Value of the Bébé-Vision test in the screening of strabismus and anisometropic amblyopia in infants

PURPOSE: To evaluate the accuracy of the Bébé-Vision test for detecting strabismic, ametropic and anisometropic amblyopia in childhood. METHODS: We screened 199 infants under 20 months of age. The screening consisted of a full orthoptic examination by a trained orthopist (cover test, fixation test), a forced choice preferential looking technique (Bébé-Vision test) prior to cycloplegia to test visual acuity, cycloplegic refraction by retinoscopy, and examination of the fundi. RESULTS: Fifteen infants were abnormal on orthoptic examination (clinical evidence of esotropia and/or limitation of abduction and/or amblyopia). The Bébé-Vision test demonstrated a significant interocular difference on the same side of the suspected amblyopic eye in 3 cases and on the opposite side in 3 cases, and no difference in 9 cases. The monocular Bébé-Vision test was abnormal in 51 cases and there was an abnormal cycloplegic refraction in 33 cases. Statistical analysis of these tests demonstrated a very low sensitivity (42%) and a good specificity (90%) for the Bébé-Vision test in detecting amblyopia related to refractive error. CONCLUSION: The Bébé-Vision test does not reliably reveal strabismic or anisometropic amblyopia and is not recommended as a screening test. Diagnosis should continue to be based mainly on the classical clinical methods.     

Optokinetic nystagmus in strabismus: are asymmetries related to binocularity?

PURPOSE: Strabismus may be associated with an asymmetry of monocular horizontal optokinetic nystagmus (OKN). It is unclear whether OKN asymmetries are associated with deficiency in binocular and/or stereovision. In the current study, patients with different degrees of binocularity were investigated. METHODS: OKN was examined in the dominant and nondominant eyes of four groups of patients: (1) no measurable binocularity (NB), (2) poor binocularity (PB)-that is, showing binocularity on the Bagolini Test and/or rudimentary stereovision, (3) good binocularity (GB) with good stereoacuity after squint surgery, and (4) a control group. Monocular OKN was elicited with black-and-white stripes moving temporally to nasally (TN) or nasally to temporally (NT) at velocities of 15, 30, 45, and 60 deg/s. Eye movements were recorded with infrared oculography. RESULTS: Only subjects in the NB group showed a significant OKN asymmetry, with preference for TN stimulation in dominant and nondominant eyes. Subjects with PB did not have significant OKN asymmetries but reduced OKN gains in both stimulus directions. Subjects with GB had normal mean OKN gains without asymmetry. Larger OKN asymmetries were correlated with younger age at detection of strabismus if NB and GB were grouped together, but not if each group was analyzed separately. CONCLUSIONS: For the first time, a large groups of patients classified by level of binocular vision has been investigated. The results show that OKN gain and asymmetry are associated with the development of binocular vision. OKN investigation may be helpful to identify patients with binocularity or binocular potential in strabismus.     

Visually evoked response (VER) in amblyopia: A diagnostic and prognostic indicator?

A study comprising 15 cases of anisometropic amblyopia and 15 cases of strabismic amblyopia was undertaken to analyse the alterations in the visually evoked response (VER) in amblyopia. Ten normal cases were taken to standardize the technique. A Nicolet Clinical Averager CA₁₀₀ was used to record the VER. A full ophthalmic check up including cycloplegic refraction, visual acuity recording and fixation pattern by visuscope was carried out in all the cases.

In normal cases the amplitude and implicit time of VER showed no statistically significant difference between the two eyes. However, a wide inter-subject variability was observed. the maximum amplitude was seen with a check size of 60′. In amblyopic eyes (both strabismic and anisometropic) there was a significant reduction in the amplitude and a significant increase in the implicit time when compared to the normal fellow eye. A significant amplitude difference of more than 5 μV, as also a significant increase of implicit time (more than 10 msec) was noticed only when the visual acuity was below 6/18. Recording of VER in amblyopic eyes with visual acuity less than 6/60 mostly resulted in no discernible pattern. A non-recordable pattern on VER in amblyopic eyes signifies a poor visual acuity and possibly suggests a bad prognosis for the treatment of amblyopia.     

Comparing distance visual acuity measurement with a novel eye chart and the Landolt C chart in a population of children aged 6–18 years

Purpose

The Handy Eye Chart? is designed to assist in evaluating the visual acuity of patients with non-standard communication styles. The Handy Eye Chart? has been previously validated against the early treatment diabetic retinopathy study (ETDRS) chart. The aim of this research is to compare visual acuity outcomes with The Handy Eye Chart? against the international gold standard, the Landolt C chart, in a population of children.

Methods

Sixty participants between the ages of 6 and 18 were recruited at the Pediatric Section of the Department of Ophthalmology at the Emory Eye Center. Visual acuity was evaluated using The Handy Eye Chart? and the Landolt C Chart, altering the order of administration between charts. The visual acuity data were compared using t test, linear regression, and Bland–Altman analysis.

Results

The mean difference in visual acuity was 0.02 logMAR (CI 0.009–0.04, p = 0.002). The correlation coefficient was 0.98. The Bland–Altman analysis shows the 95% limits of agreement between the charts to be ?0.14 to 0.09 logMAR.

Conclusions

The Handy Eye Chart? is a valid measure of visual acuity when compared with the international gold standard, the Landolt C Chart.

     

Screening and treating amblyopia: are we making a difference?

PURPOSE: To determine the rate of amblyopia in native Jewish Israelis compared with those who immigrated from the former Soviet Union (U.S.S.R.) after they were 10 years of age. METHODS: Health records of all 16-year-old subjects examined in the Israel Defense Forces Recruitment Center between 1998 and 2003 were analyzed. The number of subjects with best corrected visual acuity (BCVA) of 6/12 or less in at least one eye among native Israelis and among those who immigrated to Israel from the U.S.S.R. after they were 10 years of age was determined. Subjects who had any ocular disease except cataract, corneal opacity, strabismus, or ptosis were excluded. RESULTS: Of 305,712 subjects examined between 1998 and 2003, 292,255 were enrolled in the study. Of those, 260,186 (89%) were born in Israel and 32,069 (11%) were born in the U.S.S.R. and immigrated to Israel after they were 10 years of age. There were 2565 (0.98%) native Israelis and 483 (1.5%) immigrants who had BCVA of 6/12 or less in at least one eye (chi(2) test, P < 0.00001). The rate of amblyopia among subjects who had refractive errors was 14.6% among immigrants, as opposed to 8.0% among native Israelis (P < 0.0001), whereas amblyopia rates among those with strabismus, cataract, or ptosis were similar in native Israelis and immigrants (34.4%, 38.6%, 12.8% as opposed to 34%, 37.5%, 15.4%, respectively, P = 0.5-0.61). CONCLUSIONS: The difference in the rate of refractive amblyopia as opposed to strabismic and deprivation amblyopia may be due to the difference in vision screening methods between both countries.     

Can human amblyopia be treated in adulthood?

Amblyopia is a common visual disorder that results in a spatial acuity deficit in the affected eye. Orthodox treatment is to occlude the unaffected eye for lengthy periods, largely determined by the severity of the visual deficit at diagnosis. Although this treatment is not without its problems (poor compliance, potential to reduce binocular function, etc) it is effective in many children with moderate to severe amblyopia. Diagnosis and initiation of treatment early in life are thought to be critical to the success of this form of therapy. Occlusion is rarely undertaken in older children (more than 10 years old) as the visual benefits are considered to be marginal. Therefore, in subjects where occlusion is not effective or those missed by mass screening programs, there is no alternative therapy available later in life. More recently, burgeoning evidence has begun to reveal previously unrecognized levels of residual neural plasticity in the adult brain and scientists have developed new genetic, pharmacological, and behavioral interventions to activate these latent mechanisms in order to harness their potential for visual recovery. Prominent amongst these is the concept of perceptual learning--the fact that repeatedly practicing a challenging visual task leads to substantial and enduring improvements in visual performance over time. In the normal visual system the improvements are highly specific to the attributes of the trained stimulus. However, in the amblyopic visual system, learned improvements have been shown to generalize to novel tasks. In this paper we ask whether amblyopic deficits can be reduced in adulthood and explore the pattern of transfer of learned improvements. We also show that developing training protocols that target the deficit in stereo acuity allows the recovery of normal stereo function even in adulthood. This information will help guide further development of learning-based interventions in this clinical group.     

Myopic strabismus fixus: a mitochondrial myopathy?

PURPOSE: Ultrastructural analysis of extraocular muscle in a case of myopic strabismus fixus. DESIGN: Interventional case report. METHODS: Incisional biopsy and ultrastuctural analysis of recti muscles in a female patient with myopic strabismus fixus. RESULTS: Ultrastuctural analysis revealed evidence of mitochondrial myopathy. CONCLUSION: Acquired strabismus fixus due to high myopia may be a manifestation of mitochondrial myopathy, a finding that has not been previously reported.     

Synoptophore versus prism and cover test measurements in strabismus.: A question of instrument convergence?

It has long been advocated that the accuracy of the synoptophore is affected by the artificial viewing conditions it provides and the patient's awareness of its proximity, which results in an increase in the angle in ET and a decrease in XT. The aim of this retrospective study was to investigate the agreement between distance horizontal strabismus measurements taken with the synoptophore and PCT. Fifty-four measurements (n = 42: 28 with ET, 14 with XT) were analysed. The PCT was repeated by a second examiner and the measurements (n = 17) were compared to those of the first examiner's prism measurements. The main finding was a high agreement between the measurements obtained by the two methods (ICC: R = 0.91). There was an eso-shift of the deviation at the synoptophore (compared with the PCT) in 26% and an exo-shift in 28%. Therefore, over-convergence was just as likely to occur as un-der-convergence. The findings cannot support the popular notion that the synoptophore exaggerates the angle in ET and understates it in XT. Furthermore, it was shown that the variability between the two measurement methods was similar to the inter-examiner variability for the PCT. It was concluded that the synoptophore measurements are valid and that the phenomenon of over-convergence with this device ('instrument convergence') is not a relevant clinical entity.     

Can interocular pattern reversal visual evoked potential and motor reaction time differences distinguish anisometropic from strabismic amblyopia?

PURPOSE: With the use of the pattern reversal visual evoked potential and the motor reaction time, we sought to differentiate anisometropic amblyopia from strabismic amblyopia on the basis of the visual transmission time. METHODS: Pattern reversal visual evoked potentials and motor reaction times were obtained in nine normal subjects, eight anisometropic and seven strabismic amblyopes. RESULTS: Our results show that while the peak time of the pattern visual evoked potential in anisometropic amblyopia and strabismic amblyopia was significantly delayed, it could not distinguish the two types of amblyopia. In contrast, a significantly longer interocular increment in strabismics compared to anisometropes was found with the reaction time, but not with the pattern visual evoked potential. CONCLUSION: Our findings thus show that it is possible to distinguish strabismic from anisometropic amblyopes using interocular differences in reaction time measurements. Our results bring support to the contention that the two types of amblyopia represent different neural abnormalities.     

Eye patching as a treatment for amblyopia in children aged 10�C16?years

Purpose

To investigate the effects of full-time patching regimen on the treatment of amblyopia in children aged 10?C16 years.

Methods

Forty-seven patients with a mean age of 12.09 ± 1.65 years were included in this study. All of the patients received eye patching for the entire day, 6 days a week, during the first 3 months. The patients who achieved visual acuity of 0.00 logMAR at the third month were provided with additional patching treatment (4?C6 h/day). On the other hand, the patients who showed no change in their visual acuity or an increase of less than 0.00 logMAR at the third month had 3 more months of eye patching for the entire day, 6 days a week.

Results

Prior to treatment, the best mean visual acuity of the amblyopic eyes was 0.48 ± 0.25 (range 1.00?C0.15) logMAR. After follow-up, the visual acuity of the amblyopic eyes was 0.20 ± 0.22 (range 1.00?C0.00) logMAR. Thus, visual acuity in the amblyopic eyes improved by 0.2 log unit or more in 38 of 47 patients (81%).

Conclusions

The present results show that patching in older children with amblyopia improves visual acuity with no serious complications. The use of patching in children to improve amblyopia seems promising.     

Are changes in visual acuity and astigmatism after corneal cross-linking (CXL) in keratoconus predictable?

Graefe's Archive for Clinical and Experimental Ophthalmology - To evaluate changes in corrected distance visual acuity (CDVA), ratio of anterior and posterior corneal radii over the thinnest...