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Refractive Errors, Myopia, and Presbyopia
Published in Ching-Yu Cheng, Tien Yin Wong, Ophthalmic Epidemiology, 2022
Ka Wai Kam, Chi Pui Pang, Jason C. S. Yam
Hyperopia (or hypermetropia) refers to the condition where lights are focused behind the retina. Thus distant objects can be seen more easily but light rays emerging from near objects cannot be converged sufficiently on to the retina. People with hyperopia therefore often complain about difficulties with near visual tasks and require additional converging lenses as a refractive correction. Hyperopia, defined as a SER of ≥+2.0 D, is common during infancy and childhood. While neonates are born with hyperopia, from 3 months of age onwards, most infants display a progressive change in mean refraction from +2.0 D to approximately +0.75 D, a process of emmetropization. Some high hyperopes may fail to emmetropize and slowly evolve towards low hyperopia. In particular, moderate to high hyperopia (≥+4.0 D) is known to reduce visual function, including visual acuity, stereoacuity, and accommodative response,144 and increase the risk of esotropia.145,146
The Myopic Model
Published in John William Yee, The Neurological Treatment for Nearsightedness and Related Vision Problems, 2019
It is easier to treat hyperopia instead of myopia during development. With hyperopia the lens assumes most, if not all, of the deviated shape. I would just entice the lens to bulge instead of the lens and eyeball. The drill is simpler and is performed less often for maintenance. My youngest participant was 5 years of age with hyperopia of +2.50 in both eyes. I improved her vision to the extent where she only visits me once every 2 months and then gradually once every 4 months. The intention is not just to improve her visual acuity further but to maintain it by reestablishing the synchronization between the lens and eyeball.
Sensory organs
Published in Aida Lai, Essential Concepts in Anatomy and Pathology for Undergraduate Revision, 2018
Hyperopia Shortened eyeballSymptoms: – blurred near visionComplications: – angle-closure glaucomaManagement: – convex lens
Association between post-concussion symptoms and oculomotor deficits among adolescents
Published in Brain Injury, 2021
Sowjanya Gowrisankaran, Ankoor S. Shah, Tawna L. Roberts, Emily Wiecek, Ryan N. Chinn, Karameh K Hawash, Michael J. O’Brien, David R Howell, William P Meehan, Aparna Raghuram
The optometric and ophthalmic examinations consisted of a comprehensive eye evaluation including visual acuity, confrontation visual fields, pupillary examination, oculomotor evaluation, anterior segment evaluation, dilated fundoscopic examination, and refraction (myopia defined as spherical equivalent refractive error ≤ −0.25 diopter (D); hyperopia defined as spherical equivalent refractive error ≥ +0.25 D). Cycloplegic refraction data were available for 127 of the 140 patients; in the remaining 13 patients, dry refraction was used. All patients were examined by one optometrist (AR) and one ophthalmologist (AS), both of whom followed a standard clinical protocol for all patients. All patients with hyperopia ≥ +1.50 D, myopia ≤ −0.75 D, astigmatism > 0.75 D, and anisometropia > 0.75 D wore habitual refractive error correction during assessment.
Sterile Excimer Laser Shaped Allograft Corneal Inlay for Hyperopia: One-year Clinical Results in 28 Eyes
Published in Current Eye Research, 2021
Cafer Tanriverdi, Ayse Ozpinar, Sezer Haciagaoglu, Aylin Kilic
Another method of refractive treatment of hyperopia is clear intraocular lens exchange. Ferrer-Blasco et al.30 reported that UDVA was 20/20 and above in 46.6% of patients with hyperopia implanted with AcrySof® ReSTOR® SN6AD3 intraocular lens (+ 4.00 D near addition). In their study, they reported that CDVA exhibited two-line loss in 7.6% of eyes and two-line gain in 11.5% of eyes. According to Alfonso et al.,31 in low-moderate hyperopic eyes implanted with a trifocal intraocular lens, MRSE in the postoperative 6th month was within ± 0.5 D in 81% of eyes and within ± 1 D 99% of eyes. In the high hyperopic group, they found that MRSE was within ± 0.5 D in 78% of eyes and within ± 1 D in 95% of eyes. Although the results are quite acceptable with clear lens replacement in patients with hyperopia, the risks of intraocular surgery are not completely eliminated. For this reason, we believe that corneal surgical procedures that can have similar clinical results should be preferred in the treatment of hyperopia.
Optical mechanisms regulating emmetropisation and refractive errors: evidence from animal models
Published in Clinical and Experimental Optometry, 2020
Ranjay Chakraborty, Lisa A Ostrin, Alexandra Benavente‐perez, Pavan Kumar Verkicharla
Both the optical power in the anterior segment of the eye and axial length determine refractive state.2004 Emmetropisation is an active, visually guided mechanism whereby the axial length and the combined optical powers of the cornea and lens precisely match with each other to eliminate neonatal refractive errors, and bring the eye to perfect focus (also known as emmetropia). In non‐accommodating emmetropic eyes, visual images of distant objects are clearly focused at the retinal photoreceptors. Any disruption to this homeostatic mechanism of ocular growth results in the development of refractive errors. In myopia, or near‐sightedness, the eye is too long for the optical power of the cornea and lens, and images of distance objects focus in front of the photoreceptor plane. In hyperopia, or far‐sightedness, the eye is too short for the optics, and images of distant objects focus behind the photoreceptor plane.