Severe microcornea with anterior segment malformation in a mother and her son

A male infant with microcornea, anterior segment dysgenesis and congenital cataracts, but with a normal ocular posterior segment is reported. His mother also had extreme microcornea, no useful vision from birth, but had globes of grossly normal size.

Is early surgery for congenital cataract a risk factor for glaucoma?

AIMS

To estimate the risk of aphakic glaucoma after lensectomy for congenital cataract and its association with surgery within the first month of life.

METHOD

A retrospective case notes review was conducted of all patients who had lensectomy for congenital cataract during their first year of life at Great Ormond Street Hospital between 1994 and 1997. Patients with pre-existing glaucoma, anterior segment dysgenesis, and Lowe syndrome were excluded. The risk of aphakic glaucoma after surgery was estimated using Kaplan-Meier survival analysis.

RESULTS

80 patients, undergoing 128 lensectomies were eligible. Of these, six patients (nine eyes) were lost to follow up. Based on eye count, the risk of glaucoma by 5 years after lensectomy was 15.6% (95% CI 10.2 to 23.4). Based on patient count, the 5 year risk of glaucoma in at least one eye following bilateral surgery was 25.1% (95% CI 15.1 to 40.0). The incidence of glaucoma remained at a constant level for the first 5 years after surgery. After early bilateral lensectomy, within the first month of life, the 5 year risk of glaucoma in at least one eye was 50% (95% CI 27.8 to 77.1) compared to 14.9% (95% CI 6.5 to 32.1) with surgery performed later (log rank test, p = 0.012). There was no significant difference (Kolmogorov-Smirnov test: unilateral lensectomy p = 0.587, bilateral lensectomy p = 0.369) in 5 year visual outcomes between eyes operated before and after 1 month of age.

CONCLUSION

Bilateral lensectomy during the first month of life is associated with a higher risk of subsequent glaucoma than with surgery performed later. The reason for this is unclear but it may be prudent, in bilateral cases, to consider delaying surgery until the infant is 4 weeks old. As the incidence of glaucoma is similar for each year after surgery, long term glaucoma surveillance is mandatory.

Familial vestibulocerebellar disorder maps to chromosome 13q31-q33: a new nystagmus locus

PURPOSE

To determine a gene locus for a family with a dominantly inherited vestibulocerebellar disorder characterised by early onset, but not congenital nystagmus.

DESIGN

Observational and experimental study.

METHODS

We carried out a phenotypic study of a unique four generation family with nystagmus. We performed genetic linkage studies including a genome wide search.

RESULTS

Affected family members developed vestibulocerebellar type nystagmus in the first two years of life. A higher incidence of strabismus was noted in affected members. Haplotype construction and analysis of recombination events linked the disorder to a locus (NYS4) on chromosome 13q31-q33 with a lod score of 6.322 at theta=0 for D13S159 and narrowed the region to a 13.8 cM region between markers D13S1300 and D13S158.

CONCLUSIONS

This study suggests that the early onset acquired nystagmus seen in this family is caused by a single gene defect. Identification of the gene may hold the key to understanding pathways for early eye stabilisation and strabismus.

Hermansky-Pudlak syndrome: infrequent bleeding and first report of Turkish and Pakistani kindreds

Hermansky-Pudlak syndrome (HPS) is a rare disorder characterised by oculocutaneous albinism, a bleeding tendency, and lipofuscinosis. This retrospective study reviews the clinical history and haematological features of 23 cases of HPS. Information was gathered from patient notes and by direct interview. Thirteen of the 23 children were of Turkish origin, 12 being members of four kindreds from the Turkish/Kurdish border. Four children originated from Pakistan. Haemorrhage was uncommon; two experienced significant bleeding (intracranial and retinal haemorrhage in one and menorrhagia in another), and twelve minor symptoms. Results of laboratory evaluation of platelet function were not predictive of bleeding; in particular the PFA-100 analyser was not sensitive to the HPS defect. The most sensitive test of platelet fuction was quantitation of platelet nucleotides. The occurrence of Turkish and Pakistani kindreds with HPS is novel and follow up for long term complications described in Puerto Rican patients as well as genetic analysis is ongoing.

Albinism

Albinism is a heterogeneous group of conditions having in common a hereditary error of melanin metabolism resulting in misrouting of optic nerve fibers during embryogenesis, underdevelopment of the neuroretinas, and in varying degrees of hypopigmentation of eyes, skin, and hair.

Outcome of lens aspiration and intraocular lens implantation in children aged 5 years and under

AIMS

To determine the visual outcome and complications of lens aspiration with intraocular lens implantation in children aged 5 years and under.

METHODS

The hospital notes of all children aged 5 years and under, who had undergone lens aspiration with intraocular lens implantation between January 1994 and September 1998, and for whom follow up data of at least 1 year were available, were reviewed.

RESULTS

Of 50 children who underwent surgery, 45 were eligible based on the follow up criteria. 34 children had bilateral cataracts and, of these, 30 had surgery on both eyes. Cataract was unilateral in 11 cases; thus, 75 eyes of 45 children had surgery. Cataracts were congenital in 28 cases, juvenile in 16, and traumatic in one case. The median age at surgery was 39 months (range 11-70 months). Follow up ranged from 12-64 months (median 36 months). Of 34 children with bilateral disease, 25 (73.5%) had a final best corrected visual acuity of 6/12 or better, while seven (20.5%) achieved 6/18 or less; in one child the vision improved from UCUSUM to CSM but another, who had only one eye operated on, was unable to fix or follow with this eye preoperatively or 2 years postoperatively. Of 11 children with unilateral cataract, five (45.5%) had a final best corrected visual of 6/12 or better, and six (54.5%) 6/18 or less. A mild fibrinous uveitis occurred in 20 (28.2%) eyes in the immediate postoperative period, but resolved with topical steroids. One child had a vitreous wick postoperatively requiring surgical division. Glaucoma, endophthalmitis, or retinal detachment have not been observed so far in any patient postoperatively.

CONCLUSION

From this series the authors suggest that, in children aged 5 years and under, lens aspiration with intraocular lens implantation is a safe procedure, with a good visual outcome in the short term. Further studies are needed to investigate these outcomes in the long term.

Oto-facio-cervical (OFC) syndrome is a contiguous gene deletion syndrome involving EYA1: molecular analysis confirms allelism with BOR syndrome and further narrows the Duane syndrome critical region to 1 cM

Branchio-oto-renal (BOR) syndrome is an autosomal dominant disorder involving hearing loss, branchial defects, ear pits and renal abnormalities. Oto-facio-cervical (OFC) syndrome is clinically similar to BOR syndrome, with clinical features in addition to those of BOR syndrome. Mutations in the EYA1 gene (localised to 8q13.3) account for nearly 70% of BOR syndrome cases exhibiting at least three of the major features. Small intragenic deletions of the 3' region of the gene have also been reported in patients with BOR syndrome. We have developed a fluorescent quantitative multiplex polymerase chain reaction for three 3' exons (7, 9 and 13) of the EYA1 gene. This dosage assay, combined with microsatellite marker analysis, has identified de novo deletions of the EYA1 gene and surrounding region in two patients with complex phenotypes involving features of BOR syndrome. One patient with OFC syndrome carried a large deletion of the EYA1 gene region, confirming that OFC syndrome is allelic with BOR syndrome. Microsatellite analysis has shown that comparison of the boundaries of this large deletion with other reported rearrangements of the region reduces the critical region for Duane syndrome (an eye movement disorder) to between markers D8S553 and D8S1797, a genetic distance of approximately 1 cM.

Pharmaceutical management of the childhood glaucomas

Glaucoma in childhood is a diverse, blinding group of conditions, which presents a major therapeutic challenge. Treatment is primarily surgical with medical treatments used as an adjunct. None of these drugs has been granted approval by the regulatory agencies for use in children, but they are used on a compassionate basis. Issues of efficacy and safety of these medications in children are discussed. beta-adrenoceptor blockers have been employed as first line pharmaceutical therapy for many years. Recently three new classes of drugs have been developed for use in glaucoma in adults. beta-blockers remain first line therapy if there are no contraindications such as asthma. Topical carbonic anhydrase inhibitors (CAI) appear to be less effective than beta-blockers, but seem safe systemically, although associated with local irritation. They are useful as an adjunct to beta-blockers or as first line therapy when beta-blockers are contraindicated. Prostaglandins have not proved as effective in childhood glaucoma as in adult glaucoma, although it works well in some patients with juvenile open angle glaucoma (JOAG) and others with aphakic glaucoma. alpha-adrenergic agonists, although effective at least in the short-term, have serious, potential systemic side effects, which demand close observation when used in neonates and young infants.

Vertical or asymmetric nystagmus need not imply neurological disease

AIM

To indicate that congenital idiopathic nystagmus (CIN) and sensory defect nystagmus (SDN) can be vertical or asymmetric in some children.

METHODS

Of 276 children presenting with nystagmus for electrophysiological testing, 14 were identified as having CIN or SDN, yet had a nystagmus which was either vertical (n=11) or horizontal asymmetric (n=3). Flash electroretinograms and flash and pattern visual evoked potentials (VEPs) were recorded in all patients. Eye movement assessment, including horizontal optokinetic nystagmus (OKN) testing, was carried out in 11/14 patients.

RESULTS

Eight patients (seven with vertical, one with asymmetric horizontal nystagmus) had congenital cone dysfunction. One patient with vertical and another with asymmetric nystagmus had cone-rod dystrophy. One patient with vertical upbeat had congenital stationary night blindness. Two patients (one downbeat, one upbeat nystagmus) had normal electrophysiological, clinical, and brain magnetic resonance imaging findings and were classified as having CIN. One patient with asymmetric nystagmus showed electrophysiological and clinical findings associated with albinism. Horizontal OKN was present in 80% of patients tested, including the three cases with horizontal asymmetric nystagmus. This is atypical in both CIN and SDN, where the OKN is usually absent.

CONCLUSIONS

Vertical and asymmetric nystagmus are most commonly associated with serious intracranial pathology and its presence is an indication for neuroimaging studies. However, such nystagmus can occur in children with retinal disease, albinism, and in cases with CIN. These findings stress the importance of non-invasive VEP/ERG testing in all cases of typical and also atypical nystagmus.

A study of EEG, electroretinogram, visual evoked potential, and eye movements in classical lissencephaly

EEG, flash electroretinogram (ERG), and visual evoked potential (VEP) findings are described in eight children with classical lissencephaly (six girls, two boys), with a mean age of 17.6 months (range 2 to 60 months). The EEG shows typically high-voltage activity. Eye movements were formally recorded in two patients, and both showed features associated with oculomotor apraxia. The ERG and VEP to flash stimulation were normal in all cases. Two subjects had pattern reversal stimulation, and their pattern VEPs were within normal limits. Some patients with lissencephaly may appear to have delayed visual maturation on first presentation, and EEG and eye movement studies are valuable in indicating neurological deficiency at an early stage in these subjects.

Visual-evoked potential evidence of chiasmal hypoplasia

PURPOSE

To show that chiasmal hypoplasia or aplasia need not be an isolated developmental anomaly and to examine the spectrum of associated clinical findings to explore the possibility that these patients may represent a phenotypic manifestation of a developmental gene anomaly.

DESIGN

An observational case series.

PARTICIPANTS

Five infants, between several weeks and 7 months of age, in whom the electrophysiologic characteristic of chiasmal hypoplasia had been noted were included.

METHODS

Flash electroretinography and flash and pattern visual-evoked potentials (VEPs) were elicited from all patients. Clinical ophthalmologic examinations, including funduscopy, were performed, and all patients had magnetic resonance imaging (MRI) brain scans.

MAIN OUTCOME MEASURES

The occipital distribution of monocular VEP response peaks was studied. The symmetry of lateral channel responses was compared for monocular stimulation.

RESULTS

All five patients had a crossed asymmetry in the monocular VEP occipital distribution, which is consistent with a paucity of fibers crossing at the chiasm. The MRI findings supported this electrophysiologic observation, illustrating degrees of chiasmal hypoplasia and variable coincidence of other midline abnormalities of the brain. Optic disc appearances varied from normal to hypoplastic and colobomatous.

CONCLUSIONS

The ophthalmologic and MRI findings of five patients who showed a crossed asymmetry in monocular flash VEPs are consistent with a paucity of axons crossing at the chiasm. The similarities between achiasmia in humans and mice due to a Pax2 gene anomaly are discussed.

Chorioretinal lesions in patients and carriers of chronic granulomatous disease

OBJECTIVE

To investigate the frequency of retinal lesions in patients with chronic granulomatous disease (CGD) and to seek such lesions in carriers.

STUDY DESIGN

Seventy-four individuals from 33 families were recruited; 38 had CGD (30 X-linked and 8 autosomal recessive inheritance). All participants (including 33 control subjects) underwent measurement of visual acuity, anterior segment examination by slit lamp, and dilated funduscopy.

RESULTS

Nine of 38 (23.7%) of the affected children had chorioretinal lesions compared with 0 of 33 control subjects. All 9 were known to have X-linked CGD and absent gp91(phox). The "typical" retinal abnormality consisted of "punched out" chorioretinal lesions associated with pigment clumping lying along major retinal vessels. Unexpectedly, 3 XL-CGD asymptomatic carriers also had typical chorioretinal lesions.

CONCLUSION

Retinal lesions are relatively common in patients with XL-CGD and may interfere with vision and thus should be sought in such patients.

The eye in epidermolysis bullosa

AIMS

To describe the ophthalmic findings in a large cohort of epidermolysis bullosa (EB) patients managed in one large specialist centre.

METHODS

A case note review of consecutive patients seen at Great Ormond Street Children's Hospital. Data on the dermatological disease, ophthalmic history, and examination were collected and coded onto a data sheet.

RESULTS

181 patients: 50 (28%) simplex EB; 15 (8%) junctional EB; 28 (15%) autosomal dominant dystrophic EB; 72 (40%) autosomal recessive dystrophic EB; nine patients (5%) with dystrophic EB whose inheritance could not be ascertained; and seven cases (4%) of EB that could not be classified. Ocular problems were found in 12% (n = 6) of simplex patients and 40% (n = 6) of those with junctional disease. One patient (of 28) in the autosomal dominant dystrophic group had ocular involvement and 51% (37/72) of patients in the autosomal recessive dystrophic group had ophthalmic complications: corneal (25/72), lid ectropions (3/72), lid blisters (5/72), and symblepharon (3/72).

CONCLUSION

Ophthalmic complications are common in EB overall but the incidence varies widely with subtype. Ophthalmic complications are the most severe in the dystrophic recessive and junctional subtypes where there is a need for extra vigilance. The major treatment modality was use of ocular lubricants.

Early VEP and ERG evidence of visual dysfunction in autosomal recessive osteopetrosis

Autosomal recessive (AR) osteopetrosis has a rapid course and manifests in the first months of life. Visual loss occurs because of optic nerve compromise, and more rarely retinal dysfunction (which may be a part of a primary neurodegeneration). The only curative treatment currently available is bone marrow transplantation (BMT). It has been suggested that BMT is contraindicated if AR osteopetrosis is associated with a primary neurodegeneration. Visual impairment tends to be irreversible after BMT. The young age of the patients makes reliable, objective tests of visual function especially important. We have reviewed the flash electroretinograms (ERGs) and flash and pattern visual evoked potentials (VEPs) recorded without sedation from 15 patients with AR osteopetrosis, 11 of whom were recorded longitudinally. The most frequent, early indication of visual dysfunction was a delay in the pattern or flash VEP latency. This first affects the pattern reversal VEP to small checks. Importantly this often preceded fundal changes of optic disc pallor, and evidence of optic nerve compression on neuroimaging. Only two patients had ERG evidence of retinal dysfunction affecting both rods and cones. One of these patients had a distinctive fundal appearance, but did not have evidence of associated neuronal degenerative disease. The other patient was lost to follow-up. In the patients reviewed in this study successful BMT and optic nerve decompression did not result in VEP improvement. Fundoscopy, VEP and ERG testing are indicated when the diagnosis of AR osteopetrosis is suspected and provide a useful means of monitoring visual involvement.

Review of aphakic glaucoma after surgery for congenital cataract

This article describes the clinical presentation of glaucoma in eyes operated on for congenital cataract and reviews current theories as to its pathophysiology. The literature does not provide a conclusive explanation for the seeming increase in aphakic glaucoma in children. Long-term studies comparing like groups may help resolve this question.

Achiasmia in a case of midline craniofacial cleft with seesaw nystagmus

Images

Visual acuity in unilateral cataract

BACKGROUND

Patching the fellow eye in infancy is a well recognised therapy to encourage visual development in the lensectomised eye in cases of unilateral congenital cataract. The possibility of iatrogenic deficits of the fellow eye was investigated by comparing the vision of these patients with untreated unilateral patients and binocularly normal controls.

METHODS

Sweep visual evoked potentials (VEPs) offer a rapid and objective method for estimating grating acuity. Sweep VEPs were used to estimate acuity in 12 children aged between 4 and 16 years who had had a congenital cataract removed in the first 13 weeks of life. The acuities of aphakic and fellow phakic eye were compared with the monocular acuities of similarly aged children who have good binocular vision, and with children with severe untreated uniocular visual impairment. Recognition linear acuities were measured with a linear Bailey-Lovie logMAR chart and compared with the sweep VEP estimates.

RESULTS

A significant difference was found between Bailey-Lovie acuity of the fellow eye of the patient group and the right eye of binocular controls, and the good eye of uniocular impaired patients (one way ANOVA, p < 0.01). However, this was not evident for a similar comparison with sweep VEP estimates. There was no significant difference between the right and left eye acuities in binocular controls measured by the two techniques (paired t test).

CONCLUSION

A loss of recognition acuity in the fellow phakic eye of patients treated for unilateral congenital cataract has been demonstrated with a logMAR chart. This loss was not apparent in children who have severe untreated uniocular visual impairment and may therefore be an iatrogenic effect of occlusion. An acuity loss was not apparent in the patient group using the sweep VEP method. Sweep VEP techniques have a place for objectively studying acuity in infants and in those whose communication difficulties preclude other forms of behavioural test. The mean sweep VEP acuity for the control groups is 20 cpd--that is, about 6/9. When acuities higher than this are under investigation--for example, in older children, slower transient VEP recording may be more appropriate, because higher spatial frequency patterns are not as visible at higher temporal rates (for example, 8 Hz used in sweep VEP recordings).

Bilateral epiretinal membranes: a new finding in Hunter syndrome

Hunter syndrome or Type II mucopolysaccharidosis is a rare disorder of mucopolysaccharide metabolism. We report the cases of two brothers with Hunter syndrome with the previously undocumented ocular finding of bilateral epiretinal membranes. Epiretinal membranes are an uncommon finding in the paediatric age group.

An unusual presentation of Smith-Magenis syndrome with iris dysgenesis

A boy who presented with iris dysgenesis is described. He was shown to have Smith-Magenis syndrome with a deletion of 17p11.2.

Intermittent horizontal saccade failure ('ocular motor apraxia') in children

BACKGROUND

Ocular motor apraxia (OMA) in childhood is a poorly understood condition involving a failure of horizontal saccades. OMA is thought to be rare but the literature indicates wide clinical associations. OMA is often identified by abnormal head movements, but failure of reflexive quick phases has been reported in all but a few patients. The extent of this oculomotor disorder was examined in a large group of children with diverse clinical backgrounds.

METHODS

The degree of quick phase failure during horizontal vestibular and optokinetic nystagmus was measured using DC electro-oculography and video in 74 affected children, aged 17 days to 14 years.

RESULTS

All children showed an intermittent failure of nystagmic quick phases, except for total failure in one case. Other visuomotor abnormalities were common including saccadic hypometria (85%), low gain smooth pursuit (70%), neurological nystagmus (28%), strabismus (22%), and vertical abnormalities (11%). Non-ocular abnormalities were common including infantile hypotonia (61%), motor delay (77%), and speech delay (87%). There was a wide range of clinical associations including agenesis of the corpus callosum, Joubert syndrome, Dandy-Walker malformation, microcephaly, hydrocephalus, vermis hypoplasia, porencephalic cyst, megalocephaly, Krabbe leucodystrophy, Pelizaeus Merzbacher disease, infantile Gaucher disease, GM1 gangliosidosis, infantile Refsum's disease, propionic acidaemia, ataxia telangiectasia, Bardet-Biedl syndrome, vermis astrocytoma, vermis cyst, carotid fibromuscular hypoplasia, Cornelia de Lange syndrome, and microphthalmos. Perinatal and postnatal problems were found in 15% including perinatal hypoxia, meningitis, periventricular leucomalacia, athetoid cerebral palsy, perinatal septicaemia and anaemia, herpes encephalitis, and epilepsy. Only 27% were idiopathic.

CONCLUSION

Quick phase failure is a constant feature of OMA, whereas abnormal head movements were detected in only about half, depending on the underlying diagnosis. This oculomotor sign is better described as an intermittent saccade failure rather than as a true apraxia. It indicates central nervous system involvement, has wide clinical associations, but it is not a diagnosis.

Delayed visual maturation in infants: a disorder of figure-ground separation?

Delayed visual maturation (DVM) is characterised by visual unresponsiveness in early infancy, which subsequently improves spontaneously to normal levels. We studied the optokinetic response and recorded pattern reversal VEPs in six infants with DVM (aged 2-4 months) when they were at the stage of complete visual unresponsiveness. Although no saccades or visual tracking with the eyes or head could be elicited to visual objects, a normal full-field rapid buildup OKN response occurred when viewing biocularly or during monocular stimulation in the temporo-nasal direction of the viewing eye. Almost no monocular OKN could be elicited in the naso-temporal direction, which was significantly poorer than normal age-matched infants. No OKN quick phases were missed, and there were no other signs of "ocular motor apraxia." VEPs were normal in amplitude and latency for age. It appears, therefore, that infants with DVM are delayed in orienting to local regions of the visual field, but can respond to full-field motion. The presence of normal OKN quick-phases and slow-phases suggests normal brain stem function, and the presence of normal pattern VEPs suggests a normal retino-geniculo-striate pathway. These oculomotor and electrophysiological findings suggest delayed development of extra-striate cortical structures, possibly involving either an abnormality in figure-ground segregation or in attentional pathways.

Neuroradiological and eye movement correlates in children with intermittent saccade failure: "ocular motor apraxia"

Ocular motor apraxia (OMA) is a clinical sign involving the intermittent inability to initiate saccades, and a failure of quick phases during optokinetic nystagmus (OKN) and vestibular nystagmus (VN). Some patients have no other associated abnormalities (idiopathic), whereas others have a variety of neurological conditions. We quantified the severity of the saccade failure and correlated it with neuro-radiological and other oculomotor findings in 62 children (aged 17 days - 14 years). Saccades, smooth pursuit, OKN and VN were recorded using electrooculography and the extent of "locking up" (absent quick phases during OKN and VN) was measured. Saccades were usually hypometric. Pursuit and OKN gains were normal in the majority of the idiopathic cases but were low in those with other neurological conditions. Twenty-four patients had essentially normal scans, whereas 38 had abnormal scans: Delayed myelination, cerebellar abnormalities (particularly involving the vermis), and agenesis of the corpus callosum were the most common findings. A significant positive correlation was present between increasing neuro-radiological deficits and severity of "locking up" during OKN. Principal component analysis showed that brainstem and cerebellar vermis abnormalities were the main factors involved. A pathophysiological basis of OMA is discussed in the light of animal and clinical studies.

The optokinetic response differences between congenital profound and nonprofound unilateral visual deprivation

BACKGROUND

The occurrence of monocular naso-to-temporal optokinetic nystagmus (OKN) asymmetry, as a reflection of the immature oculomotor system in infants, and its persistence with early onset monocular visual deprivation, is well known. This asymmetry has been linked with poor binocular function and attributed to disruption of the development of binocular cortical projections to the pretectum. Optokinetic nystagmus symmetry in patients with congenital uniocular total pattern vision deprivation has not been fully investigated.

METHODS

The authors compared the optokinetic responses in six children with "profound" uniocular visual deprivation, who were born with untreated conditions (microphthalmos and persistent hyperplastic primary vitreous), with ten aphakic children treated early for congenital unilateral cataracts (nonprofound unilateral visual deprivation). Eye movements were recorded using dc-electro-oculography, and OKN was elicited using a full-field patterned curtain. Flash and pattern visual-evoked responses were also measured in each subject.

RESULTS

Latent nystagmus was present in six children in the nonprofound group, whereas none was detected in the profound group. All children in the nonprofound group showed statistically significant monocular naso-to-temporal asymmetry for either eye. Subjects in the profound group had symmetric OKN.

CONCLUSIONS

The authors conclude that unequal input from the two eyes and interocular rivalry lead to OKN asymmetry. Their results suggest that if vision from one eye is so negligible that it does not compete with the neuroanatomic connections of the fellow eye, then the input from this eye remains undisturbed, and OKN remains symmetric.

Modulation of amblyopia therapy following early surgery for unilateral congenital cataracts

BACKGROUND

Stimulus deprivation amblyopia is the principal cause of visual impairment in infants with unilateral congenital cataract. Even if lensectomy is undertaken at an early age, intensive postoperative occlusion of the phakic eye is essential for the development of useful vision in the aphakic eye. Despite this, the optimum method of regulating occlusion therapy is uncertain.

METHODS

Interocular acuity differences identified using clinical preferential looking techniques (Keeler cards) were used to regulate target levels of phakic eye occlusion in a prospective evaluation of 10 systemically, metabolically, and neurologically normal infants in whom dense unilateral cataract was diagnosed before 8 weeks of age, and operated upon by 10 weeks. Actual occlusion levels were recorded each day by parents in a diary. The development of preferential looking acuity in the phakic and aphakic eye were compared with prediction intervals derived from observations on 43 normal children.

RESULTS

Aphakic eye preferential looking acuities were within the normal range at last review in all but one infant. Interocular acuity differences were < or = 0.5 octave in all children older than 1 year of age at last review, and > or = 1 octave in three of four children less than 1 year old at last review (Fisher exact p = 0.033). Phakic eye acuities were within the normal range in all infants at all visits.

CONCLUSION

Within the first 2 years of life, normal preferential looking acuity may be achieved in both eyes of infants undergoing early surgery for unilateral congenital cataract if occlusion therapy is modulated according to interocular acuity differences quantified by clinical preferential looking techniques.

Improvement in visual acuity in children with ectopia lentis

The early development of vision in an eye with a dislocated lens is often poor, leading to disappointing postoperative results due to amblyopia. A retrospective review of the best corrected visual acuity of 49 eyes of 27 children with ectopia lentis, who were rendered aphakic either spontaneously or by lensectomy, showed a gradual improvement. Nineteen eyes achieved an early postoperative acuity of 6/12 or better. Of the remaining 30 eyes, 21 were followed up for 1 or more years. During this period, an improvement of two or more Snellen visual acuity lines was noted in all but one of the eyes.

Cytomegalovirus retinitis in AIDS

Cytomegalovirus retinitis is common in adults with AIDS but has been reported infrequently in children with perinatally acquired HIV infection. The cases are presented of two infants with vertically acquired HIV infection who developed disseminated cytomegalovirus infection and retinitis, and who posed difficult management issues.

Familial posterior lenticonus

Posterior lenticonus tends to be unilateral and there is no evidence that this is a familial condition. We report three cases of bilateral posterior lenticonus in boys. The mothers of all three cases had posterior lenticular changes, less severe than their sons. We suggest that bilateral posterior lenticonus may be inherited in an X-linked fashion.

Eye movements in a familial vestibulocerebellar disorder

Eye movement abnormalities consisting of poor or absent smooth pursuit and vestibulo-ocular reflex suppression, gaze-paretic and rebound nystagmus, slow build-up of optokinetic nystagmus, mildly hyperactive vestibulo-ocular reflex, and a high incidence of strabismus were inherited in an autosomal dominant fashion in 10 members of a non-consanguineous English caucasian family. The onset was in early childhood, but was not congenital. In 7 cases there was no tremor, dizziness, consistent ataxia, or other cerebellar signs that are often associated with these ocular motor deficits, and apart from strabismus, patients were asymptomatic. Magnetic resonance imaging of the propositus was normal. After childhood there appears to be no progression, with the oldest affected member being 40 years. Two members had been prone to falling in childhood, and one admitted to dizziness when tired. This condition, which is probably benign, has not been previously described and may represent a very mild variant of episodic ataxia or a new vestibulocerebellar syndrome.

Aspects of albinism

Genetic, clinical and electrophysiological aspects of albinism are described. Emphasis is placed on electrophysiological features which help to distinguish albinism from other clinical conditions, and on stimulating and recording factors which can affect the clarity of VEP results.

Electrophysiological assessment of visual pathway function in infants

The flash ERG and VEP have conspicuous immature features during the first 4 months following birth. The most marked maturational changes occur in ERG amplitude and VEP latency. Concurrent recording of the skin ERG and VEP provides information which is very useful in helping to arrive at a diagnosis in the young infant with nystagmus who appears to be blind and has a fundus of normal appearance. ERG and VEP features associated with Leber's Amaurosis, congenital cone dysfunction, albinism, optic nerve hypoplasia and unilateral hemisphere dysfunction are described.

Neonatal cataract: aetiology, pathogenesis and management

We review the epidemiology, aetiology, pathogenetic mechanisms and clinical management of neonatal cataract. Visual development and the effects of visual deprivation in the infant with congenital cataract are discussed and related to the timing of surgery. Surgical techniques and the important operative and post-operative complications are discussed. We review post-operative management and compare the different techniques available for aphakic correction, and describe the VEP changes found in patients with monocular cataract.

Childhood albinism. Visual electrophysiological features

Flash ERGs and VEPs, and VEPs to pattern onset and pattern reversal stimulation were recorded in young albino children and compared to age-matched, normally pigmented, controls. In albinos, the ERG had a significantly larger a-wave, and significantly shorter latencies for both the a-wave and b-wave. VEPs to flash, pattern onset and pattern reversal stimulation all showed an occipital crossed asymmetry when comparing responses from each eye. However, the findings for flash stimulation were more consistent and reliable than those to either form of pattern stimulation.

Visual screening in a school for hearing-impaired children

Hearing-impaired children use vision to compensate for impaired auditory information. This fact, and the relatively high incidence of visual defect among the deaf population, render regular visual screening essential. The Royal School for Deaf Children, Margate, caters for children with a wide range of needs; screening involving a single-assessment structure for all pupils is felt to be inappropriate. This paper describes the implementation of a 'tiered' screening system, and the factors affecting allotment of pupils to particular 'tiers'. The screening structure is illustrated by a case study, and generalization of the system to other educational settings is discussed.

A new system for the measurement of ocular motility using a personal computer

A new system (automated Hess screen, AHS) for the measurement of ocular motility using a personal computer is described. The subject is seated with his/her head restrained at a fixed distance from a colour monitor and views the screen through red/green goggles. A red target is displayed on the screen and the subject is instructed to move a green stimulus (using a joystick control) until the stimulus appears to be centred on the target. A button on the joystick is pressed and the computer registers the relative position of the target and stimulus. This procedure is repeated for a range of target locations (positions of gaze) and the entire routine is then repeated with the other eye fixing, by reversing the colour of the target and stimulus. The oculomotor fields may be displayed on the screen, printed, plotted or saved on a magnetic disc. A prototype system (based on an IBM AT with a 20 in monitor viewed from 25 cm) has been evaluated in a clinical environment on a sample of patients with a wide range of oculomotor problems, and compared with the electronic Hess screen (EHS). In general, the shapes of the oculomotor fields obtained using the two instruments were similar, but the AHS tended to measure a slightly converged displacement of the plots relative to the EHS and to record larger deviations, particularly in patients with incomitant fields. However, the test-retest reliability and the diagnostic value of the charts obtained were similar for both instruments. There was no significant difference between the durations of the examinations with the EHS and AHS. The AHS is a viable alternative to the EHS.

Albinism in childhood: a flash VEP and ERG study

Flash visual evoked potentials (F. VEPs) and electroretinograms (ERGs) were recorded in a total of 20 young children with albinism (age range 5 months to 11 years, mean 4 years). All recordings were made without sedation. There were 13 oculocutaneous cases (one with Hermansky-Pudlak syndrome) and seven ocular albinos. Monocular flash stimulation commonly elicited an asymmetrical occipital VEP distribution with a well lateralised component at around 80 ms which was of opposite polarity in a comparison of VEPs from each eye. None of the normally pigmented matched controls or obligate female carriers showed this anomalous distribution. The albino electroretinogram, compared with controls, recorded under fully darkened conditions had a significantly larger a wave and significantly shorter latencies for both a and b waves. The accentuated ERG and asymmetrical VEP recorded in infants and young children with albinism permits distinction of these patients from those with congenital cone dysfunction and idiopathic nystagmus, with whom they may be confused by a clinical examination only.

Microphthalmos in a family

Details of 22 members from three generations of a family exhibiting systemic and ocular abnormalities are presented. The former include mild mental retardation and a high incidence of abortion or death in the neonatal period. Ocular features comprise: microphthalmos, strabismus, hypermetropia, reduced ocular axial length and abnormal peripapillary pigmentation. The microphthalmos was seen in three forms: bilateral, severe or mild and severe microphthalmos of one eye with the fellow eye mildly affected. No individual with any degree of microphthalmos had a normal sized fellow eye and no normal individual produced an affected child. The genetic implications are discussed. The possible aetiologies of the various features are discussed and that this condition is a neurocristopathy is also considered.