertensive retinopathy, including generalized arteriolar narrowing, cotton-wool

Fig. 22.2 (a) Color photograph documenting hyperten- sion-induced optic neuropathy, along with hypertensive retinopathy and choroidopathy. Intraretinal hemorrhages, cotton-wool spots, exudates, and areas of choroidal ischemia are readily apparent. The patient was admitted to the

Table 22.2 Differential diagnosis of hypertensive retinopathy (Adapted from [12])

spots, and small intraretinal hemorrhages. (b) Fluorescein angiogram (FA) reveals localized areas of capillary nonperfusion

emergency department for management of markedly elevated blood pressure of 240/120. (b) Color photograph of same patient, showing early resolution of hypertensive features now 2 weeks following control of systemic hypertension (BP 120/72)

Table 22.3 Selected reported risk factors for hypertensive retinopathy

Fig. 22.3 (a) Color photograph showing multiple punctate areas of choroidal ischemia (Elschnig spots) in a young patient with acute hypertension. The patient had mild visual blurring. (b) Early frame of FA documenting

Fig. 22.4 Color photograph revealing an exudative, serous retinal detachment in a patient with extreme choroidal ischemia secondary to hypertension

Controversies and Perspectives

After 150 years, there remains no consensus clinical grading system for hypertensive retinopathy.

punctate areas of blocked fluorescence corresponding to the regions of choroidal ischemia. (c) Later frame of the FA revealing punctate spots of hyperfluorescence corresponding to the areas of choroidal ischemia

The three-step classification discussed here is straightforward but not universally accepted.

Because most patients with hypertensive retinopathy are asymptomatic, there are legitimate questions regarding screening. Some authors have suggested that all hypertensive patients undergo regular dilated fundus examinations, although

Fig. 22.5 (a) Color photograph of a hypertensive patient who developed a retinal arterial macroaneurysm, surrounded by intraand subretinal hemorrhage, superonasal to the macula. (b) Early frame of the FA showing

hyperfluorescence at the site of the macroaneurysm, surrounded by blockage of fluorescence secondary to the hemorrhage. (c) Later frame of the FA showing leakage at the site of the macroaneurysm

there is no convincing evidence in support of this recommendation [5]. The National High Blood Pressure Education Program Education Working Group recommends screening hypertensive children for retinopathy [23], although one study of hypertensive children showed a low rate of retinal findings, all of which were mild [24].

Using retinal findings to guide systemic treatment is an imperfect strategy. Direct ophthalmoscopy has been reported to correlate poorly with blood pressure measurements in patients with mild to moderate hypertension, with significant interobserver and intraobserver variability [25]. Digital fundus photography and automated image analysis may improve the diagnostic accuracy of retinal imaging in the future [26].

Summary

It has been suggested that treatment of the underlying hypertension may lead to improvement of

hypertensive retinopathy [27], yet there are no data from randomized clinical trials regarding this [28]. Calcium channel blockers have been proposed as possible neuroprotective agents to treat hypertensive retinopathy [29], but at the present time, evidence of their effectiveness in hypertensive patients is lacking.

Focal Points

•Hypertension is common among adults in the United States.

•Posterior segment manifestations are common in hypertensive patients.

•Hypertensive retinopathy is associated with increased risks of stroke, cognitive impairment, and cardiovascular death.

•Hypertension increases the risks of other retinal diseases, including retinal vascular occlusions, diabetic retinopathy, and anterior ischemic optic neuropathy.