Anisometropia and its association with refraction development in highly myopic children

CLINICAL RELEVANCE

Anisometropia can affect visual development in children. Investigations of anisometropia in high myopes would explore potential causes related to anisometropia, highlighting the management of anisometropia in high myopia.

BACKGROUND

The prevalence of anisometropia ranged from 0.6% to 4.3% in general paediatric population and from 7% to 14% in myopes. Anisometropia is regarded as an associated factor for myopia development, while myopia progression is a stimulus driving anisometropic development. The purpose of this study was to investigate the prevalence of anisometropia and its association with refraction development in Chinese children with high myopia.

METHODS

In the cohort study, a total of 1,577 highly myopic (spherical equivalent ≤-5.0D) children aged 4-18 years were included. Refractive parameters (dioptre of sphere, dioptre of cylinder, corneal curvature radius, and axial length) of both eyes were measured after cycloplegia. The prevalence and degree of anisometropia were compared among refractive groups (non-parametric tests or chi-square tests), and regression analyses were used to determine associated factors of anisometropia. The statistical significance was set to P < 0.05 (two-tailed).

RESULTS

In highly myopic children with a mean (standard deviation) age of 13.06 (2.80) years, the proportions of spherical equivalent anisometropia, cylindrical anisometropia and spherical anisometropia ≥1.00 D were 34.5%, 21.9% and 39.9%, respectively. There was more spherical equivalent anisometropia associated with more severe astigmatism (P for trend <0.001). In the multivariate regression analysis, more spherical equivalent anisometropia, cylindrical anisometropia and spherical anisometropia were associated with higher degrees of astigmatism (standard beta = -0.175, -0.148 and -0.191, respectively). More spherical anisometropia was associated with better spherical power (standard beta = 0.116).

CONCLUSION

The proportion of anisometropia in highly myopic children was high, compared with previously reported general population, and more severe anisometropia was associated with higher degree of cylindrical power, but not spherical power.

A Comparison of Autorefraction and Subjective Refraction in an Academic Optometry Clinic

BACKGROUND

 Refractive error is the most common cause of decreased visual acuity. Refractive measurement in adults consists of cycloplegic (objective) and manifest (subjective) refraction. Although the effectiveness of autorefraction is a crucial factor, there needs to be more information on its accuracy and precision on each autorefractor compared with subjective measurement in Thai patients.

OBJECTIVE

 To compare the accuracy and precision of the two autorefractors' findings in Rajavithi Hospital, OptoChek Plus, and TOMEY Auto Refractometer RC-5000, with each other and with those of the subjective method.

MATERIALS & METHODS

 An observational study was conducted at the Ophthalmology clinic in Rajavithi Hospital from March 1, 2021, to March 31, 2022. All subjects were tested using the two autorefractors (OptoChek Plus and TOMEY Auto Refractometer RC-5000) and subjective refraction. One eye per subject was included in the study.

RESULTS

 Forty-eight patients (48 eyes) were enrolled in the study. The difference between spherical powers obtained by OptoChek and subjective refraction was not significantly different; however, there was a significant difference between those calculated by Tomey and the subjective method (p=0.77, p=0.04 respectively). The variations between cylindrical powers arrived at by the two autorefraction techniques and those calculated by the subjective method were significantly different (OptoChek and Tomey p-=0.01, p-value<0.001, respectively). In addition, 95% of the limit of agreement (95% of LOA) was low in the cylindrical measurement of each autorefractor compared with subjective refraction. (84.61%, 86.36%, respectively). No statistically significant difference between the spherical equivalent calculated by the two autorefractors and that of subjective refraction was observed in the present study (OptoChek: p-value=0.26 and Tomey: p-value=0.77).

CONCLUSIONS

 There was a clinically significant difference between the cylindrical power calculated by the two autorefractors and those obtained from subjective refraction. Patients with high astigmatism should be monitored closely when measured by autorefractors, as there can be a slightly lower agreement between objective and subjective refraction.

[Design of Adjustable Liquid Simulated Eye for Spherical Power Detection of Eccentric Photographic Vision Screening Instrument]

A liquid simulated eye was designed to detect different spherical diopter indexes in the type inspection of medical equipment vision screening instrument. This liquid test simulation eye design is composed of three parts: lens, cavity and retina-imitation piston. By using the principle of geometric optics and the optical scattering effect of human retina, the relationship between the accommodation displacement of the designed adjustable liquid simulated eye and the spherical mirror power was calculated and analyzed. The designed liquid test simulated eye can be applied to vision screening instruments, computer refractometers and other optometry equipments based on photography principle in spherical lens measurement and so on.

Association between Thyroid Function and Ocular Parameters

During development, thyroid hormones play an important role in eye development, while in adults, some pathological thyroid conditions can affect the normal functioning of the eyes. Thyroid eye disease is the most well-known eye pathology caused by a pathological thyroid condition. Few studies have investigated the association between ocular parameters and thyroid function. Thus, in this study, we aimed to examine whether thyroid activity affects ocular parameters. This cross-sectional study included 4633 healthy adults recruited within the 10,001 Dalmatians project of the Croatian Biobank. The plasma levels of thyroid-stimulating hormone (TSH), free triiodothyronine (fT3), free thyroxine (fT4), thyroglobulin (Tg), thyroglobulin antibodies (TgAb), and thyroid peroxidase antibodies (TPOAb) were measured by an immunoassay. We determined 20 ocular parameters for each participant (10 for each eye, including corneal radius, corneal thickness, anterior chamber depth, anterior chamber angle, lens thickness, posterior chamber length, axial length, intraocular lens power (IOL), spherical power, and cylinder power). Patients with hyperthyroidism had thicker corneas compared to euthyroid individuals. Corneal thickness was also negatively associated with plasma TSH levels. Intra-ocular lens power was higher in patients with clinical hypothyroidism, while spherical power was higher in euthyroid individuals with positive antibodies compared to euthyroid individuals. Intra-ocular lens power negatively correlated with fT4 levels, while spherical power positively correlated with TgAb, TPOAb, and Tg levels and negatively correlated with TSH levels. The anterior chamber angle was positively associated with plasma TSH levels and TPOAb levels and negatively associated with plasma fT4 levels. These findings suggest an interesting interplay between ophthalmic measures and thyroid status, detectable even in the general adult population.

A comparison of the Plusoptix S09 with an autorefractometer of noncycloplegics and cycloplegics in children

The aim of the study is to compare outcome measures of refractive error obtained using the Plusoptix S09 photorefractor and an autorefractometer of noncycloplegics and cycloplegics in children.We reviewed the medical records of 40 patients (77 eyes) who were classified using 2 methods. The patients were first assigned to 2 groups consisting of 11 eyes with ≥+3.0 D and 66 eyes with <+3.0 D, and then to 2 groups of 12 and 65 eyes with cycloplegic and noncycloplegic refraction of spherical powers ≥+2.0 D and <+2.0 D, respectively. We compared the outcome measures of refractive error using the Plusoptix S09 photorefractor and an autorefractometer of noncycloplegics and cycloplegics.There was no statistically significant difference between the Plusoptix S09 photorefractor and cycloplegic autorefractometer in the spherical power and spherical equivalent. In contrast, there was a statistically significant difference between the Plusoptix S09 photorefractor and noncycloplegic autorefractometer (P < 0.001). There was a statistically significant difference between the spherical equivalent of the Plusoptix S09 photorefractor and cycloplegic autorefractometer in children with hyperopia ≥+3.0D and with cycloplegic and noncycloplegic refraction of spherical power ≥+2.0 D. We also found a significant difference between the outcomes of the Plusoptix S09 photorefractor and cycloplegic autorefractometer in the spherical power and spherical equivalent for children with hyperopia ≥+3.0 D.The refractive error of the Plusoptix S09 photorefractor was similar to that of the cycloplegic autorefractometer, in contrast to the noncycloplegic autorefractometer. However, the Plusoptix S09 photorefractor is an inaccurate tool to estimate the refractive errors of children with moderate hyperopia.