Hypermetropia (Farsightedness)
Refractive Error Essentials
1. Pathophysiology
In hypermetropia, parallel rays of light from infinity are focused behind the retina when the eye is in a state of rest (accommodation relaxed). This occurs due to:
- Axial: Shortened axial length of the eyeball (most common).
- Curvatural: Decreased curvature of the cornea or lens.
- Index: Decrease in the refractive index of the lens.
2. Clinical Classification
| Category | Definition |
|---|---|
| Simple | Physiological variation in the shape of the eye. |
| Pathological | Due to disease/congenital malformation (e.g., microphthalmos, nanophthalmos). |
| Functional | Due to paralysis of accommodation (e.g., cycloplegia). |
3. NEET PG High-Yield Pearls
- Accommodation: Young hypermetropic patients can overcome their refractive error by active accommodation, leading to symptoms of asthenopia (eyestrain) during near work.
- Complications: Strong association with Accommodative Esotropia (constant effort to accommodate triggers convergence, leading to inward eye turn) and Primary Angle-Closure Glaucoma (due to small eye/shallow anterior chamber).
- Management: Corrected with convex (+) lenses.
- Note: Most infants are physiologically hypermetropic at birth, which gradually decreases as the eye grows.