WEB RGP

Process of Prescribing：

Decide BC with a testing lens

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Check eyesight with a testing lens and decide diopter

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Diameter 9.0mm is recommended

▓ Prescribing Method of RGP lens

Measurement: horizontal diameter of iris, pupil size at low diopter, maximal& minimal radian of the central cornea (keratometer).
Decide lens parameters:
Curvature of central optic zone of lens:
⊙astigmatism<1.50D: lens BC=maximal cornea radian, or 0.05mm wider.
⊙astigmatism>1.50D: lens BC is 0.05mm～0.15mm smaller than the maximal cornea radian.
Diameter of lens optic zone:
As least 2mm wider than the pupil diameter at mean diopter.
Lens diameter:
At least 2mm smaller than the horizontal diameter of iris, 9.0mm～9.6mm normally.
Select lens: lens of moderate oxygen permeability and high wettability is recommended.
Evaluate lens fitting with fluorescein (15 minutes after wear, wait for stable tear situation appears).
⊙Static fitting: lens situated in the center, not affected by eyelids.
⊙Fluorescein pattern: lens center, lens inner periphery, lens width, clearance.
⊙Dynamic fitting: lens centralization, movement (extent, speed, pattern). Select other testing lens if the fit is not ideal (repeat the same evaluation).
Vision evaluation
Decide reflection and vision with a testing lens.

▓ Comparison of RGP Fitting Pattern (with astigmatism)

Good Fit
	A moderate touch area between the lens and cornea. Diameter transverse: 180 degree, Diameter longitudinal: 90 degree Suitable clearance and lens width.

Tight Fit
	Fluorescein centered. Diameter transverse: 180 degree, narrow lens width, low clearance.Diameter longitudinal: Diameter longitudinal: 90 degree, moderate or small lens width and clearance.

Loose Fit
	Lens center touch with cornea, Diameter transverse: 180 degree, Diameter longitudinal: 90 degree Large lens width and clearance.

▓ Comparison of RGP Fitting Pattern(without astigmatism)

Good Fit
	A moderate touch area between the lens and cornea, Light push at inner periphery, Good centralizationGood movement: 1.0mm～1.5mm.Bearing: 0.4mm

Tight Fit
	Fluorescein centered, Strong push at inner periphery, Lens well centered but with poor movement. Try larger base curve to get right fit (0.15mm larger).

Loose Fit
	Lens center touches with cornea. Fluorescein gathered at inner periphery,Wide bearing, Poor centralization, Excessive movement, Try smaller base curve to get right fit (0.15mm smaller)

▓ Characteristics of RGP lens

Can correct moderate to high myopia and astigmatism.
Prevent myopia from progressing in the youth.
Better oxygen permeability, optical property and consistency than traditional soft lens.
High oxygen permeability to lower the possibility of eye disease.
Good vision acuity combined with UV-preventing function.
Easy care, long time wear.
Good for patients with reflection errors or keratoconus, light eye dryness.
Good option for the individuals don't accept soft lens.

▓ Characteristics of RGP lens

Diopter	0.00DS～±20.00DS
BC	7.2mm～8.2mm (others can be customized)
Diameter	8mm～11mm (others can be customized)
DK	58、100
DK/L	480，900
Color	Blue crystal-like, aqua
Reflection Index	1.475
Proportion	1.05(g/cm³)
Contact Angle	14 degree
Regression Angle	小于10度
Young's coefficient	4.490(kg/cm²)
Tensile strength	173kg/cm²