Anisometropia

This cross-sectional, retrospective, and experimental investigation was conducted at the tertiary clinic’s ophthalmology department. The local ethics commission gave its approval to the study protocol, which followed the guidelines of the Helsinki Declaration. After notifying all of the cases and their parents about the study’s goal, informed consent was attained in writing from the participants or their legal guardians.
The study was composed of three groups: One group was the amblyopic eyes of patients with anisometropic hypermetropia, another group was the fellow eyes of patients with anisometropic hypermetropia, and a final group of healthy controls. When the best-corrected visual acuity of the amblyopic eye was poorer than 20/30 and was at least two Snellen lines inferior to that of the other eye, the participant was identified as amblyopic (14 (link)). Anisohypermetropia is a condition in which one eye’s refractive error (spherical equivalent) is ≥1.5 diopters higher than the other (14 (link)).
Participants who visited the ophthalmology clinic for a routine checkup and had best-corrected vision of 20/20 and no other ocular or systemic diseases except modest refractive errors (between−1.00 and +1.00 diopters) were selected for the control sample. For data analysis, just the observations regarding the control group’s right eye were utilized. Cases with any of the following conditions were excluded: Age lower than 11, strabismus, eccentric fixation, previous ocular surgery, not suitably cooperative enough for OCT tests, ocular diseases (retinal diseases, glaucoma, cataract, etc.), and any systemic conditions.
Complete ophthalmological tests were performed on all cases, such as best-corrected visual acuity screening using a basic Snellen chart, which was later adapted to the logarithm of the minimal angle of resolution (logMAR) for the statistical studies, and cycloplegic refraction using a keratometer/autorefractor (KR-8100, RM8900, Topcon, Tokyo, Japan), EDI-OCT examination, extraocular movements, cover-uncover and cover test, fundus examination, and slit-lamp biomicroscopy. All ocular tests were performed between the hours of 10 a.m. and 12 a.m. to avoid affecting the diurnal deviations in CT.
Spectral-domain OCT’s (EDI-OCT; Spectralis, Heidelberg Engineering GmbH, Heidelberg, Germany) increased depth imaging mode was used to measure the choroidal vascularity index (CVI). The images were viewed and measured using the Heidelberg Eye Explorer software (Version1.8.61.0; Heidelberg Engineering). Only scans with a high quality (> 25Q) were considered. Manual CT values were taken in three areas: 500 μm temporal, 500 μm nasal, and subfoveal CT. The CT was determined as the vertical distance between the inner surface of the choroidal-scleral junction and the outside edge of the hyperreflective retinal pigment epithelium. Finally, the OCT scans produced were analyzed using an image processing tool in order to determine CVI.
Image processing was conducted using free and open-source software (http://fiji.sc/). The OCT scans were viewed using the ImageJ version 1.53 platform as part of a system previously reported by Agrawal et al., (15 (link)) which was used to evaluate the images (National Institutes of Health, Bethesda, MD, USA). First, the software’s default scale was used to indicate the length unit (as μm) and pixel distance (as 200 μm). To identify the choroid-scleral junction, the pictures were transformed to 8-bit format and binarized utilizing Niblack autolocal criterion. The polygon tool was then used to calculate the total choroidal area between the choroid-scleral junction and the retinal pigment epithelium. This section was saved for the manager of the region of interest (ROI). The photos were then transformed to the Red-Green-Blue color model, and then the ROI manager picked the dark pixels that represented the luminal region using the color threshold tool. Finally, both areas within the ROI manager’s region were chosen and combined using the “AND” command to determine the region of vascularity inside the selected polygon. The CVI was calculated as the proportion of luminal area (LA) to total choroidal area. By deducting the LA from the overall choroidal area, the pixels of light color indicated the stromal region (Fig. 1). Two researchers (HK and DK), who were given the participants’ blind data, measured the CT and CVI values one at a time. In the statistical analysis, the means of the two researchers’ measurements were used.

BCVA was tested at 3 m with a linear Konstantin Moutakis VA chart.23 (link) The decimal VA was then converted to the logarithm of the minimum angle of resolution (logMAR). BCVA best eye <0.65 decimal (>0.19 logMAR) was considered subnormal.
Refraction was tested under cycloplegia caused by a mixture of phenylephrine (1.5%) and cyclopentolate (0.85%), using an autorefractor (Topcon A6300/KR-8800; Topcon Corporation, Tokyo, Japan). Significant refractive errors were defined as follows: hyperopia ≥2.5 dioptres (D), spherical equivalents (SE), myopia ≥0.5 D SE, anisometropia ≥1.0 D SE and astigmatism ≥1.0 D.