Myopia

METHODS. COMET enrolled 469 ethnically diverse children (ages, 6–11 years) with myopia between –1.25 and –4.50 D. They were randomly assigned to either progressive addition lenses (PALs) with a +2.00 addition (n = 235) or single vision lenses (SVLs; n = 234), the ...

PURPOSE: To determine the mean angle kappa and its determinants in the population of Tehran, Iran. METHODS: In a cross-sectional survey with random cluster sampling, a total of 442 participants aged> 14 years were selected from 4 municipality districts of Tehran for Orbscan acquisitions. Exclusion criteria were history of eye surgery for refractive errors, cataract or glaucoma, and use of topical medication or any type of contact lens at the time of the study. Mean angle kappa in different age and gender groups and its association with ...

Purpose: To compare thickness measurements of the central 6.0 mm of the cornea obtained with the Orbscan® II topography system and topographical ultrasound pachymetry. Setting: School of Optometry, University of Santiago de Compostela, Galicia, Spain. Methods: In 24 right eyes, pachymetric measurements were taken at the center and 1.2 mm and 3.0 mm on the superior and inferior hemimeridians. A 1‐sample t test was applied to assess the significance of the relationship between Orbscan II and ultrasound methods. The relationship between the 2 was assessed by analyzing regression and plotting the differences against the mean corneal thickness. Orbscan II data were analyzed in 3 ways: (1) without the application of an acoustic equivalent correction factor; (2) with a correction factor of 0.92, as recommended by the manufacturer; (3) with correction using the equations derived in this study. The data were systematically compared with those of ultrasound pachymetry. Results: Before the cor...

Medina, A. Int Ophthalmol (2017). doi:10.1007/s10792-017-0493-7


ABSTRACT

Purpose
To confirm the prediction of emmetropization feedback theory that myopia can
be prevented by correcting the hyperopia of a child at risk of becoming myopic.
Methods
We conducted such myopia prevention treatment with twins at risk. Their
hyperopia was partially corrected by one half at age 7 and in subsequent years
until age 16.
Results
Hyperopia progressively decreased in all eyes as expected. None of the twins
developed myopia. The spherical equivalent refractions of the followed eyes
were +1 and +1.25 D at age 16. Feedback theory accurately predicted these
values.
Conclusions
The treatment of the twins with partial correction of their hyperopia was
successful. Prevention of myopia with this technique is relatively simple and
powerful. The use of this myopia prevention treatment has no adverse effects.
This prevention treatment is indicated in children with a hyperopic reserve at risk
of developing myopia.

The rate of visual impairment has been on a steady increase with several implicating factors. This has led to a more detailed attention in the trend of occurrence of visual defects and diagnosis. Among several reports, it has been recorded that medical students tend to have the most reported visual defects among other professions. Medical schools at Singapore, Taiwan, Denmark and Norway showed prevalence of eye defects among their students at the rate of 89.8%, 90%, 50% and 50.3% respectively. This study therefore aimed at recognizing the prevalence of common eye defects such as myopia, hypermetropia, colour blindness (daltonism) and astigmatism as well as identifying various factors responsible for the occurrence of these visual defects. A total of 200 medical students (aged 14 to above 40 years) in Dominica were examined. Refractive error and colour blindness were checked by using standard rudimentary tests. Additional demographical data was obtained through self-administered questionnaire. Among the students tested, 49.5% presented with at least one eye

To assess corneal anatomic changes after LASIK with a high-speed corneal and anterior segment optical coherence tomography (CAS-OCT) system. Cross-sectional observational study. Fifty-one eyes of 26 healthy persons undergoing LASIK. The CAS-OCT prototype operated at a 1.3-mum wavelength and 2000 axial scans/second. The corneas were scanned with a flap profile pattern (horizontal line, 512 axial scans) and a flap map pattern (4 radials, 256 axial scans each). Both patterns are 8 mm long and are centered on the corneal vertex. LASIK flaps were created using either a mechanical microkeratome (Hansatome; Bausch & Lomb, Inc., Rochester, NY) or a femtosecond laser (Pulsion; IntraLase Corp., Irvine, CA). Intraoperative pachymetry was performed using a 50-MHz ultrasound probe. Three OCT scans were obtained on preoperative and post-LASIK visits up to 6 months. An automated algorithm was developed to process the OCT images and to calculate corneal, flap, and stromal bed thickness profiles and...

Myopia is an important public health problem that entails substantial societal and personal costs. It is highly prevalent in our society, affecting at least 25% of the adult population in the United States [1] and is even more common in Asian countries, affecting up to 84% of ...

Experimental design phase of a pilot study at Annapolis is described, using reading glasses, +1.5 D. to +3.0 D. to alleviate college myopia. College students often become 1.0 to 2.0 diopters more myopic, so reading glasses were explored to partially cancel the effects of the study environment. N = 25 different sets of (+)Add lenses are evaluated, for required adjustment period and reading comfort. Three computer models are developed to predict refraction versus time. Basic control system equations predict exponential myopia shift of refractive state R(t) with time constant t0 = 100 days. Linear, exponential and Gompertz computer results are compared calculating refraction R(t) during the college years, showing correlation coefficients |r| = 0.96 to 0.97, accurate +/−0.31 D. over a 14 year interval. Typical college myopia rate is −0.3 to −0.4 D/yr. Reading glasses may be a simple, practical solution to stabilize college myopia.

To examine early myopia-related optic disc and retinal changes in a Singapore Chinese adolescent sample without confounding ocular or systemic disease. Population-based cross-sectional study. Children aged 12 to 16 years at a follow-up visit for Singapore Cohort Study of Risk Factors for Myopia. Detailed eye examinations, including cycloplegic autorefraction and contact biometry, were performed. Retinal photographs were acquired using nonmydriatic retinal photography among children who attended follow-up examinations in 2006, and were graded for myopia-related optic disc signs and macular changes by a single experienced grader. Optic nerve head parameters were measured adjusting for camera and ocular magnification with appropriate formulae. Optic disc changes (tilt, beta peripapillary atrophy [β-PPA], and optic nerve parameters) and macular changes (staphyloma, lacquer cracks, Fuchs' spot, and chorioretinal atrophy). Retinal photography data were available for 1227 children (median age, 14 years; range 12-16). Tilted optic discs were found in 454 subjects (37%), and were associated with myopic spherical equivalent refractions (-3.6 diopters [D] vs -1.3 D; P<0.0001), higher cylindrical error (0.9 vs 0.7 D; P = 0.0001) and longer axial length (24.93 vs 23.96 mm; P<0.0001). The pattern of distribution of the axes of the tilted discs and corneal curvature were similar (P = 0.4). All linear optic nerve parameters, except vertical disc diameter (P = 0.15), were significantly smaller in eyes with than without tilted discs (P <0.001) after adjusting for confounders. Apart from 20 cases, all eyes with tilted optic discs had associated β-PPA. We identified only 1 case each (0.1% prevalence) of staphyloma and lacquer cracks in this sample. In this Asian adolescent population, tilted optic discs were highly prevalent, in contrast with the lower prevalence reported in Caucasian populations. Eyes with tilted discs tended to have smaller optic cups with smaller cup-to-disc ratios, and were associated with myopic refraction, higher astigmatism, and longer axial length. There were similar patterns of distribution between the axis of disc tilt and the axis of corneal curvature, which could have embryologic origins. In contrast with optic disc changes, myopic macular changes were rare in this age group, suggesting that these changes may develop later in life. The authors have no proprietary or commercial interest in any of the materials discussed in this article.

High myopia is a major cause of uncorrectable visual impairment. It imposes major challenges and costs for refractive correction, and for the treatment of associated pathological complications. In the last 60 years, there has been a marked increase in the prevalence of high myopia in younger generations in developed countries in East and Southeast Asia, and there are signs of similar, but less pronounced increases in North America and Europe. In some parts of the world, 70-90% of children completing high schools are now myopic, and as many as 20% may be highly myopic. It is now clear that myopia results from excessive axial elongation of the eye, and this greater rate of axial elongation appears to be environmentally driven. Experimental studies have examined the biochemical mechanisms involved in regulation of axial elongation; and, from these studies, some options have emerged for preventing the development of myopia or slowing myopia progression. Atropine eye drops have been quit...

A 25-year-old man received iris-claw phakic intraocular lenses (pIOLs) (Artisan, Ophtec) of -11.5 diopters (D) in the right eye and -13.0 D in the left eye; both pIOLs had a 6.0 mm optic and 8.5 mm haptics. Twenty months postoperatively, the best corrected visual acuity was 20/400 in the right eye and 20/25 in the left eye. Slitlamp examination revealed microcystic bullae, keratic precipitates, stromal edema, and ciliary injection in both eyes. Central corneal thickness was 704 microm in the right eye and 639 microm in the left eye; specular biomicroscopy showed reduced endothelial cell density of 548 cells/mm(2) and 564 cells/mm(2), respectively. The pIOL in the right eye was eventually explanted.

To report ocular perforation that occurred during retrobulbar injection in 7 highly myopic eyes. Seven patients with a diagnosis of globe injury during retrobulbar injection for ocular anesthesia before cataract surgery were managed by vitreoretinal surgery. All injections were performed by ophthalmologists. The surgeon recognized the perforation in 4 cases at the time of injection. The preoperative vision was hand motion perception in 4 eyes and light perception in 3 eyes. All patients underwent vitreoretinal surgery because of the presence of vitreous hemorrhage and/or retinal detachment diagnosed by funduscopy or ultrasonography. At the time of surgery, all eyes had vitreous hemorrhage and 4 eyes had rhegmatogenous retinal detachment. The number of vitreoretinal procedures performed was: 1 procedure in 4 patients, 2 procedures in 2 patients, and 3 procedures in 1 patient. The period of follow-up ranged from 4 months to 4 years, averaging 20 months. At the end of the follow-up per...

Refractive errors are a major cause of visual impairment in the population. To find the pattern of refractive errors among patients evaluated in a tertiary care hospital in the western region of Nepal. The present hospital-based retrospective study was conducted in the Department of Ophthalmology of the Manipal Teaching Hospital, situated in Pokhara, Nepal. Patients who had refractive error of at least 0.5 D (dioptre) were included for the study. During the study period, 15,410 patients attended the outpatient department and 10.8% of the patients were identified as having refractive error. The age of the patients in the present study ranged between 5 - 90 years. Myopia was the commonest refractive error followed by hypermetropia. There was no difference in the frequency of the type of refractive errors when they were defined using right the eye, the left eye or both the eyes. Males predominated among myopics and females predominated among hypermetropics. The majority of spherical er...

To compare treatments with wavefront optimized and custom-Q ablations. Two consecutive groups of eyes were treated for myopia and astigmatism with surface ablation. One group was treated with wavefront optimized ablation and the second group was treated with custom-Q ablation. Preoperative and 3-month postoperative Q-values, higher order aberrations, low contrast visual acuity, and classic outcome parameters were analyzed. The wavefront optimized ablation group was comprised of 46 eyes of 23 patients with a mean spherical equivalent refraction (SE) of -3.64 diopters (D) (range: -1.15 to -8.25 D); mean Q-value changed from -0.33 preoperatively to 0.06 postoperatively. The custom-Q ablation group was comprised of 42 eyes of 21 patients with a mean SE of -3.24 D (range: -1.47 to -8.00 D); mean Q-value changed from -0.36 preoperatively to -0.03 postoperatively. A statistically significant difference in postoperative change in Q-values (P = .049) between the two groups was noted, but the...

Measurement of ocular wavefront aberration is becoming a popular clinical technique due to recent technical advances and an increasing awareness of its potential for practical application in the fields of surgical and optical refractive correction. In addition, information about the status of peripheral refraction determined from ocular wavefront aberrations is now being used to monitor the progression of myopia and other refractive errors in children, and as a basis for the study of the process of emmetropization. Several finite, anatomically accurate, wide-angled, model eyes have been proposed previously in an effort to produce a schematic eye that accurately reproduces vision under different practical circumstances. This paper compares these models in terms of their wavefront aberration, image quality metrics and peripheral refraction profiles and contrasts these with data from real eyes to assess their relative utility.