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Glaucoma: Overview

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Glaucoma is an eye condition characterized by increased intraocular pressure that damages the retina and optic nerve, leading to irreversible blindness if left untreated. The human eye has various components, including the cornea, iris, pupil, lens, and optic nerve. Aqueous humor is secreted by the epithelium of the ciliary body in the posterior chamber and flows through the trabecular meshwork and canal of Schlemm, maintaining normal intraocular pressure. The trabecular meshwork and the canal...
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In open-angle glaucoma, the iridocorneal angle remains open, but the trabecular meshwork becomes stiff, slowing down the outflow of aqueous humor. This causes a buildup of aqueous humor in the anterior chamber, leading to a sudden increase in intraocular pressure. The treatment for open-angle glaucoma focuses on reducing the elevated intraocular pressure by either decreasing the secretion of aqueous humor or increasing its outflow.
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Angle Closure Glaucoma: Treatment01:28

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Angle-closure glaucoma, or closed-angle glaucoma, is an eye condition where the iris bulges out and blocks the iridocorneal angle, resulting in a buildup of aqueous humor and increased intraocular pressure. Immediate medical attention is necessary due to the sudden onset of symptoms. The treatment for angle-closure glaucoma includes short-term and long-term approaches. Short-term treatment involves using eye drops like pilocarpine to lower intraocular pressure by increasing aqueous humor...
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At the molecular level, visual signals trigger transformations in photopigment molecules, resulting in changes in the photoreceptor cell's membrane potential. The photon's energy level is denoted by its wavelength, with each specific wavelength of visible light associated with a distinct color. The spectral range of visible light, classified as electromagnetic radiation, spans from 380 to 720 nm. Electromagnetic radiation wavelengths exceeding 720 nm fall under the infrared category,...
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Subjective Refraction Test Using a Smartphone for Vision Screening
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Astigmatism profile in the elderly population: Tehran Geriatric Eye Study.

Hassan Hashemi1, Amir Asharlous2, Abbasali Yekta3

  • 1Noor Research Center for Ophthalmic Epidemiology, Noor Eye Hospital, Tehran, Iran.

Japanese Journal of Ophthalmology
|August 10, 2022
PubMed
Summary

Astigmatism is highly prevalent in elderly Iranians, affecting over 80%. Key associated factors include male gender, older age, lower education, cataracts, and myopia, with anisorule astigmatism being common.

Keywords:
Anisorule astigmatismAstigmatismDirect symmetryLens opacityMirror symmetry

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Area of Science:

  • Ophthalmology
  • Geriatric Medicine
  • Public Health

Background:

  • Astigmatism is a common refractive error impacting vision quality.
  • Understanding its prevalence and risk factors in the elderly is crucial for eye care strategies.

Purpose of the Study:

  • To determine the prevalence of astigmatism and its associated factors in an elderly population.
  • To examine astigmatism symmetry patterns in this demographic.

Main Methods:

  • A population-based cross-sectional study was conducted in Tehran, Iran, in 2019.
  • Stratified multistage random cluster sampling included individuals over 60 years.
  • Participants underwent comprehensive optometric examinations and slit-lamp biomicroscopy.

Main Results:

  • The prevalence of astigmatism (>-0.50 D) was 83%. Astigmatism >-1.00 D and >-2.00 D affected 52% and 19% respectively.
  • Independent factors associated with astigmatism included male gender, older age, low education, posterior subcapsular cataract, pseudophakia, and myopia.
  • Anisorule astigmatism was present in 57%, with the against-the-rule-oblique type being most common (36%).

Conclusions:

  • Astigmatism is highly prevalent in the elderly population of Tehran.
  • Anisorule astigmatism is common, particularly the against-the-rule-oblique type.
  • Posterior subcapsular cataract, prior cataract surgery, and myopia are significant associated factors.