|Year : 2022 | Volume
| Issue : 5 | Page : 61-66
Ophthalmological care of patients with craniofacial disorders
Jaime Grant, Joe Abbott, Desiderio Rodrigues, Sally L Painter
Department of Craniofacial Surgery, Birmingham Women and Children’s Foundation NHS Trust, Birmingham, UK
|Date of Submission||04-Apr-2022|
|Date of Acceptance||04-Apr-2022|
|Date of Web Publication||19-Sep-2022|
Dr. Jaime Grant
Department of Craniofacial Surgery, Birmingham Children’s Hospital, Steelhouse Lane, Birmingham B4 6NH
Source of Support: None, Conflict of Interest: None
| Abstract|| |
Patients presenting with craniofacial conditions present a unique challenge from an ophthalmological view point. There are no set guidelines as to their management or their long-term monitoring and follow-up. Largely, this should be the remit of a dedicated craniofacial team. Here we present pertinent ophthalmological pathology occurring in combination with craniosynostosis alongside the protocol employed in Birmingham Children’s Hospital for the management of these patients.
Keywords: Amblyopia, anisometropia, craniosynostosis, glaucoma, papilledema, proptosis, strabismus
|How to cite this article:|
Grant J, Abbott J, Rodrigues D, Painter SL. Ophthalmological care of patients with craniofacial disorders. J Pediatr Neurosci 2022;17, Suppl S1:61-6
| Introduction|| |
Synostosis of the cranial sutures can occur in isolation or as part of a wider syndrome. The presence and likelihood of ophthalmological pathology are determined by the suture(s) involved, and whether the synostosis is part of a genetic syndrome. When considering the ophthalmological sequelae of these conditions, one must consider whether it is a:
- Finding due to anatomical variance due to the synostosis—either of the skull base or the orbital or the extraocular muscles;
- Finding as part of a syndrome but unrelated to the anatomical variance caused by the synostosis;
- Finding due to raised intracranial pressure (ICP);
Knowing the ophthalmological findings helps in treatment planning: both in terms of planning investigation for an associated condition (e.g., raised ICP) or surgical planning (e.g., for squint surgery in unicoronal synostosis). The ophthalmological findings are best understood in the context of the genetics, radiological findings, developmental progress, and symptomatology of a child; hence, there is importance of multi-disciplinary work-up for children with craniofacial disorders.
| Strabismus|| |
Strabismus, or ocular misalignment, is common in the pediatric population, with an incidence of 2% in the UK. The incidence of strabismus is increased in children with craniosynostosis, with some studies reporting rates in the region of 50% for all subtypes. Strabismus occurs in all subtypes of craniosynostosis, although it is much more common in syndromic craniosynostosis, unicoronal synostosis, and in those cases in which surgery has involved the orbit. Conversely, synostosis which affects the sagittal, metopic, or lambdoid sutures has an incidence of strabismus similar to the normal population.
Anatomical differences, and variance in osteological anatomy, alter the position of the orbital musculature., Coronal synostosis results in excyclorotation of the muscle cone, therefore altering the effective pulling forces of the muscles. In particular, with regard to syndromic cases, there can be variations in the musculature of the orbit per se with diminutive, bifid, or even absent ocular muscles. Surgery to the orbit can alter muscular insertions, and strabismus as a complication of surgery for craniosynostosis is documented in the literature. Close examination of orbital magnetic resonance imaging (MRI) will enable ophthalmic surgeons to detect the presence or absence of extraocular muscles. Excyclorotation of the muscular cone can be seen and measured on coronal slices [Figure 1]D and E.
|Figure 1: Eye alignment showing that eyes are straight in the primary position (B), but elevate on adduction of the right eye (A) and left eye (C). This corresponds to alteration in orbital anatomy shown on coronal CT scan (D) and excycloration of the muscle cone shown on T2-weighted coronal MRI scan (E)|
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Children with craniosynostosis often have a V-pattern due to excyclorotation of the muscles, especially in the context of multi-suture or syndromal disease. In normal orbital anatomy, the medial rectus is a primary adductor. If the musculature becomes excyclo-rotated, the medial rectus also elevates the eye [Figure 1A]-C]. The subsequent upward movement on attempted adduction can mimic an inferior oblique overaction or a superior oblique palsy. In abduction, the lateral rectus becomes a depressor mimicking inferior rectus overaction. When coronal synostosis is bilateral, this can produce a see-saw pattern of eye movements as the adducting eye elevates, whereas the abducting eye depresses.
Those with a unilateral coronal synostosis can tilt their head away from the side of the synostosis in order to align the images from each eye. With their head in the compensatory head posture, ocular alignment may be normal. It is only when the head posture is normalized that the vertical heterotropia is noticed.[6 This is an ocular torticollis; a head position which offers an advantage in terms of binocularity (using both eyes at the same time to perceive one image with depth-awareness) for a child. In this situation],[ squint surgery to the extra-ocular muscles can move the position of binocularity and remedy the compensatory head posture. This scenario is distinct from an abnormal head position driven by a musculoskeletal imbalance seen commonly in lambdoid synostosis when eye movements are normal and the abnormal head position cannot be improved by squint surgery. Sometimes],[ both situations occur in the same child warranting ophthalmic examination whenever a head posture and cranial synostosis co-occur to determine the etiology of the head position.
Unusual eye movement patterns can be found in combination with esotropia or exotropia. Levels of binocularity can be variable],[ but must be preserved],[ if present.
An ophthalmic surgeon and orthoptist skilled in the assessment and management of strabismus should be an integral member of any multidisciplinary team managing craniosynostosis. Usually],[ surgical management of strabismus is performed after surgery for the craniosynostosis as the latter can impact on the strabismus (both in offering an improvement or worsening). Due to the low incidence of squint in sagittal synostosis, metopic and lambdoid synostosis, and the lack of requirement for orbital dissection, pre-operative examination for strabismus is not required; however, in all other conditions, an examination should be undertaken. In addition, due to the reports of fronto-orbital procedures causing iatrogenic strabismus postulated to be due to trochlear release and peri-orbital dissection, children should have an eye assessment post-operatively and ideally this is compared with a pre-operative baseline, although in very young children less than a year of age quantitative assessment of ocular motor status is challenging because of limited cooperation even in skilled hands.
It is imperative to measure uniocular visual acuity in an age appropriate manner. Ocular alignment and eye movements and binocularity should be recorded in both a neutral head position and with an adopted head position. Prism cover tests, with stable measurements, enable accurate surgical planning. Surgery should be offered if there is a potential to preserve binocularity, or the child has symptomatic diplopia, a head tilt, or cosmetic or psychological concerns. Consenting for strabismus surgery in the context of craniosynostosis should include the possibility of unexpected outcomes due to unusual anatomy and the increased likelihood of subsequent procedures. If surgery is to be performed for a head tilt, even when the vertical deviation is corrected, the child may still adopt a head position due to habit, anomalous retinal correspondence, or musculoskeletal imbalance. The latter can be improved sometimes quite considerably, with physiotherapy in some instances.
Correction of the V-pattern can be approached by many different techniques. Inferior displacement of the medial rectus and superior displacement of the lateral rectus can collapse a V-pattern. Weakening of the ipsilateral inferior oblique, with either a recession or myectomy, can improve elevation in adduction. Tightening of the superior oblique can achieve the same result. It is the experience of the authors that a simple recess-resect procedure (when the lateral rectus is recessed or weakened and the medial rectus is shortened to correct a divergent squint) to correct the horizontal deviation will often improve the V pattern, without the need for displacement of the insertions.
Dissection around the orbits during fronto-orbital, fronto-facial, facial bipartition, or orbital box osteotomy procedures may lead to malposition of the globes and/or the ocular muscles or pulleys. This can lead to iatrogenic strabismus, and therefore utmost care and attention to both surgical planning and tissue handling must be employed in these cases. In addition, with regard to tissue handling and planning, care must be taken in osteotomies nearing or traversing the lacrimal apparatus and duct system to avoid inadvertent injury and subsequent requirement for repair for sequelae such as epiphora.,,,
| Anisometropia|| |
Refractive errors and anisometropia are more common, certainly in unicoronal synostosis where it is postulated to be due to oblique astigmatism caused by changes in the corneal curvature as a result of the anatomical deformation in this condition.,, It is however also more common in syndromic synostosis and does not appear to be impacted upon by craniofacial surgery. All children attending ophthalmic department should be refracted, with increased likelihood of glasses wear in those with coronal synostosis. Untreated refractive error or anisometropia can result in amblyopia. It is worth noting that achieving comfortable glasses fit, and therefore compliance with glasses wear, can be troublesome in those with craniosynostosis. Often the combination of hypertelorism, shallow orbits, and an underdeveloped midface means that glasses slip off the nose, the frames of glasses can be too narrow, and the arms of the frames too short. Placing both glasses arms and hearing aids or bone-anchored hearing aid behind the ears can mean that glasses wear is uncomfortable. Specialist dispensing opticians can modify frames to suit the child’s face. Spending extra time ensuring a comfortable fit is more likely to result in compliance. Customized, 3D printed glasses frames show promise as a solution to this problem.
| Amblyopia|| |
Amblyopia is found in approximately 4% of normal children’s population. The prevalence of amblyopia in craniosynostosis varies widely in the literature with rates quoted from 6.3% to as much as 86%. Any relative difference in visual quality will result in one eye being favored over the other and a subsequent relative deprivation of the visual cortex. If left untreated, vision will be reduced on the affected side. Craniosynostosis can result in amblyopia secondary to anisometropia, strabismus, or corneal scarring, secondary to exposure keratopathy, or a combination of all of the above. Regular assessments to measure uniocular visual acuities, eye alignment, fixation preferences, ocular health, and refraction will detect an interocular difference, which, if undetected and untreated, results in amblyopia which cannot be addressed once the visual system has reached maturity by the age of 5–7 years. Treatment of the underlying cause is necessary to prevent amblyopia. Once an interocular difference in vision (>0.2 Log MAR) has been found, treatment of the underlying cause followed by deprivation of the better seeing eye through patching, atropinization, or optical blur is required. Amblyopia treatment is most successful if the interocular difference in vision is small; compliance with occlusive treatments is good and treatment starts at a young age.
| Proptosis|| |
Proptosis occurs in those conditions resulting in a decrease in bony orbital volume. It can be variable in severity. An examination of eyelid closure must be assessed as to whether the ocular surface is protected. Incomplete lid closure at night is common; however, if the child has a good Bell’s phenomenon (ability to elevate the eyes under the lids), the cornea is protected. Children who have incomplete lid closure or have corneal exposure overnight often have red eyes and may wake with painful or watery eyes. Prolonged exposure can result in corneal breakdown, infection, vascularization, scarring, and potential loss of vision.
Step-wise management to protect corneal health is recommended. In the first instance, lubricants to use during the daytime, or while the child is asleep, are sufficient for mild proptosis with little lagophthalmos. Taping of the eyelids can be performed during sleep, but is often not well tolerated and risks inadvertent corneal injury. For children with increased scleral show, difficulty with exposure, or those for whom the appearance of their eyelid shape is unacceptable, narrowing the palpebral aperture is appropriate. This is commonly achieved by performing a lateral tarsorrhaphy: shortening the horizontal palpebral aperture will also narrow the vertical palpebral aperture. This reduces scleral show and improves the effectiveness of the blink and lid closure. In an acute or emergency situation, temporary tarsorrhaphies can be effective and sight saving and replaced with a permanent tarsorrhaphy in less urgent situations. When a lateral tarsorrhaphy is inadequate, medial tarsorrhaphies (sometimes termed canthoplasties) can be proven to be effective.
Globe dislocation (where the globe becomes trapped in front of retracted eyelids) is an emergency and must be reduced immediately to avoid sequelae such as chemosis, which can prevent the lids returning anterior to the globe, and loss of vision [Figure 2]A and B. Gentle anterior movement of the lateral canthus can release the tension on the lids and allow the lids to be replaced in their anatomical position. If the globe cannot be replaced behind the eyelids, it is imperative that the ocular surface is kept hydrated with lubricants until lids can be replaced in front of the eye. Fronto-facial advancement surgery can be used to increase the orbital volume and reposition the orbital rim and lids. The decision as to what to offer is made after careful consideration of the anatomy, the age of the child, and the acceptability to the child and parents.
|Figure 2: Globe prolapse in Pfeiffer’s syndrome (A) can be prevented with lateral tarsorrhaphy and narrowing of the palpebral aperture (B)|
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| Glaucoma|| |
A Medline search for glaucoma and craniosynostosis (/s) yields 10 results—all of which are case reports. However, in particular in Crouzon syndrome, there is evidence to suggest that FGFR2 plays a role in ocular anterior chamber dysgenesis and therefore these patients are at higher risk of developing glaucoma and this should be borne in mind.
| Papilledema/Changes in Visual Evoked Potentials|| |
Papilledema is the term given to bilateral swollen optic nerves caused by raised ICP. The likelihood of raised ICP increases with the number of sutures closed, and whether there is an associated syndrome. Raised ICP can be asymptomatic, or the child may be unable to express their symptoms. Regular screening of optic nerve appearance is a necessary aspect of craniofacial care, to inform whether raised ICP is likely. Detection of papilledema requires further investigation, such as brain imaging and/or ICP monitoring, and possible subsequent intervention. While papilledema is an indicator of raised ICP, a normal optic nerve appearance does not preclude a raised ICP. Resolution of papilledema after cranial vault surgery can take months, or be incomplete, with persistent chronic optic nerve swelling. Optic atrophy, as a result of untreated papilledema, is rare in well-monitored patients, due to preemptive monitoring and a proactive approach to management., Whenever possible, imaging of the optic disc makes identification of genuine pathological change of the appearance more sensitive and specific for raised ICP and is a powerful but simple tool. This can be facilitated by opportunistic imaging of the optic nerve in younger children when general anesthesia occurs for neuroimaging or other surgeries.
Due to the low prevalence of ICP issues in non-syndromic cases, there is not a requirement for routine direct monitoring of papilledema in these instances and instead this is sought out only when dictated by symptoms suggestive of raised ICP. In syndromic cases, however, this should be evaluated routinely and regularly via fundoscopy.
Visual evoked potentials (VEPs) measure the amplitude and latency of the electrical potential passing through the optic nerve to the visual cortex. Changes in latency and amplitude can be serially monitored using VEPs and used as an indication of optic nerve dysfunction, even in the absence of papilledema. VEPs are beneficial in children who are unable to comply with formal visual acuity testing, as they serve as a marker of visual ability. Recovery of optic nerve function, post-cranial vault surgery, can also be seen on VEPs.,
| Surgical Sequelae|| |
Central retinal artery occlusion (CRAO)
Raised intraocular pressure due to direct pressure on the globe during prone positioning may result in irreversible vision loss due to CRAO. This risk can be minimized by avoiding direct pressure over the eye balls as shown in [Figure 3] or similar maneuver.
|Figure 3: Positioning of the patient with protection of the globe to prevent CRAO|
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Monitoring of visual development
The frequency and duration of ophthalmic and orthoptic assessment of children with craniosynostosis are dependent on the number and location of suture involvement and whether they are known to have a genetic syndrome. The intensity reduces once children are able to express their symptoms and once their craniofacial surgery has been completed. Pre-operative assessment of ocular alignment and optic nerve appearance serves as a baseline assessment and point of reference.
There is no consensus or published guidelines with regard to the frequency or the manner in which monitoring is undertaken. The pathway used in Birmingham Children’s Hospital, UK, is shown in [Table 1].
| Summary|| |
Declaration of patient consent
The authors certify that they have obtained all appropriate patient consent forms. In the form the patient(s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed.
Financial support and sponsorship
Conflicts of interest
There are no conflicts of interest.
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[Figure 1], [Figure 2], [Figure 3]