Ocular manifestations of trauma

Introduction

Common ocular manifestations of trauma will be reviewed, including eyelid and corneal lacerations, hyphema and blunt trauma, and retinal detachments.

Eyelid lacerations are common in performance horses.1 The extent of eyelid injury can vary from involving only a portion of a single eyelid or can affect large sections of both the upper and lower eyelids. During the initial evaluation, a complete ocular examination should be performed to identify the extent of the trauma and identify any concurrent abnormalities such as corneal ulceration, uveitis, ocular hemorrhage, or retinal damage (e.g., retinal detachment). Even with severe lacerations, the eyelids are highly vascularized and often heal well with primary closure. In rare cases, when eyelid trauma is so severe that repair is not possible such that the eyelids are completely severed and/or there is extensive concurrent ocular damage (globe rupture, large corneal laceration with iris prolapse), then enucleation is generally indicated. Eyelid lacerations should be repaired surgically. When repairing an eyelid laceration, the goal is to maintain integrity of the eyelid margin with as perfect apposition as possible. Gentle debridement of any necrotic tissue may be needed to obtain clean, fresh wound edges; however, overly aggressive eyelid debridement or excision of too much eyelid margin can result in persistent exposure keratitis and discomfort. Postoperatively, the horse should be fitted with a protective visor to prevent self-trauma. Treatment consists of topical antimicrobials administered three to four times daily, systemic anti-inflammatories for 3-5 days, and often systemic antibiotics. Topical treatment should be continued until skin sutures are removed in 10-14 days. Prognosis for eyelid lacerations is generally good as long as surgery was performed accurately.

Corneal lacerations - When treating a corneal ulcer, if the lesion is greater than 50 percent of the depth of the cornea, then surgical therapy, such as a conjunctival or amnion graft, should be considered to prevent possible perforation.2 The prognosis is worse if the corneal laceration involves the limbus; significant hyphema is present; the lens is perforated; if a large uveal prolapse through the incision is present; or if the dazzle and consensual pupillary light reflexes are absent. Examination of a perforated eye should include complete ophthalmic examination (including evaluation of dazzle and consensual pupillary light reflexes) with the horse adequately tranquilized and eyelid nerve blocks done to ensure that no further damage is done as a result of the examination. If the posterior segment (vitreous and retina) of the eye cannot be visualized on the ophthalmic examination, then an ultrasound should be considered. If the vitreous is hyperechoic (i.e., blood or cellular infiltrate) or a retinal detachment is observed on the ultrasound, then the prognosis for return to vision is very poor. Repair of the laceration should be done as soon as possible to prevent further inflammation and contamination of the intraocular structures. Enucleation should be considered if there is no consensual PLR; a large uveal prolapse is present; or if ultrasound results suggest a poor prognosis for return of vision.

Hyphema and Blunt trauma - Blunt trauma can manifest as eyelid swelling, eyelid lacerations, corneal ulceration, cornea rupture, hyphema, lens luxation or cataract, vitreous hemorrhage and/or retinal detachment. If the clinician suspects blunt trauma, a complete ophthalmic examination is performed. If this is not possible due to opacities of the ocular media, , then an ocular ultrasound should be performed to assess the ocular posterior segment. Very commonly with severe blunt trauma, there is blepharoedema, limbal corneal rupture with iris prolapse, hyphema, and retinal detachment. Such severe trauma is generally not reparable, generally requiring an enucleation be performed.

In a recent study,³ the most frequent ocular findings after blunt ocular trauma included cataract (36/55, 65.5%), corneal edema (26/55, 47.2%), decreased intraocular pressure (23/55, 41.8%), aqueous flare (19/55, 34.5%), lens subluxation, luxation, or lens loss (18/55, 32.7%), fibrin in the anterior chamber (18/55, 32.7%), hyphema (16/55, 29.1%), peripapillary depigmentation (“butterfly lesion”) (16/55, 29.1%), conjunctival hyperemia (16/55, 29.1%), corneal fibrosis (15/55, 27.3%), corpora nigra avulsion (14/55, 25.5%), blepharospasm (13/55, 23.6%), and iridodialysis (11/55, 20.0%).

Retinal Detachment - A retinal detachment is the separation of the neurosensory retina (NSR) from the outer retinal pigmented epithelium (RPE). The retina can detach as a result of fluid accumulation between the NSR and RPE, a retinal tear and migration of fluid from the vitreous into the intraretinal space, blunt force trauma, or traction toward the vitreous secondary to resolution of vitreal hemorrhage or after hyalitis. Accumulation of fluid between the NSR and RPE is most commonly the result of inflammation, with ERU being the most common cause. The retina may re-attach with folds or wrinkles, most commonly radiating outward from the optic nerve. In a retrospective study of 40 horses (46 eyes) with retinal detachment,4 the detachment was partial in 14 horses and complete in 32 horses. The etiology was diagnosed to be ERU in 27 horses (33 eyes) (67.5%) and trauma in 10 horses (10 eyes) (25%). The prognosis for vision in horses with retinal detachment is grave with many eyes going on to enucleation or evisceration. The underlying cause of inflammation needs to be managed, and if management is successful, a bullous detachment may re-attach if the inflammation is resolved and the RPE is able to pump the fluid out of the intraretinal space.