Types Of Myopia Research Articles

The impact of visual environment on the evolution of myopia

Our study represents the impact of the visual environment on the evolution of myopia. We established a statistical study of different types of myopia in Morocco. We classed with degrees of myopia. The long-term work of near vision increases a vision-postural stress leads to an increase in accommodative visual stress and convergence, and the correction with traditional lenses leads to hyperopic defocusing peripheral, which stimulates the elongation of the optical axis [1, 4]. We found that the number of myopia is changing during the four years of study and that the correction by traditional lenses does not allow us to slow down the evolution of myopia., this type of management and the visual environment leads us to an increase in the degrees and number of myopia during the four years. The increase in the power of myopia can lead to a pathological state that is preoccupant. We find that the visual environment has an impact on the increase of different types of myopia, especially average myopia in young people. So we have to try new alternatives for myopia compensation as special lenses for myopia braking and orthokeratology lens contact as well as behavioral and environmental measures to decrease visuals.

Long-term results of laser in situ keratomileusis for myopia

Laser in situ keratomileusis (LASIK) is still the most popular refractive surgery in the world. The aim of the study is to assess the long term clinical outcomes of LASIK in treating patients with different types of myopia. Pre- and postoperative distance visual acuity, refractive spherical equivalent (SE) and clinical examinations of dry eye disease were recorded. Values obtained at baseline and controls were compared with each other. While preoperative mean uncorrected distance visual acuity (UDVA) of low and moderate myopic patients was 0.1±0.07 on Snellen eye chart, and it was 0.86 ±0.11 at the 6th month and 0.92 ±0.05 at the 3rd year. At the last control examination, the percertages of manifest refractive SE in the range of ±0.50D and ±1.00D were 78.3%, 88.3%, respectively. The mean UDVA of high myopic patients was 0.03 ±0.02 preoperatively, and it was 0.84 ±0.16 at the 6th month and 0.69 ±0.21 at the 3rd year. UDVA at 3 years was significantly decreased compared with 6 month postoperatively.(p=0.01) At the last control examination of this group, the percentages of manifest refractive SE in the range of ±0.50D and ±1.00D were 48.3%, 66.1 %, respectively. These also decreased from 6 month to 3 years postoperatively.The mean tear break-up time and schirmer-1 values, which decreased in the postoperative first year visits of the patients, were close to the preoperative values at the last control. There were no statistically significant difference between the preoperative and 3rd year comparisons.(all p>0.05) In conclusion, LASIK is an effective and safe procedure in patient with myopia, preoperative higher SE is a predictor of low postoperative efficacy.

Peripheral vitreochorioretinal dystrophy in patients with various types of myopia

Background. Over the past decade, there has been an in¬crease in myopia prevalence in the world; in many countries it is considered as epidemic. In case of an unfavorable course, myopia becomes the cause of retinal pathology, which in se¬vere cases leads to an irreversible decrease in corrected visu¬al acuity and to visual impairment that occurs at working age. Purpose. To analyze the relationship between the occurrence of peripheral vitreochorioretinal dystrophy (PVCD) in patients with myopia depending on its type: refractive and axial. Material and methods. A retrospective cohort analysis involved 304 patients (608 eyes) of 13 to 70 years old with acquired myopia: mild (19.40%), moderate (42.93%) and high (37.67%). In all cases, myopia was complicated by PVCD. All patients were divided into 2 groups according to the type of myopia: refractive and axial myopia. Biometric data (LENSTAR LS 900) and keratometry (“Huvitz”, South Korea) were used as criteria for patient selection. Results. The distribution of patients showed that PVCD most often occurs in the group of patients with axial myopia of moderate (44.48%) and high (39.70%) degrees. In the group of patients with mild axial myopia, the incidence was 15.80%. A clear correlation was noted between the development of PVCD and the axial elongation. In contrast, in patients with refractive myopia, the incidence of PVCD was two times higher in case of mild myopia (50.00%) than in cases of moderate (29.69%) and high myopia (20.31%) put together. Conclusion. The study revealed that PVCD is almost 8,5 times more likely to occur in case of axial myopia than in case of refractive myopia. A possible cause of PVCD development in case of axial myopia is an increase in the axial length, while in case of refractive myopia its possible cause is the increase in the eyeball’s transverse size. Regardless of the type of myopia and its degree, the study of the periphery of the retina is an essential element of diagnostics for timely detection of PVCD and monitoring the progression of axial myopia is an important criterion for its prevention.

Investigating the effect of space frequency modulation of visual stimuli on the visual acuity of the optic cortex

BACKGROUND AND OBJECTIVE: The choice of the response of the visual cortex to different space frequencies has been studied in several studies. The importance of the present study is to investigate the role of space frequency modulation in determining the magnitude of different neoplasms, and measure various types of myopia. The purpose of this study was to investigate the effect of modulation of visual acuity space frequencies on the response of the visual cortex in bipolar mode by magnetic resonance imaging. METHODS: In an analytical study, 12 people (5 males and 7 females) participated in the study. It was decided that they were right-handed, had no specific disease (neurological and systemic) and had no refractive errors. The pupil size was measured by visual acuity; magnetic resonance imaging was performed using a Phillips MRI device with a magnitude 1.5 Tesla magnetic field. Since the duration of each test was 4 minutes (consisting of 8 blocks of 30 seconds). IRCT:2016021326538N2 FINDINGS: There was a significant relationship between refractive error and fuzzy state with diopter 1.00+ lens at mid-frequency (p=0.005) and high (p=0.03). Additionally, there was a refractive error between the refractive error and false positives with a diopter of 3.00+ lens at high space frequency (p=0.009). The variation in the number of activated vasks is significant only in the mid space frequency, and in comparison with the refractive error and artificially constructed near-diopter 1.00+ lens (p=0.026). CONCLUSION: Considering the efficacy of optic optics due to proximity to the response of the visual cortex, the necessity of correcting any refractive errors in visual science studies and related studies, such as neuroscience studies, as well as the separation and separation of refractive errors from neurological factors affecting the cortex response, Becomes. © 2017, Babol University of Medical Sciences. All rights reserved.

Association of Insulin-Like Growth Factor-1 Gene Polymorphisms with Different Types of Myopia in Egyptian Patients.

To investigate the effect of the insulin-like growth factor-1 (IGF-1) gene's rs6214 and rs5742632 polymorphisms on IGF-1 expression levels and their association with different types of myopia in Egyptian patients. A case-control format was used that included 272 patients with myopia and 136 controls. The IGF-1 gene rs6214 and rs5742632 polymorphisms were genotyped using polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) analyses. IGF-1 levels were measured by an enzyme-linked immunosorbent assay. In patients with high-grade myopia, the frequencies of the IGF-1 rs6214 GA and AA genotypes, and the A allele were significantly increased compared to the control group: 41.9% vs. 33.8%, 17.7% vs. 8.9%, and 38.9% vs. 25.7%, respectively. Subjects with the GA and AA genotypes and carriers of A allele were significantly more likely to have high-grade myopia: odds ratios (OR) = 1.75, 95% confidence interval (CI) = 1.03-2.9, and p = 0.03; OR = 2.8, 95% CI = 1.3-6.0, and p = 0.003; and OR = 1.8, 95% CI = 1.25-2.61, and p = 0.001, respectively. A nonsignificant association of the IGF-1 gene rs5742632 polymorphism with the two myopia groups was also observed. The IGF-1 levels were significantly increased in patients with high-grade myopia and simple myopia compared to the control group (p < 0.05). In addition, our results showed a nonsignificant association of the IGF-1 (rs6214-rs5742632) haplotype with either simple myopia or high-grade myopia. We found a significant association of the IGF-1 gene rs6214 polymorphism in Egyptian patients with simple myopia and high-grade myopia. IGF-1 levels were significantly increased in relation to the IGF-1 rs6214 genotypes, while a nonsignificant association was found between IGF-1 level and the IGF-1 (rs5742632) genotypes.

Comparative characteristics of morphometric, biometric and biomechanical parameters of myopic eyes in children with different types of progressive myopia

Aim. With the progression of myopic process in children the changes of morphometric, biometric and biomechanical parameters of eyeball are observed. In order to study these parameters in the axial and refractive myopia 32 patients (64 eyes) with axial and 26 patients (46 eyes) with refractive myopia have been examined.Methods and results. It has been established that in patients with axial and refractive progressive myopia in 56.4% of cases there is a decrease of peripapillary zone thickness of nerve fiber and decrease of ganglion cells layer thickness, an increase of corneal-compensated intraocular pressure by 1.3 times, and also the reduce of corneal hysteresis by 1.2 times.Conclusion. These changes do not depend on the degree of refraction and are associated with an increase in axial length of the eye and decrease in the biomechanical properties of the root-scleral capsule regardless the type of myopia.

Возрастные показатели диаметра роговицы у пациентов с разными видами миопии и у лиц с эмметропией и гиперметропией

<p style="text-align: justify;"><span style="color: #800000;"><span style="font-size: 13.0080003738403px; line-height: 1.538em;"><span style="color: #800000;">https://doi.org/10.31288/oftalmolzh20134915</span></span></span> <p style="text-align: justify;"><span style="color: #800000;"><strong><span style="font-size: 13.0080003738403px; line-height: 1.538em;">The age parameters of the corneal diameter in the patients with the different types of myopia and in the persons with emmetropia and hyperopia</span></strong></span>

Impact of near-distance computer work on wavefront aberration in different types of myopia

Background Both accommodative abnormality and higher order wavefront aberrations associated with near work are interrelated with blurry retinal image.It is very important to investigate the higher order wavefront aberrations in stable and progressive myopic eyes before and after near work. Objective The present study was to observe the high order aberration change of myopic eyes before and after computer work upon near work stimulation as well as the relationship of high order aberration changes to types of myopia. Methods The case-controlled design was used in this clinical study.Sixty right eyes of 60 subjects were enrolled,including 30 progressive myopias and 30 stable myopias with matched age and gender.Refractive errors of the subjects were completely corrected by the wearing of spectacles.The subjects remained the work for 1 hour in front of a computer monitor with 40 cm distance under the dark environment and nature pupil size,and the height of the eye and monitor center kept the same level.The changes of wavefront aberration in test eyes were measured with Complete Ophthalmic Analysis System before and after 1 hour of continuous computer work.The influences of computer-work and myopia types on wavefront aberration were analyzed in 3,4,5 mm pupil size.Root-mean-square (RMS) of aberrations was calculated as the index of higher order wavefront aberrations. Results There were no significant differences in the higher order wavefront aberrations before and after computer work for the two types of myopic eyes under the 3,4,5 mm pupil.The RMS of higher order wavefront aberrations were similar between progressive myopia and stable myopia under the 3 mm pupil condition.Total higher order RMS,6th-order,5th-order and 3rd-order RMS were significantly higher in progressive myopic group compared with stable myopic group under the 4 mm pupil size ( RMS3:F =5.985,P =0.016 ; RMS5:F =3.975,p=0.049;RMS6:F=8.130,P=0.005:RMST:F=6.493,P=0.012) and 5mm pupil size(RMS3:F=13.132,P=0.000;RMS5:F =4.032,P=0.047 ; RMS6:F =4.393,P=0.038:RMST:F=10.508,P=0.002 ).The spherical aberrations were higher in progressive myopic group under the 3,4,5 mm pupil conditions in comparison with stable myopic group,but these alterations were insignificant between two types of myopias ( P＞0.05 ). Conclusions Higher order wavefront aberrations of progressive myopic eyes is comparable higher than the stable myopic eyes.Computer reading task dose not significantly impact the higher order wavefront aberrations on myopic eyes. Key words: Myopia/progressive, stable; Wavefront aberration; Computer work

Definition of high myopia by parapapillary atrophy. The Beijing Eye Study

Definition of high myopia by parapapillary atrophy. The Beijing Eye Study

Congenital and developmental myopia.

Both hereditary and environmental factors are important in the interactive growth of the ocular tissues responsible for determining the refractive state of the eye. Myopia has a low prevalence in otherwise healthy children and is seen with an increased prevalence early in life in many systemic and ocular diseases. Predicting how refractive error will change in any individual child after birth or at any stage of ocular development is not possible at present, although, trends can be seen in longitudinal studies. In the disease states associated with an increased prevalence of myopia, information regarding the time of onset of myopia and the specific values for the refractive components, is lacking, so that underlying mechanisms of myopia development and whether the myopia is congenital or developmental, are not known. In adults, three different types of myopia can be characterised on the basis of clinical characteristics which have prognostic significance for ocular disease. The mechanisms of ocular growth that lead to these forms of myopia are not clear. At present, treatments to prevent or slow myopic progression have been marginally beneficial and of questionable value.