Blunt Ocular Trauma

• Blunt ocular trauma (BOT) happens when a significant external force impacts the eye and orbit, increasing intraocular pressure and compressing the eye's contents.
• This can harm various eye structures and interfaces.
• Blunt ocular trauma refers to closed or open globe injuries caused by a blunt object, excluding lacerations or perforations.
• Blunt ocular trauma appears in horses due to their eye position, "flight nature," and potential for significant force generation.
• Close-quarters housing can also increase risk.
• Unsupervised events mean many instances are unwitnessed.
• Observed signs include orbital fractures, eyelid issues, hemorrhage, corneal abrasion, and hyphema.
• Other signs are uveitis, corpora nigra avulsion, lens issues, phacoceles, cataract development, and retinal detachment.
• The non-specific nature of these signs can make diagnosing blunt ocular trauma challenging without confirmed trauma.
• The aim of this study was evaluate the frequency of clinical signs in blunt ocular trauma cases versus non-trauma-induced uveitis.
• This could aid in recognition, separation and impact treatment, prognosis, and pre-purchase examinations.
• The documentation included color and infrared photography.
• Ophthalmic medical records were reviewed from January 2013 to December 2019 from two locations.
• Cases were included if there was a witnessed trauma, additional traumatic injury, specific ocular findings, or a blunt ocular trauma diagnosis in the record.
• Horses with recurrent uveitis episodes were excluded.
• A complete ophthalmic exam was performed with slit lamp biomicroscopy and indirect ophthalmoscopy.
• Photographs were taken with color and converted infrared cameras, and intraocular pressures were measured.
• Board-certified veterinary ophthalmologists evaluated all horses.
• Age, sex, eye, and clinical findings were recorded, with trauma classified as confirmed or suspected.
• Data was analyzed to determine common clinical signs, and non-trauma-related uveitis cases served as a comparison.
• The comparison group consisted of horses diagnosed with non-trauma-related uveitis, excluding those with prior ophthalmic surgery or primary corneal disease.

Statistical Analysis

• Statistical analyses used SAS 9.4 with a significance threshold of 0.05.
• Analyses included confirmed and suspected blunt ocular trauma, then confirmed cases only.
• Breed and sex differences were tested using Fisher's exact tests, while age differences were tested using a Welch's t test.
• Generalized linear mixed models tested associations between blunt ocular trauma presence, laterality, and clinical findings.

Results of the study

• The study included 1476 horses, with 223 having complete records (288 eyes).
• Blunt ocular trauma inclusion criteria was met by fifty-five eyes (55 horses).
• 14 cases were confirmed and 41 were suspected.
• The rate of confirmed and suspected blunt ocular trauma cases was 3.7%.
• There were 17 mares, 28 geldings, and 3 stallions; 7 without sex recorded.
• Average age in confirmed blunt ocular trauma cases was 9.1 years and suspected cases 13.9 years.
• Warmbloods were the most common breed (20 horses), then Quarter Horses, ponies, and Arabians.
• Causes were a kick from another horse, post collision, polo ball blow, and collision while shod.
• 233 eyes (168 horses) were diagnosed with non-trauma-related uveitis and served as the comparison group (15.8%)
• The non-traumatic uveitis comparison group comprised of 64 mares, 87 geldings, and 11 stallions; 6 without sex recorded.
• Average age of horses with non-traumatic uveitis group was 11.3 years.
• Warmbloods were again the most common breed (72 horses), then Quarter Horses, spotted horses, Knabstruppers, gaited horses etc.
• There was no significant affect due to sex and age on likelihood of blunt ocular trauma.
• Ponies were more likely to have blunt ocular trauma when both confirmed and suspected cases were included.
• Fifty-nine clinical findings were recorded for each eye from both groups.

Prominent Signs Examined

• Most frequent ocular findings after known or suspected blunt ocular trauma include cataract (65.5%), corneal edema (47.2%), decreased intraocular pressure (41.8%), aqueous flare (34.5%), lens subluxation, luxation, or loss (32.7%), fibrin in the anterior chamber (32.7%), hyphema and peripapillary depigmentation (29.1%), conjunctival hyperemia (29.1%), corneal fibrosis (27.3%), corpora nigra avulsion (25.5%), blepharospasm (23.6%), and iridodialysis (20.0%).
• The comparison group of non-traumatic uveitis: cataract (55.4%), decreased intraocular pressure (48.9%), aqueous flare (47.6%), keratic precipitates (47.6%), corneal edema (42.9%), corneal vascularization (42.0%), conjunctival hyperemia (36.9%), vitreal degeneration (31.8%), miosis (31.8%), blepharospasm (23.2%), synechiae (22.3%), and corpora nigra atrophy (21.5%).
• Eleven of the clinical signs were only present in the non-traumatic uveitis group.
• Signs positively associated with blunt ocular trauma were periocular abrasions/lacerations, blepharoedema, hyphema, fibrin in the anterior chamber, and peripapillary depigmentation.
• Additional signs of blunt ocular trauma are corneal fibroisis, shallow or collapsed anterior chamber, corpora nigra avulsion, iridodialysis, lens subluxation/luxation/loss, retinal detachment, and globe rupture.
• Chemosis was significantly associated with blunt ocular trauma in the confirmed group, and corneal vascularization and keratic precipitates were associated with a decreased likelihood of blunt ocular trauma.

Discussion

• This study highlights the frequency of reported clinical signs in both blunt ocular trauma and non-traumatic uveitis and their significance.
• Specific findings may differentiate blunt ocular trauma from other uveitis types.
• While not every case will present all signs, any combination suggestive should be evaluated carefully.
• Presentation cataracts occurred often at onset, at 65.5% of the cases and this agreed with human literature.
• The current study recorded peripapillary depigmentation as a statistically significant positive association with blunt ocular trauma.

Conclusions

• The study identifies key ocular signs and combinations associated with blunt ocular trauma in horses.
• This enables differentiation from other uveitis types, impacting treatment, prognosis, and pre-purchase exams.
• Recognizing correlations facilitates useful recommendation.