Global OK-Vision

  1. GOV
  2. About GOV
  3. GOV Fitting Guide
  4. High Myopia and Myopic Mulifocal
  5. Hyperopiaand Multifocal
  6. Low Myopia
  7. FAQ

GOV H LENSES


The GOV® H & HP lenses, incorporating the US patented Dual geometric (DG) design (US#:6,652,095 & #7,070,275) to enhance the peripheral flattening and highlight the central steepening, is fabulous for hyperopia & presbyopia correction. The H lens is good up to +6.00 hyperopia. Higher hyperopia could be tried up to +10. The back optical zone radius, or BOZR of a GOV® H lens is designed steeper than the central cornea curvature, by +0.25 to +6.00 D (or hyperopia target power), plus an over target of -0.75 D to ensure sufficient reduction. The optical zone is set aspheric for faster molding. An aspheric alignment curve ensures proper centration of the lens.

GOV HP LENSES


The HP lens is good from plano to +6.00 (or hyperopia target power) with an Add of +0.50~+3.00. Higher hyperopia & presbyopia could be tried up to +10 with and ADD up to +5.00. The back optical zone radius, or BOZR of a GOV® HP lens is designed steeper than the central corneal curvature for the targeted far power as well as the ADD but not any over target. The optical zone is set aspheric for molding faster with precision control for achieving central-near simultaneous vision.

The dual geometric H & HP lenses may exert a positive force on mid-peripheral portion of the cornea to form a flat mid-peripheral ring for highlighting the central steepening, which is much more effective than exerting negative force over the corneal apex for traditional molding. The DG design ensures a wide & precisely formed far zone to be a base for progressive presbyopia molding. The fluorescein pattern for DG lens is similar to a bull’s eye for Myopic Ortho-K except the obvious central pooling. The force exerted by the flat (secondary) plateau zone is the key for precision control of the hyperopia molding, which ensures a wide far zone for protrusion of the reading button by HP design.

An aspheric alignment curve and precisely determined lens size ensure proper centration of the lens, which is critical for HP progressive molding.

Both H and HP lens, the back surfaces of optical zone (BOZR) are aspheric.
Whereas the front surfaces are created differently:
a. The front surface of an H lens is figured to neutralize the ADD effect of the aspheric BOZR for better far vision with the lens.
b. The front surface of an HP lens is figured to enhance the ADD effect of the aspheric BOZR for better near vision with the lens. That is to say, HP lens, with full ADD on peripheral portion of the lens, can be used as multi-focal RGP for far and near.
Unlike reverse geometric lenses for myopia Ortho-K, dual geometric H and HP lenses are less likely to seal off wearing it during awakening hours. It would be safer, when better vision is required, to wear the H or HP lenses for awakening hours such as driving at night. Practitioners still have to monitor the lens movement for the initial 6-8 hours to determine whether daywear schedule is allowable.
The HP lens will reshape the central cornea steeper for a reading button. Just like the central-near multi-focal soft contact lenses, the wearers may experience more or less interference with the far vision especially in nighttime, which should be properly warned for all drivers.

GOV HP2 LENSES


The same principals of HP near centre apply with HP2 , but with a distance center design. This allows practitioners to provide improved distance visual acuity options for presbyopic patients.

GOV H & HP GUIDE