This article reviews the indications, preoperative evaluation, surgical management and postoperative care for orbital decompression patients. The orbit contains the eye, extra ocular muscles, orbital fat, and other neural and vascular tissues. Orbital decompression is an operation aimed at expanding the orbital volume generally by removal of one or more portions of bone, or orbital walls. An oculofacial plastic surgeon may recommend this type of surgery to treat various conditions, as described below.
Indications for orbital decompression
The most common indication for orbital decompression is related to potential damage to the eye or optic nerve due to proptosis or compression on the optic nerve. The etiologies of the proptosis include thyroid eye disease, congenital shallow orbits, relative maxilla hypoplasia, orbital tumors, and orbital hemorrhage, although orbital decompression is rarely done for the latter two etiologies. Orbital decompression is done to reduce the bulgy appearance of the eyes, either for functional (medical) or cosmetic reasons (cosmetic orbital decompression), by removing orbital fat and bone. Another rare indication for orbital decompression is compressive optic neuropathy.
Anatomy of eye/orbit
A thorough understanding of the eye/orbit is essential when evaluating patients for possible orbital decompression. The orbit is a solid structure that houses the eyeball, fat, muscles, vessels, and nerves. The orbit itself is surrounded by the maxillary sinus inferiorly, ethmoid sinus medially, brain superiorly, and temporalis muscle temporally. Orbital decompression involves removing or thinning various safe orbital walls (and orbital fat), thereby expanding the eye socket, allowing the eyeball to settle back. It can be customized according to the need of proptosis reduction along with functional and cosmetic needs.
Clinical examination of the eye, orbit, and surrounding structures is critical to determine the etiology of the proptosis, severity of the proptosis, and other contributing factors. Orbital/head imaging (CT and/or MRI) would assist in determination of the cause of the proptosis and help assist in planning for the customized surgery by visualizing the position/thickness of various orbital bones and surrounding structures.
Eye/eyelid/orbit examination, including:
- Full eye exam (vision, ocular motility, pupil, intraocular pressure, anterior segment exam, dilated fundus exam)
- Eyelid examination (eyelid position, function, lagophthalmos, etc)
- Orbital exam (bony structure, presence of any masses, retropulsion, Hertels measurements)
- Periocular exam (edema, erythema, etc)
The degree of proptosis varies from subtle to very severe, with symptoms ranging from none to various symptoms. When compressive optic neuropathy occurs there may be visual field defects, color vision loss, an afferent pupillary defect, and vision loss. Examination of the cornea may reveal punctate epithelial erosions from dry eyes. If the erosions are concentrated in the inferior portion of the cornea it may be a sign that the patient is experiencing lagophthalmos, or inability to fully close the eyelids.
Proptosis can be subtle without any symptoms. Oftentimes the patient will notice some "bulging" of their eyes in photos or as noted by friends or family members. Patient may also note tearing which is worse with proptosis due to exposure of the cornea and increased surface area of the eye, resulting in increase evaporation of the tear film. Some patients with thyroid eye disease note pain around the eye which is thought to occur from pressure on the sensory nerves around the orbit. More severe symptoms of proptosis may include the inability to close the eyes (lagophthalmos), diplopia, and decreased vision.
Physical examination is critical in diagnosing proptosis and its severity. Looking at old patient's eye/face photos can be useful as well.
The main diagnostic tool is orbital/head imaging (CT or MRI), although certain blood tests may add value depending on the etiology of the proptosis.
Eyelid retraction and globe malposition can give illusion of bulgy eyes.
Lubrication (and other dry eye therapy) is useful for treating some of the symptoms of proptosis, depending on its severity. Other medications may be needed, depending on the etiology of the proptosis. Proptosis itself is treated surgically (via orbital decompression).
Orbital decompression is performed under general anesthesia. Orbital decompression is performed for either functional or cosmetic reasons. More orbital decompression (greater amount of bony and fat removal or debulking) is usually necessary for functional (medically necessary) orbital decompression and usually less is needed for cosmetic orbital decompression. The surgical principle is the same in both, where various amounts of orbital fat and orbital bone is removed. The best and safest first orbital wall to remove (or thin out) is the lateral orbital wall, followed by the medial wall, and last the orbital floor. More reduction with added risk is taken as more walls are decompressed. Incisions are hidden in the lateral upper eyelid crease (for lateral orbital decompression), caruncle or transcaruncular (for medial wall decompression) and lower eyelid conjunctiva (for orbital floor decompression).
Orbital decompression is done on outpatient basis, usually one eye at a time although both eyes can be done together. Since there are no eye patches placed, the patient is immediately able to see after surgery. There is some pain in the first day of the surgery, controlled by oral pain medication. There is fair amount of bruising/swelling around the eye which lasts up to 2 weeks. The patient is asked to limit physical activity for 10 days and not blow their nose. Follow up is one week, one month, and three months after surgery.
- Double vision
- Under correction
- Over correction
- Other rare complications
The effect of orbital decompression is noticed soon after surgery with high success rate.