Can constipation lead to visual loss?

Jeffrey CW Chan 陳志宏, Kenneth KW Li 李啟煌

HK Pract 2013;35:24-26

Summary

Constipation, defined as difficulty in the passage of hard stools, is one of the most commonly encountered conditions in general practice. One local survey conducted in 2003 showed a prevalence of 14% in Hong Kong.¹ However, it often remains unrecognized as an important condition until complications such as anal fissures, haemorrhoids and per rectal bleeding developed. Less commonly known, visual loss and ocular disorder have occurred as a complication of constipation, as in the present case. The most common cause of constipation is idiopathic (functional), but it can also be due to secondary causes including organic diseases of the large bowel, endocrine / metabolic diseases or drugs. We report a case of a gentleman who presented with a two-day history of sudden loss of right eye central vision and central scotoma. The diagnosis in this case was valsalva retinopathy as a result of constipation, which was a side effect caused by medications (trimetazidine and omeprazole) for his chest pain.

摘要

便秘被定為排泄硬糞便時遇到困難, 是一種基層醫療常見的問題。一個在2007年做的本地調查發現在香港的患病率是百分之十四。但是像本個案一樣, 便秘往往不被發現直至有以下其中的併發症出現．肛門側裂, 痔瘡, 以及少有的眼部併發症。自發性或功能性便秘是最常見的病因, 但它亦可以因大腸器官性疾病、內分泌或者新陳代謝性疾病和藥物引致。本文的個案是一個男性患有2日病歷的右眼突發性失去中央視野和中央盲點。診斷是便秘引致的持續閉氣用力性視網膜病, 便秘是病人用來治療他胸痛的藥物（Trimetazidine 和Omeprazole）的副作用。

Case Report

A 58-year-old man with a past medical history of hypertension and obstructive sleep apnoea syndrome presented to the emergency department of our United Christian Hospital with a two-day history of right eye central visual loss. His visual acuities were 6/9 and 6/6 in the right and left eye respectively. Anterior segment examination, including intraocular pressure, were within normal limits. On fundal examination of the right eye, there was a small area of haemorrhage (measuring a third of an optic disc diameter) over the superonasal aspect of the macula (Figures 1A & 1B). On further questioning, the patient revealed that he had been suffering from constipation during the previous two weeks, after starting trimetazidine and omeprazole for chest pain. In view of the history and the clinical finding of premacular haemorrhage, the diagnosis of valsalva retinopathy was made. The valsalva retinopathy was most likely caused by straining during bowel motions. The patient was managed conservatively, and three months after presentation the premacular haemorrhage resolved spontaneously (Figure 2) and his visual symptoms subsided. His visual acuity was then 6/7.5 in both eyes. His constipation also resolved after adjustment of the medications by the physicians.

Discussion

Valsalva retinopathy, first described in 1972 ², is a form of retinopathy with retinal haemorrhage due to a sudden increase in intra-thoracic and intra-abdominal pressure following a valsalva manoeuver. This leads to an increase in intraocular venous pressure and rupture of retinal capillaries in the perifoveal region. The location of the haemorrhage is at the sub-internal limiting membrane or rarely, into the vitreous. Various kinds of activities or conditions have been reported to cause valsalva retinopathy, including weight lifting, sexual activity ⁴, colonoscopy ⁵, oesophagogastroduodenoscopy ⁶, severe coughing, vomiting and constipation. The typical presenting complaint is sudden, painless decrease in vision. Depending on the amount and extent of pre-retinal haemorrhage, patients can suffer from only a small central or paracentral scotoma to severe visual loss, if the haemorrhage is extensive. On fundoscopy, premacular haemorrhage of various sizes ranging from less than half a disc diameter to several disc diameters may be seen. Typically, one eye is involved; but bilateral involvements have been reported.

The main differential diagnoses of premacular haemorrhage include hypertensive retinopathy, branch retinal vein occlusion and exudative age-related macular degeneration (AMD) (Table 1).

In hypertensive retinopathy, arterioles narrowing and arteriovenous nicking are observed in the early stage. Sustained and poorly controlled hypertension will lead to the formation of flame-shaped retinal haemorrhages, retinal oedema and hard exudates due to disruption of the inner blood-retinal barrier and increased vascular permeability. Cotton wool spots which are neuronal debris accumulated in the nerve fiber layer may also be observed. Optic disc swelling and hard exudates arranged in a macular star configuration are seen in malignant hypertension.

In branch retinal vein occlusion, there are dilated and tortuous retinal venous vessels. Dot-blot haemorrhages, flame-shaped haemorrhages, retinal oedema, with or without cotton-wool spots are observed. These features are typically located at one quadrant of the retina.

Exudative age-related macular degeneration (AMD) can result in macular haemorrhage due to choroidal neovascularization, but the haemorrhage is typically subretinal and can be associated with subretinal fluid, hard exudate and macular edema. Fundal fluorescein angiography can be helpful if exudative AMD is suspected.

In the present case, a typical history of sudden painless visual loss following a valsalva manoeuver, together with a clinical finding of premacular haemorrhage, and in the absence of other signs of hypertensive retinopathy or branch retinal vein occlusion, one would be able to make a correct diagnosis. Serial fundus photographs can be used to monitor the progression of the retinal haemorrhage. Certain conditions including diabetes, hypertension, anaemia or other blood dyscrasias could cause retinopathy with retinal haemorrhages. Therefore complete blood count, fasting blood glucose and blood pressure can be ordered to exclude other causes of retinal haemorrhage.

The management of valsalva retinopathy is mainly conservative as the preretinal haemorrhage will resolve spontaneously. Patients should be advised against occurence of any further valsalva maneuver taking place. Underlying predisposing factors, such as constipation in the present case, should be managed. The prognosis of valsalva retinopathy is generally very good with visual recovery in most cases after resolution of the haemorrhage. In cases where there are large areas of premacular haemorrhage resulting in severe visual loss, Nd:YAG laser treatment can be used to puncture the posterior hyaloid face which allows drainage of haemorrhage into the vitreous cavity, leading to earlier visual rehabilitation.