2d:I[856015,["/_next/static/immutable/chunks/1xzisbplk9czp.js","/_next/static/immutable/chunks/3j2i1faptc_-9.js","/_next/static/immutable/chunks/0fma7nlq6immz.js","/_next/static/immutable/chunks/08tq8rmv423j5.js","/_next/static/immutable/chunks/1chr5wkk3j58k.js","/_next/static/immutable/chunks/37kmmh_zm4dov.js","/_next/static/immutable/chunks/311zvdjfxff-f.js","/_next/static/immutable/chunks/1a_hqhrsle_n_.js"],"default"] 2e:T5baa,

Summary Table

Feature	Detail
Risk Factors	Family history (both parents myopic increases risk significantly), prolonged near work (reading, screens), reduced outdoor time in childhood, East Asian ethnicity, higher educational attainment
Etiology	Excessive axial elongation of the globe (axial myopia) or increased refractive power of the cornea/lens (refractive myopia)
Patient Presentation	Difficulty seeing distant objects clearly; squinting to improve distance vision; may report headaches or eye strain; children may sit close to the TV or hold books very near
Classic Physical Exam	Reduced distance visual acuity on Snellen chart that corrects with a concave (minus) lens; normal near vision; fundoscopy may show temporal crescent (peripapillary atrophy) or tilted disc in pathologic cases
Key Diagnostic Results	Refraction test showing a negative diopter value; axial length measurement showing elongated globe (>24 mm in adults); retinal exam for degenerative changes in high myopia
Management	Corrective concave (minus/diverging) lenses (spectacles or contact lenses); atropine low-dose drops for progression control in children; orthokeratology; refractive surgery (LASIK/PRK) in stable adult myopia
Keywords	"Blurry distance vision," "squinting," "concave lens," "negative diopter," "axial elongation," "myopic crescent," "lattice degeneration"

1. Pathophysiology

Myopia occurs when parallel light rays entering the eye at rest converge anterior to the retina rather than directly on it. This creates a blurred retinal image for distant objects while near vision remains intact, because divergent rays from close objects naturally focus further back.

The most common mechanism is axial myopia, where the anteroposterior length of the globe is disproportionately long relative to the refractive power of the cornea and lens. Each additional millimeter of axial length corresponds to roughly 2.5 to 3.0 diopters of myopia. Less commonly, refractive myopia results from excessive curvature of the cornea or an increase in the refractive index of the lens (as seen in nuclear sclerotic cataracts, where the lens becomes denser and bends light more sharply).

The reason a concave (minus) lens corrects the problem is straightforward: a diverging lens shifts the focal point posteriorly, placing it back onto the retinal plane. This is why the prescription is written with a negative sign (e.g., $-3.00\ D$).

In pathologic (degenerative) myopia, typically defined as myopia exceeding $-6.00\ D$ or axial length beyond 26 mm, the progressive stretching of the sclera leads to thinning of the retina and choroid. This mechanical stretch explains the downstream complications: lattice degeneration, posterior staphyloma, lacquer cracks in Bruch's membrane, and choroidal neovascularization. It also increases lifetime risk of retinal detachment and macular hole, both of which are commonly tested associations.

During childhood, visual input plays a regulatory role in eye growth. Prolonged accommodation for near work is hypothesized to stimulate axial elongation through biochemical signaling cascades involving the retina, choroid, and sclera. Conversely, outdoor light exposure is protective, likely through dopamine release from the retina, which inhibits scleral remodeling and axial growth.

2. Classification and Clinical Manifestation

Classification	Diopter Range	Axial Length	Clinical Features
Low (mild) myopia	$-0.50$ to <$-3.00\ D$	Mildly elongated	Blurred distance vision only; benign course; no fundus changes
Moderate myopia	$-3.00$ to $-6.00\ D$	Moderately elongated	More pronounced distance blur; may begin to show mild peripapillary atrophy
High myopia	Beyond $-6.00\ D$	>26 mm	Temporal myopic crescent, lattice degeneration, vitreous floaters, increased risk of retinal detachment and glaucoma
Pathologic (degenerative) myopia	Usually beyond $-8.00\ D$, progressive	>26.5 mm, progressive elongation	Posterior staphyloma, lacquer cracks, Fuchs spot (pigmented macular scar from CNV), macular hole, rhegmatogenous retinal detachment

Classification by Mechanism

Subtype	Cause	Clinical Clue
Axial myopia	Globe too long	Most common form; familial; progressive in childhood
Refractive (index) myopia	Lens or cornea refractive power too high	Seen in nuclear sclerotic cataract ("second sight" phenomenon), keratoconus, or poorly controlled diabetes (lens swelling)
Pseudomyopia	Ciliary muscle spasm (excess accommodation)	Young patient with sudden-onset myopia after prolonged near work; resolves with cycloplegic refraction

A commonly tested clinical pearl: "second sight" in elderly patients refers to a temporary improvement in near vision caused by nuclear sclerotic cataract increasing the refractive index of the lens, producing an acquired myopic shift. The patient happily discards reading glasses but develops worsening distance vision. This is a classic vignette distractor.

3. Diagnostic Workup

Test	Role	Key Findings
Snellen chart	Best initial test for visual acuity	Reduced distance acuity (e.g., 20/60) that corrects to 20/20 with minus lens
Manifest refraction	Quantifies the refractive error	Negative diopter value
Cycloplegic refraction	Gold standard in children	Rules out pseudomyopia by paralyzing the ciliary muscle with cyclopentolate or atropine; reveals true refractive error
Autorefraction	Objective screening	Automated estimation of refractive error; useful for screening but less precise than manual refraction
A-scan biometry / optical biometry	Axial length measurement	Elongated axial length (>24 mm); used in research and preoperative planning
Dilated fundus exam	Retinal evaluation	Screens for lattice degeneration, posterior staphyloma, retinal tears/holes, myopic macular degeneration
OCT (optical coherence tomography)	Macular assessment in high myopia	Detects myopic traction maculopathy, foveoschisis, macular hole, choroidal neovascularization

The workup begins with a Snellen chart, which establishes the baseline visual acuity deficit. If the patient's distance vision improves with a pinhole occluder, this confirms a refractive error rather than a retinal or optic nerve problem. The pinhole test is a quick bedside maneuver that narrows incoming light to a small pencil beam, eliminating peripheral rays and effectively bypassing the refractive error.

The next step is refraction, either manually with a phoropter or objectively with an autorefractor. In children, cycloplegic refraction is essential because young patients have strong accommodative tone that can mask hyperopia or exaggerate myopia (pseudomyopia). Cycloplegic agents (cyclopentolate 1% or atropine 1%) paralyze the ciliary muscle and reveal the true resting refractive state.

In patients with high or pathologic myopia, a dilated fundus exam is mandatory to evaluate for sight-threatening complications. Lattice degeneration appears as circumferentially oriented, thinned retinal patches with white lines (sclerosed vessels) and is the most common predisposing lesion for rhegmatogenous retinal detachment. If macular pathology is suspected, OCT provides cross-sectional imaging to detect traction, schisis, or neovascular membranes.

4. Management and Treatment

Modality	Indication	Key Details
Spectacles (concave lens)	All ages, all severities	First-line correction; safest option; full-time wear for distance
Contact lenses	Lifestyle preference, anisometropia, keratoconus	Daily disposables preferred for hygiene; risk of microbial keratitis with overnight wear
Low-dose atropine (0.01% to 0.05%)	Myopia progression control in children aged 4 to 12	Nightly instillation; slows axial elongation by 50 to 60%; minimal pupil dilation and accommodation loss at low concentrations
Orthokeratology (Ortho-K)	Myopia control and temporary correction	Rigid gas-permeable lenses worn overnight to reshape the cornea; effect is reversible; moderate evidence for slowing progression
Peripheral defocus lenses (e.g., DIMS, DOT)	Myopia control in children	Spectacle lenses that impose myopic defocus on the peripheral retina; reduces progression by approximately 50 to 60%
LASIK	Stable adult myopia, typically $-1.00$ to $-8.00\ D$	Excimer laser ablation of corneal stroma after creating a flap; requires stable refraction for at least 1 year; contraindicated in thin corneas (<500 microns), keratoconus, pregnancy
PRK (photorefractive keratectomy)	Thin corneas, contact sport athletes	Surface ablation without flap creation; longer recovery but avoids flap complications
Phakic IOL (e.g., ICL)	Very high myopia beyond LASIK range (>$-8.00\ D$)	Implantable collamer lens placed behind the iris; preserves corneal tissue; reversible
Prophylactic laser retinopexy	Symptomatic retinal tears or high-risk lattice degeneration	Laser barricade around the lesion to prevent retinal detachment

Acute considerations: If a highly myopic patient presents with sudden onset of flashes, floaters, and a curtain-like visual field defect, this is a retinal detachment until proven otherwise. The next best step is an emergent dilated fundus exam and urgent ophthalmology referral. Surgical repair (pneumatic retinopexy, scleral buckle, or pars plana vitrectomy) is time-sensitive.

Progression control in children is one of the most testable management concepts. Current evidence supports low-dose atropine (0.01% to 0.05%) as the pharmacologic intervention with the best efficacy-to-side-effect ratio. Higher concentrations (0.5% to 1%) are more effective at slowing elongation but cause photophobia and loss of accommodation, making them poorly tolerated. Treatment is typically continued for at least 2 years, and a rebound effect (accelerated progression) may occur after cessation, particularly with higher doses.

Refractive surgery is reserved for adults with stable refraction for at least 12 months, confirmed by serial refraction measurements. Contraindications to LASIK include keratoconus (or forme fruste keratoconus on topography), residual stromal bed thickness below 250 microns, active ocular surface disease, pregnancy or breastfeeding (hormonal corneal changes), and autoimmune conditions affecting the cornea.

5. Differential Diagnosis and Distractors

Differential Diagnosis	Why It Is Similar	Key Discriminator
Hyperopia (farsightedness)	Also a refractive error causing blurred vision	Hyperopia causes near vision difficulty (in older patients) or accommodative strain; corrected with a convex (plus) lens; focal point falls behind the retina
Astigmatism	Blurred vision at all distances	Distorted/streaked images rather than uniformly blurred; corrected with a cylindrical lens; caused by unequal corneal curvature
Presbyopia	Progressive difficulty with near tasks	Onset after age 40 due to loss of lens elasticity; near vision affected, not distance; corrected with reading glasses (plus lens)
Nuclear sclerotic cataract	Can cause a myopic shift ("second sight")	Elderly patient with progressive lens opacification; glare and reduced contrast sensitivity; slit lamp shows central lens yellowing/browning
Keratoconus	Progressive refractive error with increasing myopia and astigmatism	Irregular astigmatism not fully correctable with spectacles; Munson sign (V-shaped indentation of lower lid on downgaze); corneal topography shows inferior steepening
Pseudomyopia (accommodative spasm)	Sudden onset of blurred distance vision in a young patient	Resolves completely with cycloplegic refraction; history of intense prolonged near work; no true axial elongation
Papilledema / intracranial hypertension	Blurred vision and headaches	Bilateral disc edema, transient visual obscurations, pulsatile tinnitus; visual acuity often preserved early; a neurological rather than refractive cause

The most common trap in a vignette is confusing pseudomyopia with true myopia in a pediatric patient. The key discriminator is that pseudomyopia disappears on cycloplegic refraction. Another frequent distractor is the elderly patient with "improving near vision" who actually has a nuclear sclerotic cataract rather than true refractive improvement.

6. Traps and High-Yield Pearls

The most common way students lose points on myopia-related questions is by failing to recognize the complications of high myopia when the vignette buries the refractive history in the social or past medical history section. A patient presenting with acute flashes and floaters who "wears thick glasses" or has a refraction of $-9.00\ D$ is at elevated risk for retinal detachment, and the next best step is always an urgent dilated fundus exam, not reassurance or a prescription change.

Another frequent pitfall is the "second sight" vignette: an elderly patient who can suddenly read without glasses. Students may incorrectly attribute this to an improvement in refractive status, but the correct answer is a nuclear sclerotic cataract causing an acquired myopic shift. The lens is getting denser and bending light more, temporarily aiding near focus while degrading distance acuity and contrast.

For pediatric questions, remember that the question may test your knowledge of myopia progression control. Low-dose atropine, orthokeratology, and peripheral defocus lenses are evidence-based interventions. Outdoor time (at least 2 hours per day) is the most commonly cited modifiable environmental protective factor. If the vignette describes a child with rapidly progressing myopia and asks for the best intervention to slow progression, atropine 0.01% to 0.05% nightly is the answer, not simply updating the glasses prescription.

Finally, always recall the lens mnemonic: myopia = minus lens = concave = diverges light. The focal point is in front of the retina, so you need to push it back. Hyperopia is the opposite: plus lens, convex, converges light. Confusing the lens type is a basic but surprisingly effective distractor on board-style questions.

1e:["$","$L2d",null,{"article":{"id":"aedbe4a2-7644-4064-9696-3845f6350caf","title":"Miopia","content":"$2e","category":"Oftalmologi","created_at":"2026-05-13T10:14:07.635199+00:00","status":"published","subcategory":null},"questionCount":1,"sections":[{"id":"section-pathophysiology","num":"01","title":"Pathophysiology"},{"id":"section-classification-and-clinical-manifestation","num":"02","title":"Classification and Clinical Manifestation"},{"id":"section-diagnostic-workup","num":"03","title":"Diagnostic Workup"},{"id":"section-management-and-treatment","num":"04","title":"Management and Treatment"},{"id":"section-differential-diagnosis-and-distractors","num":"05","title":"Differential Diagnosis and Distractors"},{"id":"section-traps-and-high-yield-pearls","num":"06","title":"Traps and High-Yield Pearls"}],"hasSummaryTable":true}]