Infantile cataracts

Cataracts are one of the most treatable causes of visual impairment during infancy. Recent epidemiological studies have shown that they have a prevalence of 1.2 to 6.0 cases per 10,000 infants. The morphology of infantile cataracts can be helpful in establishing their etiology and prognosis. Early surgery and optical correction have resulted in an improved outcome for infants with either unilateral or bilateral cataracts. While contact lenses continue to be the standard means of optically correcting an infant's eyes after cataract surgery, intraocular lenses are gaining in popularity as an alternative means of optically correcting these eyes. Post-operative complications occur more commonly after infantile than adult cataract surgery and many of these complications do not develop until years later. As a result, it is critical that children be followed closely on a long term basis after infantile cataract surgery.

Prevalence of, and risk factors for, physical ill-health in people with Prader-Willi syndrome: a population-based study

The medical findings from a population-based study of Prader-Willi syndrome (PWS) are discussed (in which birth incidence of PWS was estimated at 1:22,000 and death rate at over 3% per annum). In this study the prevalence of specific medical disorders that might account for a shortened life expectancy were investigated. Of all people with a possible diagnosis of PWS, only those meeting clinical criteria and/or with a confirmed genetic diagnosis were included in the study. Sixty-six individuals, 40 males and 26 females with a mean age of 19 years (range of 0 to 46 years) agreed to participate in the population-based study group. A prevalence rate of 25% for non-insulin dependent diabetes mellitus (NIDDM) was found in adults. Mean age at onset was 20 years. Those with NIDDM had a higher past maximum body weight and a greater likelihood of positive family history. Nearly 50% across the age groups reported a history of recurrent respiratory infections. High rates of fractures (29%), leg ulceration (22% in adults), sleep disorders (20%), and severe scoliosis (15% in childhood) were also reported. It is postulated that hypotonia is a possible contributory factor to the risk of strabismus, scoliosis, and respiratory infections. Other causes of morbidity, in particular the high rates of NIDDM, may be due to a failure to manage over-eating resulting in severe obesity. Early diagnosis and clear guidance to families about these risks and how they might be prevented is recommended. It is hypothesized that the high pain threshold may result in the presence of some illness not being apparent.

Binocular vision in a virtual world: visual deficits following the wearing of a head-mounted display

The short-term effects on binocular stability of wearing a conventional head-mounted display (HMD) to explore a virtual reality environment were examined. Twenty adult subjects (aged 19-29 years) wore a commercially available HMD for 10 min while cycling around a computer generated 3-D world. The twin screen presentations were set to suit the average interpupillary distance of our subject population, to mimic the conditions of public access virtual reality systems. Subjects were examined before and after exposure to the HMD and there were clear signs of induced binocular stress for a number of the subjects. The implications of introducing such HMDs into the workplace and entertainment environments are discussed.

Skew Deviation Revisited

Skew deviation is a vertical misalignment of the eyes caused by damage to prenuclear vestibular input to ocular motor nuclei. The resultant vertical ocular deviation is relatively comitant in nature, and is usually seen in the context of brainstem or cerebellar injury from stroke, multiple sclerosis, or trauma. Skew deviation is usually accompanied by binocular torsion, torticollis, and a tilt in the subjective visual vertical. This constellation of findings has been termed the ocular tilt reaction. In the past two decades, a clinical localizing value for skew deviation has been assigned, and a cogent vestibular mechanism for comitant and incomitant variants of skew deviation has been proposed. Our understanding of skew deviation as a manifestation of central otolithic dysfunction in different planes of three-dimensional space is evolving. The similar spectrum of vertical ocular deviations arising in patients with congenital strabismus may further expand the nosology of skew deviation to include vergence abnormalities caused by the effects of early binocular visual imbalance on the developing visual system.

Strabismus after balanced medial plus lateral wall versus lateral wall only orbital decompression for dysthyroid orbitopathy

PURPOSE

This study aimed to determine the relative incidence and time course of new-onset strabismus after balanced medial plus lateral wall orbital decompression versus decompression of the lateral wall alone for dysthyroid orbitopathy.

METHODS

The study design was a retrospective nonrandomized comparative case series. Thirty-two consecutive patients underwent balanced medial plus lateral wall orbital decompression or lateral wall orbital decompression for dysthyroid orbitopathy. The incidence, duration, and treatment of postoperative strabismus was recorded for each patient.

RESULTS

Significant preoperative strabismus was present in 31% (4/13 patients) of the balanced decompression group and in 26% (5/19 patients) of the lateral wall decompression group. Only 25% (1/4) of cases of preexisting strabismus in the balanced decompression group resolved postoperatively without muscle surgery, whereas 60% (3/5) of cases in the lateral wall decompression group resolved postoperatively without surgery. Preoperative strabismus was absent in 69% (9/13) of patients in the balanced decompression group and in 74% (14/19) of patients in the lateral wall decompression group. New-onset, persistent postoperative strabismus developed in 33% (3/9) of patients in the balanced decompression group and in 7% (1/14) of patients in the lateral wall decompression group.

CONCLUSION

Lateral wall orbital decompression may produce less new-onset, persistent postoperative strabismus than balanced medial plus lateral wall orbital decompression for dysthyroid orbitopathy.

A reassessment of infantile esotropia. XLIV Edward Jackson memorial lecture

Essential infantile esotropia is an early acquired, not a congenital, condition, although congenital factors may favor its development between the ages of 3 and 6 months. It must be distinguished from other forms of esotropia with an onset between birth and the first six months of life. The cause of essential infantile esotropia remains unknown, but advances in our knowledge can be expected from the rapidly emerging discipline of infant psychophysics. In analyzing treatment results, a clear distinction must be made between normal, subnormal, and anomalous forms of binocular cooperation. While complete restoration of normal binocular function is rarely, if ever, achieved, anomalous binocular cooperation has many functional advantages over suppression or diplopia and should not be disturbed by overzealous treatment. Subnormal binocular vision is considered to be an optimal, microtropia a desirable, and a residual small angle heterotropia an acceptable end stage of surgical therapy. In a study of 358 surgically treated patients with a documented onset of essential infantile esotropia before age 6 months, subnormal binocular vision was present in 71 (20%), a microtropia in 25 (7%), and a small angle esotropia or exotropia in 140 (39%) of the patients. Surgical alignment before completion of the second year of life improved the chances for an optimal treatment result.(ABSTRACT TRUNCATED AT 250 WORDS)

Heterotopic muscle pulleys or oblique muscle dysfunction?

INTRODUCTION

The description of connective tissue sleeves that function as pulleys for the rectus extraocular muscles (EOMs) suggests that abnormalities of EOM pulley position might provide a mechanical basis for some forms of incomitant strabismus. Pulleys determine the paths and thus the pulling directions of EOMs.

METHODS

High-resolution magnetic resonance images spanning the orbits were obtained in primary position, upgaze, and downgaze for each subject. Paths of the EOMs were measured with reference to the orbital center and permitted inference of pulley locations.

RESULTS

Data from 18 orbits of orthotropic subjects defined means and SDs of normal EOM pulley coordinates. Eight patients, aged 17 to 60 years, had heterotopic EOM pulleys, defined as displaced at least 2 SDs from normal. We found one to eight heterotopic pulleys (considering both orbits) in each of four patients who had been diagnosed with marked superior oblique (SO) overaction and mild to marked inferior oblique (IO) underaction. Each patient had superior mislocation of at least one lateral rectus pulley by 1.8 to 4.9 mm. Three patients diagnosed with mild to moderate IO overaction and mild to moderate SO underaction in only one orbit had one to three heterotopic EOM pulleys. Each of those patients had at least one lateral rectus pulley inferiorly dislocated by 1.9 to 4.9 mm. The final patient, who was diagnosed with mild IO underaction and normal SO function bilaterally, had bilateral superior mislocation of the medial rectus pulleys by greater than 2 mm. Computer simulations using the Orbit program (Eidactics, San Francisco) incorporating individually measured pulley positions reproduced the clinical patterns of incomitant strabismus in all cases without postulating abnormalities of oblique muscle innervation or contractility.

CONCLUSION

Heterotopic EOM pulleys can cause patterns of incomitant strabismus that have been attributed to oblique muscle dysfunction. Even isolated mislocations of less than 2 mm, coupled with smaller mislocations of the other pulleys, can produce the clinical appearance of bilateral oblique dysfunction. Pulley heterotopy should be considered in the differential diagnosis of incomitant strabismus and oblique dysfunction.

Neural mechanisms underlying amblyopia

The nature of the neural basis of amblyopia is a matter of some debate. Recent neurophysiological data show correlates of amblyopia in the spatial properties of neurons in primary visual cortex. These neuronal deficits are probably the initial manifestation of the visual loss, but there are almost certainly additional deficits at higher levels of the visual pathways.

Screening for retinoblastoma: presenting signs as prognosticators of patient and ocular survival

OBJECTIVE

To correlate 3 common presenting signs of retinoblastoma with patient and ocular survival and to assess the efficacy of current pediatric screening practices for retinoblastoma.

METHODS

A retrospective study was conducted of 1831 retinoblastoma patients from our center (1914-June 2000). Patient survival (excluding deaths from other primary neoplasms) and ocular survival (presenting eyes) rates were calculated and analyzed using the Kaplan-Meier method.

RESULTS

Leukocoria correlated with excellent patient survival (>86%, 5 years) but poor ocular survival in unilateral (4%, 5 years) and bilateral patients (29%, 5 years). A total of 308 (19%) of 1654 patients presented with strabismus: patient survival was excellent (90%, 5 years), and ocular survival was poor (17%, 5 years) yet better than leukocoria. Patients who had a family history of retinoblastoma and were clinically screened for retinal tumors from birth were diagnosed younger (8 months of age) and earlier (Reese Ellsworth group 1 = 26 [58%] of 45) and had better ocular survival than nonscreened patients with a family history. More patients were initially detected by family/friends (1315 [80%] of 1632) than pediatricians (123 [8%] of 1632) or ophthalmologists (156 [10%] of 1632).

CONCLUSION

Most US children whose retinoblastoma is diagnosed initially present with leukocoria detected by a parent, despite routine pediatric screening for leukocoria via the red reflex test. Initial disease detection at the point of leukocoria or strabismus correlated with high patient survival rates and poor ocular survival rates for the presenting eye. Saving eyes and vision requires disease recognition before leukocoria, as demonstrated by the better ocular salvage rate among patients who had a positive family history and received clinical surveillance via early, routine dilated funduscopic examinations by an ophthalmologist.

Strabismus presenting after cataract surgery

Strabismus presenting after cataract surgery is etiologically related to a heterogenous group of disorders. Clinical data from 63 patients so affected revealed four broad etiologic categories: 1) pre-existing disorders that preceded the cataract surgery, but were rendered asymptomatic by the occluding cataract (e.g., thyroid eye disease, cranial nerve palsy, myasthenia); 2) disorders precipitated by prolonged occlusion by a cataract (e.g., sensory deviations, decompensation of heterophorias, and central disruption of binocular vision); 3) disorders resulting from surgical trauma to extraocular muscles and orbital soft tissues. Traumatic injury to the inferior rectus muscle secondary to retrobulbar anesthesia injection, a specific subset, is postulated to result from a Volkmann's type ischemic contracture, a well-known osseofascial compartment syndrome occurring in peripheral skeletal muscles. 4) Disorders related to resulting aphakia/pseudophakia and associated optical aberrations (e.g.; anisophoria, ocular dominance reversal, and color/brightness disparity). The diagnostic and therapeutic implications of these findings are discussed.

Paralytic strabismus in children. Etiologic incidence and management of the third, fourth, and sixth nerve palsies

The results of a retrospective study of the etiologic incidence of all cases of third fourth, and sixth nerve palsies in patients at Wills Eye Hospital and St Christopher's Hospital are reported. A total of 121 patients ranging in age from birth to sixteen were studied. Thirty-two cases of third nerve palsy, eighteen cases of fourth nerve palsy, and sixty-two cases of sixth nerve palsy were identified in this series. Nine additional cases illustrated combinations of multiple nerve involvement. With few exceptions, acquired third nerve palsy in children is an ominous sign whereas the congenital form is generally indicative of developmental anomaly or birth trauma. Acquired sixth nerve palsy in a child is always a matter of concern since it may represent the first sign of a brain-stem glioma. Active force studies may be carried out periodically to assess the speed of recovery and indicate when it is time to initiate a more aggressive role in the surgical management. The surgical results in children with paralytic strabismus that have been carefully evaluated offer a favorable prognosis.

Visual and visuospatial development in young children with Williams syndrome

This study investigated the relation between sensory visual problems and the severity of visuospatial difficulties in a large group of young children with Williams' syndrome (WS). A questionnaire describing visual and associated problems was completed by the families of 108 children with WS and detailed follow-up assessments were conducted, including visual, spatial, motor, visuocognitive, and linguistic tests of 73 of these children (mean age 7 years 3 months; 40 males, 73 females). Children with WS showed a much higher incidence of common paediatric sensory vision problems (strabismus, visual acuity loss, amblyopia, reduced stereopsis) than normally developing children. It was found that delays with respect to age normative values increased with age on all tests. No significant correlation was found between the presence of a visual deficit and the severity of the visuospatial problems, suggesting that the difficulties children with WS have in understanding spatial arrangements are not simply a result of their earlier sensory visual problems. Results confirm the dissociation between visuospatial and language abilities in children with WS, and support the neurobiological model of a split between ventral and dorsal stream processing of visual information with a generalized deficit in dorsal stream processing in young children with WS.

Ophthalmic sequelae of infantile hemangiomas of the eyelids and orbit

The major findings in a study of 51 infants and children with infantile hemangioma of the eyelid were as follows: Visual complications occurred in 27 patients. The most common complications were amblyopia (in 22) and strabismus (in 17). Amblyopia of 6/60 (20/200) or less was probably caused by stimulus-deprivation, but amblyopia in the range of 6/30 (20/100) to 6/12 (20/40) was likely caused by anisometropia or strabismus. Eyelid occlusion of six months or more invariably resulted in amblyopia of 6/60 (20/200) or less. Occlusion for even one month carried a risk of amblyopia. Each child must be considered individually for therapy, which must be started as early as possible. Patients should receive careful follow-up from the beginning to prevent severe amblyopia. For difficult cases, we need more efficacious, safe methods to induce regression of these tumors.

Early clinical experience with the Baerveldt 350-mm2 glaucoma implant and associated extraocular muscle imbalance

PURPOSE

The Baerveldt glaucoma implant is a new commercially available aqueous drainage device. Clinical data on the performance of the implant are relatively limited. The purpose of this investigation is to explore potential advantages and disadvantages of this implant over the more widely used Molteno implant.

METHODS

Retrospective analysis was performed on 37 eyes of 36 patients with refractory glaucoma who underwent placement of a mid-sized Baerveldt 350-mm2 implant. Patient selection was based on previous failure of conventional medical, laser, and surgical management, with poor prognosis for further glaucoma surgery and adjunctive antifibrosis therapy.

RESULTS

Significant postoperative extraocular motility restriction and heterotropia were found in the operated eyes. Twenty-three (77%) of 30 eyes measured have significant heterotropia in primary gaze and restriction of gaze into the quadrant of the implant. As a result, 11 (65%) of 17 functionally binocular patients have diplopia in primary gaze.

CONCLUSIONS

Pending further study, the authors are avoiding placement of the Baerveldt 350-mm2 implant in both binocular and monocular patients due to the high frequency of induced heterotropia and motility restriction.

Cyclodeviation in acquired vertical strabismus

The prevalence and pattern of cyclodeviation can differentiate among superior oblique palsy, dysthyroid ophthalmopathy, myasthenia gravis, and skew deviation. Excyclodeviation was detected in 30 of 33 patients with superior oblique palsy, eight of 15 patients with dysthyroid ophthalmopathy, three of six patients with nondysthyroid restrictive ophthalmopathy, and one of 13 patients with myasthenia. No cyclodeviation was found in cases of skew. Incyclodeviation was found in two patients with dysthyroid ophthalmopathy, two with nondysthyroid restrictive ophthalmopathy, and three with myasthenia. The amount of cyclodeviation did not vary between head-tilt positions, but did vary between primary and eccentric gaze positions, usually in the same direction as the amount of hyperdeviation. The patient's awareness of the presence of cyclodeviation varied with the degree of cyclodeviation, being 100% (4/4) for 15 degrees, 86% (12/14) for 10 degrees, and only 55% (11/21) for 5 degrees.

A comparison of grating visual acuity, strabismus, and reoperation outcomes among children with aphakia and pseudophakia after unilateral cataract surgery during the first six months of life

PURPOSE

The method of correcting aphakia after unilateral cataract extraction during infancy is controversial. Some authorities advocate correction with an intraocular lens (IOL) whereas others advocate correction with a contact lens (CL). We compared grating visual acuity, alignment, and reoperative outcomes in age-matched children treated with these 2 modalities at 5 clinical centers.

METHODS

Twenty-five infants born in 1997 or 1998 with a dense unilateral congenital cataract who had cataract surgery coupled with (IOL group, n = 12) or without (CL group, n = 13) primary IOL implantation were enrolled in this study. All patients were prescribed half-time occlusion therapy. In July 1999, their grating visual acuities, ocular alignments, and reoperation rates were assessed.

RESULTS

The mean grating visual acuity (LogMAR) for the affected eye was 0.70 +/- 0.32 for the IOL group and 0.87 +/- 0.31 for the CL group (P =.19). The mean interocular difference in grating visual acuity was 0.26 +/- 0.30 for the IOL group and 0.50 +/- 0.28 for the CL group (P =.048). The incidence of strabismus (>10 PD) was 75% in the IOL group compared with 92% in the CL group (P =.24). The incidence of reoperations was 83% in the IOL group compared with 23% in the CL group (P =.003).

CONCLUSIONS

Our preliminary data suggest that correcting aphakia after unilateral congenital cataract surgery with primary IOL implantation results in an improved visual outcome but a higher rate of complications requiring reoperation. A randomized clinical trial, the Infant Aphakia Treatment Study, is planned to further study the optimal treatment for aphakia following unilateral cataract extraction during infancy.

Optic nerve hypoplasia with good visual acuity and visual field defects: a study of children of diabetic mothers

Seventeen children, born of severely diabetic mothers, exhibited segmental optic nerve hypoplasia with normal visual acuity and altitudinal or sector field defects corresponding to the hypoplastic areas of the disc. This is the first group of patients with optic nerve hypoplasia in which a possible cause has been identified. Optic nerve hypoplasia is neither a rare abnormality usually associated with serious central nervous system defects, nor is it always accompanied by decreased visual acuity.

Ophthalmological problems associated with preterm birth

As survival of preterm infants improves, the long-term care of consequent ophthalmic problems is an expanding field. Preterm birth can inflict a host of challenges on the developing ocular system, resulting in the visual manifestations of varied significance and pathological scope. The ophthalmic condition most commonly associated with preterm birth is retinopathy of prematurity, which has the potential to result in devastating vision loss. However, the visual compromise from increased incidence of refractive errors, strabismus, and cerebral vision impairment has significant impact on visual function, which also has influence on other developmental aspects including psychological and educational. In this review, the normal ocular development is discussed, aiming to exemplify the impact of early exteriorisation on one of the more naive organs of prematurity. This is then related to the incidence and visual consequences of many types of deficit, including refractive error, strabismus, and loss of visual function in preterm populations, with comparisons to term infant studies. Often these conditions are linked with causal and resultant factors being impossible to segregate, but the common factor of increased rates of all types of ophthalmic deficits demonstrates that children born prematurely are indeed premature for life.

Ocular involvement in the fetal alcohol syndrome

Maternal alcohol abuse during pregnancy causes malformations of the eyes with serious consequences to the vision of the affected children. A high percentage (up to 90%) of children suffering from the fetal alcohol syndrome have eye abnormalities, including malformation in the outer eye region, disorders of motility, and defects of different intraocular structures. Two kinds of malformations stand out as most typical--hypoplasia of the optic nervehead (up to 48%) and increased tortuosity of the retinal vessels, especially of the arteries (up to 49%). Visual acuity is often moderately or severely reduced. Considering the developmental timing of different tissues of the eye, one can presume that there is a risk for deleterious effects of alcohol on eye structures at any point of time from early gestation until development is completed.

Acute comitant esotropia in children with brain tumors

If acute onset of esotropia is comitant, its cause is generally believed to be benign. Although this is, by and large, true, it is now clear that acute comitant esotropia may be associated infrequently with central nervous system illness. We describe six children who presented with acute onset of comitant esotropia, and who were found to have tumors of the brain stem or cerebellum. Four of the patients underwent strabismus surgery after appropriate neurologic and neurosurgical treatment was completed. In none of these patients was ocular motor fusion reestablished.

Recognition and repair of the "lost" rectus muscle. A report of 25 cases

Twenty-five consecutive cases of lost muscle over a 10-year period are presented with regard to etiology, clinical presentation, operative findings, and treatment results. All patients showed a large-angle strabismus and all muscles had marked limitation of excursion in its field of action. This complication of ocular surgery or trauma, unlike the slipped muscle which has its empty capsule attached to the sclera, is characterized by the absence of any attachment of the muscle or its capsule to the sclera. Eleven of the 25 muscles were retrievable largely because of attachments through intermuscular septum to adjacent oblique muscles. The remaining 14 muscles were considered irretrievable, and these patients underwent a muscle transposition procedure. The clinical features and surgical repair of the lost muscle are described and compared with those of the slipped muscle.

Ipsilateral hypertropia after cataract surgery

BACKGROUND

Reports of acquired strabismus caused by injection of local anesthetics during cataract surgery have increased recently. The authors proposed a mechanism to explain the occurrence of strabismus with apparent overactive muscles after cataract surgery.

METHODS

The authors studied 19 patients in whom strabismus developed after cataract surgery. Prism and cover test in the diagnostic positions of gaze and forced-duction testing were used to identify the affected muscles.

RESULTS

The deviation was greater in the field of action of the presumed tight muscle in 16 of 19 patients. An ipsilateral hypertropia with superior rectus muscle overaction subsequently developed in two patients with an initial hypotropia. An overaction of the ipsilateral lateral rectus muscle causing an exotropia developed in one patient with initially limited abduction.

CONCLUSIONS

Myotoxicity from direct injection of local anesthetics into an extraocular muscle probably causes transient paresis followed by segmental contracture of the involved muscle. Mild contractures result in strabismus with a motility pattern of an overactive muscle. Larger amounts of contracture lead to restrictive strabismus. The risk of strabismus may be decreased by administering the local anesthetic into sub-Tenon space using a blunt-tipped cannula when performing cataract surgery.