Bony orbital development after early enucleation in humans

[Ocular prosthetics in children-Possibilities and challenges]

One of the greatest challenges for ocularists is prosthetic fitting in children, especially in children with congenital anomalies such as clinical anophthalmia or functionless (blind) microphthalmia. The most frequent reason for prosthetic fitting in children is a condition following enucleation for retinoblastoma, followed by trauma and congenital pathologies. The standard treatment after enucleation or evisceration begins intraoperatively with the selection of an suitable implant and the use of a conformer at the end of the operation to shape the prosthetic cavity. An initial prosthesis can be fitted 4 weeks postoperatively, with a final fitting taking place 3 months later. If iatrogenic scarring or scarring due to an infection of the prosthetic cavity occurs, the approach of the ocularist must be appropriately adapted with the use of modified prosthesis shapes and shorter treatment intervals. Surgical options include scar excision and oral mucosa or amniotic membrane transplantation. Congenital anomalies require the shortest treatment intervals and even more so for anophthalmia than for microphthalmia. The strategy is characterized by simultaneous stimulation of the soft tissue of the ocular adnexa as well as the bony orbit. As self-inflating hydrogel expanders are no longer available, conservative prosthetic treatment is the only option. Close cooperation between child/parent, ocularist and ophthalmic plastic surgeon is the best prerequisite for a good long-term treatment outcome.

An age-related algorithm for management of micro-orbitism from anophthalmia: a systematic review with supplemental case reports

Management of pediatric anophthalmia and resultant micro-orbitism is challenging. The efficacy and safety of treatment methods vary with age as bony changes grow recalcitrant to implants in those at skeletal maturity and osteotomies become technically challenging following frontal sinus pneumatization. This study aims to review methods for managing micro-orbitism and develop an age-based treatment approach. A systematic literature review was conducted. Data were screened and extracted by two investigators and relevant English-language primary-literature was analyzed. Information on sample-size, number of orbits, intervention, age, complications, and prosthetic retention was obtained. Representative case reports are presented, in addition. Nineteen studies met inclusion: 294 orbits in 266 patients were treated. Two studies reported distraction-osteogenesis. Two studies utilized bone grafting. Osteotomies were performed in 41 patients from three studies. Use of solid implants was detailed in two studies. Three studies described osmotic implant. Four studies described inflatable implants. Other techniques were described by three of the included studies, two of which utilized dermis-fat grafting. All but one study were observational case reports or case series. Across all studies regardless of surgical technique, risk of bias and heterogeneity was high due to attrition bias and selective outcomes-reporting. Selection of therapy should be tailored to skeletal-age to optimize outcomes; those 0-4 yrs are managed with dermis-fat grafts, 5-7 yrs managed with implants, and 8+ yrs managed with osteotomies. For those 8+ yrs with aerated frontal sinuses or insufficient bone stock, we propose onlay camouflage prosthetics which improve projection, increase orbital volume, and avoid risk for frontal sinus injury.

Orbital Growth is Associated with Eyeball Size: A Study Using CT-based Three-dimensional Techniques

AIM OF THE STUDY

This study was aimed to investigate the growth patterns and the relationship of the eyeball and the orbit using computed tomography (CT)-based three-dimensional (3D) techniques.

MATERIALS AND METHODS

A total of 175 Chinese patients who had undergone craniofacial or orbital CT scans were enrolled. This study only included data from the unaffected eye and orbit. Images were processed using 3D reconstruction to obtain the eyeball and the orbit parameters.

RESULTS

In early postnatal years, the sizes of eyeball and orbit increased significantly with age (p < 0.001) and reached a turning point at a critical age (8.967 and 12.800 years for the eyeball and orbit volume, respectively). The orbital index and orbital depth index, showing the shape of the orbital aperture and walls, decreased significantly with age (p < 0.001). In all ages, the orbit size was correlated with eyeball size (p < 0.001). The eye-orbit index, equivalent to the ratio of eye volume to orbital volume, declined steadily with age (p < 0.001).

CONCLUSIONS

The eyeball and orbit developed rapidly in early postnatal years, and then matured at a critical age. The eyeball size significantly contributed to the orbital growth; this contribution may be reduced as the eye-orbit index decreased with age. To the best of our knowledge, this is the first report on the growth and interrelation of the eyeball and the orbit using CT-based 3D techniques.

Reconstruction of the Orbit and Anophthalmic Socket Using the Dermis Fat Graft: A Major Review

PURPOSE

To perform a comprehensive review of dermis fat graft (DFG) in socket reconstruction and illustrate the technical nuances and outcomes using a retrospective case review.

METHODS

A literature search of 143 texts was reviewed. A retrospective case series of 34 patients following primary or secondary DFG after enucleation at a single institution (2009-2019) was performed. Clinical outcomes were statistically analyzed. Variables investigated included age, sex, race, surgical indication, muscle reattachment, complications, motility, eyelid position, prosthesis fit, and need for additional surgery.

RESULTS

The history of DFG, use in socket reconstruction, primary and secondary indications, and surgical techniques are described. Thirty-two adults and 2 pediatric cases of DFG were reviewed; 18.75% indications were primary and 81.25% were secondary. Good eyelid position was observed in 83.3% of patients with primary DFG versus 37.5% with secondary DFG (p = 0.07). Postoperative complications occurred in 58.8% of patients, were typically mild, and resolved with minimal or no intervention. No statistically significant differences were found between occurrence of any particular complication in primary versus secondary DFG placement (p = 0.36) or between primary and secondary DFG placement and the need for additional surgery (p = 1.0). Among the 67.7% patients who had implant exposure or extrusion as an indication for DFG, 39.1% required additional surgery within 2 years. Advanced age was not associated with higher complication rates (p = 0.12).

CONCLUSIONS

DFG is an excellent option for socket reconstruction, particularly in cases involving pediatric patients, complicated orbits, history of multiple previous surgeries, and inflamed, contracted, or scarred sockets.

Congenital Microphthalmia with Intraorbital Cyst: A Rare Case Report

Microphthalmia is considered to be the most common congenital malformation of the eye after congenital cataract. However, its association with intraorbital cyst is considered to be very rare. Most of the lesions are still misdiagnosed as orbital tumor and teratomas as there is a general paucity of data reported in literature. Herein, we report a rare case of congenital microphthalmia with intraorbital cyst in an eight-month-old male patient.

Use of the anterolateral thigh flap for reconstruction of the pediatric anophthalmic orbit

Children with acquired anophthalmia pose unique reconstructive challenges. With implant-based reconstruction, the current standard of care, there is a tendency toward intraorbital and adnexal tissue contraction and an increasing volume discrepancy with orbital growth, resulting in enophthalmos and eyelid retraction, and also difficulty in retaining an ocular prosthesis. We describe a novel technique for secondary reconstruction of the pediatric anophthalmic orbit using a small free anterolateral thigh (ALT) flap. The technique involves release of retracted eyelids and restoration of orbital volume with an ALT flap based on the superficial temporal vessels. The purpose of this study is to detail the results of treatment of a series of four consecutive patients with unilateral acquired anophthalmia managed with ALT flaps. Improved symmetry, successful retention of an ocular prosthesis, and patient satisfaction were achieved in all cases.

Bony orbital maldevelopment after enucleation

One common belief in ophthalmology is that enucleation at an early age will result in bony orbital maldevelopment and facial asymmetry. However, the age range in which enucleation is associated with risk of orbital maldevelopment and the extent of asymmetry remains controversial. In this study, patients who had undergone unilateral enucleation at different ages without orbital implantation were analysed to investigate bony orbital development after enucleation. A total of 87 Chinese adult patients were included. Their bony orbital volume and orbital aditus area were measured using three-dimensional reconstructive models based on patients' computer tomography scans. The ratio of the parameter values of the affected orbit to the unaffected orbit was calculated and described as the orbital symmetry index. The results showed that the bony orbit grew until approximately 18 years old. Enucleation after that age did not affect the orbit, whereas enucleation before that age led to significant orbital maldevelopment. The relative reduction ranged up to 20% in orbital volume and 17% in the orbital aditus area. The extent of orbital maldevelopment was correlated to the age of enucleation. The symmetry index of orbital volume = -0.0003x(2)  + 0.0159x + 0.8112 (x = the age of enucleation). The symmetry index of the orbital aditus area = -0.0002x(2)  + 0.0119x + 0.8504 (x = the age of enucleation). The regression formulae were used to predict the severity of orbital asymmetry after unilateral enucleation, and evaluate the necessity and efficacy of interventions following enucleation.

Worldwide enucleation techniques and materials for treatment of retinoblastoma: an international survey

Purpose

To investigate the current practice of enucleation with or without orbital implant for retinoblastoma in countries across the world.

Methods

A digital survey identifying operation techniques and material used for orbital implants after enucleation in patients with retinoblastoma.

Results

We received a response of 58 surgeons in 32 different countries. A primary artificial implant is routinely inserted by 42 (72.4%) surgeons. Ten (17.2%) surgeons leave the socket empty, three (5.2%) decide per case. Other surgeons insert a dermis fat graft as a standard primary implant (n=1), or fill the socket in a standard secondary procedure (n=2; one uses dermis fat grafts and one artificial implants). The choice for porous implants was more frequent than for non-porous implants: 27 (58.7%) and 15 (32.6%), respectively. Both porous and non-porous implant types are used by 4 (8.7%) surgeons. Twenty-five surgeons (54.3%) insert bare implants, 11 (23.9%) use separate wrappings, eight (17.4%) use implants with prefab wrapping and two insert implants with and without wrapping depending on type of implant. Attachment of the muscles to the wrapping or implant (at various locations) is done by 31 (53.4%) surgeons. Eleven (19.0%) use a myoconjunctival technique, nine (15.5%) suture the muscles to each other and seven (12.1%) do not reattach the muscles. Measures to improve volume are implant exchange at an older age (n=4), the use of Restylane SQ (n=1) and osmotic expanders (n=1). Pegging is done by two surgeons.

Conclusion

No (worldwide) consensus exists about the use of material and techniques for enucleation for the treatment of retinoblastoma. Considerations for the use of different techniques are discussed.

Measurements of Orbital Volume using Cone-Beam Computed Tomography in Eye Movement Abnormalities

Purpose

To measure the orbital volume in adult patients with unilateral eye movement abnormalities originating in childhood.

Methods

Cone-beam computed tomography was performed in 2 patients with eye movement abnormalities. A 28-year-old woman was treated because of right divergent squint originating at 8 years of age after penetrating corneal trauma. A 38-year-old man was examined because of abnormal head posture caused by left superior oblique underaction originating at 6 years of age. Orbital scans were analyzed with Cranioviewer 3D craniofacial cephalometric program. We measured bony orbital area in 6 slices (in ventro-dorsal direction per 4.8 mm) in every orbit on coronal scans.

Results

The volume was more in the orbit with unilateral divergent squint and less in the orbit with unilateral superior oblique underaction compared to the contralateral orbital volume measurements.

Conclusions

Cranioviewer 3D craniofacial cephalometric program is suitable for volumetric analysis of the bony orbit on cone-beam computed tomography files. The development of the orbit can be influenced by extraocular muscle movements.

Is orbital volume associated with eyeball and visual cortex volume in humans?

BACKGROUND

In humans orbital volume increases linearly with absolute latitude. Scaling across mammals between visual system components suggests that these larger orbits should translate into larger eyes and visual cortices in high latitude humans. Larger eyes at high latitudes may be required to maintain adequate visual acuity and enhance visual sensitivity under lower light levels.

AIM

To test the assumption that orbital volume can accurately index eyeball and visual cortex volumes specifically in humans.

SUBJECTS AND METHODS

Structural Magnetic Resonance Imaging (MRI) techniques are employed to measure eye and orbit (n = 88) and brain and visual cortex (n = 99) volumes in living humans. Facial dimensions and foramen magnum area (a proxy for body mass) were also measured.

RESULTS

A significant positive linear relationship was found between (i) orbital and eyeball volumes, (ii) eyeball and visual cortex grey matter volumes and (iii) different visual cortical areas, independently of overall brain volume.

CONCLUSION

In humans the components of the visual system scale from orbit to eye to visual cortex volume independently of overall brain size. These findings indicate that orbit volume can index eye and visual cortex volume in humans, suggesting that larger high latitude orbits do translate into larger visual cortices.

Measurement of orbital volume after enucleation and orbital implantation

Introduction

This article reports experience relating to the measurement of orbital volume by means of cone beam computed tomography (CBCT) and Cranioviewer program software in patients who have undergone enucleation and orbital implantation.

Patients and Methods

CBCT scans were made in 30 cases, 10 of which were later excluded because of various technical problems. The study group therefore consisted of 20 patients (8 men and 12 women). The longest follow-up time was 7 years, and the shortest was 1 year. In all 20 cases, the orbital volume was measured with Cranioviewer orbital program software. Slices were made in the ventrodorsal direction at 4.8 mm intervals in the frontal plane, in both bony orbits (both that containing the orbital implant and the healthy one). Similar measurements were made in 20 patients with various dental problems. CBCT scans were recorded for the facial region of the skull, containing the orbital region. The Cranioviewer program can colour the area of the slices red, and it automatically measures the area in mm.

Results

In 5 of the 20 cases, the first 4 or all 5 slices revealed that the volume of the operated orbit was significantly smaller than that of the healthy orbit, in 12 cases only from 1 to 3 of the slices indicated such a significant difference, and in 3 cases no differences were observed between the orbits. In the control group of patients with various dental problems, there was no significant difference between the two healthy orbits. The accuracy of the volume measurements was assessed statistically by means of the paired samples t-test.

Summary

To date, no appropriate method is avaliable for exact measurement of the bony orbital volume, which would be of particular importance in orbital injury reconstruction. However, the use of CBCT scans and Cranioviewer orbital program software appears to offer a reliable method for the measurement of changes in orbital volume.

Eye size at birth in prosimian primates: life history correlates and growth patterns

Background

Primates have large eyes relative to head size, which profoundly influence the ontogenetic emergence of facial form. However, growth of the primate eye is only understood in a narrow taxonomic perspective, with information biased toward anthropoids.

Methodology/Principal Findings

We measured eye and bony orbit size in perinatal prosimian primates (17 strepsirrhine taxa and Tarsius syrichta) to infer the extent of prenatal as compared to postnatal eye growth. In addition, multiple linear regression was used to detect relationships of relative eye and orbit diameter to life history variables. ANOVA was used to determine if eye size differed according to activity pattern. In most of the species, eye diameter at birth measures more than half of that for adults. Two exceptions include Nycticebus and Tarsius, in which more than half of eye diameter growth occurs postnatally. Ratios of neonate/adult eye and orbit diameters indicate prenatal growth of the eye is actually more rapid than that of the orbit. For example, mean neonatal transverse eye diameter is 57.5% of the adult value (excluding Nycticebus and Tarsius), compared to 50.8% for orbital diameter. If Nycticebus is excluded, relative gestation age has a significant positive correlation with relative eye diameter in strepsirrhines, explaining 59% of the variance in relative transverse eye diameter. No significant differences were found among species with different activity patterns.

Conclusions/Significance

The primate developmental strategy of relatively long gestations is probably tied to an extended period of neural development, and this principle appears to apply to eye growth as well. Our findings indicate that growth rates of the eye and bony orbit are disassociated, with eyes growing faster prenatally, and the growth rate of the bony orbit exceeding that of the eyes after birth. Some well-documented patterns of orbital morphology in adult primates, such as the enlarged orbits of nocturnal species, mainly emerge during postnatal development.

Abnormal orbital growth in children submitted to enucleation for retinoblastoma treatment

Enucleation is typically performed for the treatment of advanced retinoblastoma in children. After enucleation, the orbit undergoes abnormal development. In this study, orbital asymmetry was calculated using computed tomography measurements obtained from patients who experienced enucleation for unilateral retinoblastoma. Influence factors analyzed included: type of treatment, use of orbital implants, and patient's age at diagnosis. A total of 42 children underwent enucleation with a mean follow-up period of 4.8 years. For 28 patients, treatment included enucleation alone, 14 patients received enucleation plus radiation therapy. Thirty patients kept orbital implants long term. The mean orbital volume asymmetry for treated versus contralateral orbits was 16.8%. Mean asymmetry in orbital volume was greater for patients who underwent enucleation combined to radiation therapy (23.7% vs. 13.3%, P=0.05) and for patients without long-term maintenance of the prosthetic implants (29.3% vs. 11.8%, P<0.01). In conclusion, orbital volume is abnormally affected in children after enucleation of 1 eye for the treatment of retinoblastoma, and computed tomography can precisely quantify the asymmetry that develops. Orbital implants improve volumetric growth after enucleation, with 2-fold greater orbital asymmetry achieved without an implant.

Followup of a Dog with an Intraocular Silicone Prosthesis Combined with an Extraocular Glass Prosthesis

Because of unpredictable corneal changes, evisceration and implantation of a silicone prosthesis does not always lead to a satisfying cosmetic result. This paper describes the use of an intraocular silicone prosthesis in combination with an extraocular glass prosthesis and shows a followup of two and a half years in a nonexperimental study. An intraocular silicone prosthesis was implanted after evisceration of the left eye in a five-month-old Bernese mountain dog. A glass prosthesis was fitted four weeks after evisceration. Two and a half years after the operation, the dog is in good health and free of medication. No short-term or long-term complications were seen. The owners do not have trouble with handling the glass prosthesis. The combination of both prostheses shows a perfect solution to retrieve a normal looking and moving eye after evisceration.

Orbital asymmetry in development: an anatomical study

The aim of this study was to analyze the human orbital asymmetry during development. One hundred twenty-seven identified human dry skulls, with sex, age, date and cause of death record, in good preservation state, were used. Bones that had evidence of trauma, malformations or other pathology were excluded. The sample was divided into 4 age groups: I--intra-uterine life (n=20), II--newborn up to 2 years old (n=43), III--three up to 20 years old (n=27) and IV--21 up to 76 years old (n=37). The skulls were photographed in normal frontalis and images were analyzed with the software AutoCAD 2002 in real scale. The obtained measurements were: greater horizontal diameter (HD), greater vertical diameter (VD), orbital perimeter and orbital base area. All skulls showed asymmetry in all measures, except 4 of them that showed symmetry in VD and perimeter. The asymmetry occurred in all ages, being calculated as a percent rate for VD--2.73%, HD--4.48%, area--4.77% and perimeter--2.47%. There was predominance in asymmetric rate in female skulls and only in the group II the difference between gender was statistically significant (p<0.05). The right orbit presented larger measures. The asymmetric rate was assumed as the normal anatomic pattern.

Anophthalmia and microphthalmia

Anophthalmia and microphthalmia describe, respectively, the absence of an eye and the presence of a small eye within the orbit. The combined birth prevalence of these conditions is up to 30 per 100,000 population, with microphthalmia reported in up to 11% of blind children. High-resolution cranial imaging, post-mortem examination and genetic studies suggest that these conditions represent a phenotypic continuum. Both anophthalmia and microphthalmia may occur in isolation or as part of a syndrome, as in one-third of cases. Anophthalmia/microphthalmia have complex aetiology with chromosomal, monogenic and environmental causes identified. Chromosomal duplications, deletions and translocations are implicated. Of monogenic causes only SOX2 has been identified as a major causative gene. Other linked genes include PAX6, OTX2, CHX10 and RAX. SOX2 and PAX6 mutations may act through causing lens induction failure. FOXE3 mutations, associated with lens agenesis, have been observed in a few microphthalmic patients. OTX2, CHX10 and RAX have retinal expression and may result in anophthalmia/microphthalmia through failure of retinal differentiation. Environmental factors also play a contributory role. The strongest evidence appears to be with gestational-acquired infections, but may also include maternal vitamin A deficiency, exposure to X-rays, solvent misuse and thalidomide exposure. Diagnosis can be made pre- and post-natally using a combination of clinical features, imaging (ultrasonography and CT/MR scanning) and genetic analysis. Genetic counselling can be challenging due to the extensive range of genes responsible and wide variation in phenotypic expression. Appropriate counselling is indicated if the mode of inheritance can be identified. Differential diagnoses include cryptophthalmos, cyclopia and synophthalmia, and congenital cystic eye. Patients are often managed within multi-disciplinary teams consisting of ophthalmologists, paediatricians and/or clinical geneticists, especially for syndromic cases. Treatment is directed towards maximising existing vision and improving cosmesis through simultaneous stimulation of both soft tissue and bony orbital growth. Mild to moderate microphthalmia is managed conservatively with conformers. Severe microphthalmia and anophthalmia rely upon additional remodelling strategies of endo-orbital volume replacement (with implants, expanders and dermis-fat grafts) and soft tissue reconstruction. The potential for visual development in microphthalmic patients is dependent upon retinal development and other ocular characteristics.

Perspective on Orbital Enucleation Implants

The philosophy and design of orbital enucleation implants have evolved significantly over the past 50 years. Animal studies and improved imaging techniques have changed our understanding about the physiology and anatomy of the post-enucleation orbit. Changes in implant design and biomaterials have reduced complication rates. It is our impression that for many ophthalmic professionals in training, the rational behind the current thinking in implant design and biomaterials is unclear. This is in part related to the older literature on orbital enucleation implants, which is scattered and at times contradictory. This review aims to present the historical information in a coherent and concise form; provide evidence based review of changes in the practice patterns of enucleation; identify areas of continuing controversy; and highlight gaps in the scientific literature about orbital implants, in particular, the poor understanding of implant and prosthesis motility.

Expansion of the Socket and Orbit for Congenital Clinical Anophthalmia

BACKGROUND

Congenital clinical anophthalmia requires fitting an artificial eye, achieving a pleasing aspect of the palpebral apparatus, and stimulating growth of the orbit, as well as of the entire midface.

METHODS

Out of 25 patients with clinical anophthalmia, 22 were treated according to a new protocol (first described by Wiese et al. in 1999) and followed for up to 6 years. In 10 patients, anophthalmia was bilateral, in nine patients, it was on the right side only and in three it was on the left side only. Treatment consisted of implantation of an osmotic expander to first stimulate growth of the conjunctival sac and eyelids followed by serial implantation of osmotic expanders to stimulate growth of the orbit (and thus of the midface). The material used was a copolymer of methylmethacrylate and N-vinylpyrrolidone.

RESULTS

Fitting of an artificial eye was without any problem within the first year of life for the most part. Growth of the orbit was stimulated by more than 65 percent of a healthy one. Aesthetically, the results were very largely pleasing. Complications were encountered, especially when the wrong expander sizes had been implanted.

CONCLUSION

Using osmotic expanders of this type, through a staged therapy of minor operations, promises to achieve all goals before the child enters school.

Is eye size related to orbit size in human subjects?

The purpose of this study is to determine if there is an association between eye size and the volume of the orbit in adult subjects. Thirty-three subjects with varying degrees of ametropia (+1.00 to -12.75 D) underwent magnetic resonance scan of the orbit. Results show that the larger myopic eye was not associated with a larger orbit.

[Treatment of congenital clinical anophthalmos with high hydrophilic hydrogel expanders]

INTRODUCTION

Children presenting with congenital anophthalmos usually develop a smaller bony orbit, a constricted mucosal socket, and a shortened eyelid fissure. This causes problems when fitting these patients with a prosthesis. Clinical evaluation of the Wiese self-inflating hydrogel expanders has demonstrated their ability to expand the socket and eyelid fissure for inserting a more realistic prosthesis in shorter periods of time.

PATIENTS AND METHOD

The study included 13 consecutive anophthalmic patients, eight unilateral and five bilateral. Each patient received a hemispherical osmotic tissue expander in the rudimentary mucosal socket and later a sphere implanted in the deeper soft orbital tissue.

RESULTS

The use of hydrogel expanders enlarged the lid and palpebral fissure in all children, with good cosmetic results. It allowed insertion of custom-made glass prostheses with good cosmetic appearance very early in life. Growth of the bony orbit may be stimulated successfully by these expanders in the soft orbital tissue.

CONCLUSIONS

The enlargement of constricted mucosal sockets and short palpebral fissures using self-inflating hydrogel expanders is a new and successful concept in treating congenital anophthalmos.

Abnormalities of orbital volume

New information on the physiopathology and treatment of orbital volumes pathologies is described: 1) In post-enucleation or evisceration socket syndrome placing of synthetic material (HA-TCP) directly in the intraconal orbital fat can correct most of the symptoms. However the best approach is to prevent orbital volume deficiencies during first surgery using an implant large enough to allow a future prosthesis of a volume less than 2 mL. New procedures for placing the implant after enucleation or evisceration are described. 2) In proptosis related to Graves' orbitopathy relative indications are given for orbital decompression by removal of fat or bone.