Refractive Error Research Articles

Comparing the morphology of optic nerve head and lamina cribrosa in full-term and preterm school-aged children.

To evaluate the morphology of lamina cribrosa (LC) in preterm school-aged children. A study of 120 eyes from 120 patients, including 42 full-term children (control group), 41 preterm children without retinopathy of prematurity (ROP), 16 children with ROP treated with intravitreal bevacizumab (IVB), and 21 children with ROP treated with laser. Five parameters of LC were measured by optical coherence tomography, including Bruch's membrane opening (BMO) diameter, minimum rim width (MRW), LC depth, prelaminar tissue (PLT) thickness, and LC curvature index (LCCI). The PLT thickness increased with age in full-term and preterm children (β = 30.1, P = 0.003 and β = 19.6, P < 0.001, respectively). LC depth and LCCI showed no differences between full-term and preterm children. Worse refractive errors in preterm children were associated with greater MRW and PLT thickness (β = -17.1, P = 0.001 and β = -5.7, P = 0.03, respectively). However, this relationship was not found in full-term children. Laser-treated children had greater MRW, PLT, temporal peripapillary retinal nerve fibre layer, and foveal thickness than full-term or other preterm children (all P < 0.05). Prematurity and ROP treatment may have an impact on the structural development of the LC. Refractive status plays a vital role in the LC structure of preterm children. This highlights the refractive errors of preterm children at school age that merit greater attention.

Refractive and ocular biometric characteristics of non-myopic and pseudomyopic eyes in mild hyperopic Chinese children aged 3–12 years

PurposeTo investigate the refractive and ocular biometric characteristics of children with mild hyperopia and distinguish between non-myopic and pseudomyopic eyes before cycloplegia. MethodsThe eligible children underwent refractive error measurements using a NIDEK autorefractor before and after the administration of 0.5 % tropicamide. Ocular biometric parameters, including axial length (AL), anterior chamber depth (ACD), and lens thickness (LT), were measured using the IOLMaster 700 before cycloplegia. We performed comparative analyses between the non-myopic and pseudomyopic groups, categorized based on whether the spherical equivalent (SE) before cycloplegia exceeded −0.50 diopters (D). Univariable and multivariable regression analyses were performed to control for confounding factors. ResultsThe final analysis included 968 eyes. The participants with pseudomyopia were more likely to be boys (P = 0.029), younger (P = 0.004), less hyperopic (P < 0.001) after cycloplegia, and exhibit a higher delta SE (P < 0.001) compared to the non-myopic participants. Pseudomyopic eyes were associated with a shallower ACD (P = 0.004) and thicker LT (P < 0.001) than non-myopic eyes. After adjusting for sex, age, and SE, pseudomyopic eyes showed increased AL (P = 0.001) and LT (P < 0.001) and decreased ACD (P = 0.005) compared with non-myopic eyes before cycloplegia. ConclusionsAmong the children with mild hyperopia, pseudomyopia was more common in younger boys with a lower cycloplegic SE and higher delta SE. A thicker LT, shallower ACD, and increased AL may indicate the presence of pseudomyopia, which may provide insights into the rapid progression of myopia in children with pseudomyopia.

Keratorefractive lenticule extraction in eyes with post-herpetic scars

Correcting refractive errors by remodeling the corneal curvature with an excimer laser (which emits ultraviolet radiation) may reactivate a latent Herpes Simplex Virus (HSV), resulting in keratitis. New techniques using infrared sources, such as femtosecond-assisted Keratorefractive Lenticule Extraction (KLEx), may thus provide a safer approach to eyes with previous HSV keratitis; however, no cases of KLEx in such cases have been reported. As a result, we present three cases in which KLEx successfully corrected myopia. Three myopic eyes from three patients with a known history of healed HSV keratitis that occurred more than 12 months before surgery underwent KLEx. All patients received oral antiviral prophylaxis before and after surgery. In case 1, the post-HSV scar was semiperipheral, involving only a portion of the treated area; surgery went smoothly, with the intrastromal lenticule well delineated and dissected even through the scar. In cases 2 and 3, the healed scar was peripheral and did not interfere with surgery. After 6 months, all three cases had good visual acuity without complications. Finally, KLEx combined with antiviral prophylaxis can effectively correct myopia in eyes with healed HSV. The femtosecond laser can penetrate non-dense, peripheral corneal scars.

Safety and Effectiveness of Smooth Incision Lenticular Keratomileusis (SILK™) Using the ELITA™ Femtosecond Laser System for Correction of Myopic and Astigmatic Refractive Errors [Letter

Safety and Effectiveness of Smooth Incision Lenticular Keratomileusis (SILK™) Using the ELITA™ Femtosecond Laser System for Correction of Myopic and Astigmatic Refractive Errors [Letter

Prevalence of Refractive Error in School Children in South-West Tamil Nadu

Prevalence of Refractive Error in School Children in South-West Tamil Nadu

Influence of Age, Sex, and Refractive Error on Intraocular Pressure Measurement Using Applanation Tonometer Among Healthy Individuals in Shahat

The present study aimed to estimate the distribution of IOP and the relation with gender, age, and refractive error in a healthy Libyan population. This observational cross-sectional study was conducted in Cyrenaic Teaching Hospital from December 2023 to February 2024. 200 patients who presented to the hospital took part in the questionnaire. A Goldman applanation tonometer was used to measure IOP following the instillation of a drop of Benzoyl Peroxide. There were no significant differences noted between IOP in the right and left eyes. There was a correlation between IOP and age, but there was no correlation between IOP and gender (p &lt; 0.05). IOP is one of the most important indicators for monitoring the health of the eyes. Concerning age, the mean IOP increased with age and refractive errors. Conclusion: This study supported the hypothesis that age and high myopia are major risk factors for ocular hypertension development.

A study on refractive error patients in chennai city using structural equation modelling

A lot of individuals in Chennai are suffering from refractive errors. Myopia, hyperopia, astigmatism, and presbyopia are among the majority prevalent forms of corneal abnormalities. The existence of blurred vision in both the left and right eyes in people who use contact lenses is found by 17 independent and 2 dependent variables using Structural Equation Modelling (SEM). The results are interpreted by Tests for goodness of fit in models, test for individual Parameter estimate for both independent and dependent variables and the linear relationship between the variables were performed.

Risk Factors for Amblyopia

Amblyopia is characterized by loss of visual acuity without visible organic cause, although it is attributed to abnormal brain development. It is prevalent in children from zero to 8 years, but there are cases of older patients and even adults. This article aims to systematize the main risk factors for amblyopia in studies carried out in ophthalmic care centers. For this purpose, a documentary review of academic and scientific material was carried out. Two risk factors were identified, ocular type such as strabismus, myopia, isolated or combined astigmatism, refractive errors, and non-ocular such as prematurity, low birth weight, and maternal smoking. Risk factors are genetic risk factors, failure to detect and treat early, due to socio-environmental factors like poverty and lack of ophthalmic services, or extraordinary situations such as the COVID-19 pandemic.

Prevalence and Pattern of Ocular Diseases among Rural Dwellers in Affa, Enugu State

Background: The prevalence and pattern of different ocular diseases among rural dwellers vary in different parts of the world. It is usually influenced by a numerous factor, including but not limited to utilization of eye care services, socio-economic status, and level of education. Aim: To identify the most prevalent eye diseases and their pattern of occurrence, among rural dwellers in South East Nigeria, with a view to influence targeted health policies and subsequently, targeted interventions to improve eye health in the region. Methods: The study was a cross sectional study involving patients willing to participate in the study during a one-day free eye outreach organized by the Ophthalmology department, ESUTH Parklane at Affa Community in Udi Local Government Area of Enugu state. A preliminary visit was made one week prior to the health outreach, by some members of the outreach team to mobilize the community, seek their consent and fix a date through their leaders. On the day for the outreach, the objective of the eye screening was explained to the participants in both English and their local language. Subsequently, informed consent was obtained and each subject registered and the bio-data documented. Registered participant had their unaided and aided Visual Acuity (VA) of each eye determined. Then, the anterior and posterior segment was examined. Data collected were recorded using a proforma and later inputted into a computer, cleaned and analysed using SPSS version 21. Results were presented in tables and represented in frequencies percentages. Association between variables were done using t-test and p- value of &lt;0.05 was considered significant. Results: One hundred and sixty-eight participants were screened during the outreach programme/study with mean age of 40+0.5years. There were more females 116 (69.1%) than males 52 (30.9%), giving a female to male ratio of 2:1 and they are predominantly Christians and farmers. The common ocular problems among the participants include cataract 53 (22.6%), refractive error 37 (15.8%), Pterygium 35 (14.9%). Cataract was the most common eye disease among the outreach participants and responsible for 22.6% of all ocular problems. Normal visual acuity was found more in participants &lt; 50 years of age, mild visual impairment occurred more in participants 51-70 years while moderate visual impairment to blindness were seen more in patients &gt;70 years. Conclusion: In this study, the commonest ocular problems among the participants include Cataract, Refractive error, and Pterygium which are reversible causes of visual impairment and blindness. Therefore, health policies and advocacies should be directed towards reducing the burden of these reversible causes of visual impairment and blindness among the rural dwellers which constitute greater proportion of our population.

Refractive Errors in Thalassemia Patients

Purpose: The objective of this study was to evaluate the frequency of refractive error among thalassemia patients. METHOD: This cross sectional study was performed in duration of six months at Sir Ganga Ram hospital from July, 2023 to August, 2023. A total of hundred (n=100) thalassemia patients, were included in this study between the age range of 17 to 30 years. All subjects with thalassemia were previously diagnosed. Objective refraction was accomplished with Auto-Refractometer (Axis), and vision was examined with Snellen chart/Log Mar chart. SPSS version 26 was used to analyze the results. Chi-Square test was applied to find the significance of data. P-value &lt;0.05 was considered as significant. Results: The mean age of participants was 21.28±3.39 years. In the right eye of thalassemia patients, the result showed that 51% were emmetropic, 11% had hyperopia, 1% had hyperopic astigmatism, 20% had myopia, and 17% had myopic astigmatism. In the left eyes of patients, 52% were emmetropic, 10% had hyperopia, 2% had hyperopic astigmatism, 18% had myopic astigmatism, and 18% had myopia. P-value was 0.043. Conclusion: The cross sectional study results conclude that patient’s vision may not be significantly affected by thalassemia. Thalassemia patients were more effected with Myopia. While hyperopic astigmatism was least effected.

Laser vision correction and binocular vision – case reports

Laser vision correction (LVC) is the removal of refractive errors, by changing the geometry of the cornea. It doesn’t directly affect binocular vision. However, the condition of the patient’s binocular vision is a very important. That affects the quality of life, which also indirectly translates into the patient’s satisfaction with the LVC procedure. Based on the presented cases, this article proves how important it is to examine binocular vision before laser vision correction. The influence of the prismatic effect of spectacle lenses on the control of binocular vision and the risk of strabismus decompensation, whichis most often associated with double vision. The described cases are people with problems with binocular vision. The article includes methods of treatment (contact lens test, vision therapy) to check and eliminate the above-mentioned problem.

Comparative study of pterygium excision with suture and sutureless conjunctival autograft

Introduction and aim. This is a prospective interventional study to compare corneal astigmatism before and after pterygium excision with conjunctival autograft, to determine the difference in mean corneal curvatures before and after pterygium excision, to evaluate the safety and efficacy of autologous blood technique, and sutured conjunctival autograft for primary pterygium. Material and methods. Patients were divided into group A – pterygium excision+sutured conjunctival limbal autograft and group B – pterygium excision+autologous conjunctival limbal autograft under local anesthesia. The preoperative and post operative K1 and K2 values and BCVA were noted. Results. There was statistically significant reduction in mean astigmatism at each post operative follow up in group A at 1 week (p=0.0249), 2 weeks (p=0.004), 1 month (p=0.0031) and at 3 months (p=0.0009) and similarly in group B post operative follow up at 1 week (p=0.0011), 2 weeks (p=0.0021), 1 month (p=0.0009) and at 3 months (p=0.0003). Conclusion. Pterygium surgery decreases the cylindrical error and reverts corneal curvatures to normal, thus improving subjective visual acuity. Astigmatism produced by the pterygium is reduced after surgery We found autologous conjunctival autograft is superior than sutural conjunctival autograft. Pterygium causes astigmatism depending upon the size of pterygium it should be surgically removed to prevent obstruction in the vision.

Evaluation of Causes of Visual Impairment Among Bespectacled Between the Age 18-23: A Study from Tamil Nadu, India

Visual impairment is internationally related to severe public health, social, and economic challenges. Uncorrected refractive error is one of the main targets of the global movement to end preventable visual disability, as it is a treatable source of vision impairment. With precise information about the prevalence and underlying causes of vision impairment in the general population, health organizations may find it simpler to develop infrastructure and human resource strategies, as well as to distribute resources properly. The design of screening programs to identify individuals who are more vulnerable to eye issues may also be facilitated by having this knowledge. Wearing spectacles, also called glasses, is the practice of wearing frames with lenses in front of the eyes, usually with the intention of improving vision. There are additional reasons to wear glasses, including fashion, eye protection, and concealing visual defects. Even with the rising popularity of contact lenses and refractive surgery, wearing glasses is still the most prevalent technique to correct refractive difficulties. Despite its many built-in advantages, namely the capacity to control usage, spectacles do have some significant disadvantages. Many people who require glasses are unable to afford them, and if they are prescribed incorrectly, they may cause irritation to the eyes. Refractive errors are a major cause of visual impairment worldwide. People who lack professional skills in eye care or dispensing have abused the system due to irregularities in the distribution of spectacles.

BCLA CLEAR presbyopia: Management with scleral techniques, lens softening, pharmaceutical and nutritional therapies

The aging eye undergoes the same progressive crosslinking which occurs throughout the body, resulting in increased rigidity of ocular connective tissues including the lens and the sclera which impact ocular functions. This offers the potential for a scleral treatment that is based on restoring normal biomechanical movements. Laser Scleral Microporation is a laser therapy that evaporates fractional areas of crosslinked tissues in the sclera, reducing ocular rigidity over critical anatomical zones of the accommodation apparatus, restoring the natural dynamic range of focus of the eye.Although controversial and challenged, an alternative theory for presbyopia is Schachar’s theory that suggests a reduction in the space between the ciliary processes and the crystalline lens. Widening of this space with expansion bands has been shown to aid near vision in people with presbyopia, a technique that has been used in the past but seems to be obsolete now.The use of drugs has been used in the treatment of presbyopia, either to cause pupil miosis to increase depth of focus, or an alteration in refractive error (to induce myopia in one eye to create monovision). Drugs and laser ablation of the crystalline lens have been used with the aim of softening the hardened lens. Poor nutrition and excess exposure to ultraviolet light have been implicated in the onset of presbyopia. Dietary nutritional supplements, lifestyle changes have also been shown to improve accommodation and the question arises whether these could be harnessed in a treatment for presbyopia as well.

An assessment of the thickness of the retinal nerve fiber layer around the optic disc using spectral domain optical coherence tomography in myopia patients at an industrial hospital in India

Myopia is rising as a silent epidemic across the globe with marked ocular morbidity and pathological changes. The retinal nerve fiber layer (RNFL) thinning is indicative of glaucomatous damage; it remains uncertain whether RNFL thickness would vary with the refractive status of the eye. It is therefore important to investigate whether any correlation exists between RNFL measurements and axial length/refractive error in myopia. Purpose. To assess the peripapillary RNFL thickness by spectral domain optical coherence tomography (SD-OCT) and to determine the correlation between axial length and peripapillary RNFL thickness in myopia patients. Material and methods. A total of 100 patients (200 eyes) with low, moderate and high myopia (ave -3.58 ± 2.45 D) aged 15 to 40 years were examined to assess the peripapillary RNFL thickness by SD-OCT and to determine the correlation between axial length (AL) and peripapillary RNFL thickness myopia patients. Results. Average 360-degree RNFL thickness (mean ± SD) was 92.25 ± 10.04 μm. In the low myopic group this parameter was 98.82 ± 6.67 μm, in the moderate myopic group — 89.28±5.23 μm, and in the high myopic group — 78.54 ± 7.32 μm. The average 360-degree mean RNFL thickness in patients with AL &lt; 24 mm was 100.06 ± 5.92 μm, in patients with AL between 24–26 mm — 89.48 ± 4.59 μm, and in patients with AL &gt; 26 mm — 78.2 ± 6.77 μm. There was significant association between thinning of the average 360-degree RNFL thickness with increasing degree of myopia and AL (p &lt; 0.0001). Conclusion. The study shows RNFL thickness decreases with increase in refractive error and increase in axial length of myopic eyes. The degree of myopia may affect the RNFL thickness differently.

Prevalence and Causes of Visual Impairment and Blindness Among Students of Blind Schools of Bihar, India

Aim: Visual impairment and blindness are serious public health issues, especially in developing countories, like India. Data on causes of childhood visual impairment and blindness in Bihar are limited. The aim of this study was to determine the leading causes of visual impairment and blindness in blind schools of Bihar Study design: A cross sectional study was done in seven blind schools of Bihar Methods: Seven blind schools were visited after taking permission from principal. Written informed consent from parents was taken. Detailed ocular and systemic examination was done for all 218 students. Comprehensive eye examinations were performed, including distance visual acuity, anterior and posterior segment examinations, refraction, color vision, and visual field testing. Anatomical and etiological categorization of causes of visual impairment/Blindness was done. Results: A total 218 students were examined. 90.82% of students were blind and 9.17% severely visually impaired. Major anatomical causes of visual impairment and blindness were Microphthalmos (24.31%), Anophthalmos (23.39%), Optic Atrophy (9.63%) and Corneal Scar (7.80%). Etiologically the most common cause was of unknown etiology followed by postnatal factors. Preventable or treatable causes, such as glaucoma, cataract, and refractive errors, represented 22.48% of the cases Conclusion: Blindness and Low vision due to congenital ocular conditions affecting whole globe was the most common cause, further population based studies are needed to know the exact magnitude of problem and to make strategies to decrease the incidence. There is a need to strengthen current primary preventions strategies while tertiary referral centers, Low Vision setups, awareness program regarding Low Vision, special education, rehabilitation, ocular disability benefits and many more things need to be set up in the different health zones of the state to manage childhood preventable and avoidable blindness.

Diagnosis of Dry Eye Syndrome During the Preparing Patients for Cataracts Phacoemulsification. Literature Review

The increasing patient demands for quality of life after surgery necessitate optimization of approaches in the field of surgical intervention, reduction of the frequency of refractive errors and correction of tactics of postoperative interventions. Literature data indicate that refractive errors are possible after surgical treatment for cataracts associated with the presence of dry eye syndrome in the preoperative period. Tear film is used as the first refractive medium, and the size of the refractive change at air­tear film interfaces is the most innovative of any interface in any other optical system. Thus, changes of tear film physiology affect overall vision with higher order aberrations and irregular astigmatism occurring. The presented literature review analyzes data from scientific studies aimed at studying risk factors for the development of dry eye syndrome and diseases associated with it when phacoemulsification of cataracts occurs. Considering the fact that, according to various studies, the incidence of dry eye syndrome after cataract surgery ranges from 9.8 to 96.6% in cataract surgery in collaboration with dry eye surgery, adequate approaches within the framework of preoperative preparation are an urgent development. The lack of clear recommendations for effective preoperative screening and respiratory preparation for surgery, unreliable biometric data, and lack of treatment strategy for postoperative dry eye syndrome are indicators of detectors to obtain the desired results. Adequate diagnosis and preparation of ocular surfaces before biometric measurements can reduce refractive errors after surgery.

Refractive errors in patients with Bardet Biedl syndrome

ABSTRACT Purpose Bardet-Biedl Syndrome (BBS) is a rare autosomal recessive ciliopathy. Within corneal development, primary cilia serve a critical role. We sought to investigate the association of BBS with corneal astigmatism among a cohort of patients with BBS. Methods This was a cross-sectional, retrospective study performed at a pediatric ophthalmology department of a tertiary hospital. The study enrolled 45 patients with genetically confirmed Bardet-Biedl syndrome, encompassing a total of 90 eyes observed from February 2011 to August 2021. Spherical and cylindrical refractive errors and keratometry outcome measures, including diopter (D) values at the flattest and steepest axes, were recorded. Corneal astigmatism of greater than 3D is considered extreme corneal astigmatism based on previously published data. Results Among 45 patients (M:26; F:19), the mean age was 16.4 ± 8.2 years, and the mean best-corrected visual acuity was 20/60. The most common molecular diagnosis was BBS1, seen in 24 of 45 (53.3%). Among all the patients, the mean spherical refractive error was −2.9 ± 3.8D. The mean cylindrical refractive error was 2.6 ± 1.5D. The mean keratometry values at the flattest axis was 43.5 ± 5.3D (39.4–75.0) and at the steepest axis was 47.2 ± 7.3D(41.5–84.0). Among all the patients with BBS, the mean corneal astigmatism was 3.7 ± 1.0D(0.5–7.1), which is considered extreme. Conclusion A cohort of individuals with BBS demonstrated high corneal astigmatism. These results suggest an association between corneal astigmatism and primary ciliary dysfunction and may assist in clinical management and future therapeutic targets among BBS and other corneal disorders.

Evaluation of lamina cribrosa curvature index in different types of glaucoma.

The aim of this study was to evaluate the lamina cribrosa curvature index in different types of glaucoma in comparison with clinical findings and conventional measurement methods. Patients older than 18years who were followed up in Glaucoma Unit of Department of Ophthalmology at Fırat University Faculty of Medicine, whose disease had been under control at least for 1year, who had at least three reliable visual fields, whose refractive error was between - 6 and + 5 diopter and who did not have any disease other than glaucoma that would affect the visual field, were included in the study. Clinical and demographic characteristics, visual field, optical coherence tomography and lamina cribrosa curvature index (LCCI) results were evaluated. The study patients were divided into six groups: early-stage primary open-angle glaucoma (POAG) as group 1 and intermediate-advanced stage POAG as group 2, pseudo-exfoliation glaucoma (PEXG) as group 3, normal tension glaucoma (NTG) as group 4, ocular hypertension patients whom subsequently developed POAG as group 5 and healthy control as group 6. A total of 189 eyes of 101 patients were included in our study. Forty-seven patients were male (46.5%) and 54 were female (53.5%). The mean age was 62.43 ± 1.49years. LCCI, mean deviation (MD), visual field index (VFI), pattern standard deviation (PSD) and retinal nerve fiber layer thickness (RNFL) values were analyzed in all groups and Pearson correlation analysis showed statistically significant correlation between PSD and RNFL measurements with LCCI values in all groups. MD value was correlated with LCCI in groups 2, 3 and 4, while VFI value was correlated with LCCI in all groups except group 5. When the groups were compared with each other according to the Post-Hoc Tamhane test, LCCI measurement showed statistically significant results in accordance with MD, VFI, PSD and RNFL values. The LCCI assessment is mostly consistent with conventional tests. In this study, in which different types of glaucoma and healthy subjects were examined simultaneously, LCCI shows promise as a detailed and reliable assessment method.

The most common contact lens-related complications: A brief review of the literature

Introducion and purpose Millions of people use contact lenses every day. Their primary and most common use is correcting refractive errors. Despite their beneficial purpose, contact lens use has many complications. It is estimated that 5 to 50% of patients may develop at least a single complication. The state of knowledge Contact lens-related complications are multifactorial. One of the main reasons for contact lens discontinuation is contact lens discomfort. Patients most often report dryness, burning, and irritated eyes. Other disorders can be briefly divided into conjunctival and corneal complications. The most common conjunctival and allergic complication of contact lens use is giant papillary conjunctivitis. Other significant conditions involving the conjunctiva can also be superior limbic keratoconjunctivitis or allergic or toxic conjunctivitis. Corneal complications, on the other hand, seemed to be much more severe. These include superficial punctate keratitis, peripheral corneal ulceration, and contact lens-related keratitis. Also, abrasion can occur due to improper eye hygiene or mechanical damage during lens replacement. It should also be remembered that prolonged use of lenses can lead to hypoxia and corneal edema. Summary This paper briefly outlines the possible complications of contact lens use. It is important to remember that despite their appropriate use, sometimes significant complications can occur. Noteworthy, corneal, or conjunctival complications require discontinuation of the lenses and appropriate treatment.