|LETTERS TO THE EDITOR
|Year : 2018 | Volume
| Issue : 3 | Page : 304-305
An analysis of macular thickness in amblyopic eyes in rural India by spectral optical coherence tomography
Sumita Sethi, Aakansha Siwach, Ruchi Dabas, Sunil Verma
Department of Ophthalmology, BPS Government Medical College for Women, Sonepat, Haryana, India
|Date of Web Publication||29-Oct-2018|
Dr. Sumita Sethi
BPS Government Medical College for Women, Khanpur Kalan, Sonepat, Haryana
Source of Support: None, Conflict of Interest: None
|How to cite this article:|
Sethi S, Siwach A, Dabas R, Verma S. An analysis of macular thickness in amblyopic eyes in rural India by spectral optical coherence tomography. Oman J Ophthalmol 2018;11:304-5
|How to cite this URL:|
Sethi S, Siwach A, Dabas R, Verma S. An analysis of macular thickness in amblyopic eyes in rural India by spectral optical coherence tomography. Oman J Ophthalmol [serial online] 2018 [cited 2019 Apr 24];11:304-5. Available from: http://www.ojoonline.org/text.asp?2018/11/3/304/244324
Functional loss in amblyopia has been well studied and accepted, and there is not much evidence for morphological changes in macula of amblyopic eyes.,, We conducted the study to evaluate the possible morphological changes in macula of amblyopic eyes in the form of altered macular thickness and to compare macular thickness of amblyopic eyes with their fellow eyes (internal controls) and with nonamblyopic individuals (external controls).
After approval from the institutional ethics committee, 54 individuals with unilateral amblyopia in the age group of 7–40 years (mean age, 17.3 ± 7.8 years) were included as cases; they were divided into the following three groups: anisometropic (Group I; n = 17), strabismic (Group II; n = 20), and combined anisometropic and strabismic (Group III; n = 17). Fellow eyes were enrolled as internal controls (n = 54); age-matched nonamblyopic individuals as external controls (n = 28). Macular map analysis on spectral-domain optical coherence tomography was performed to measure retinal thickness in 9 subfields as per early treatment diabetic retinopathy study (ETDRS) grid comprising three concentric circles of 1, 3, and 6 mm. Macular thickness was expressed as mean ± standard deviation (μ) and unpaired t-test was used to compare the corresponding subfields of cases with controls; P ≤ 0.05 was considered statistically significant.
In our study, the overall thickness of central subfield was significantly increased in cases (275.4 ± 35.5 μ) as compared to internal controls (257.8 ± 33.8 μ) (P = 0.01) and external controls (247.89 ± 25.42 μ) (P = 0); this was not significant in the other quadrants. On further analysis in different subgroups, it was observed that the central retinal thickness was significantly increased in the amblyopic eye (274.35 ± 36.38 μ) in Group I (P = 0.04) in comparison to normal fellow eyes (251.75 ± 22.73 μ) and in the amblyopic eyes (263.24 ± 36.80 μ) in Group III (P = 0.02) in comparison to normal fellow eyes (237.00 ± 25.66); however, in Group II, though the central retinal thickness was increased in the amblyopic eyes (286.65 ± 31.39) in comparison to the fellow normal eyes (275.60 ± 34.78), the difference was not statistically significant (P = 0.30).
Our results were in accordance to the study by Wang et al. who observed the mean retinal thickness in the center of fovea in amblyopic eyes to be significantly increased as compared to their normal fellow eyes. They, however, had included only anisometropic individuals in the age group of 7–11 years and had excluded individuals with strabismus. From the fact that the retinal thickness in our study was not increased in the strabismic group, it can be assumed that the anisometropes could possibly be the main contributing factors for the increased retinal thickness in our study.
The increased retinal thickness in the central foveal zone has a lot of practical significance. The study by Ju et al. and few other functional studies raised the possibility that visual abnormalities could be related to selective deficits in foveal vision. Fovea is the last region of macula to reach maturity and foveola has distinct architecture with the peak density of cones. Thus, though fovea is well adapted for high-acuity vision, it is vulnerable to any insult in the course of gestation or postnatal development, both functionally and structurally.
Structural changes in fovea of amblyopic individuals as found in our study could raise the possibility that visual abnormalities in amblyopes could be related to selective deficits in foveal vision.
We would like to acknowledge the Indian Council of Medical Research for support of this study.
Financial support and sponsorship
The study was undertaken as the Short-Term Student Project of Indian Council of Medical Research, 2015.
Conflicts of interest
There are no conflicts of interest.
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