Hyphaema

36 Hyphaema




INITIAL PRESENTATION


Abnormal appearance – red



PRESENTING SIGNS


Hyphaema is blood in the anterior chamber, and therefore presents as a red eye! Normally it is acute in onset. The owners might be aware of a traumatic incident – road traffic accident, kick in the face by a horse or accidental blow to the eye by a football for example. However, there might be no antecedent event known. The patient might be well in themselves, or have other clinical signs depending on the underlying cause for the bleeding. One or both eyes might be affected and vision can clearly be impeded. Many patients show no particular signs of ocular discomfort, but some exhibit the typical signs of ocular pain – namely blepharospasm, photophobia and increased lacrimation. Owners will normally present patients to the surgery rapidly since the dramatic appearance of hyphaema is alarming to them, even if the patient seems otherwise well.



CASE HISTORY


The history of patients with hyphaema can be very variable depending on the underlying cause. As mentioned above, a traumatic incident might be known. The patient might have had access to rat poison or similar toxins, or have recently travelled abroad and come into contact with infectious agents such as the tick-borne diseases. A history of previous systemic disease such as hepatic or renal insufficiency might be present, or the patient might have known neoplastic disease elsewhere in the body. It might be undergoing treatment for hypertension or have an underlying cardiac problem. In young animals a congenital abnormality might be present and examination of litter mates and sire and dam could be useful. Thus it is very important to take a thorough case history for any patient presenting with hyphaema – there are numerous potential causes, some of which can be ruled out immediately from the history, while others will require further investigation.



CLINICAL EXAMINATION


A general clinical examination must be performed on any patient presenting with hyphaema. Careful examination for haemorrhages elsewhere in the body – gums, skin, into the gastrointestinal tract for example – should be undertaken. The patient should be checked for signs of trauma – bruising around the face, scuffed nails, other injuries including skull fractures and so on. Chest auscultation and abdominal palpation can be informative. Occasionally the patient will be pyrexic if an infectious aetiology is present.


Ophthalmic examination will include careful assessment of the globe for evidence of trauma – blunt or penetrating. Subconjunctival haemorrhage is frequently present following blunt trauma, while a corneal injury might be noted following sharp trauma. Fluorescein testing should be performed. Vision should be assessed. The amount of blood present in the anterior chamber will determine the appearance – a small bleed will settle to the ventral anterior chamber and a fluid line will be noted, while a more severe bleed can present with the anterior chamber full of blood such that no intraocular structures can be evaluated (Figure 36.1).


image

Figure 36.1 Total hyphaema in a 4-year-old West Highlight White terrier. The dog ran into the door jamb while chasing a cat out of the kitchen the previous day, and thus a traumatic aetiology was suspected.


If the pupil can be seen, reflexes should be checked. If it cannot be seen, then the indirect response in the fellow pupil is important since this can indicate whether the fundus and optic nerve in the affected eye are responsive to light. If there is no constriction of the fellow pupil when light is shone into the affected pupil, this might suggest severe posterior segment damage and the prognosis for any return of vision is guarded. The dazzle reflex should be similarly checked and carries comparable prognostic information.


The colour of the blood can give an indication regarding chronicity – in acute bleeds it will be bright red, while if present for several days it becomes much darker in colour. If clotted there might be ‘clumps’ seen in the pupil, mixed with fibrin and other inflammatory mediators (Figure 36.2), while unclotted blood will sink to the ventral anterior chamber.


image

Figure 36.2 Clotted hyphaema in a hypertensive cat.


The fellow eye should be evaluated. If trauma is not the cause for the hyphaema, then a systemic disease could be present. In many such cases there will be bilateral ocular abnormalities, although these are not necessarily symmetrical. Small petechiae might be visible on the iris providing it is not very darkly coloured when appreciation of such haemorrhages is much more difficult. Fundus examination might reveal retinal haemorrhages or vessel abnormalities suggestive of a vasculitis or hypertension. Retinal detachment might be present. If vitreal haemorrhage is present, this will be seen as strands or clumps of blood obscuring the view of the fundus (see Case 33.2 and Figure 33.4).


Intraocular pressure should be measured, if possible, and can be normal, reduced or elevated in cases of hyphaema. Treatment choices will vary according to intraocular pressure and hence measurement is important.




DIFFERENTIAL DIAGNOSES


There are many potential causes for hyphaema (see Figure 36.3):


• Trauma – blunt or penetrating

• Coagulopathies – inherited clotting problems, following dicoumarin poisoning, acquired with renal or hepatic disease

• Blood dyscrasias – hyperviscosity, anaemia, polycythaemia, thrombocytopenia of various causes

• Hypertension

• Vasculitis – due to tick-borne diseases (e.g. ehrlichia)

• Intraocular neoplasia

• Associated with uveitis, glaucoma or retinal detachment where neovascularization has occurred

• Associated with congenital abnormalities – collie eye anomaly, persistent hyperplastic primary vitreous, persistent hyperplastic tunica vasculosa lentis, retinal dysplasia.

image

Figure 36.3 Decision-making tree – causes of hyphaema.



CASE WORK-UP


If there is total hyphaema, such that intraocular examination is not possible, then ultrasonography should be performed. This is of particular help following blunt trauma, where evaluation of intraocular structures can be essential regarding the prognosis for return of vision, or even saving the eye. Thus the globe outline should be evaluated. With severe blunt trauma posterior scleral rupture can occur and such eyes should undergo early enucleation. If the globe appears intact, evidence of vitreal haemorrhage or debris, retinal detachment and lens damage can be assessed.


The prognosis for purely anterior chamber bleeding is much better than if the posterior segment is also involved. In addition to checking for traumatic damage, neoplastic processes might be identified on ocular ultrasound – a ciliary body mass, for example, can cause quite severe haemorrhage. If suitable probes are not available for ocular examination (7.5–12 Hz normally), or if the practitioner is not familiar with the interpretation of ocular ultrasonograms, then referral should be considered.


If there is evidence of trauma to the globe, skull radiography might be warranted.


If there is no suggestion of trauma, from the history and clinical examination, and especially if the condition is bilateral, laboratory investigation is necessary. Blood samples for complete haematology and biochemistry (including electrophoresis) and clotting profiles should form the baseline evaluation. Blood pressure should be measured. Depending on the findings, further investigations such as urinalysis, abdominal ultrasonography and radiography, serology for specific infectious agents and bone marrow biopsy might be advised.




NURSING ASPECTS


All patients with hyphaema should be kept quiet. If allowed to bark or get excited the blood will mix with the aqueous again and resorption will be reduced. Activity levels certainly affect the distribution of blood – owners will frequently comment that the eye looks better in the morning, after the pet has been asleep and settled, but becomes more red during the day purely as a result of ocular and general movement and not because there has been further bleeding.


Thus cage rest (with sedation if required) is advised. Topical medication will normally be prescribed. Some patients have serious, potentially life-threatening systemic disease and general supportive as well as specific nursing duties will be applicable.

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Sep 10, 2016 | Posted by in SMALL ANIMAL | Comments Off on Hyphaema

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