Short-Term Saccadic Adaptation in Patients With Anisometropic Amblyopia

Introduction We aim to compare retrobulbar blood flow parameters between the amblyopic eye and the fellow eye in patients with anisometropic amblyopia. Methods Peak systolic velocity (PSV) and end-diastolic velocity (EDV) of the ophthalmic artery (OA), central retinal artery (CRA), and posterior ciliary artery (PCA) were measured by color Doppler imaging (CDI), and the resistivity index (RI) and pulsatility index (PI) were calculated in 62 patients aged 12-40 years with anisometropic amblyopia. Results The mean PSV values of OA, CRA, and PCA in amblyopic and fellow eyes were 30.38 ± 10.34, 8.45 ± 2.27, and 8.03 ± 2.77, and33.73 ± 14.46, 8.35 ± 2.05, and 8.81 ± 2.77, respectively. The mean EDV values of OA, CRA, and PCA in amblyopic and fellow eyes were 6.86 ± 2.64, 1.47 ± 1.59, and 1.94 ± 2.03, and 8.57 ± 4.30, 1.80 ± 1.73, and 2.32 ± 1.20, respectively. The mean RI values of OA, CRA, and PCA in amblyopic and fellow eyes were 0.77 ± 0.10, 0.85 ± 0.14, and 0.78 ± 0.15, and 0.75 ± 0.07, 0.79 ± 0.20, and 0.74 ± 0.13, respectively. OA-PSV and OA-EDV values were significantly lower in the amblyopic eye than in the healthy eye (p < 0.05). OA-RI values were significantly higher (p < 0.05) in the amblyopic eye than in the healthy eye. Conclusions Considering the decrease in PSV and EDV and the increase in RI, which are the blood flow parameters of the amblyopic eye, our study may provide guidance to focus on increasing blood flow in the treatment of amblyopia.

To compare the macular and nerve fiber layer thicknesses as measured by optical coherence tomography (OCT) in amblyopic and fellow eyes. Fifty patients with monocular strabismic (n = 25) or anisometropic (n = 25) amblyopia (best corrected visual acuity (BCVA) ranging from 20/40 to 20/400) were included in a prospective cross-sectional descriptive study. A refractive error more than 5 diopters in either eye or an axial length difference between the eyes of more than 1 mm was excluded in the anisometropic group. In all cases, the thickness of the macular area and the peripapillary nerve fiber layer were measured by OCT in both amblyopic and fellow eyes and compared with each other. The mean age of patients was 10 ± 3.1 years (range: 6 to 18 years) in the anisometropic group and 8.9 ± 3.7 years (range: 6 to 18 years) in the strabismic group. In the anisometropic group, the mean macular thickness was significantly increased in the amblyopic eyes (222.6 ± 47.8 μm) versus the fellow eyes (205.6 ± 33.3 μm) (P = .002), although there was no significant difference observed when comparing with the prepapillary nerve fiber layer (P = .55). There was no significant correlation of above-mentioned matters in the strabismic group (P = .07 and .52). A thicker macula was found in anisometropic amblyopic eyes, but the increase of macular thickness in strabismic amblyopic eyes was not significant. Retinal involvement was not observed in the peripapillary nerve fiber layer of amblyopic eyes.

BackgroundThe aim of this study was to examine the relationship or differences in ocular structures of amblyopic eyes compared to fellow eyes in children and young adults with hyperopic anisometropic amblyopia.Material/MethodsHyperopic participants with anisometropic amblyopia, defined as the presence of best-corrected visual acuity differences of at least 2 Snellen lines and 1.5 diopters between amblyopic and fellow eyes, were studied. Using the IOL Master, Pentacam Scheimpflug imaging and Spectralis optical coherence tomography, the axial length, corneal curvature, and anterior chamber depth (ACD), as well as the thickness of the cornea, peripapillary retinal nerve fiber layer (RNFL), and macula, were compared between children and young adults and between their amblyopic and fellow eyes.ResultsIn 53 participants with hyperopic anisometropic amblyopia, there were significant differences in the anterior corneal curvature, ACD and axial length between the amblyopic and fellow eyes of all the patients. The mean central macular thickness in the amblyopic eyes was significantly thicker (P=.001) in the group aged 5 to 12 years; however, this was not the case in the group aged 13 to 42 years. There was no significant difference in average RNFL thickness in either group.ConclusionsWe found significantly greater mean central macular thickness in anisometropic amblyopic eyes among participants aged 5 to 12 years, but not among those who were older. Similarly, the interocular differences in axial length parameters seemed to be related to the central macular thickness differences between the amblyopic and fellow eyes in the younger group.

BackgroundSteady-state pattern electroretinogram (PERG) and frequency doubling technology (FDT) perimetry can be used to selectively investigate the activity of the M-Y ganglion cells in adult anisometropic amblyopes.MethodsFifteen normal subjects (mean 27.8±4.1 years) and 15 adults with anisometropic amblyopia (mean 28.7±5.9 years) were analyzed using steady-state PERG and FDT.ResultsThe amplitude of steady-state PERG was significantly different not only among the control group and both the amblyopic eye (P=0.0001) and the sound eye group (P=0.0001), but also between the latter two groups (P=0.006). The difference in FDT mean deviation was statistically significant not only between the control group and amblyopic eye group (P=0.0002), but also between the control group and the sound eye group (P=0.0009). The FDT pattern standard deviation was significantly higher in the control group rather than in the amblyopic eye (P=0.0001) or the sound eye group (P=0.0001). A correlation was found between the reduction in PERG amplitude and the increase in FDT-pattern standard deviation index not only in amblyopic (P=0.0025) and sound (P=0.0023) eyes, but also in the healthy control group (P=0.0001).ConclusionThese data demonstrate that in anisometropic amblyopia, there is an abnormal functionality of a subgroup of the magnocellular ganglion cells (M-Y), and the involvement of these cells, together with the parvocellular pathway, may play a key role in the clinical expression of the disease.

Purpose:To report retinal nerve fiber layer thickness (RNFLT) in eyes with amblyopia compared with contralateral healthy eyes.Methods:In this cross-sectional study, we included patients with anisometropic amblyopia, strabismic amblyopia, and mixed amblyopia. All subjects underwent complete ophthalmic examination, including RNFLT measurement with time-domain OCT (Stratus OCT) and scanning laser polarimeter (GDX VCC). A paired “t” test was used to compare average and quadrant-wise RNFL thickness between the amblyopic and contralateral normal eyes. In addition, an analysis of variance test was used to compare various RNFL thickness parameters between the three groups.Results:A total of 33 eyes of 33 subjects with anisometropic amblyopia, 20 eyes of 20 subjects with strabismic amblyopia, and 38 eyes of 38 subjects with mixed amblyopia were included. In the anisometropic amblyopia group, the average RNFLT in the amblyopic eye was 98.2 mm and 99.8 mm in the fellow normal eye (P = 0.5), the total foveal thickness was 152.82 mm (26.78) in the anisometropic eye and 150.42 mm (23.84) in the fellow eye (P = 0.38). The difference between amblyopic and contralateral normal eye for RNFL and macular parameters was statistically insignificant in all three groups. The RNFL thickness in four quadrants was similar in the amblyopic and non-amblyopic eye between all three groups and statistically non-significant.Conclusion:Our study showed that RNFL thickness was similar in amblyopic and non-amblyopic eyes between all three amblyopia groups.

PurposeTo determine the differences and reproducibility of blood flow among hyperopic anisometropic, fellow, and control eyes.MethodsWe retrospectively studied 38 eyes of 19 patients with hyperopic anisometropia (8.2 ± 3.0 years of age) and 13 eyes of eight control patients (6.8 ± 1.9 years). We measured the optic nerve head (ONH) and choroidal circulation using laser speckle flowgraphy (LSFG) and analyzed the choroidal mean blur rate (MBR-choroid), MBR-A (mean of all values in ONH), MBR-V (vessel mean), MBR-T (tissue mean), and sample size (sample), which are thought to reflect the ONH area ratio, area ratio of the blood stream (ARBS). We then assessed the coefficient of variation (COV) and intraclass correlation coefficient (ICC) and compared the differences among amblyopic, fellow, and control eyes in MBR, sample, and ARBS.ResultsThe ONH, MBR-A, MBR-T, and ARBS of amblyopic eyes were significantly higher than those of fellow eyes (P < 0.01, P < 0.05, and P < 0.05, respectively), and control eyes (MBR-A and ARBS, P < 0.05, for both comparisons). The sample-T (size of tissue component) in amblyopic eyes was significantly smaller than that in fellow and control eyes (P < 0.05). Blood flow in the choroid did not differ significantly between the eyes. The COVs of the MBR, sample, and ARBS were all ≤10%. All ICCs were ≥0.7. The COVs of pulse waveform parameter fluctuation, blowout score (BOS), blowout time (BOT), and resistivity index (RI) in the ONH and choroid were ≤10%.ConclusionThe MBR value of the LSFG in children exhibited reproducibility. Thus, this method can be used in clinical studies. The MBR values of the ONH in amblyopic eyes were significantly high. It has been suggested that measuring ONH blood flow using LSFG could detect the anisometropic amblyopic eyes.

Objective To investigate the thicknesses of macular inner retinal layers in children with anisometropic amblyopia using spectral domain optical coherence tomography (SD-OCT). Methods Thirty-seven children with anisometropic amblyopia and fifty-seven children with normal vision were recruited in the study. Both eyes of children with anisometropic amblyopia and the right eyes of normal controls underwent scanning with the Spectralis OCT. The segmentation of retinal layers was performed automatically to measure individual inner retinal layers in the five sectors of the macular. An independent sample t-test was applied to compare the mean layer thicknesses of anisometropic eyes and fellow eyes with those of control eyes. Results There was no significant difference in the total macular thickness between amblyopic and control eyes. However, in the peripheral macular area, three of the four quadrants of both the ganglion cell layer (GCL) and the inner plexiform layer (IPL) thicknesses were significantly reduced in amblyopic eyes compared to control eyes. Moreover, two of the four quadrants of the GCL thickness and three of the four quadrants of the IPL thickness in the peripheral macular area were significantly reduced in fellow eyes than in control eyes. Conclusion The SD-OCT data revealed differences in the thicknesses of some macular inner retinal layers in both eyes of children with anisometropic amblyopia compared with those with emmetropia, indicating that structural changes might exist in the retina of children with amblyopia.

Background/Objectives: This study aimed to evaluate macular choroidal blood flow dynamics and structural alterations in children with hyperopic anisometropic amblyopia and compare these findings with those of the fellow eyes. Methods: This retrospective observational study included 36 eyes from 18 children (mean age: 4.9 years) with unilateral hyperopic anisometropic amblyopia. Central choroidal thickness (CCT) was measured using enhanced depth imaging optical coherence tomography. Macular choroidal hemodynamics were assessed using laser speckle flowgraphy. Mean blur rate (MBR) was used as an index of blood flow, whereas beat strength (BS) was used as a measure of pulsatility. Ocular perfusion pressure (OPP) was also calculated. All parameters were compared between amblyopic and fellow eyes. Results: Amblyopic eyes demonstrated significantly greater CCT compared with fellow eyes (407.6 ± 84.9 µm vs. 326.4 ± 79.1 µm). Conversely, macular MBR was significantly lower in amblyopic eyes (9.28 ± 3.60 AU vs. 10.94 ± 4.68 AU), as was BS (5.73 ± 3.07 AU vs. 7.28 ± 3.59 AU). No significant differences were observed in central retinal thickness or OPP between amblyopic and fellow eyes. In amblyopic eyes, CCT was not significantly correlated with macular MBR or BS. Conclusions: Amblyopic eyes exhibited significant central choroidal thickening accompanied by reduced macular blood flow and pulsatility. These findings suggest that localized macular hemodynamic dysregulation may contribute to the pathophysiology of hyperopic anisometropic amblyopia.

The present study aimed to explore temporal frequency discrimination in amblyopia, and the influence of attentional load on amblyopic temporal cognition. Twenty anisometropic amblyopes, 20 strabismic amblyopes and 20 normal subjects were recruited. A flickering disk was used for visual stimuli. A two-alternative, forced-choice staircase paradigm was used to measure the temporal frequency discrimination thresholds of amblyopic eyes, fellow eyes and normal dominant eyes under reference temporal frequencies of 5, 10 and 20 Hz. The just-noticeable differences data were analyzed statistically. In addition, the temporal frequency discrimination thresholds of the subjects were measured under different conditions of attentional load. The changes in temporal frequency discrimination thresholds were compared between amblyopic and normal eyes when attention was loaded. At the reference temporal frequencies of 5 and 10 Hz, temporal thresholds of amblyopic eyes were significantly increased compared with fellow eyes (P<0.05). Regarding strabismic amblyopia, temporal thresholds of fellow eyes were increased compared with normal eyes (P<0.05). However, no correlation was identified between the temporal-frequency discrimination thresholds and the LogMAR visual acuities in amblyopic eyes. In addition, higher attentional load caused greater changes in temporal thresholds in amblyopic eyes, but the situation was not the same for lower attentional load. In conclusion, in the present study a deficit of temporal frequency discrimination in amblyopic eyes and the fellow eyes of strabismic amblyopes was identified. Furthermore, the influence of attentional load on temporal frequency discrimination in amblyopic eyes was increased compared with normal eyes.

Objective To investigate the outcome of anisometropic amblyopia therapy in children aged 7-17 years old and to identify factors which influence the outcome of treatment. Methods A retrospective study of 72 patients with anisometropic amblyopia aged 7-17 years old were included in this study. All the patients received refractive correction, occlusion of the sound eye and red scintillation. In addition, patients with eccentric fixation received Haidinger brush and afterimage therapy. Corrected visual acuity was considered improved as visual acuity was elevated by ≥2 lines. Results The best corrected visual acuity of the amblyopic eye was 0.28±0.18, 0.49±0.28, 0.60±0.32, 0.70±0.35 before treatment, after 3 months’, 6 months’ and 1year treatment. Among all the 72 patients, 55 patients’ visual acuity improved after 1-year treatment (76.4%). Only 8 patients’ visual acuity improved in 21 patients with eccentric fixation (38.1%), while 47 patients’ visual acuity improved in 51 patients with centric fixation (92.2%). 13, 33, 9 patients’ visual acuity improved in 26 severe, 37 moderate, 9 mild anisometropic amblyopia patients respectively. No one could get improved visual acuity without compliance. Conclusions Good results can be attained through combined therapy in older children with anisometropic amblyopia. The results are related to the initial severity of amblyopia, fixation of the amblyopic eye and compliance. Better outcome can be obtained in patients with mild to moderate amblyopia, centric fixation and good compliance. Key words: Anisometropic amblyopia; Older children; Therapy of amblyopia

Abnormal early visual development can result in a constellation of neural and visual deficits collectively known as amblyopia. Among the many deficits, a common finding is that both saccadic and manual reaction times to targets presented to the amblyopic eye are substantially delayed when compared to the fellow eye or to normal eyes. Given the well-known deficits in contrast sensitivity in the amblyopic eye, a natural question is whether the prolonged reaction times are simply a consequence of reduced stimulus visibility. To address this question, in Experiment 1 we measure saccadic reaction times (RT) to perifoveal stimuli as a function of effective stimulus contrast (i.e., contrast scaled by the amblyopic eye's contrast threshold). We find that when sensory differences between the eyes are minimized, the asymptotic RTs of our anisometropic amblyopes were similar in the two eyes. However, our results suggest that some strabismic amblyopes have an irreducible delay at the asymptote. That is, even when the sensory differences of the stimulus were accounted for, these observers still had large interocular differences (on average, 77 ms) in saccadic reaction time. In Experiment 2, to assess the role of fixation on saccadic reaction time we compared reaction time with and without a foveal target (the “gap effect”). Our results suggest that, while removing the fixation target does indeed speed up reaction time in the amblyopic eye, the gap effect is similar in the two eyes. Therefore, the gap effect does not eliminate the irreducible delay in the amblyopic eye. Finally, in Experiment 3 we compared the interocular differences in saccadic and manual reaction times in the same observers. This allowed us to determine the relationship between the latencies in the two modalities. We found a strong correlation between the differences in saccadic and manual reaction times; however, the manual RT difference is about half that of saccadic RT, suggesting that there may be two separable effects on saccadic reaction time: (a) a central problem with directing actions to a target, related to disengagement of attention at the fovea, which results in delays in both saccadic and manual reaction times, and (b) a further delay in saccadic reaction times because of the motor refractory period from a previous saccade or microsaccade, made in an attempt to stabilize the amblyopic eye of strabismics.

Successful Treatment of Anisometropic Amblyopia with Spectacles Alone

Occlusion and levodopa-carbidopa treatment for childhood amblyopia

Abnormal cortical processing of pattern motion in amblyopia: Evidence from fMRI

The aim of this study was to compare three different methods to measure visual acuity (VA) in healthy and amblyopic preschool children: a Snellen E chart (SE), a single Lea symbols (SLS), and a crowded Lea symbols (CLS). Seventy-eight eyes of 54 patients (28 females, 26 males) were included in this cross-sectional, comparative study. The control group consisted of 30 healthy cases, and the amblyopic group consisted of 24 patients with amblyopia. Best-corrected VA (BCVA) measurements with SLS, CLS, and SE were compared in control eyes (CE), amblyopic eyes (AE), and fellow eyes (FE) separately. The mean age of the cohort was 5.7±0.7years (range 5-7years). The mean refractive error was +1.02±0.36 D (diopter, spherical equivalent) in CE, +5.59±2.45 D in AE, and +3.96±2.38 D in FE. The median BCVA (logMAR) was (in order of SLS, CLS, and SE) 0.00 [interquartile range (IQR) 0.10], 0.10 (IQR 0.10), 0.00 (IQR 0.10) in CE, 0.25 (IQR 0.33), 0.35 (IQR 0.30), 0.25 (IQR 0.38) in AE, and 0.10 (IQR 0.08), 0.10 (IQR 0.00), 0.10 (IQR 0.10) in FE. There was no statistically significant difference between the three methods in terms of the CE or FE (p>0.05). In contrast, there was a statistically significant difference in AE (p<0.05). The mean VA measurement with SLS was higher compared with CLS in AE. A positive and strong correlation between the three charts was found in all of the groups (p<0.001). We found SLS, CLS, and SE to be consistent: all three methods can be used to obtain measurements of VA in healthy and amblyopic preschool children.