Overview
This lecture covers the treatment of hypermetropia, including lens correction options, clinical principles for prescriptions, and pediatric guidelines.
Basics of Hypermetropia & Treatment
- In hypermetropia (farsightedness), light focuses behind the retina due to a small eyeball or flat cornea.
- The main treatment is prescribing convex (converging) lenses to shift the image onto the retina.
- Convex lenses can be provided as spectacles or contact lenses.
Identifying Convex Lenses
- Convex lenses are thicker at the center and thinner at the periphery.
- Looking through a convex lens magnifies objects.
- Moving a convex lens causes the image to shift in the opposite direction.
- Concave lenses have the opposite properties.
Principles of Prescribing for Hypermetropia
- Always perform a cycloplegic examination to paralyze accommodation and reveal the total hypermetropic error.
- Cycloplegic agents include cyclopentolate and atropine.
- Do not prescribe correction for hypermetropia less than 1 diopter unless the patient is symptomatic.
Guidelines for Children
- Children under 4 years can accept full cycloplegic correction.
- Children over 4 years (school-going) should be under-corrected by one-third and gradually increased over time.
- Always under-correct school-age children initially, then increase correction as tolerated.
Special Cases: Squint & Amblyopia
- In exophoria (outward squint) with hypermetropia, under-correct by 1-2 diopters to avoid aggravating the squint.
- In accommodative convergent squint (esotropia), provide full hypermetropic correction.
- Full correction is also required if amblyopia (lazy eye) is present.
- Follow up every six months to adjust prescription as the child’s eye grows.
American Academy of Ophthalmology Pediatric Guidelines
- For isometropia (same refractive error in both eyes):
- Prescribe at >+6D (0-1 year), >+5D (1-2 years), >+4.5D (2-3 years) without squint.
- If esotropia present, treat at >+2D (0-2 years), >+1.5D (2-3 years).
- For anisometropia (difference between eyes): use lower cutoffs (2.5D, 2D, 1.5D).
- Intervene earlier if strabismus or risk of amblyopia is present.
Key Terms & Definitions
- Hypermetropia — farsightedness; light focused behind the retina.
- Convex lens — converging lens, thicker in the center, used for hypermetropia correction.
- Cycloplegic examination — process using drugs to paralyze accommodation for accurate refractive error measurement.
- Exophoria — outward deviation of the eyes.
- Esotropia — inward deviation of the eyes (convergent squint).
- Amblyopia — "lazy eye," reduced vision in one eye.
Action Items / Next Steps
- Review previous lectures on latent, facultative, and manifest hypermetropia.
- Memorize pediatric prescription cutoffs and correction principles.
- Schedule 6-month follow-up for pediatric hypermetropic patients.