Double trouble: exudative hypertensive retinopathy in a patient with retinitis pigmentosa

Abstract

A young female suffering from chronic kidney disease presented with retinal features suggestive of retinitis pigmentosa (RP). Cystoid intraretinal changes were noted at the macula in both eyes on optical coherence tomography. Careful clinical examination and fluorescein angiography revealed disc oedema, macular hard exudates and flower petal leakage in both eyes. A clinical diagnosis of RP with leaking cystoid macular oedema (CMO) because of hypertensive retinopathy was made. Exudation and macular oedema subsided with hypertension control and posterior sub-Tenon steroid injection. Although CMO does not typically leak on fluorescein angiography in RP, this need not always be true. Clinical signs and fluorescein angiography help in the differentiation of macular oedema when more than one aetiology may be responsible.

Background

Cystoid macular oedema (CMO) is a common occurrence in retinitis pigmentosa (RP) and may be seen in 10%–50% of these eyes.¹ Various mechanisms have been proposed to account for CMO in RP which include retinal pigment epithelium (RPE) pump dysfunction, muller cell dysfunction, anti-retinal or anti-RPE antibodies and blood retinal barrier breakdown.^1–3 Clinical macular oedema in RP lacks leakage into the cystic spaces on fundus fluorescein angiography. The presence of leaking CMO in the setting of RP should raise the suspicion of other coexisting pathology.

The current report describes a case of leaky CMO in a young female patient with RP, also suffering from hypertension due to chronic kidney disease. Atypical features of hard exudates in the macular area prompted us to perform fluorescein angiography. Macular exudation is known to occur in severe forms of hypertensive retinopathy.⁴ This case highlights the importance of clinical signs and fluorescein angiography features in the differentiation of macular oedema when more than one aetiology may have been responsible.

Case presentation

A 24-year-old average built woman presented with gradually progressive, painless diminution of vision and night blindness in both eyes over the past few years. The family and personal history were unremarkable. The patient had chronic kidney disease along with systemic hypertension. The blood pressure at examination was 160/100 mm Hg. The patient gave a history of fluctuations in her blood pressure over the past 1 week as assessed by the treating nephrologist.

The best corrected visual acuity in the right and left eye were 20/60 and 20/100, respectively. The anterior segment examination was unremarkable. Dilated fundus examination showed severe arterial attenuation, bony spicule pigmentation and waxy disc pallor, consistent with RP (figure 1A,B). There was no vitritis. A note was made of the hard exudates and cystoid oedema at the macula, silver wiring of the blood vessels and disc oedema in both eyes. There were no arteriovenous crossing changes, flame shaped retinal haemorrhages and features suggestive of retinal venous occlusion.

Figure 1.

Multimodal retinal imaging of a patient of retinitis pigmentosa with coexistent chronic kidney disease. Standard 45° fundus image of both eyes shows blurred disc margin, subtle neuroretinal rim pallor, hard exudates and cystoid oedema at the macula and silver wiring of vessels (A,B). Swept source optical coherence tomography of the macular area shows cystoid oedema in both eyes (C,D). Fluorescein angiography in late phase shows characteristic flower petal leak at the macula and disc leak (E,F).

Investigations

The swept source optical coherence tomography (Triton, Topcon, Oakland, New Jersey, USA), of the macula showed cystoid intraretinal changes in both eyes (figure 1C,D). In view of features of exudative hypertensive retinopathy like disc oedema and hard exudates, fundus fluorescein angiography was performed that revealed macular leakage in flower petal pattern and disc leakage (figure 1E,F).

Differential diagnosis

A clinical diagnosis of RP with leaking CMO because of severe hypertensive retinopathy was made.

Treatment

The patient was advised to consult her nephrologist for optimising the blood pressure. Also, topical dorzolamide was started in both the eyes three times per day.

The patient was lost to follow-up and returned 3 months later with a decrease in the hard exudates but no change in the macular oedema. After informed consent, posterior sub-Tenon injection of triamcinolone acetonide (20 mg in 0.5 mL) was given in the left eye. The importance of management of blood pressure was impressed on the patient.

Outcome and follow-up

Eight weeks after the steroid injection, the best-corrected visual acuity was 20/40 in right eye and 20/20 in the left eye. The hard exudates and disc oedema had resolved (figure 2A,B). Optical coherence tomography showed residual small cystoid spaces in the right eye and resolved oedema in the left eye (figure 2C,D).

Figure 2.

Follow-up retinal imaging after posterior sub-Tenon steroid injection in left eye and strict blood pressure control. Fundus image shows resolution of disc oedema in both eyes and resolution of macular oedema in the left eye (A,B). Swept source optical coherence tomography of the macular area confirms significant decrease in oedema in both eyes, left more than right (C,D).

The clinical picture remained unchanged until 6 months after the injection. The ultra-wide field pseudocolour and autofluorescence imaging at final follow-up are shown in figure 3A–D. Autofluorescence imaging showed a hyperautofluorescent parafoveal ring and hypoautofluorescent peripheral lesions, characteristic of RP (figure 3C,D). The patient is under regular follow-up at the nephrology department and awaits a renal transplant.

Figure 3.

Wide field fundus imaging at last follow-up. Pseudo-colour image of both eyes shows disc pallor, arteriolar attenuation and peripheral pigmentary retinopathy suggestive of retinitis pigmentosa (A,B). Autofluorescence imaging shows a hyperautofluorescent ring in parafoveal region in both eyes and hypoautofluorescent peripheral lesions (C,D).

Discussion

The simultaneous presence of chronic kidney disease and RP in the current case was likely coincidental. While several signs were typical of RP in this case, arterial attenuation, an important marker of hypertensive retinopathy, is seen in RP as well. Disc oedema has also been described in the setting of RP and may occur because of inflammation resulting from fast photoreceptor degeneration.³

Independent of the chronic kidney disease and consequent hypertension, RP may also have abnormality of the ocular blood flow, perhaps due to the associated primary vascular dysregulation.⁵ Not only the retinal and choroidal blood flow is reduced in these eyes, the vascular plexus density is also reduced.^{5 6}

The presence of hard exudates in RP in the absence of vascular cause is atypical and prompted us to perform a fundus fluorescein angiography. The ‘leaking’ CMO on fundus fluorescein angiography confirmed that aetiology is unlikely to be RP. The presence of silver wiring and disc oedema in the absence of vitreous inflammation confirmed the diagnosis of severe hypertensive retinopathy. Compensatory arteriolar narrowing and arteriovenous crossing changes may not occur with acute rise in blood pressure in young patients.

The severe form or angioplastic form of hypertensive retinopathy is characterised by exudative changes at the macula and sclerosis of the retinal vessels.⁴ The exudation, if not chronic, tends to reverse with control of the systemic condition itself. However, the oedema persisted in our patient after 3 months of presentation. The continued presence of oedema prompted us to treat it with posterior sub-Tenon injection of steroid depot. Steroids as well as anti-vascular endothelial derived growth factors have been found useful in hypertensive retinopathy.^{7 8} The steroid injection resulted in complete resolution of oedema in the left eye along with visual improvement. Better control of hypertension could also have contributed to the resolution, as the improvement was seen in the right eye as well, though not completely.

Learning points.

• Cystoid macular oedema (CMO) commonly occurs in retinitis pigmentosa (RP).

• CMO in a patient of RP need not always be non-leaky.

• Clinical examination and investigation such as fluorescein angiography can help in the differentiation of macular oedema in a complex setting, where more than one aetiology may be responsible.