Commotio retinae

Description

After blunt eye trauma, the transmission of pressure to the retina occasionally results in axoplasmic stasis, intracellular swelling within the outer retinal layers and fragmentation of photoreceptors. This results in homogeneous areas of pale, swollen retina known as commotio retinae. As commotio retinae implies that the eye has been subjected to considerable force, the clinician is obliged to exclude other traumatic injury to the eye and surrounding structures.

Symptoms

The effect on visual fields and central visual acuity is variable. In most patients, visual deficits are detectable only on formal testing. Central visual acuity is affected only if the macula is involved.

Signs

The affected area of retina appears normal immediately after the trauma; it becomes pale grey and opaque over the following several hours. The overlying retinal vessels appear normal and are not obscured from view unless the nerve fibre layer is also affected.

Comprehensive examination of both eyes, with scleral indentation, is required in all cases of blunt trauma sufficient to cause commotio retinae. (Scleral indentation is contraindicated in the presence of hyphaema, or when penetrating ocular injury cannot be excluded.) For example, some traumatic ocular conditions are:

Choroidal rupture: pale streaks, often crescent-shaped and concentric to the optic disc.
Preretinal haemorrhage: confined collections of blood, often with a flat upper border and curved lower border (‘boat-shaped’).
Retinal break: full-thickness retinal tear, often horseshoe-shaped (risk of retinal detachment).
Traumatic optic neuropathy: relative afferent papillary defect, decreased color vision
Other ocular conditions, e.g. hyphema, corneal abrasion, periocular bruising, ruptured globe, orbital blow-out fracture, retrobulbar hemorrhage.

Prevalence

Unknown.

Significance

Commotio retinae may be associated with serious traumatic ocular injuries. Regular review is required to detect and treat subacute complications of ocular trauma, such as retinal detachment and elevated intraocular pressure.

Differential diagnosis

Retinal detachment; branch retinal artery occlusion; white without pressure; Purtscher’s retinopathy: retinal whitening associated with compressive chest trauma or other systemic conditions (Fig. 38.2).

Management

A full ocular assessment for other traumatic conditions is indicated, as listed above. Systemic physical assessment may also be required, depending on the mechanism of injury.

Ocular tests, imaging investigations Visual fields are recorded as a baseline measurement. With fluorescein angiography the affected areas block background choroidal fluorescence.

Review As most cases resolve spontaneousty over a few weeks, initial review is recommended at 2 weeks. When a retinal break has been sustained, retinal

Fig. 38.1

Commotio retinae.

Fig. 38.2

Retinal whitening (cotton-wool paches) and retinal hemorrhages associated with Purtscher’s retinopathy: a differential diagnosis of commotio retinae.

detachment may be delayed by several months – probably because the vitreous is slow to degenerate and liquefy. The patient is advised to seek medical attention should symptoms of retinal detachment develop (flashing lights, floaters, shadow moving across the field of vision). Macular holes may occur at the time of injury, or following subsequent vitreous detachment.
Permanent retinal pigment epithelium changes are common, usually with a focal granular pattern in the area of injury.

Advice No treatment is known to facilitate the resolution of commotio retinae. The prognosis for vision is generally excellent. Uncommonly, permanent loss of central vision occurs after photoreceptor damage at the macula, macular hole and/or retinal detachment.