Enophthalmos is defined as posterior displacement of a normal-sized globe relative to the lateral orbital rim.1 Although the definition is not entirely unbiased, some authors have endorsed absolute measurements on exophthalmometry as less than 10.0 to 12.0 mm.1 Other anatomic factors, such as orbital structure, can also influence clinical perception of enophthalmos. To the cataract surgeon, periorbital anatomy and orbital anatomy are usually of secondary concern. In some instances, however, such as when the eye is set deep in the orbit, accessing the eye with standard approaches can result in unnecessarily difficult surgery and a higher risk for complications. The first step is to understand the underlying etiology of the anatomic aberration. Only then is it possible to plan the cataract surgery, especially with respect to administering safe periocular anesthesia, performing an effective wound construction, ensuring adequate intraoperative visualization and, ensuring the surgeon's physical comfort and confidence during the procedure.
A 55-year-old woman initially presented with pain in the left eye. She reported the onset of intermittent episodes of severe pain in the left eye several months before the initial visit. An outside provider had originally diagnosed an “eye infection,” which was treated with topical antibiotics. After 2 months without relief, the patient sought a second opinion and was found to have elevated intraocular pressure (IOP) in the left eye with evidence of acute angle-closure glaucoma. A temporizing laser peripheral iridotomy was performed in the left eye, and the patient was referred to the glaucoma service for further workup.
At the time of presentation to tertiary care, the corrected distance visual acuity was 20/15 in the right eye and 20/20 in the left eye. External examination showed a pupillary distance of 63 mm, inner canthal distance of 38 mm, palpebral fissure height of 7.9 mm bilaterally, distance from upper lid margin to the pupillary light reflex (margin reflex distance) of 3.5 mm bilaterally, and palpebral fissure width of 24.1 mm on the right and 24.5 mm on the left. She had a prominent brow and deep-set eye. Axial displacement of the globe from the lateral orbital rims was measured as 18.0 mm in the right eye and 17.5 mm in the left eye.
Pneumatic tonometry measured an IOP of 19 mm Hg in the right eye and 47 mm Hg in the left eye. The central corneal thickness was 564 μm and 595 μm, respectively. Slitlamp examination of the left eye showed 1+ conjunctival injection, a fixed midposition pupil (4.3 mm diameter) with transillumination defects, posterior synechiae, and a partially patent peripheral iridotomy.
Automated static perimetry found no scotomata in the right eye (mean deviation −1.77 dB), and diffuse depression with a cecocentral scotoma in the left eye (mean deviation −5.90 dB). Fundus examination showed a normal disc appearance bilaterally with no disc edema, hyperemia, notching, or cupping. There was evidence of vascular tortuosity and dot and blot hemorrhages throughout the macula and periphery bilaterally, ostensibly from impending central retinal vein occlusion (CRVO). Optical coherence tomography showed no age-adjusted thinning of the retinal nerve fiber layer bilaterally. Given that the patient was in pain; that the IOP in the left eye was high, ostensibly due to phacomorphic angle closure; and that she was at risk for CRVO, the decision was made to begin aggressive medical therapy to lower the IOP and to proceed with lensectomy and goniosynechialysis in the left eye. Biometry measurements showed an axial length of 21.84 mm bilaterally.
In addition to the challenges of a relatively small eye, she had an orbital structure that would make cataract surgery difficult. She had an unusual facial appearance, inferiorly positioned superior orbital rims, and deep-set eyes, bilaterally and symmetrically. Her forehead was tall, appearing as sagittal synostosis reminiscent of scaphocephaly, with incomplete frontal overhang and very little space between the superior orbital rim and the globe. There was no midface hypoplasia or hypertelorism, and the lacrimal drainage system and eyelids were within normal limits (Figure 1).
Examination of the patient's father and her daughter showed similar facial features, present from an early age. In addition, they had a dystonic condition with progressive difficulty walking. However, and extensive neurologic workup failed to detect the exact cause and categorize the patient with a known syndrome.
Once supine in the operating room, the severity of the deep-set eyes with overhanging superior rims was thought to be incompatible with the standard approach of topical anesthesia cataract extraction with phacoemulsification. Even with the patient in the Trendelenburg position, attempts to reposition the patient's head and neck were met with pain and discomfort and she was unable to remain stationary; thus, this initial attempt at surgery was aborted.
Two weeks later, she was returned to the operating room, this time with plans to perform surgery under general anesthesia. She was placed in the reverse Trendelenburg position, and her neck was extended. This maneuver moved the prominent brow posteriorly and placed the eye at a near ideal position for intraocular surgery from a temporal approach. If this maneuver were not sufficient for adequate exposure, the surgeon planned to anchor the superior rectus muscle and rotate the eye inferiorly and medially. However, the exposure was satisfactory without further changes in the surgical plan and a temporal clear corneal incision (CCI) was created easily. The posterior synechiae were broken with 3 rounds of topical cyclopentolate 1.0% and phenylephrine 2.5% drops, and the pupil was sufficiently dilated for phacoemulsification. The surgery proceeded successfully without complications. The implementation of the general anesthesia and the position change did not significantly prolong the surgery.
Although this patient's orbital anatomic variation was compatible with her life and did not necessitate treatment for more than 50 years, it made cataract surgery challenging. Here, we discuss how to recognize challenging anatomy preoperatively and how to plan cataract surgery so that variations of orbital anatomy do not become an impediment.
In evaluating cataract patients with potentially problematic orbital configurations, it is useful to consider the etiology, not only in planning the surgery but also for overall long-term management of the patient. With A-scan ultrasound biometry, distinguishing enophthalmos from nanophthalmos is relatively straightforward. Several mechanisms result in enophthalmos: fat atrophy, structural abnormality, and traction. Fat atrophy is likely the most common underlying etiology, given the natural attrition of orbital fat with age as well as the widespread use of prostaglandin analogs, which are well known to cause deepening of the superior sulcus and relative enophthalmos via fat atrophy.1,2 Other conditions can cause attrition of fat; these include orbital trauma, radiation, vascular anomalies, and a variety of systemic diseases, including Parry-Romberg disease, scleroderma, and lipodystrophies.3 Fat atrophy caused by systemic conditions is usually bilateral, and a thorough history, physical examination, laboratory workup, and imaging are useful in recognizing these etiologies.1 Enophthalmos secondary to fat atrophy or fat displacement and scarring (eg, orbital floor fracture) usually does not present planning difficulties for cataract surgery.
Numerous developmental craniofacial abnormalities can lead to structural enophthalmos and might require surgical planning changes for intraocular procedures. These abnormalities are typically best observed on clinical examination and orbital imaging. These include the craniosynostoses, clefting disorders, and other orbital cranial malformations such as cephaloceles. We believe that such a malformation, albeit forme fruste, occurred in the patient described in our report. Other causes of structural abnormality include silent sinus syndrome, sphenoid wing dysplasia of neurofibromatosis, history of orbital fracture, and Paget disease of bone.1,4,5
Posterior traction, probably the most rare of the etiopathologies of enophthalmos, might occur as a result of extraocular muscle fibrosis, as seen in Duane syndrome.1 Another rare entity that can cause unilateral enophthalmos is scirrhous breast carcinoma.6 Of course, recognition of these entities requires detailed history-taking and examination, with particular attention paid to ocular motility, as well as neuroimaging and, typically, biopsy confirmation.
For patients with orbital structural anomalies, intraocular surgery considerations begin at the point of orbital regional anesthesia. With deep-set globes, the required angle of needle insertion might vary from the traditional retrobulbar block position used in cataract extraction. Angling the needle more than 10 degrees from the transverse plane at the inferolateral point of insertion can lead to excessive deviation of the needle, risking globe perforation.7,8 Other globe dystopias, such as forward-set eyes, can also lead to risk for damage to apical structures during retrobulbar block. As such, in patients with deeply recessed globes or tight eyelid margins, a transcutaneous block approach might be safest.9
A deep-set orbital structure also affects the access and wound construction in cataract extraction. A low or prominent brow makes temporal or superotemporal tunnel preferable.10 Likewise, anterior displacement of the wound in the form of CCI rather than scleral tunnel improves access and integrity of wound, as was the case in our patient.11 To further improve access to the globe, ideal head and neck positioning should be sought, if tolerated by the patient. Extension of the neck might displace the brow slightly posteriorly to expose the limbal area better in the primary position of the eye. Performing femtosecond laser–assisted cataract surgery rather than conventional phacoemulsification confers additional difficulties in achieving access to eyes with enophthalmos. Some authors suggest that a deep-set globe might be a contraindication to laser use in cataract extraction because of the impaired interface between the laser and globe, although others suggest that removing the speculum is sufficient to improve the interface.12,13 There are also considerations for postoperative outcomes because there is evidence that wound deformation is more common in deep-set eyes.12
In the setting of structural enophthalmos impeding cataract extraction, the surgeon should take into consideration certain modifications to standard phacoemulsification surgery. Use of general anesthesia or a transcutaneous block, positioning the patient in neck-extreme extension, and creating temporal or superotemporal CCIs might improve surgical access and minimize complications.
None of the authors has a financial or proprietary interest in any material or method mentioned.
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