. 2006 Dec;104:437–452.

APPENDIX 2 TABLE B.

APPLICATION OF THE POWER MATRIX TO A MODEL EYE: DEFINITION OF CARDINAL POINTS AND THEIR DERIVATIVES

CARDINAL POINT OR ITS DERIVATIVE	FORMULA FROM THE POWER MATRIX DEFINED BY OPTICAL SCIENCE	ANATOMICAL OR EYE-RELATED DEFINITIONS
Lens T = Lens system total length	$T = \sum_{l = 1}^{5} t_{l}$ , distance between corneal and last refraction surface	Anterior Segment Length (ASL)
	J = L − T, where L = Eye Axial Length	Posterior Segment Length (PSL)
First (Object) Focal Point	$F_{1} = 1000 \cdot n \cdot \frac{a}{b}$ where n = object space refractive index = 1 (air)	Eye Focal Length
Second (Image) Focal Point	$F_{2} = 1000 \cdot n^{'} \cdot \frac{- d}{b}$ where n′ = image space refractive index = 1.336 (aqueous)
First (Object) Principal Point	$H_{1} = 1000 \cdot n \cdot \frac{a - 1}{b}$ where n = object space refractive index = 1 (air)	First (Object) Principal Point
Second (Image) Principal Point	$H_{2} = 1000 \cdot n^{'} \cdot \frac{1 - a}{b}$ where n′ = image space refractive index = 1.336 (aqueous)	Second (Image) Principal Point measured from cornea: H′₂ = T − H₂
First (Object) Nodal Point	$N_{1} = 1000 \cdot \frac{a \cdot n - n^{'}}{b}$ where n = object space refractive index = 1 (air) n′ = image space refractive index = 1.336 (aqueous)	First (Object) Nodal Point
Second (Image) Nodal Point	$N_{2} = 1000 \cdot \frac{n - d \cdot n^{'}}{b}$ where n = object space refractive index = 1 (air) n′ = image space refractive index = 1.336 (aqueous)	Second (Image) Nodal Point measured from cornea: N′₂ = T − N₂
First (Object) Focal Length = distance between First Principal Point and First Focal Point	$E F L_{1} = 1000 \cdot n \cdot \frac{- 1}{b}$	Eye Focal Length
Second (Image) Focal Length = distance between Second Principal Point and Second Focal Point	$E F L_{2} = 1000 \cdot n^{'} \cdot \frac{1}{b}$
Image Distance = distance between Second Principal Point and Image Plan	I = L − T + H = L − H′₂
Image vergence in diopters	$V^{'} = 1000 \cdot n^{'} \cdot \frac{1}{I}$ , where I = image distance
Magnification = ratio of image size to object size	$M = 1 + \frac{b}{V^{'}}$	Magnification
Object vergence in diopters	V = −b −V′	Object Vergence