We are offering both PAL, SV & Vista PAL

PAL

Progressive addition lenses (PAL) or multifocal lenses, are prescription lenses used to correct presbyopia wherein earlier instead of progressive lenses we were using bifocals & reading glasses.

They are characterized by a gradient of increasing lens power, added to the wearer’s correction for the other refractive errors. The gradient starts at the wearer’s distance prescription, at the top of the lens and reaches a maximum addition power, or the full reading addition, at the bottom of the lens. The length of the progressive power gradient on the lens surface depends on the refractive index of the lens, with a final addition power between 0.75 and 3.50 dioptres for most wearers. The addition value prescribed depends on the level of presbyopia of the patient and is closely related to age and to a lesser extent, existing prescription.


 
Advantages and Use

Wearers can adjust the additional lens power required for clear vision at different viewing distances by tilting their head to view through the appropriate part of the vertical progression.
The lens location of the correct addition power for viewing distance usually only requires small adjustments to head position, since near vision tasks such as reading are usually low in the visual field and distant objects higher in the visual field.Progressive addition lenses avoid the discontinuities in the visual field created by the majority of bifocal and trifocal lenses and are more cosmetically attractive. Since bifocal and related designs are associated with ‘old age’, proponents have suggested the lack of segments on the lens surface of a progressive lens appears more ‘youthful’ since the single vision lenses associated with younger wearers are free of segments or lines on the surface.The lens power progressively increases between the high-power and low-power region of the lens. This specialized lens surface provides an accurate power distribution for both near and distant vision and reduces the number of optical aberrations.


 
Disadvantages

Initially progressive lenses suffered from the disadvantage of the power progression creating regions of aberration away from the optic axis, yielding poor visual resolution(blur),which varies in relation to the quality of the lens.However, with the latest generation of advanced progressive lenses manufacturers claim acceptance rates of 90%-98%.Clinicians generally agree that in order to avoid adaptation problems it is best to start wearing progressive lenses early in the development of presbyopia (around 40 years of age for most people) while the prescribed addition powers are low. The wearer can then adapt to the increases in a series of steps in addition power over a number of years as their presbyopia progresses.


 

SV

Single vision has the same optical focal point or correction over the entire area of lens.

Refractive Index

In Ireland, the refractive index is generally specified with respect to the yellow He-d Fraunhofer line , commonly abbreviated as nd. Lens materials are classified by their refractive index, as follows:

Normal Index – 1.48 =nd < 1.54

Mid Index – 1.54 =nd < 1.60

High Index -1.60 =nd < 1.67

Ultra high index- 1.74 = nd

This is a general classification. Indexes of nd values that are = 1.60 can be, often for marketing purposes, referred to as high-index. Likewise, Trivex and other borderline normal /mid- index materials , may be referred to as mid –index.


 
Advantages of higher indexes
  • Thinner and lighter lenses.
  • Higher the index, lighter and thinner the lenses become.
  • Improved UV protection over CR-39 and glass lenses.
  • Flatter lenses compared to 1.50 index.


 
Disadvantages of Increased Indices

The only disadvantage is that high index lenses have lower Abbe number meaning, amongst other things, increased chromatic aberration.However with the advancement in lens treatments this aspect can be taken care of.

 

Material Plastic

Index

ABBE

Specific Gravity (gcm3)

UVB/UVA

Reflected Light(%)

Minimum Thickness type/min (mm)

CR-39 Hard Resin1.49591.31100%/90%7.97?/2.0
Trivex
(Average)
1.53441.11100%/100%8.70?/1.0
Mid Index1.54471.21100%/98%8.96 
1.561.56371.23100%/100%9.52 
Polycarbonate1.586301.20100%/100%10.27?/1.5
Crown Glass1.525592.5479%/20%8.59 
photogrey Extra1.523572.41100%/97%8.59 
1.60 Glass1.604402.62100%/61%10.68 
1.70 Glass1.70302.93100%/76%13.47 
1.80 Glass1.80253.37100%/81%16.47 
1.90 Glass1.893314.02100%/76%18.85 

High-Index lenses are the right choice if you want thinner, spectacles that are as attractive and comfortable as possible.

Thinner, lighter high-index lenses are especially recommended if you have a strong prescription for near sightedness , farsightedness or astigmatism.

Most spectacle wearers are nearsighted, which requires corrective lenses that are thin in the center but thicker at the edge of the lens. The stronger the prescription , the thicker the edges.

Most of today’s fashionable frames are made of plastic or metal with rims thinner than the lens itself. Also, popular rimless mountings mean that the edges of the lenses are completely exposed. In either case, the lens edges are highly visible, and thicker edges can be a cause of peripheral aberration and detract from the appearance of your eyewear.

Lenses correct refractive errors by bending light as it passes through the lens. The Amount of light-bending ability (lens power) that’s needed to provide good vision is indicated on the spectacles prescription provided by your optometrist.


 
Availability in Single Vision
Index
ClearColorPower Range
1.74 PlasticClear-18.00D/ +10.50D
1.67 PlasticClear-17.00D/ +17.00D
1.60 PlasticClear-12.00D/ +10.00D
1.59 PolycarbonateClear-12.00D/ +9.00D
1.53 TrivexClear-10.00D/ +7.00D
1.50 CR 39Clear-10.00D/ +11.00D
1.50 BiconcaveClear-10.00D/ +16.00D
1.56 BiconcaveClear-10.00D/ -18.00D
1.50 Lenticular CR 39Clear-16.00D/- 10.00D, +8.00D/ +4.00D
1.50 Omega CR 39Clear+8.00D/ + 14.00D

 

Transitions

ClearColorPower Range
1.74 PlasticGrey/ Brown-18.00D/ +10.00D
1.67 PlasticGrey/ Brown-14.00D/ +8.50D
1.60 PlasticGrey/ Brown-12.00D/ +8.50D
1.59 PolycarbonateGrey/ Brown-10.00D/ +8.00D
1.53 TrivexGrey/ Brown-8.00D/ +8.00D
1.50 CR 39Grey/ Brown-10.00D/ +8.00D

 

Transitions Xtractive

ClearColorPower Range
1.67 PlasticGrey-12.00D/ +7.00D
1.60 PlasticGrey-12.00D/ +8.00D
1.53 TrivexGrey-8.00D/ +8.00D
1.59 PolycarbonateGrey-10.00D/ +8.00D
1.50 CR 39Grey-10.00D/ +8.00D

 

Polarised

ClearColorPower Range
1.67 PlasticGrey/ Brown-13.00D/ +8.00D
1.60 PlasticGrey/ Brown-13.00D/ +8.00D
1.53 TrivexGrey/ Brown-8.00D/ +8.00D
1.59 PolycarbonateGrey/ Brown/ Grey/ Copper-10.00D/ +8.00D
1.50 CR 39Grey/ Brown-8.00D/ +8.00D

 

Drivewear

ClearColorPower Range
1.50 CR 39Brown-10.00D/ +8.00D
1.59 PolycarbonateBrown-10.00D/ +8.00D

 

Sunlite

ClearColorPower Range
1.56 PlasticGrey/ Brown-12.00D/ +10.00D

 

Acclimates

ClearColorPower Range
1.50 CR39Grey/ Brown-10.00D/ +8.00D

 

Mineral

ClearColorPower Range
1.90 GlassWhite-24.00D/ -4.00D
1.80 GlassWhite-24.00D/ -4.00D
1.70 GlassWhite-24.00D/ +8.00D
1.60 GlassWhite-10.00D/ +8.00D
1.60 GlassPGX/ photobrown-10.00D/ +8.00D
1.52 GlassWhite-10.00D/ +8.00D
1.52 GlassPGX/ photobrown– -10.00D/ +8.00D
MAX +6.00 CYL

 

Introducing Vista PAL

Progressive-Lenses-ParametersProgressive Lenses Parameters
  • Wide and smooth progression zone
  • Wide reading zone
  • Distortion free and wide distance vision zone
  • Balanced & minimized distortions in the peripheries.
  • Lens design Technology–Eye Element technology
 
 

Eye path

Eye-pathThe natural eye path changes according to prescription.
Difference between additions can be between 3.5° and 8°

 
 
 

Eye path of different Add

Eye-path-of-different-AddFor a patient with a low add, this could be his eye path if he moves to the reading area of the lens.

So, if he is using a conventional PAL, he may not have problems. But, for a wearer that has a high add, his eye actually converges more, and at the same time, it doesn’t drop as low as when his add power was lower. Presuming the wearer requires a +3.00 reading add and he is being prescribed with a conventional PAL, his eye may only reach say, +2.75d. So, because of this, that is why you find that you may have to increase the addition for some patients.

 
 

 
Minimizing distortions
 
   
Controlling the distortion is the key to the ultimate progressive lens Topographic Map

Wide Choice of Tints

Eye Element Technology

Vista Progressive Lenses has precise hi-tech Eye Element Technology that ensures accurate analysis necessary for sophisticated lenses. By observing exact vision requirements, designers can finally create tailor-made lenses.

 

The technology that enables us to design progressive lenses through an exact simulation of the natural human eye view.
 
 
   
The surface of the lens is scanned by a 3D measuring system, mapping the curvatures of the lens. The optical power is created by 3 parameters: thickness, index and curvatures Light does not always travel straight into the eye

Eye Element technology allows the progressive wearer to view clearly without moving their head….

……regardless of the path, light travels

 
 

The surface data & a highly advanced mathematical algorithm are the basis to Eye-Element Technology which takes into account numerous parameters:

  • Lens index refraction
  • Lens prescription
  • Lens center thickness
  • Distance from the eye to the back vertex of the lens
  • Distance from the lens to the object
  • Object’s angular position in the eye’s field of vision
  • Pantoscopic tilt of the frame
  • Pupil distance
  • Thickness reduction prism, and more.

Designed for any size


 

Summary

 Surround Vision: Vista Progressive ensures improved peripherial vision because it is designed through an exact simulation Of the eye.
 Prism Balance: Vista Progressive guarantees perfect binocular vision enabling patients to clearly perceive an object’s depth and dimension.
 Super Clarity: Vista Progressive is based on the advanced Eye Element Technology, vision clarity is enhanced even more, bringing it to an optimal level in every vision zone.
 Soft Design: A technological breakthrough, Vista’s Eye Element Technology ensures the softest lens design for every vision zone.