Primary Eye and Vision Care Dr. Andrea Isabelle V. Sumaya Refractive Status Quiz

Refractive Status

• Refractive status is defined by the relationship between the posterior principal focus, the eye's refractive mechanism, and the retina with accommodation relaxed.
• The refractive mechanism includes the cornea, aqueous humor, crystalline lens, and vitreous humor.
• The retina is the image plane in the eye that receives all necessary information.

Factors That Influence Refractive Status

• Length of the eyeball
• Power of the cornea
• Power of the lens
• Depth of anterior chamber
• Radius of curvature

Classification of Refractive Status

• Emmetropia: Posterior principal point is focused on the retina with accommodation relaxed.
• Amteropia: Variation from emmetropia, with the posterior principal point focused in front of or behind the retina with accommodation relaxed.
• Myopia: Refractive condition where parallel rays of light converge to focus in front of the retina with accommodation relaxed.
• Hyperopia
• Astigmatism

Myopia

• Historical background: mentioned by Aristotle, defined by Johannes Kepler in 1611, and classified by Donders in 1866.
• Causes:
  • Long axial length
  • Too strong refractive system for its axial length
  • High refractive power
  • Short/steep corneal curvature
  • Index of refraction: too high (aqueous, cornea, lens nucleus/core) or too low (lens cortex, vitreous)
  • Increased depth of anterior chamber
  • Cataract formation
  • Diabetes mellitus
  • Hereditary
  • Prolonged near activities (enforced accommodation)

Classification of Myopia

• Amount:
  • Low: 0.25-3.00 d
  • Medium: 3.00-6.00 d
  • High: 6.00 d and above
• Origin:
  • Correlative/simple: simple, benign, stationary
  • Component/degenerative: pathological, progressive, malignant, degenerative
• Onset and Course:
  • Stationary: reaches a stage with no change
  • Temporarily progressive: temporary progress but also stops
  • Permanently progressive: associated with 6.00 d and above
• Age-related Prevalence and Age of Onset:
  • Congenital: error present at birth
  • Youth-onset: before the age of 20
  • Early adult-onset: 20-40 years old
  • Late adult-onset: 40 years old and above

Signs and Symptoms of Myopia

• Symptoms:
  • Blurring of vision at far distances
  • Asthenopia
• Signs:
  • Dilated pupil
  • Squinting
  • Staring expression
  • Exophthalmos (high amount of myopia)
  • Myopic crescent

Management of Myopia

• Minus/concave lenses
• Spectacle correction
• Contact lenses
• Orthokeratology
• Visual training
• Surgical approach (LASIK)

Management Approach

• By age:
  • /= 1.50 d: CX will be based on visual demand at school
  • 5-10 years old: CX will be based on the improvement of the visual acuity
  • >10 years old: CX will be based on the improvement of the visual acuity
• By muscular anomaly:
  • • EXO: full CX
  • • ESO: partial CX that will not severely affect the VA

Pseudomyopia

• A condition of tonic spasm of accommodation that frequently makes an emmetrope or hyperope appear to be myopic
• Revealed by inconsistencies between objective and subjective testing procedures, anomalies of convergence, spasmodic results in subjective routine, and history of the patient
• Other names: school myopia, college myopia, false myopia, refractive myopia, functional myopia, night myopia/nocturnal myopia

Night Myopia/Nocturnal Myopia

• The amount of myopia that usually appears in dim illumination
• Uncorrected myopia is less noticeable during the day; ambient luminance reduces the size of the eye's pupil
• Symptoms:
  • Blurred vision only in low luminance
  • Feeling of discomfort while maintaining fixation in low illumination level
  • Difficulty in night driving
  • Halos around light
• Causes:
  • Spherical aberration
  • Chromatic aberration
  • Keratoconus (irregular corneal curvature)

Test your knowledge on refractive status, including its definition, classifications, causes, signs, symptoms, types, and management. Learn about the relationship between posterior principal focus, refractive mechanisms, and the retina in the same eye with relaxed accommodation.