Macular and peripapillary retinal nerve fibre layer thickness in adults with amblyopia

Evaluation of Ganglion Cell-Layer Complex and Macular Vessel Density in Amblyopic Eyes with Optical Coherence Tomography Angiography

Purpose: This study aimed to compare and quantify the ganglion cell complex (GCC), macular thickness, and vessel density (VD) in amblyopic eyes and their corresponding fellow eyes using optical coherence tomography angiography (OCTA). Methods: This cross-sectional study analyzed 32 unilateral amblyopic patients, examining both of their eyes. The study assessed parameters such as GCC thickness, macular thickness (total, inner, and outer layers), and VD in the optic nerve and macular region using spectral-domain OCTA. Results: This study analyzed data from 30 unilateral amblyopic patients with a mean age of 28.7 ± 18.3 years. Amblyopic eyes had lower mean best-corrected visual acuity compared with healthy eyes. However, no significant differences were found in retinal nerve fiber layer (RNFL) thickness, GCC thickness, and overall retinal thickness between amblyopic and fellow eyes when accounting for factors such as axial length and signal strength index. In patients older than 30 years, amblyopic eyes had a higher global loss volume (GLV) compared with fellow eyes (p = 0.02). In addition, blood VD within the optic disc and superficial/deep capillary plexuses in different macular regions were significantly lower in amblyopic eyes compared with fellow eyes. Conclusions: This study found significant differences in VD and the GLV index between amblyopic eyes and healthy eyes, particularly in older patients. However, there were no notable differences in macular thickness and RNFL thickness. Further research is needed to determine the clinical relevance of these findings.

Retinal nerve fiber layer thickness in amblyopia

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 μm and 99.8 μm in the fellow normal eye (P = 0.5), the total foveal thickness was 152.82 μm (26.78) in the anisometropic eye and 150.42 μm (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.

[Correlation of chorioretinal parameters with anatomical, optical and functional indicators of eyes with amblyopia of various origins]

Purpose. To measure thickness of the central retina and choroid, retinal nerve fiber layer and ganglion cell complex in the macular region, retinal nerve fiber layer in the peripapillary region in eyes with various types of amblyopia, and to analyze its relationship with best corrected visual acuity, refraction and axial eye length.

MATERIAL AND METHODS

The study included 50 patients aged 5 to 16 years (mean age 10.04±3.01 years). All patients were divided into 6 groups: 1 - relative amblyopia with congenital myopia (23 eyes); 2 - dysbinocular amblyopia (14 eyes); 3 - refractive amblyopia (16 eyes); 4 - anisometropic amblyopia (7 eyes); 5 - paired eyes of patients with amblyopia (20 eyes); 6 - control group (20 eyes). Chorioretinal parameters were determined using the RS-3000 Advance 2 spectral optical coherence tomography system («Nidek», Japan). Correlation analysis was performed using the Pearson's linear correlation coefficient (r). The level of significance of the differences was determined by the standard Student's t-test.

RESULTS

Morphological changes in the sensory and choroid membranes of the eye were revealed in groups with amblyopia of various origins compared to the control group, as well as in the fellow eyes. Intergroup comparison showed the presence of more significant disorders in refractive and relative amblyopia due to congenital myopia. Correlation analysis showed that structural changes in the posterior pole are more related to the anatomical and optical parameters of the eyes.

CONCLUSION

Optical coherence tomography allows detection of microscopic structural anomalies in the posterior pole of the eye in amblyopia of various origins, assists in differential diagnosis of this condition with organic pathology, and - most importantly - helps peer deeper into the pathogenesis of this disease.

Impact of ocular dominance on circumpapillary and macular retinal nerve fibre layer thickness and ganglion cell layer thickness in a healthy pediatric population

OBJECTIVE

This study was designed to evaluate potential differences in circumpapillary retinal nerve fibre layer (cpRNFL) thickness and segmented macular retinal layers between dominant and nondominant eyes on spectral-domain optical coherence tomography in a pediatric population.

DESIGN

Cross-sectional study.

PARTICIPANTS

89 healthy children attending a general pediatric clinic.

METHODS

Participants underwent sighting dominant testing and macular and cpRNFL spectral-domain optical coherence tomography. Segmented macular layer thicknesses and cpRNFL thickness were compared for individual patients based on their ocular dominance.

RESULTS

Ocular dominance occurred particularly in the right eye (64.7%). Dominant and nondominant eyes did not differ significantly in axial length or spherical equivalent refraction; axial length: 22.99 ± 1.17 mm versus 22.98 ± 1.19 mm; p = 0.51 and spherical equivalent refraction: -0.09 ± 2.68 D versus 0.32 ± 2.93 D; p = 0.41. In the comparison of the macular ganglion layer the average thickness in the 1 mm central Early Treatment Diabetic Retinopathy Study area was significantly different between the dominant and nondominant eye (16.56 ± 6.02 μm vs 17.58 ± 8.32 μm; p = 0.02). However, when compensating with Bonferroni, this difference was no longer statistically significant. There were no differences in the analyses of average global and sectorial cpRNFL thickness in dominant and nondominant eyes.

CONCLUSION

Dominant eyes demonstrated no significantly thicker average macular retinal nerve fiber layer (mRNFL), Ganglion cell layer (GCL) thickness or cpRNFL thickness. No ocular characteristic was found to be associated with the relative dominance of an eye in eyes with low anisometropia.

Inter-Ocular Symmetry of Vascular Density and Retinal Thickness in Unilateral Anisometropic Amblyopia

Background

Inter-ocular symmetry of macular vascular anatomy in healthy subjects has been well documented in previous optical coherence tomography angiography (OCTA) studies. In our present study, we have demonstrated that the presence of anisometropic amblyopia in one eye does not alter this unique feature significantly. We investigated whether the presence of unilateral anisometropic amblyopia due to moderate amounts of hyperopia and/or astigmatism would have any significant influence on measurements of retinal thickness (RT) and superficial vessel density (SVD) in adult subjects.

Subjects and methods

In the study group, both eyes of 21 adult subjects with unilateral anisometropic amblyopia were enrolled. Only one eye of an age-matched control group including 33 subjects was randomly selected. RT and SVD were measured in foveal and parafoveal retinal areas and compared in amblyopic eyes, their fellow eyes and in the control group. Inter-ocular symmetry of RT and SVD in amblyopic and fellow eyes were investigated by using correlation analysis.

Results

There were statistically significant inter-ocular correlations of foveal and parafoveal RT in amblyopic and fellow eyes (P < 0.0001, for both). Foveal and parafoveal RT of the control group were not statistically different from amblyopic eyes (P = 0.072 and P = 0.46, respectively). There was no difference between foveal SVD of amblyopic eyes and control group (P = 0.10) and a significant inter-ocular correlation was found between amblyopic and fellow eyes (P = 0.029).

Conclusion

For our adult subjects, none of the investigated OCTA parameters of the amblyopic eyes were found to be statistically different from those of age-matched controls. The preservation of inter-ocular symmetry in the amblyopic and fellow eyes implies that the influence of anisometropic amblyopia in one eye would be relatively small and negligible on routine OCTA examination.

Microvascular changes in amblyopic eyes detected by optical coherence tomography angiography

PURPOSE

To investigate retinal microvascular findings detected by optical coherence tomography angiography (OCT-A) in amblyopic eyes compared with normal eyes.

METHODS

A total of 23 amblyopic (strabismic, ametropic, anisometropic, and meridional amblyopia) and 22 normal eyes were included in this prospective observational, comparative study. All patients underwent complete ophthalmological examination and OCT-A imaging. Vessel density (VD) percentage in the superficial and deep retinal vessel plexus, foveal avascular zone (FAZ) area, flow area in the outer retina and choriocapillaris, and retinal thickness in μm in a 6.00 × 6.00 mm scan size were measured and compared between groups.

RESULTS

There were no statistically significant differences between groups in terms of age (P = 0.584) and sex (P = 0.661). Mean FAZ area was smaller in the amblyopic group; however, the difference was not statistically significant (P = 0.145). The outer retina flow area was significantly wider in the amblyopic group (P = 0.03). The fovea was thicker in the amblyopic group (P = 0.02). In addition, VD in both the superficial and deep retinal plexus was significantly lower in amblyopic eyes in all quadrants except the fovea. In amblyopic subgroups, VD of anisometropic amblyopic eyes was significantly higher than other subgroups in both superficial and deep retinal plexuses at all regions except the fovea. Other measures were similar in between groups.

CONCLUSIONS

Microvascular retinal structural anomalies detectable on OCT-A could shed further light on the causes of amblyopia.

Evaluation of retinal structure in unilateral amblyopia using spectral domain optical coherence tomography

PURPOSE

To investigate potential differences in the retinal nerve fiber layer (RNFL) thickness, macular thickness and foveal thickness between amblyopic eyes and normal fellow eyes on spectral domain optical coherence tomography (SD-OCT).

METHODS

A cross-sectional study of patients ≥10 years of age with unilateral amblyopia resulting from an anisometropic, strabismic or deprivative cause. Comprehensive ophthalmic examination was completed and the retinal structures of both eyes were measured using SD-OCT. We compared the measurements obtained between the amblyopic eye and the fellow normal eye in each subject.

RESULTS

Twenty-six unilateral amblyopia patients with a mean age of 29.92 ± 14.19 years old participated in the study, of which 17 (65.4%) were classified as anisometropic, 7 (26.9%) as strabismic, and 2 (7.7%) as deprivative. For the amblyopic eye and fellow normal eye, respectively, the mean RNFL thickness was 95.87 ± 14.56 μm and 97.87 ± 14.56 μm (P = 0.628), the mean macular thickness was 270.87 ± 14.43 μm and 275.60 ± 14.43 μm (P = 0.251) and the mean foveal thickness was 250.59 ± 27.82 μm and 242.91 ± 27.82 μm (P = 0.332). SD-OCT assessments revealed no statistically significant differences between both eyes.

CONCLUSIONS

Using SD-OCT, there were no significant changes in the retinal structure of amblyopic eyes. Therefore, amblyopia does not seem to have a profound structural effect on the retinal nerve fiber layer, the macula, or the fovea.

Spatial summation across the visual field in strabismic and anisometropic amblyopia

Ricco's area (the largest area of visual space in which stimulus area and intensity are inversely proportional at threshold) has previously been hypothesised to be a result of centre/surround antagonism in retinal ganglion cell receptive fields, but recent evidence suggests a sizeable cortical contribution. Here, Ricco's area was measured in amblyopia, a condition in which retinal receptive fields are normal, to better understand its physiological basis. Spatial summation functions were determined at 12 visual field locations in both eyes of 14 amblyopic adults and 15 normal-sighted controls. Ricco's area was significantly larger in amblyopic eyes than in fellow non-amblyopic eyes. Compared to the size of Ricco's area in control eyes, Ricco's area measured significantly larger in amblyopic eyes. Additionally, Ricco's area in the fellow, non-amblyopic eye of amblyopic participants measured significantly smaller than in control eyes. Compared to controls, Ricco's area was larger in amblyopic eyes and smaller in fellow non-amblyopic eyes. Amblyopia type, binocularity, and inter-ocular difference in visual acuity were significantly associated with inter-ocular differences in Ricco's area in amblyopes. The physiological basis for Ricco's area is unlikely to be confined to the retina, but more likely representative of spatial summation at multiple sites along the visual pathway.

Decreased severity of age-related macular degeneration in amblyopic eyes

AIM

To evaluate whether people with age-related macular degeneration (AMD) and a history of amblyopia have equal severity of AMD in both eyes.

METHODS

Billing records were used to locate all people with a history of amblyopia and AMD evaluated between 1 January 2003 and 1 June 2015 at a single ophthalmology institute. Two ophthalmic graders blinded to amblyopia status determined the severity of AMD in each eye using fundus photos and a validated grading scale.

RESULTS

A total of 14 people were found to have AMD and a documented history of amblyopia. Average patient age was 77.0 years and average best corrected visual acuity was 20/160 in eyes with a history of amblyopia and 20/40 in fellow eyes without amblyopia. Eyes with a history of amblyopia were found to have a lower AMD severity score (mean lower score: -1.38; paired t-test P=0.019). Of the 11 people with asymmetric disease severity, 10 individuals had worse AMD in the non-amblyopic eye while one person had worse AMD in the amblyopic eye (P=0.0067).

CONCLUSIONS

Our pilot study suggests that eyes with a history of amblyopia may manifest decreased severity of AMD compared with non-ambylopic eyes in the same patient. Further research is warranted to investigate this clinical observation.

Changes in macular parameters in different types of amblyopia: optical coherence tomography study

PURPOSE

The purposes of this study were to investigate the changes in macular parameters (thickness, volume) and peripapillary retinal nerve fiber layer (RNFL) thickness (RNFLT) in different cases of amblyopia versus the normal fellow eyes using optical coherence tomography (OCT) and to estimate the relationship of OCT changes with various defined patients' parameters.

DESIGN

This is a prospective, observational, cross-sectional case series.

METHODS

The method involved measuring the peripapillary RNFLT, macular thickness, and macular volume via spectral domain (OCT) in different types of amblyopia and comparing with the other fellow eyes. This study was conducted at the Mansoura Ophthalmic Center.

RESULTS

A total of 64 patients with different types of amblyopia were included. The mean central macular thickness (CMT) was 196.2±50.03 µm in the amblyopic eyes versus 167±12.76 µm in the fellow eyes (P=0.000), the mean average macular thickness was 265.80±12.77 µm in the amblyopic eyes versus 259.10±3.09 µm in the fellow eyes (P=0.000), the mean macular volume was 7.59±0.32 mm³ in the amblyopic eyes versus 7.34±0.071 mm³ in the fellow eyes (P=0.002), and the mean global RNFLT was 97.00±11.60 µm in the amblyopic eyes versus 78.50±13.05 µm in the fellow eyes (P=0.029). There was a discrepancy between the different amblyopic types. Age and the axial length were the only independent variables that statistically significantly correlated with the CMT.

CONCLUSION

The unilateral amblyopic eyes were prone to have a higher CMT and thicker global RNFL compared to those of the sound fellow eyes. Retinal variations between different types of the amblyopia differ from one type to another. The age could be considered as a predictor of the disease worsening and treatment prognosis. Further studies are required to emphasize these results.

Comparative electrophysiological responses in anisometropic and strabismic amblyopic children

Purpose

To compare anisometropic hypermetropic amblyopic and strabismic amblyopic responses to pattern electroretinogram (PERG) and pattern visual evocated potential (PVEP).

Materials and methods

Fifty-six patients – 18 hypermetropic anisometropic amblyopic children (mean age 9.70±2.5 years), 19 strabismic amblyopic children (mean age 10.30±2.6 years) and 19 normal emetropic subjects (mean age 10.10±2.2 years) – were enrolled in this study. After routine ophthalmic examination, PERG and PVEP were recorded in response to checks reversed at the rate of two reversals/second stimulating macular area.

Results

The difference between hypermetropic anisometropic amblyopia and strabismus amblyopia with respect to P100/P50/N95 wave latencies (P=0.055/0.855/0.132) and P100/P50/N95 amplitudes (P=0.980/0.095/0.045) was not statistically significant. However, there was a significant statistical difference between strabismic amblyopia group and controls for P100/P50/N95 latencies (P=0.000/0.006/0.004).

Conclusion

Our findings indicated that despite clinical differences between anisometropic amblyopic and strabismic amblyopic patients, no differences were found in the responses of PVEP and PERG. The abnormal components of the PVEP and PERG in amblyopic subjects could reflect a retinal dysfunction in the visual pathway.

Retina and Optic Disc Characteristics in Amblyopic and Non-amblyopic Eyes of Patients with Myopic or Hyperopic Anisometropia

Objectives:

To compare retinal and optic disc characteristics between amblyopic and non-amblyopic eyes in patients with myopic and hyperopic anisometropia measured with optical coherence tomography (OCT).

Materials and Methods:

Patients with myopic (25 patients: 17 female, 8 male; median age 27 years, range 16-40 years) and hyperopic (31 patients: 19 female, 12 male; median age 20 years, range 13-41 years) anisometropic amblyopia were included. Eye examination included determination of best-corrected visual acuity (BCVA) with a Snellen chart, measurement of manifest and cycloplegic refraction after pupillary dilation, alternate cover testing, globe movement evaluation, A-scan biometry for axial length, biomicroscopy, fundus examination, and OCT scanning. Main outcome measures were spherical equivalence, BCVA, axial length, retinal nerve fiber layer (RNFL) thickness, macular thickness, macular volume, and optic disc area.

Results:

In both myopic and hyperopic patients, the absolute value of the mean spherical equivalence was significantly greater in the amblyopic than non-amblyopic eyes, and the mean BCVA was significantly less in the amblyopic than the non-amblyopic eyes. In both myopic and hyperopic patients, there were no significant differences in mean RNFL thickness, macular thickness, macular volume, axial length, or optic disc area between amblyopic and non-amblyopic eyes.

Conclusion:

The amblyopic process may have no significant effect on the RNFL, macula, or optic disc. Further studies with more patients, including postmortem studies, may clarify the retinal, histopathologic, and anatomic differences between amblyopic and non-amblyopic eyes.

A morphological study of amblyopic eyes in children failing to achieve normal visual acuity after electronically monitored long-term occlusion treatment

PURPOSE

To search for morphological abnormalities in compliant unilaterally amblyopic children with poor occlusion treatment outcomes, for the first time with electronically recorded patching dosage. We included school children with remaining interocular logMAR (logarithm of the minimum angle of resolution) difference ≥ 0.3 after patching time of more than 22 months and 1300 h total in a previous prospective study.

METHODS

Six patients with a mean age of 11.19 years were included. Four patients had anisometropic amblyopia and two patients had a mixed strabismic and anisometropic amblyopia. Best-corrected visual acuity, cycloplegic refraction, dilated fundus examination, optic disc morphology and macular thickness using optical coherence tomography (OCT), retinal visual acuity, color perception, and the presence of a relative afferent pupillary defect (RAPD) were assessed. Paired t tests were performed to compare optic disc values and macular thickness of the amblyopic eyes to those of the fellow eyes.

RESULTS

Average (± SD) logMAR VA in the amblyopic eyes was 0.42 (±0.23) with a remaining average interocular difference (IOD) of 0.51 (± 0.23), despite electronically monitored occlusion treatment of more than 1300 h. All patients presented with hyperopia and a significantly different mean spherical equivalent of + 4.73 (± 2.73) D in the amblyopic eye compared with the fellow eye (p = 0.02). A statistically significant difference in macular thickness was found between amblyopic and fellow eyes, with amblyopic eyes having an increased average thickness (p = 0.0062) and total volume (p = 0.0091) of the macula. One patient had familial hereditary primary macrodisc in both eyes.

CONCLUSIONS

Our results provide evidence that average macular thickness and total macular volume tended to be increased among these compliant amblyopic children with unsatisfactory occlusion treatment outcomes. Further studies are warranted to evaluate whether morphological changes may have an impact on the effectiveness of amblyopia treatment. Moreover, our findings suggest that greater magnitude of hyperopia and anisometropia as well as older age may be risk factors associated with a poor visual acuity outcome among compliant amblyopic children.

Retinal Nerve Fibre Layer and Macular Thicknesses in Adults with Hyperopic Anisometropic Amblyopia

Objectives. This study compared the macular and retinal nerve fibre layer (RNFL) thicknesses and optic nerves of eyes with reduced vision due to anisometropia with the contralateral healthy eyes in adults using optical coherence tomography (OCT). Methods. This cross-sectional study was conducted in Atatürk State Hospital, Sinop, Turkey. Macular and RNFL thicknesses, optic nerve disc area, cup area, and horizontal and vertical cup-to-disc ratios obtained using a NIDEK RS-3000 SLO spectral domain OCT device were compared between the amblyopic and fellow eyes in 30 adults with anisometropic amblyopia 18–55 years old who were seen in our clinic with unilateral poor vision. Results. The mean macular thickness was 266.90 ± 23.22 µm in the amblyopic eyes and 263.90 ± 22.84 µm in the fellow eyes, and the mean RNFL thickness was 111.90 ± 12.9 and 109.70 ± 9.42 µm, respectively. The two thicknesses did not differ significantly between the amblyopic and fellow eyes. There were also no significant differences between the eyes in disc area, cup area, and horizontal-vertical cup/disc ratios. Conclusion. There does not seem to be a difference in macular thickness, peripapillary RNFL, or optic disc structures between the amblyopic and fellow eyes in adults.

The assessment of anterior and posterior ocular structures in hyperopic anisometropic amblyopia

Background

The 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/Methods

Hyperopic 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.

Results

In 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.

Conclusions

We 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.

Choroidal and Peripapillary Retinal Nerve Fiber Layer Thickness in Adults with Anisometropic Amblyopia

Purpose

To evaluate choroidal thickness, macular thickness, and peripapillary retinal nerve fiber layer (RNFL) thickness in amblyopic eyes compared to fellow and normal control eyes using high-definition spectral-domain optical coherence tomography (SD-OCT).

Methods

Fifty-four without any systemic problem and ocular disease participated in this prospective study. Inclusion criteria included individuals older than 18 years with anisometropic amblyopia. Choroidal thickness, central macular thickness (CMT), and RNFL thickness were measured by using enhanced depth imaging SD-OCT. The choroidal thickness was measured at the fovea and at 500 μm intervals from the foveal center in both temporal and nasal directions. Axial length measurements of the cases were also recorded.

Results

Mean peripapillary RNFL thickness of the amblyopic, fellow, and control eyes was 107.5 ± 15.5 μm, 109.3 ± 12.7 μm, and 108.8 ± 8.6 μm, respectively (p = 0.343). The average CMT was 231.7 ± 14.7 μm in amblyopic eyes, 232.5 ± 15.7 μm in fellow eyes, and 230.8 ± 14.8 μm in control eyes (p = 0.599). Mean subfoveal choroidal thickness was significantly greater in the amblyopic eyes than in the fellow and control eyes (396.3 ± 104.3 μm, 361.0 ± 103.9 μm, 390.6 ± 91.7 μm). Mean axial measurement in amblyopic eyes was 22.7 ± 1.3 mm (20.5–26.1), in fellow eyes 23.1 ± 0.9 mm (20.9–25.0), and in control eyes 23.3 ± 0.9 mm.

Conclusions

In adults with anisometropic amblyopia, subfoveal, temporal, and nasal choroidal thickness of amblyopic eyes are significantly thicker than in fellow eyes. However, no significant differences in peripapillary RNFL thickness or CMT were found between amblyopic and fellow or control eyes.

Meta-analysis of retinal changes in unilateral amblyopia using optical coherence tomography

PURPOSE

To evaluate retinal changes in unilateral amblyopia using optical coherence tomography.

METHODS

Major literature databases were searched for relevant studies. The primary outcome parameters were foveal minimum thickness (FMT), mean foveal thickness (MFT), mean macular thickness (MMT), and peripapillary retinal nerve fiber layer (pRNFL) thickness. Efficacy estimates were evaluated by standardized mean difference (SMD) and 95% confidence interval (CI) for changes in the outcomes of interest.

RESULTS

This meta-analysis included 28 clinical trials involving 408 patients .The FMT, MFT, and MMT in the amblyopic eyes was significantly greater than that of the fellow eyes (SMD = 0.22, 95% CI 0.05-0.39, p = 0.011; SMD = 0.21, 95% CI 0.06-0.36, p = 0.005; SMD = 0.21, 95% CI 0.08-0.35, p = 0.002, respectively). Only FMT was significantly increased in the amblyopia group compared with the normal control group (SMD = 0.38, 95% CI 0.19-0.57, p&lt;0.00001). Analysis showed that pRNFL thickness in the amblyopic eyes was thicker than in the fellow eyes (SMD = 0.13, 95% CI 0.02-0.24, p = 0.016). We did not find that those outcome measures differ between strabismic and anisometropic amblyopia.

CONCLUSIONS

The pooled evidence indicates that the amblyopic process may involve the retina, especially the macula. A thicker foveola was found in the amblyopic eyes when compared with visually normal control eyes. Further larger-scale studies especially involving emmetropic normal subjects will be valuable.

Macular and retinal nerve fiber thickness in recovered and persistent amblyopia

The aim of this study was to investigate the presence of increased macular or retinal nerve fiber layer thickness (RNFLT) in amblyopic eyes, find if the increased macular or RNFLT is related to the lack of response in amblyopic eyes, and to explore whether the increased central macular thickness (CMT) in amblyopic eyes is purely related to the hyperopia. This is a prospective descriptive study. CMT and peripapillary RNFLT were measured by spectral-domain optical coherence tomography to evaluate 60 patients with unilateral-treated amblyopia (median age 11.00 year). Patients were divided into two groups: 33 patients in recovered amblyopia group and 27 patients in persistent amblyopia group. The mean CMT in the recovered group was 247.31 (±23.4) versus 246.8 (±32.7) µm (p = 0.95) for the persistent group. The mean peripapillary RNFLT was 99.13 (±12.1) versus 99.9 (±14.9) µm (p = 0.85) for the persistent group. In anisometropic amblyopia, there was no significant difference in CMT and RNFLT in either group. Also there was no relation between the type of refractive error and CMT or RNFLT. There was no significant difference in CMT and RNFLT in amblyopic eyes for both the recovered amblyopia group and the persistent amblyopia group to explain the lack of response in persistent amblyopic eyes. Additionally there was no relation between the type of refractive error and CMT or peripapillary RNFLT.

A comparison between amblyopic and fellow eyes in unilateral amblyopia using spectral-domain optical coherence tomography

Purpose

To compare the macular retinal thickness and characteristics of optic nerve head (ONH) parameters in amblyopic and fellow eyes in patients with unilateral amblyopia.

Patients and methods

A total of 21 patients with unilateral amblyopia (14 patients with anisometropic amblyopia, four patients with strabismic amblyopia, and three patients with both) were examined using spectral-domain optical coherence tomography. The mean age of the patients was 8.5±3.5 years. The examined parameters included the mean macular (full, inner, and outer), ganglion cell complex and circumpapillary retinal nerve fiber layer (cpRNFL) thicknesses, and ONH parameters (rim volume, nerve head volume, cup volume, rim area, optic disc area, cup area, and cup-to-disc area ratio).

Results

The amblyopic eyes were significantly more hyperopic than the fellow eyes (P<0.001). Among the macular retinal thickness parameters, the cpRNFL thickness (P<0.01), macular full retinal thickness (3 mm region) (P<0.01), and macular outer retinal thickness (1 and 3 mm regions) (P<0.05) were significantly thicker in the amblyopic eyes than in the fellow eyes, while the ganglion cell complex thickness, macular full retinal thickness (1 mm region), and macular inner retinal thickness (1 and 3 mm regions) were not significantly different. Among the ONH parameters, the rim area was significantly larger and the cup-to-disc area ratio was smaller in the amblyopic eyes than in the fellow eyes (P<0.05). None of the other ONH parameters were significantly different between the investigated eyes. The differences in the cpRNFL thickness and macular outer retinal thickness in the 1 mm region were significantly correlated with the difference in axial length (P<0.05, r=−0.48; P<0.01, r=−0.59, respectively) and refractive error (P<0.05, r=0.50; P<0.01, r=0.60, respectively). The other parameters were not significantly related to the difference in axial length, refractive error, or best corrected visual acuity.

Conclusion

We found significant differences in some of the morphological measurements between amblyopic and fellow eyes that appear to be independent of abnormalities in the visual cortex.

Neuroimaging of amblyopia and binocular vision: a review

Amblyopia is a cerebral visual impairment considered to derive from abnormal visual experience (e.g., strabismus, anisometropia). Amblyopia, first considered as a monocular disorder, is now often seen as a primarily binocular disorder resulting in more and more studies examining the binocular deficits in the patients. The neural mechanisms of amblyopia are not completely understood even though they have been investigated with electrophysiological recordings in animal models and more recently with neuroimaging techniques in humans. In this review, we summarize the current knowledge about the brain regions that underlie the visual deficits associated with amblyopia with a focus on binocular vision using functional magnetic resonance imaging. The first studies focused on abnormal responses in the primary and secondary visual areas whereas recent evidence shows that there are also deficits at higher levels of the visual pathways within the parieto-occipital and temporal cortices. These higher level areas are part of the cortical network involved in 3D vision from binocular cues. Therefore, reduced responses in these areas could be related to the impaired binocular vision in amblyopic patients. Promising new binocular treatments might at least partially correct the activation in these areas. Future neuroimaging experiments could help to characterize the brain response changes associated with these treatments and help devise them.

A morphological study of retinal changes in unilateral amblyopia using optical coherence tomography image segmentation

OBJECTIVE

The purpose of this study was to evaluate the possible structural changes of the macula in patients with unilateral amblyopia using optical coherence tomography (OCT) image segmentation.

PATIENTS AND METHODS

38 consecutive patients (16 male; mean age 32.4±17.6 years; range 6-67 years) with unilateral amblyopia were involved in this study. OCT examinations were performed with a time-domain OCT device, and a custom-built OCT image analysis software (OCTRIMA) was used for OCT image segmentation. The axial length (AL) was measured by a LenStar LS 900 device. Macular layer thickness, AL and manifest spherical equivalent refraction (MRSE) of the amblyopic eye were compared to that of the fellow eye. We studied if the type of amblyopia (strabismus without anisometropia, anisometropia without strabismus, strabismus with anisometropia) had any influence on macular layer thickness values.

RESULTS

There was significant difference between the amblyopic and fellow eyes in MRSE and AL in all subgroups. Comparing the amblyopic and fellow eyes, we found a statistically significant difference only in the thickness of the outer nuclear layer in the central region using linear mixed model analysis keeping AL and age under control (p = 0.032). There was no significant difference in interocular difference in the thickness of any macular layers between the subgroups with one-way between-groups ANCOVA while statistically controlling for interocular difference in AL and age.

CONCLUSIONS

According to our results there are subtle changes in amblyopic eyes affecting the outer nuclear layer of the fovea suggesting the possible involvement of the photoreceptors. However, further studies are warranted to support this hypothesis.

Macular and retinal nerve fiber layer thickness in unilateral anisometropic or strabismic amblyopia

PURPOSE

To compare the macular and nerve fiber layer thicknesses as measured by optical coherence tomography (OCT) in amblyopic and fellow eyes.

METHODS

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.

RESULTS

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).

CONCLUSION

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.

Evaluation of retinal nerve fiber layer thickness in patients with anisometropic and strabismic amblyopia using optical coherence tomography

PURPOSE

To evaluate the retinal nerve fiber layer (RNFL) thickness of eyes with amblyopia using optical coherence tomography (OCT).

METHODS

RNFL thickness measurements obtained by time-domain OCT of amblyopic eyes of patients with strabismus (35 patients) and patients with anisometropia (30 patients) were compared with their fellow eyes and age- and gender-matched healthy eyes (40 participants). RNFL thickness values of the groups were also compared and the correlation between RNFL thickness and refraction was evaluated.

RESULTS

In the strabismic and anisometropic groups, there were no statistically significant differences in average RNFL thickness between amblyopic eyes and their fellow eyes (P > .05). Temporal RNFL quadrant in the hypermetropic anisometropic group, and superior RNFL quadrant in the myopic anisometropic group were significantly thinner in amblyopic eyes compared to their fellow eyes (P < .05). RNFL thickness did not differ between strabismic amblyopic, anisometropic amblyopic, and control eyes (P > .05). In the anisometropic group, a significant correlation was found between mean RNFL thickness and refraction (P < .05).

CONCLUSION

Amblyopia is not associated with a decrease in RNFL thickness in strabismic or anisometropic amblyopia. In the anisometropic group, the inter-eye differences in RNFL thickness parameters seemed to be related to the refraction differences between the amblyopic eyes and their fellow eyes.[J Pediatr Ophthalmol Strabismus 2013;50:113-117.].

Amblyopia and binocular vision

Amblyopia is the most common cause of monocular visual loss in children, affecting 1.3%-3.6% of children. Current treatments are effective in reducing the visual acuity deficit but many amblyopic individuals are left with residual visual acuity deficits, ocular motor abnormalities, deficient fine motor skills, and risk for recurrent amblyopia. Using a combination of psychophysical, electrophysiological, imaging, risk factor analysis, and fine motor skill assessment, the primary role of binocular dysfunction in the genesis of amblyopia and the constellation of visual and motor deficits that accompany the visual acuity deficit has been identified. These findings motivated us to evaluate a new, binocular approach to amblyopia treatment with the goals of reducing or eliminating residual and recurrent amblyopia and of improving the deficient ocular motor function and fine motor skills that accompany amblyopia.

Macular and peripapillary retinal nerve fiber layer thickness in children with hyperopic anisometropic amblyopia

AIM

To compare the retinal nerve fiber layer (RNFL) thickness and macular thickness in the amblyopic eye with that in the sound eye of children with hyperopic anisometropic amblyopia using optical coherence tomography (OCT).

METHODS

A prospective, nonrandom, intraindividual comparative cohort study includes 72 children with hyperopic anisometropic amblyopia in a single center. Macular thickness, macular foveola thickness, and peripapillary RNFL thickness were compared between the amblyopia eyes and the contralateral sound eyes.

RESULTS

There were 38 male and 34 female patients, with a mean age as 9.7±1.9 years (range, 5-16 years). Hyperopic was +3.62±1.16D (range +2.00D to +6.50D) in the amblyopic eyes, which was significantly higher in the control eyes with +0.76±0.90D (range 0D to +2.00D) (P < 0.01). The mean peripapillary RNFL thickness was 113.9±7.2µm and 109.2±6.9µm in the amblyopic eye and the normal eye, respectively, reaching statistical significance (P = 0.02). The mean macular foveola thickness was significantly thicker in the amblyopic eyes than the contralateral sound eyes (181.4±14.2µm vs 175.2±13.3µm, P < 0.01), but the 1mm, 3mm or 6mm macular thickness central macular thickness was not significantly different. Degree of anisometropia in the contralateral eyes was not significantly correlated with differences of peripapillary RNFL, macular foveola thickness or central macular thickness.

CONCLUSION

Eyes with hyperopic anisometropic amblyopia are found thicker macular foveola and peripapillary RNFL than the contralateral eyes in children.