Journal article
A study of aniseikonia and Knapp's law using a projection space eikonometer
Binocular vision & strabismus quarterly, v 14(3), pp 197-201
01 Jan 1999
PMID: 10553112
Abstract
PURPOSEKnapp's Law, which states that anisometropias due to varying abnormal axial lengths between eyes would not result in inequality in relative retinal image size, provided the correcting spectacle lens was placed at the far point of the eye, has been shown to fall short in clinical practice in several studies using "direct comparison eikonometry". To test these findings using space eikonometry and to further elucidate this Law's clinical applicability, the following study was conducted.METHODSThirteen patients with suspected axial anisometropia of at least 4 Diopters were identified, selected and examined. Cycloplegic refraction, A-scan ultrasonic ocular biometry and Essilor Projection Space Eikonometry were performed.RESULTSTen of the thirteen patients had their anisometropia due primarily to ocular axial length differences. Of these ten, seven (70%) had detectable levels of aniseikonia and 3 (30%) demonstrated no aniseikonia. The other three patients whose aniso-metropia was due to combined axial and refractive components, all had aniseikonia.CONCLUSIONAs a geometric optics theory, Knapp's Law stands on its own merits. However, in clinical practice, reduction in retinal element density in high myopia limits its applicability. Such patients often do have significant aniseikonia which can produce ocular referable complaints and/or interfere with binocular vision.
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Details
- Title
- A study of aniseikonia and Knapp's law using a projection space eikonometer
- Creators
- P KramerS ShippmanG BennettD MeiningerV Lubkin
- Publication Details
- Binocular vision & strabismus quarterly, v 14(3), pp 197-201
- Number of pages
- 5
- Resource Type
- Journal article
- Language
- English
- Academic Unit
- The Eye Institute (TEI); Pennsylvania College of Optometry (PCO)
- Scopus ID
- 2-s2.0-0032869831
- Other Identifier
- 991022016328204721