The Castrop formula for calculation of toric intraocular lenses.
Castrop formula
Gaussian optics
Prediction of postoperative refraction
Toric intraocular lenses
Vergence calculation
Journal
Graefe's archive for clinical and experimental ophthalmology = Albrecht von Graefes Archiv fur klinische und experimentelle Ophthalmologie
ISSN: 1435-702X
Titre abrégé: Graefes Arch Clin Exp Ophthalmol
Pays: Germany
ID NLM: 8205248
Informations de publication
Date de publication:
Nov 2021
Nov 2021
Historique:
received:
22
03
2021
accepted:
14
06
2021
revised:
10
06
2021
pubmed:
9
7
2021
medline:
21
10
2021
entrez:
8
7
2021
Statut:
ppublish
Résumé
To explain the concept behind the Castrop toric lens (tIOL) power calculation formula and demonstrate its application in clinical examples. The Castrop vergence formula is based on a pseudophakic model eye with four refractive surfaces and three formula constants. All four surfaces (spectacle correction, corneal front and back surface, and toric lens implant) are expressed as spherocylindrical vergences. With tomographic data for the corneal front and back surface, these data are considered to define the thick lens model for the cornea exactly. With front surface data only, the back surface is defined from the front surface and a fixed ratio of radii and corneal thickness as preset. Spectacle correction can be predicted with an inverse calculation. Three clinical examples are presented to show the applicability of this calculation concept. In the 1st example, we derived the tIOL power for a spherocylindrical target refraction and corneal tomography data of corneal front and back surface. In the 2nd example, we calculated the tIOL power with keratometric data from corneal front surface measurements, and considered a surgically induced astigmatism and a correction for the corneal back surface astigmatism. In the 3rd example, we predicted the spherocylindrical power of spectacle refraction after implantation of any toric lens with an inverse calculation. The Castrop formula for toric lenses is a generalization of the Castrop formula based on spherocylindrical vergences. The application in clinical studies is needed to prove the potential of this new concept.
Identifiants
pubmed: 34236474
doi: 10.1007/s00417-021-05287-w
pii: 10.1007/s00417-021-05287-w
pmc: PMC8523386
doi:
Types de publication
Journal Article
Langues
eng
Sous-ensembles de citation
IM
Pagination
3321-3331Informations de copyright
© 2021. The Author(s).
Références
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