Amblyopia: detection, prevention, and rehabilitation.

This year's literature on the detection, prevention, and rehabilitation of amblyopia is again somewhat dominated by the topic of vision screening, specifically photoscreening and also by the therapeutic challenges of compliance and late treatment. Basic scientists also have added to our knowledge and understanding of certain interesting and clinically significant characteristics of the visual perception of amblyopes.

Abduction paralysis with hypotropia: sign of weakness of a contralateral superior oblique.

background The clinical diagnosis of extraocular motor paralysis that is caused by severe cranial trauma can often be complicated. The resulting clinical picture can make the identification of all the components of potentially treatable oculomotor problems difficult. methods We examined five cases of complete abducens nerve paralysis with marked downshoot in attempted abduction seen after severe cranial trauma. results With the patients looking in the field of gaze of the paralysis, a marked infraductive movement of the paralytic eye occurred while the other eye maintained fixation. Other clinical findings confirmed this to be a secondary deviation due to a paresis of the contralateral superior oblique. conclusion Patients with a paralysis of the lateral rectus following a severe cranial trauma who demonstrate a marked downshoot of the involved eye should be suspected of having a paresis of the contralateral superior oblique. This diagnosis has helped us effectively to treat this vertical incomitance by a simple weakening procedure of the contralateral inferior oblique.

The use of binocular visual acuity in the assessment of intermittent exotropia.

BACKGROUND: It has been suggested that a decrease in distance stereoacuity in patients with intermittent exotropia is a good indicator of diminishing control. However, there has been no adequate explanation for this reported reduction in distance stereoacuity in these patients. We postulate that the decrease in stereoacuity is related to blurred visual acuity created by an increasing demand on accommodation, which these patients use in an attempt to control the exodeviation. This can best be assessed by measuring binocular visual acuity (BVA). Analysis of BVA could provide a useful clinical tool to evaluate control measures used by patients with intermittent exotropia. METHODS: A prospective study of patients with intermittent exotropia, ranging in age from 6 to 60 years, was performed. Only those patients with the presence of either basic or divergence excess (simulated or true) type exodeviation were included in the study. The data analysis included the age of these patients, age at onset of the deviation, monocular and binocular visual acuity, oculomotor and fusional status, and near and distance stereoacuity. RESULTS: Data from 36 patients show that the measurements of BVA correlated well with a corresponding loss of distance stereoacuity but not with the size of the deviation. CONCLUSION: The decrease of stereoacuity reported in patients with exotropia can be explained by increased accommodation and decreased distance BVA. This measurement can be a simple method of quantifying the fusional control of patients with intermittent exotropia.

Detection, prevention, and rehabilitation of amblyopia.

We are seemingly entering into a photoscreening era in this new year 2000. An increasing number of publications in 1999 have dealt with this particular method of detecting vision problems in children. In the same periods, interesting and promising developments on the rehabilitation of amblyopia have been reported. Moreover, the problem of compliance with amblyopia therapy seems finally to have been solved with the help of microchips and heat sensorsi On the other hand, reports on both pharmacologic and penalization rehabilitation methods continue to show good reliability and clinical relevance. Finally, as in a previous review in 1998, we feel compelled to bring up at least one controversial issue; it is no surprise to find at least two seemingly erudite recent publications reputing not only the validity of vision screening in children, but the value of the treatment of amblyopia itself. We report here a most important study that responds to the challenge.

Successful treatment of neonatal trilateral retinoblastoma.

Trilateral retinoblastoma is a rare and almost exclusively fatal disease. Previous treatment regimens have failed to prolong life once the diagnosis is made. We present the first documented case of a patient with neonatal trilateral retinoblastoma successfully treated with chemotherapy and sequential local retinal treatment who is alive and well 26 months after diagnosis.

Paralytic strabismus.

In the past 12 months there have been many interesting publications on paralytic strabismus. Many investigators have reported on various imaging techniques helping both the clinician and the basic scientist better evaluate the causes and effects of paralytic strabismus on the extraocular muscle environment. Some interesting cases of neurologic and systemic associations have also been reported, including a unilateral pupil-sparing third nerve paralysis developing after the use of sildenafil citrate (Viagra; Pfizer, New York, New York). Advances in genetics are now helping us further understand complex entities such as progressive external ophthalmoparesis and congenital fibrosis syndrome. At the other end of the spectrum, colleagues are reporting clinical findings to help specify the diagnosis of conditions as diverse as degenerative ataxic disorders and masked bilateral superior oblique muscle paresis. Unfortunately, there were very few papers on proven new effective surgical techniques for the treatment of paralytic strabismus this year. Finally, to help clarify terminology, and when at all possible depending on the reports reviewed, the following nomenclature will be used in this paper: paralysis--complete loss of function of a muscle or group of muscles innervated by a specified (when applicable) cranial nerve or branch; paresis--incomplete loss of function; and palsy--when the authors failed to specify the degree of weakness.

Detection, prevention, and rehabilitation of amblyopia.

Although there is a continuing effort to develop effective measures for detecting amblyopia, the debate continues in many countries as to the real value of population-wide pediatric vision screening programs. Nevertheless, amblyopia still represents a significant and treatable clinical problem for the practicing ophthalmologist. In this past year's literature, we can find that many visual functions are abnormal in amblyopia, but only a few are measured to reach a diagnosis or monitor treatment. Unfortunately, the wide variety of the measurement methods and the lack of definition for a cure of amblyopia are the cause of serious criticism of our "scientific" literature on the subject. All the while, old methods of treatment are resurfacing again: optical and pharmacological penalizations. The search for a possible "pill" to either replace or at least complement conventional methods of treatment also has continued in 1997 and 1998. As well, there have been quite a few papers on the long-term management of amblyopia. Finally, this review would not be complete without reporting on the "controversy du jour:" a report that challenges the need to cure amblyopia before operating on esotropia.

The range and variability of ophthalmological parameters in normal children aged 4 1/2 to 5 1/2 years.

BACKGROUND: Some standards for childhood ophthalmological variables exist. However, for most parameters, the range of variation found in normal children remains poorly defined. METHODS: We have determined the range of normal function for a number of commonly measured ophthalmological variables in 162 children, classified normal by Gold Standard ophthalmological examination. This group is representative of almost 12,000 normal children aged 4 1/2 to 5 1/2 in Nova Scotia. RESULTS: In 56.8% of eyes the visual acuity was 6/4.5. The use of a chart with crowding bars was more discriminating between differences in higher levels of acuity and highlighted differences in acuity between the two eyes. Randot stereoacuity showed a uniform, non-Gaussian distribution of scores. Cycloplegic refractive errors were distributed about a modal value of between +0.5 and +1.0 diopter. Forty percent of eyes had no detectable astigmatism. Ninety-seven percent of subjects had no heterophoria. Fusional vergence data are presented. CONCLUSION: Our results document the complete normal range for selected ophthalmological parameters in normal preschoolers. The values obtained were in general better than expected.

Visual evoked potentials with crossed asymmetry in incomplete congenital stationary night blindness.

PURPOSE: To investigate a proposed postretinal defect in patients with the incomplete form of congenital stationary night blindness (CSNB2) and to compare visual evoked potential (VEP) results with those found in various forms of albinism. METHODS: Visual evoked potentials were performed in 10 patients with a diagnosis of CSNB2, 10 subjects with albinism, and 17 normal subjects. Visual evoked potentials were elicited monocularly with diffuse flash stimulation. Scalp electrodes were placed over each hemisphere and referred to the forehead. Interhemispheric bipolar recordings were derived, and the correlation coefficient (CC) was calculated for various segments of the interhemispheric responses. RESULTS: A crossed visual evoked potential asymmetry pattern could be demonstrated in 9 of 10 patients with CSNB2. All subjects with albinism and none of the normal subjects showed the crossed asymmetry pattern. Statistical comparison of the CC computed for various segments of the interhemispheric response shows that the pattern of inversion in CSNB2 is more prominent in the 25 to 100 msec range (median CC, -0.37) and in the 175 to 250 msec range (CC, -0.27). In subjects with albinism, all segments show a negative CC (range, -0.46 to -0.60). In normal subjects, all segments are positively correlated (range, 0.36 to 0.66). CONCLUSIONS: Crossed visual evoked potential asymmetry was found in patients with CSNB2; therefore, excessive decussation, as demonstrated by this testing procedure, should not be considered as pathognomonic for albinism.

Congenital corneal anesthesia.

PURPOSE/METHODS: The case of a 7-month-old infant illustrates the diagnostic findings, including magnetic resonance imaging, and the difficulties of treating congenital corneal anesthesia. RESULTS/CONCLUSIONS: The diagnosis of sporadic idiopathic congenital corneal anesthesia was one of exclusion. Normal gasserian ganglia were demonstrated on magnetic resonance imaging. Visual rehabilitation was successful with continuous lubrication, arm splinting at bedtime, and treatment of amblyopia. It continues to be essential for the parents to monitor the corneal status.

Negative predictive value of a population-based preschool vision screening program.

BACKGROUND: The Enhanced Vision Screening Program is a population-based vision screening program that has, at present, examined 59,782 children. Its main goal is to detect amblyopia, strabismus, and high refractive errors. An average of 11,910 4 1/2- to 5 1/2-year-old children are screened yearly. The current study determines the negative predictive value of the screening program: For a subject having passed the vision screening test, what is the probability of not having amblyopia, strabismus, or high refractive errors? METHODS: Of the 11,734 subjects who passed the vision screening, 200 were randomly chosen to undergo a strictly defined gold standard examination by an orthoptist and an ophthalmologist. RESULTS: Of the 200 randomly chosen subjects, 157 underwent the gold standard evaluation. The negative predictive value of the Enhanced Vision Screening Program was 97.6% for any potentially vision-threatening ocular condition. It was 98.7% if we considered only the visually significant ocular problems that the test was designed to detect. CONCLUSION: Because the negative predictive value of the Enhanced Vision Screening Program is not 100%, some children with amblyopia, strabismus, or refractive errors are missed. Occasionally, a rare, potentially vision-threatening condition may go undetected. Parents should be made aware of this when they receive the results of the vision screening.

Autosomal recessive cerebellar hypoplasia and tapeto-retinal degeneration: a new syndrome.

Two sisters with autosomal recessive cerebellar hypoplasia and severe nonprogressive retinal pigmentary disease are presented. This syndrome has been previously described in only 1 patient. The retinal changes may be difficult to discern and we suggest that all patients with congenital ataxia have a detailed ophthalmologic assessment, including electroretinography.

Teaching young children to use contact lenses.

Young children with surgically removed lenses and extreme nearsightedness can benefit from contact lenses, but their parents may need instruction to teach their children to accept lenses. In this study, 4 children under the age of 5 years were taught contact lens wear using a shaping procedure. Compliance was rewarded with praise and tangibles, and noncompliance was followed with brief time-out for 3 of the children and restraint for the 4th. Three children showed high compliance during an initial shaping procedure, with a decrease in compliance during initial insertion of the lenses. At 3- to 10-month follow-up, levels of compliance were high. Insertion and removal of lenses were accomplished in substantially less time, with little crying and no need for time-out. All 3 children continue to use the lenses daily, and 2 have shown improved visual acuity. The 4th child, who has Down syndrome, showed low levels of compliance with need for physical restraint throughout. Although his parents reported high compliance when he first went home, fitting difficulties and an infection resulted in plummeting of compliance, and contact lens use was discontinued. This procedure has been used successfully at the same hospital with 11 of 13 other children between the ages of 14 months and 7 years 4 months. Implications for selection of suitable candidates for this intervention and ways to decrease costs are discussed.

Epidemiology of severe eye injuries in childhood.

The authors conducted a cross-sectional study of all ocular injury cases admitted to a children's hospital between January 1978 and December 1984. Of 222 injuries reviewed, 77 (35%) resulted in some visual deficit. Males were significantly overrepresented in all age groups with an average male:female ratio of 3.5:1. The distribution of injuries was: contusions, 114 (51%); penetrating lacerations, 62 (28%); foreign bodies and burns, 11 (5%); and nonpenetrating lacerations, 35 (16%). Sixteen (7%) ocular injuries were associated with BB gun pellets and six of these children (42%) were blinded in the injured eye as a result. Two other cases of blindness resulted from ocular penetration by homemade "Jinsang Stars," underscoring the adverse influence of media on children's games. Adult supervision could have potentially prevented most cases of permanent visual deficit. The authors suggest that legislation restricting the use of BB guns be passed and that a program of adult and child eye safety education including "eye watch" warnings on potentially hazardous toys be developed.