Myopia Lecture Review

Comprehensive vocabulary and definitions from the Myopia lecture covering etiology, classification, risks, and management strategies.

Myopia

A condition where distance images focus in front of the retina because the axial length (posterior chamber) is too long.

Low Myopia

A classification of myopia based on severity defined by a refractive error of worse than $-3.00\,D$.

Moderate Myopia

A classification of myopia based on severity defined by a refractive error between $-3.00$ and $-6.00\,D$.

High Myopia

A classification of myopia based on severity defined by a refractive error of $\geq -6.25\,D$.

Primary Myopia

The most common form of myopia where the refractive (optical) power of the eye does not match the axial length, representing a failure of emmetropization.

Secondary Myopia

Myopia caused by a congenital or early onset ocular or systemic pathological process, trauma, surgery, or medication (e.g., keratoconus, cataracts, diabetes).

Pseudo-myopia

A condition caused by over-accommodation of the eye.

Emmetropization

The developmental process that matches the eye’s optical power to its axial length so that the unaccommodated eye is focused at distance.

Axial Length Refractive Relationship

A $1\,mm$ change in length of the human eye equates to an approximate $3\,D$ change in refractive error.

Hyperopic Defocus

A signaling mechanism where the retina detects the focal point behind the retina, interpreting it as a signal to stimulate eye growth (axial elongation).

Myopic Defocus

A signaling mechanism where the retina detects the focal point in front of the retina, signaling the eye to cease growth.

Staphyloma

A localized weakness in the eye wall that causes uveal tissue to protrude, often due to excessive elongation of the eye.

Myopia-associated glaucoma-like optic neuropathy

An optic neuropathy characterized by loss of neuroretinal rim and enlargement of the optic cup, occurring in highly myopic eyes at a normal IOP.

Retinal Detachment (RD) Risk Factors

Eyes with a spherical equivalent (SE) of $-1.00\,D$ to $-3.00\,D$ have a 4-fold increased risk of RD, while eyes with an SE of less than $-3.00\,D$ have a 10-fold increased risk.

Accommodative Lag Theory

The theory that high lag during near work activities induces abnormal axial growth because the eye is not focusing enough, resulting in hyperopic defocus.

Mechanical Tension Theory

The theory that increased ciliary-choroidal tension in the anterior globe causes accelerated axial growth because equatorial expansion is no longer possible.

Premyopia

A risk classification for children where the refractive error (Rx) at 6 years is $< +0.75\,D$ (plano to $+0.50\,D$).

DIMS (Defocus Incorporated Multiple Segments)

A Hoya spectacle lens featuring a $9\,mm$ diameter central zone surrounded by a zone of $33\,mm$ of $+3.50\,D$ lenslets.

HALT (Highly Aspherical Lenslet Target)

An Essilor spectacle lens featuring a $9\,mm$ diameter central zone surrounded by 11 rings of highly aspherical lenslets with power between $+3.50$ and $+6.00\,D$.

Atropine ($0.01\%$)

A long-lasting nonselective muscarinic antagonist used to slow myopia progression by altering retinal neurotransmission and boosting dopamine release.

Orthokeratology (Ortho-K)

The use of rigid contact lenses to reshape the cornea, creating peripheral myopic defocus to slow myopia progression and provide correction-free vision during waking hours.

20/20/20 Rule

A lifestyle recommendation to take regular breaks by focusing on something $20$ feet away for $20$ seconds every $20$ minutes.

Elbow Rule

A lifestyle modification advisor to avoid very close reading distances during near work.