Primary Eye and Vision Care Flashcards

Flashcards based on lecture notes covering refractive status, anomalies, and myopia.

What does Refractive Status depend on?

Depends on the position of the Retina and Axial Length by indicating the focal length of the eye or the position of its principal focus.

What is Static Refraction?

Accommodation is at rest.

What is Dynamic Refraction?

Accommodation is not at rest.

What is Emmetropia?

Refractive status with accommodation at rest wherein light converges.

What is Circle of Least Confusion?

The smallest spot of the lens can produce.

What are Refractive Anomalies?

Also known as Ametropia/Error of refraction, a variation forms a perfect coincidence of the principal focus of the eye with the retina.

What is Ametropia?

Abnormal refractive eye condition (myopia, hyperopia, or astigmatism) in which images fail to focus on the retina.

What is the average axial length of the eye?

24 mm (axial length).

What are the refractive powers according to Gullstrand's Schematic Eye?

Cornea: 43.05 Diopters, Lens: 19.11 Diopters, Complete Eye: 58.64 Diopters

What is Myopia?

The condition in which, with accommodation relaxed, parallel rays of light converge to form a focus in front of the retina.

What is Hyperopia?

The condition in which, with accommodation relaxed, parallel rays of light converge to form behind the retina.

What is Astigmatism?

A condition where a single focus for all meridians does not exist due to differing refractive powers of the various meridians.

What is Presbyopia?

An age-related condition that affects all people and is the progressive inability to see clearly at near; literally means 'OLD EYE'.

What is Refractive Ametropia?

Incorrect power of the cornea and/or the crystalline lens.

What is Axial Ametropia?

Incorrect axial length of the eyeball.

What is Combined Ametropia?

A condition with both refractive and axial ametropias.

What is Emmetropization?

Reduction in magnitude and variance of refractive error between birth and six years of age.

What is Punctum Remotum (P.R.)?

The farthest point in space at which the eye can see clearly with relaxed accommodation; a point in space which is conjugate to the retina of the static eye.

What is Punctum Proximum (P.P.)?

The nearest point in space at which the eye can see clearly with maximum accommodation; a point in space which is conjugate to the retina with maximum accommodation.

What is the Effective Power of a Lens?

The ability of the lens to correct an eye effectively at a given distance; the reciprocal of the effective focal length, which is measured from the vertex of the cornea to the far point of the eye.

What is Myopia?

The refractive error resulting from light rays from a distant object being brought to a focus in front of the retina.

Who is Aristotle?

Credited with first distinguishing myopia.

Who is Galen?

Coined the term Myopia from “Myein”(to dose) and “Ops”(eye) as he observed that the individual closed his eye (squinted) to see.

What is the Gravitational Theory of Myopia?

The eye, hanging down during close work, pulls on the optic nerve and stretches the eyeball, producing ocular obstructions.

What is the Use-abuse Theory of Myopia?

Stress is caused by repetitive overuse of the accommodation.

What is a symptom of Myopia?

Distant objects appear blur.

How is Myopia corrected?

Corrected by a concave (minus) lens.

What are the physiological characteristics of Myopia?

Axial (Long eyeball), Refractive (steep cornea/crystalline lens), Altered refractive index of crystalline lens (cataract/glucose hydration).

What are the general causes of Myopia?

Axial Length of the eyeball, Poor posture, Lack of Vitamin A, Excessive near work.

What are the actual causes of Myopia?

Eyeball is too long (measured along optic axis) - Axial Myopia, Curvature of cornea is too convex (Curvature Myopia), Lens is too convex— spasm of accommodation (Curvature Myopia), Changed index of one of the media (Index Myopia), Decreased depth of anterior chamber.

What is Correlative Myopia?

The customary type, mildly progressive.

What is Axial Correlative Myopia?

The eye is too long for its refractive power.

What is Refractive Correlative Myopia?

The refractive system is too strong for its axial length.

What is Index Myopia?

The indices of refraction are anomalous.

What is Curvature Myopia?

The radii of the curvature of various surfaces are too short (shorter radius, bigger power).

What is Aqueous Chamber Myopia?

A decrease of depth of the anterior chamber increases the refractive power of the eye.

What is Component Myopia?

Due to an abnormal development of one of the components of the ocular refracting mechanism.

What is Congenital Axial Component Myopia?

Retinal tear, myopic crescents.

What is Developmental Degenerative Component Myopia?

Changes with loss of vision due to rapid persisting progression of myopia after puberty.

What is Disease Acquired Component Myopia?

Caused by goiters, tuberculosis, measles.

What is Very Low Classical Myopia?

-0.25 to -1.00D

What is Low Classical Myopia?

-1.25 to 3.00D

What is Medium Classical Myopia?

-3.25 to -6.00D

What is High Classical Myopia?

-6.26 to -10.00

What is Very High Classical Myopia?

Above -10.00D

What is Correlative Sorsby Myopia?

-0.25 to -4.00D

What is Component Sorsby Myopia?

Above 4.00D

What are synonyms for Pseudomyopia?

School Myopia, False Myopia, Functional Myopia, Refractive Myopia

What is Pseudomyopia?

A condition of tonic spasm of accommodation in which an emmetrope or hyperope frequently appears to be a myope.

What is Nocturnal Myopia?

The type of visual impairment manifested as a decrease of visual acuity in dim light, such as twilight or night-time hours.

What is Pathological or Congenital Myopia?

Degenerative, malignant, or truly progressive; caused by a failure in the development of one of the components usually revealed in extraordinary elongation of the antero-posterior diameter.

What is Transitory Myopia?

May be induced in an eye otherwise fixed in its refractive status by a number of conditions, such as changes in the structure, position, or index of one of the media, disease, drugs, or trauma; myopia, which appears suddenly, lasts for a period of time and then disappears.

What is Traumatic or Concussion Myopia?

Caused by an eye injury such as cataractous changes resulting from a blow to the eye.

What is Photorefractive Keratectomy (PRK)?

A laser surgical procedure effective for correcting low to moderate amount of nearsightedness and astigmatism; a surface ablation technique in which the central portion of the outermost layer of the cornea is removed to reveal the underlying corneal bed for laser surfacing.

What is Radial Keratotomy (RK)?

A procedure used to decrease nearsightedness; during this procedure, radial incisions are made in the cornea of the eye with a highly precise diamond blade set to a particular depth.

What is Laser Assisted In-Situ Keratomileusis (LASIK)?

A laser surgical procedure effective for correcting most ranges of nearsightedness, farsightedness, and astigmatism, except extremely high degrees; combines corneal flap surgery with excimer laser reshaping for dramatic results and rapid visual recovery.

What is Laser Assisted Sub-Epithelial Keratomileusis (LASEK)?

The strategy is to use topically applied medicines to loosen the adhesions of the epithelial cells.

Who is Donders (1864)?

Believed that myopia occurred as a result of prolonged use of the eyes for close work, classified myopia into three categories on the basis or rate of progression: (1) stationary myopia (2) temporarily progressive myopia (3) permanently progressive myopia.

Who is Steiger (1913)?

Proposed that errors of refraction were based on biological variability; believed that the entire range of myopia should be considered as an etiological entity, determined genetically.

Who is Duke-Elder (1949)?

Classified myopia into two categories: (1) simple myopia, occurring as a result of normal biological variability, making its appearance between age 5 and puberty, and (2) degenerative myopia, a relatively rare condition, frequently leading to visual disability and even blindness.

Who is Hisch (1950)?

Used the methodology of inferential statistics to analyze refractive data from the eyes of 562 adults having myopia of 1.00 D or more; His analysis resulted in three distribution curves that he termed the alpha, beta, and gamma groups

Who is Sorsby et al. (1957)?

described both myopia and hyperopia in two broad categories based on the relationships between the components of refraction: (1) refractions between plano and ±4.00 D and (2) refractions greater than ±4.00 D

Who is Goldschmidt (1968)?

Suggested three types of myopia: (1) low myopia (2) late myopia, and (3) high myopia.

Who is Kelly (1981)?

Defining myopia as 'expansion glaucoma' brought about by an increase in intraocular pressure, described three types of myopia: (1) self-inflicted vitreous glaucoma (simple myopia) (2) anterior chamber glaucoma (malignant myopia) (3) inactive glaucoma (congenital myopia).

Who is Curtin (1985)?

Introduced a system of classification based on etiology, degree of myopia, and time of onset: (1) physiologic myopia (simple myopia), (2) intermediate myopia and (3) pathologic myopia.

What is Congenital Myopia?

This classification includes only children whose myopia persists throughout infancy and is present when entering school. The prevalence of this form of myopia, which is usually of sufficient amount to persist throughout life, is about 2%

What is Youth-onset Myopia?

This form of myopia has its onset during the period from about the age of 6 through the teenage years. During this period, the prevalence of myopia (of 0.50 D or more) increases from about 2% at age 6 to about 20% at age 20.

What is Early Adult-onset Myopia?

This form of myopia has its onset during the period from age 20 to about age 40 and brings the prevalence of myopia (of 0.50 D or more) to about 30% during this period of life.

What is Late Adult-onset Myopia?

This form of myopia has its onset beyond the age of 40, with the prevalence gradually increasing in the later years of life. The major cause of this form of myopia is incipient nuclear cataracts.

What is Adult stabilization progression of myopia?

Involving a rapid increase in myopia during early adolescence, followed by stabilization in adulthood

What is Adult continuation progression of myopia?

Involving a rapid increase in myopia during the adolescent years but with a slower rate of progression during the adult years.

What is Adult acceleration progression of myopia?

Also including adult-onset myopia, in which the rate of progression accelerated after adolescence