Prolapse of the Eyeball (Bulbus Prolapse)
Eye prolapse, medically known as bulbus prolapse or proptosis bulbi, is an acute ophthalmological emergency in which the eyeball is displaced forward from its normal position in the eye socket (orbit). The eyelids become trapped behind the eyeball, preventing spontaneous retraction. Anatomically, the eyeball is normally held in position by several structures: the extraocular muscles, the optic nerve, the conjunctiva, and the retrobulbar fat tissue. In a bulbus prolapse, these supporting structures are overstretched or even torn. The conjunctiva and cornea are then exposed unprotected to the environment, which can quickly lead to drying out and further damage. This condition requires immediate veterinary treatment, as any delay significantly worsens the prognosis for preserving the eye and vision.
Causes
The main causes of eyeball prolapse are traumatic impacts and anatomical predispositions. Trauma usually involves blunt force to the head, such as can occur in traffic accidents, bite incidents, or falls. This causes a sudden increase in pressure in the retrobulbar tissue, pushing the eyeball forward.
Brachycephalic (short-headed) dog breeds with shallow eye sockets are particularly susceptible. In these breeds, such as Pugs, French Bulldogs, English Bulldogs, Shih-Tzus, Pekingese, and Boston Terriers, even relatively minor trauma or just strong pulling on the neck fur can lead to bulbus prolapse. The anatomical peculiarity of these breeds lies in the shortened skull shape with shallow eye sockets, which provides less bony support for the eyeball and sometimes already causes a slight physiological protrusion (exophthalmos).
Other predisposing factors can be tumors in the area of the eye socket, inflammatory processes, or congenital anomalies that impair the normal support of the eyeball. In cats, eyeball prolapse is less common and almost always caused by trauma, as their eye sockets are anatomically deeper than in many dog breeds.
Symptoms
- The eye lies with its “equator” outside the eye socket.
- The eyelids are trapped behind the eye, so the eye cannot slide back on its own.
- The conjunctiva is swollen and reddened.
- The eyelid cannot be closed.
- The entire eyeball may be bloodshot.
- The cornea of the eye dries out quickly, making it appear milky and cloudy.
- The eye is highly sensitive to pain.
An eyeball prolapse is characterized by a distinctive clinical picture. The affected eyeball protrudes significantly from the eye socket, with the equator of the eye becoming visible and the eyelids trapped behind the eyeball. The conjunctiva typically appears severely reddened, swollen, and may show bleeding. As the cornea is no longer moistened by regular blinking, it quickly dries out and becomes milky-cloudy.
Affected animals show clear signs of pain such as restlessness, vocalization, or rubbing their head against objects. The eye can no longer be closed, leading to further irritation. Often, bleeding in the area of the eyeball can also be observed, ranging from slight bleeding into the conjunctiva to massive bruising.
Depending on the severity of the triggering trauma, accompanying injuries such as skull trauma, fractures of the facial bones, or injuries to the nose and mouth area may occur. In severe cases, the optic nerve may be stretched or even torn, leading to immediate blindness. The eye muscles can also be damaged, limiting the mobility of the eye even if it is possible to reposition the eyeball.
First Aid
- Cover the eye with a moist cotton ball to prevent the cornea from drying out.
- Prevent your pet from scratching the eye
- Do not attempt to manipulate the eyeball to reposition it yourself.
- Do not try to clean the eye
Diagnosis
The diagnosis of an eyeball prolapse is primarily made through clinical examination. The characteristic appearance with the protruding eyeball and the eyelids trapped behind it is usually unambiguous. Nevertheless, a thorough examination by the veterinarian is essential to assess the extent of the damage and estimate the prognosis.
After initial care and stabilization of the patient, a detailed ophthalmological examination is performed, provided the animal’s general condition allows it. This includes assessing the pupillary reflex, corneal condition, and, if possible, the fundus of the eye. An absent direct pupillary reflex may indicate damage to the optic nerve.
Imaging techniques such as X-rays or computed tomography of the skull may be indicated if accompanying fractures or intracranial injuries are suspected. Ultrasound examinations of the eye can help detect injuries to intraocular structures, which are important for prognosis.
Differential diagnosis must distinguish a true bulbar prolapse from other conditions such as pronounced exophthalmos due to retrobulbar space-occupying lesions, inflammations, or edemas. The crucial difference is that in a true prolapse, the eyelids are trapped behind the equator of the eyeball.
Further veterinary measures
Go to the veterinarian immediately after the incident.
Keeping the eyeball moist until arriving at the veterinarian is the most important measure.
The sooner the eye is surgically repositioned under general anesthesia, the better the chances for a complete restoration of vision.
If the optic nerve is injured, the eyeball must be removed. This will hardly affect your pet’s quality of life.
The treatment of an eyeball prolapse requires a quick and systematic approach. Initial care aims to prevent further damage to the eye. This includes carefully covering the exposed eyeball with a sterile, moist compress or a damp cotton ball to prevent the cornea from drying out. It is important that pet owners do not attempt to push the eyeball back themselves, as this can lead to further damage.
The definitive therapy is performed under general anesthesia and includes the following steps:
First, the eyeball and surrounding tissues are thoroughly cleaned with sterile saline solution to remove foreign bodies and contaminants. In case of severe swelling of the eyelids, a temporary lateral canthotomy (surgical widening of the outer eye angle) may be necessary to facilitate repositioning. The veterinarian then carefully repositions the eyeball by gently and evenly pushing it back into the eye socket while pulling the eyelids over the eyeball.
After successful repositioning, a temporary tarsorrhaphy (eyelid suture) is often performed, where the eyelids are partially sewn together to keep the eyeball in position and protect the cornea. This suture usually remains in place for 10-14 days.
Accompanying medical therapy includes systemic antibiotics for infection prophylaxis, pain relievers, and anti-inflammatory drugs. Locally, antibiotic and moisturizing eye drops or ointments are applied.
In cases with severe damage to the optic nerve, irreparable injuries to the eyeball, or when repositioning is not possible, enucleation (surgical removal of the eyeball) may be necessary. This decision is made based on the severity of the injury and the prognosis for maintaining vision.
Prognosis and aftercare
The prognosis for an eye prolapse depends critically on several factors: the time between the incident and veterinary treatment, the extent of damage to the optic nerve and eye muscles, and the cause of the prolapse. The faster the treatment, the better the chances of preserving the eye and vision. Generally, if the eyeball is repositioned within 1-2 hours after the incident, the prognosis is significantly more favorable.
Aftercare includes regular follow-up examinations to assess healing and early detection of complications. The tarsorrhaphy sutures are removed after about 10-14 days. During this time, it is important that the animal wears an Elizabethan collar to prevent scratching of the eye.
The post-treatment medication consists of continuing antibiotic and anti-inflammatory therapy as well as local application of moisturizing eye drops. If signs of complications such as increasing redness, discharge from the eye, or deterioration of general condition occur, a veterinarian should be consulted immediately.
Long-term consequences can occur despite successful repositioning and include chronic keratoconjunctivitis sicca (dry eye), corneal ulcers, strabismus (squinting) due to damage to the eye muscles, or partial to complete blindness due to damage to the optic nerve. Regular ophthalmological check-ups are therefore recommended even after the acute treatment phase.
Summary
Eye prolapse (bulbus prolapse) is an ophthalmological emergency that requires immediate action. It occurs particularly frequently in brachycephalic dog breeds and is usually caused by trauma. The characteristic symptoms include the eyeball protruding from the eye socket with eyelids trapped behind it, redness and swelling of the conjunctiva, and drying of the cornea.
First aid consists of keeping the eye moist and immediate transport to the veterinarian. Definitive therapy is performed under general anesthesia and includes repositioning of the eyeball, possibly after lateral canthotomy, and temporary tarsorrhaphy. In cases of severe damage, enucleation may be necessary.
The prognosis depends significantly on the time of treatment and the extent of damage. Long-term consequences can occur despite successful treatment and require regular follow-up checks. Preventive measures for owners of predisposed breeds include avoiding collars in favor of harnesses and taking special care during play activities.
Outlook on current research
Current research in the field of eye prolapse focuses on several aspects. On one hand, improved surgical techniques are being developed that allow for gentler repositioning and minimize the risk of consequential damage. These include minimally invasive procedures and special instruments designed specifically for the anatomy of brachycephalic breeds.
Another research focus is on the development of new medications to reduce swelling and inflammation in the eye area, which can facilitate repositioning. Postoperative pain therapy is also being continuously improved to optimize the healing process.
Genetic research is also gaining increasing importance, aiming to better understand the anatomical predispositions of brachycephalic breeds and reduce them through targeted breeding programs. This is part of a broader discussion about harmful breeding practices and their associated health problems.
Last but not least, new materials and techniques for the temporary stabilization of the repositioned eyeball are being researched, which are intended to allow better healing while simultaneously improving comfort for the animal.
Frequently asked questions (FAQs)
- What is an eyeball prolapse and how do I recognize it?
An eyeball prolapse (bulbus prolapse) occurs when the eyeball has protruded from its normal position in the eye socket and the eyelids are trapped behind the eyeball. The eye protrudes noticeably, the conjunctiva is red and swollen, and the animal shows signs of pain. - Which dog breeds are particularly at risk?
Particularly at risk are brachycephalic (short-headed) breeds with flat eye sockets such as Pugs, French and English Bulldogs, Shih Tzus, Pekingese, and Boston Terriers. - What should I do if my pet suffers an eyeball prolapse?
Carefully cover the eye with a damp, clean cloth, prevent the animal from scratching the eye, and take it to a veterinarian immediately. Do not attempt to push the eyeball back in yourself. - Can a prolapsed eyeball be saved?
Yes, if treatment is prompt and there is no severe damage to the optic nerve or intraocular structures, the eye can often be saved. The prognosis is better the earlier treatment is received. - How is an eyeball prolapse treated?
Treatment is performed under general anesthesia and includes cleaning, possibly a lateral canthotomy, careful repositioning of the eyeball, and usually a temporary tarsorrhaphy (eyelid suture). - What is the prognosis after an eyeball prolapse?
The prognosis depends on the time until treatment and the extent of damage. With prompt treatment and minor damage, the prognosis is good; with severe injuries to the optic nerve, blindness may result. - Can an eyeball prolapse be prevented?
For predisposed breeds, precautionary measures such as using harnesses instead of collars and avoiding situations with increased risk of injury can reduce the risk. - How long does healing take after an eyeball prolapse?
The acute healing phase lasts about 2-3 weeks, during which the tarsorrhaphy sutures are left in place. Complete healing and assessment of long-term vision can take several months. - What complications can occur after an eye prolapse?
Possible complications include keratoconjunctivitis sicca (dry eye), corneal ulcers, strabismus (squinting), and partial or complete blindness. - Can a dog live normally with only one eye?
Yes, dogs usually adapt perfectly to the loss of an eye. They quickly learn to compensate for the altered depth perception and can lead a normal, active life.
Literature
- Lutz, H., B. Kohn and F. Forterre: Diseases of the Cat. 6th updated edition 2019. 1080 p., ISBN 9783132416499
- Eule, C. (2019). Bulbus Prolapse – A Traumatic Event. Kleintier konkret, 22(3), 18-25. DOI: 10.1055/s-0039-1678931
- Gould, D., & McLellan, G. J. (2022). BSAVA Manual of Canine and Feline Ophthalmology. 4th Edition. British Small Animal Veterinary Association. ISBN: 978-1905319398
- Maggs, D. J., Miller, P. E., & Ofri, R. (2023). Slatter’s Fundamentals of Veterinary Ophthalmology. 7th Edition. Elsevier. ISBN: 978-0323613910
- Ledbetter, E. C., & Gilger, B. C. (2021). Diseases and Surgery of the Canine Cornea and Sclera. In: Gelatt, K. N., Ben-Shlomo, G., Gilger, B. C., Hendrix, D. V., Kern, T. J., & Plummer, C. E. (Eds.), Veterinary Ophthalmology. 6th Edition. Wiley-Blackwell. ISBN: 978-1119441632
- Reinstein, S. L., & Rankin, A. J. (2020). Management of Ocular Emergencies in Small Animals. Veterinary Clinics of North America: Small Animal Practice, 50(6), 1261-1276. DOI: 10.1016/j.cvsm.2020.07.002
Surgical removal of a prolapsed eyeball (Bulbus extirpation)
Healed bulbus extirpation in a Cocker Spaniel puppy