Clinical trial NCT04092361: Changes in Amblyopia Using Optical Coherence Tomography
Official title: Macular and Retinal Changes in Unilateral Amblyopia Using Optical Coherence Tomography
Study type: OBSERVATIONAL
Overall status: UNKNOWN
Conditions: Amblyopia
Lead sponsor: Assiut University
Sponsor class: OTHER
First posted: 2019-09-17
Enrollment: 28
Sex: ALL
Minimum age (years): 16
Maximum age (years): 40
Standard ages: CHILD
ADULT
Accepts healthy volunteers: no
Observational model: CASE_CROSSOVER
Time perspective: CROSS_SECTIONAL
Sampling method: NON_PROBABILITY_SAMPLE
Study population: all cooperative patients that fulfill inclusion criteria

1. Age\>16 and \<40 years
2. Patients with unilateral amblyopia ( anisometropic , strabismic and deprivational amblyopia )

Brief summary: There have been multiple trials to investigate the morphological changes in the macula and retinal nerve fiber layer of amblyopic eyes, due to the different published results and the lack of evident association between these changes and the patients' parameters. So, we perform this study to compare the variations in macular parameters (central thickness, average thickness, macular volume) and peripapillary thickness in different cases of amblyopic eyes versus the normal fellow eyes using spectral-domain optical coherence tomography. In addition, to estimate the relationship of optical coherence tomography variations with different defined patients' parameters (age, sex, best corrected visual acuity, spherical equivalent refractive error, and axial length).

Detailed description: Amblyopia remains an important cause of low visual acuity,affecting 2% to 6% of the general population. Unilateral amblyopia is defined as reduced best-corrected visual acuity secondary to an abnormal visual experience during the critical period of visual development. Classic causes include strabismus, anisometropia, form deprivation or a combination of these factors .

The normal postnatal reduction (apoptosis) of retinal ganglion cells is arrested in amblyopia which would cause increase in retinal nerve fiber layer thickness as hypothesized by Yen et al .This also would affect the normal maturation of the macula, including movement of Henle's fibers away from the foveola. This would result in increased foveal thickness. Furthermore, because of the reduced apoptosis of retinal ganglion cells, the thickness of the ganglion cell layer in the macula would also be increased.

Optical coherence tomography : is a non-contact and non-invasive technique that help in assessment of retina abnormalities. The high resolving power (10um - Time Domain, 5um - Spectral Domain) provides excellent detail for evaluating the vitreo-retinal interface, neurosensory retinal morphology, and the retinal pigmented epithelial-choroid complex. It generates cross sectional images by analyzing the time delay and magnitude change of low coherence light as it is backscattered by ocular tissues. An infrared scanning beam is split into a sample arm (directed toward the subject) and a reference arm (directed toward a mirror). As the sample beam returns to the instrument it is correlated with the reference arm in order to determine distance and signal change via photodetector measurement. The resulting change in signal amplitude allows tissue differentiation by analysis of the reflective properties, which are matched to a false color scale. As the scanning beam moves across tissue, the sequential longitudinal signals, or A-scans, can be reassembled into a transverse scan yielding cross-sectional images, or B-scans, of the subject. The scans can then be analyzed in a variety of ways providing both empirical measurements (e.g. retinal thickness/volume) and qualitative morphological information.

Eligibility criteria: Inclusion Criteria:

1. Age\>16 and \<40 years
2. Patients with unilateral amblyopia ( anisometropic , strabismic and deprivational amblyopia ) .

Exclusion Criteria:

1. Age\<16 and \>40 years.
2. Patients with structural abnormality in their eye , mentally retarded patients .

Primary outcomes:
measure: To measure retinal layers and macular thickness changes in cases of unilateral amblyopia using optical coherence tomography in comparison with the other sound eye.
timeFrame: from october 1st 2019 to october 1st 2020
Secondary outcomes:
Other outcomes:
Locations:
Study officials:
References:
citation: McKee SP, Schor CM, Steinman SB, Wilson N, Koch GG, Davis SM, Hsu-Winges C, Day SH, Chan CL, Movshon JA, et al. The classification of amblyopia on the basis of visual and oculomotor performance. Trans Am Ophthalmol Soc. 1992;90:123-44; discussion 145-8. No abstract available.
citation: Graham PA. Epidemiology of strabismus. Br J Ophthalmol. 1974 Mar;58(3):224-31. doi: 10.1136/bjo.58.3.224. No abstract available.
citation: Kiorpes L, McKee SP. Neural mechanisms underlying amblyopia. Curr Opin Neurobiol. 1999 Aug;9(4):480-6. doi: 10.1016/s0959-4388(99)80072-5.
citation: de Zarate BR, Tejedor J. Current concepts in the management of amblyopia. Clin Ophthalmol. 2007 Dec;1(4):403-14.
citation: Choi MY, Lee KM, Hwang JM, Choi DG, Lee DS, Park KH, Yu YS. Comparison between anisometropic and strabismic amblyopia using functional magnetic resonance imaging. Br J Ophthalmol. 2001 Sep;85(9):1052-6. doi: 10.1136/bjo.85.9.1052.
citation: Yen MY, Cheng CY, Wang AG. Retinal nerve fiber layer thickness in unilateral amblyopia. Invest Ophthalmol Vis Sci. 2004 Jul;45(7):2224-30. doi: 10.1167/iovs.03-0297.
citation: Hee MR, Izatt JA, Swanson EA, Huang D, Schuman JS, Lin CP, Puliafito CA, Fujimoto JG. Optical coherence tomography of the human retina. Arch Ophthalmol. 1995 Mar;113(3):325-32. doi: 10.1001/archopht.1995.01100030081025.
citation: Yoon SW, Park WH, Baek SH, Kong SM. Thicknesses of macular retinal layer and peripapillary retinal nerve fiber layer in patients with hyperopic anisometropic amblyopia. Korean J Ophthalmol. 2005 Mar;19(1):62-7. doi: 10.3341/kjo.2005.19.1.62.
citation: Yakar K, Kan E, Alan A, Alp MH, Ceylan T. Retinal Nerve Fibre Layer and Macular Thicknesses in Adults with Hyperopic Anisometropic Amblyopia. J Ophthalmol. 2015;2015:946467. doi: 10.1155/2015/946467. Epub 2015 May 7.