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FAQ
Q. How is KeraSoft2 more effective than a GP lens in the management of keratoconus?
A. A combination of controlled thickness, proprietary structure and material characteristics reduce the distortion that is usually associated with the draping of a soft lens over a keratoconic cornea. This presents a superior primary refracting surface for incoming light rays thus providing a positive support for the corrective power.

The advantages of choosing KeraSoft™2 over a GP lens are:
 - Increased comfort and longer wearing times.
- To take advantage of a relatively simple fitting procedure.
- Suitable in cases of monocular keratoconus.
- More effective where there is a residual cylindrical correction.
- Suitable when the cylindrical correction is extremely high.
- When the apex of the cone is severely displaced from the optical
   centre of the eye. 
Q. What is a SAM® lens and how does it compare with DuraWave?
 A.The SAM® designation covers the entire range of approaches by UltraVision to the correction of aberration in an optical system. Traditionally, SAM lenses controlled spherical aberration in the contact lens measured 'in air' (i.e., not on the eye) and this system is currently applied to the range of rigid lenses. The DuraWave™ and UltraWave™ designs go further and cater for the aberration of the in-situ lens which is quite different from that of the basic lens in air. Recent developments in aberration control, influenced by actual wavefront measurements, also give a measure of control over the higher order aberrations. This control makes the DuraWave™/UltraWave™ designs significantly more efficient than their conventional counterparts. 
Q. What advantages stem from the use of KeraSoft2 diagnostic lenses?
A. KeraSoft™2 diagnostic lenses have the same degree of aberration control as the final Rx lenses. This means that during the initial fittings, refractions made over these advanced forms give the best possible indication of the level of vision that may be obtained. Because most practitioners make their decision to proceed with the fitting on the vision achieved at this stage, an encouraging positive result is more likely if KeraSoft™2 diagnostic lenses are used.
Q. What is the effect of a severely displaced cone apex?
A.Wherever the apex of the cone is sited, the actual optical centre of the ocular system remains on, or close to, its geometrical centre. A rigid corneal lens will gravitate towards the apex of the cone so that in severe displacement, the optical centre of the displaced contact lens will not align with the optical centre of the eye, thus rendering the power less effective. The position of a soft lens is governed by the scleral fit so that its optical centre and that of the eye are kept in alignment. The problem with a conventional soft lens is that the off-centre cone induces distortion at the optical centre of the lens and adversely affects its performance. It is the effects of this distortion that KeraSoft™ eliminates or reduces significantly. 
Q. Why does KeraSoft frequently have a final Rx that does not resemble the original Rx?
 A.The front surface of the KeraSoft™ becomes, effectively, the front surface of the eye and therefore, the primary refracting surface for incoming light rays. Because this surface is less irregular than the underlying keratoconic (or otherwise distorted) corneal profile, light is refracted in a more regular way and frequently requires a dioptric power that is different from that required by the natural, distorted profile of the cornea. This often results in a change in both the spherical and cylindrical correcting powers as well as the axis of the cylinder. 
Q. What level of vision can be achieved with KeraSoft2?
A.This will vary with the severity of the cone but time is also a consideration. Initially, the achieved vision may be below par in advanced cases, but with time and regular wear, improvements can be realised. Generally speaking, a vision performance close to a standard of 6/9, or even 6/6, can be expected, especially on low/medium coning. In post-Keratoplasty fittings, it is usual to achieve close to optimum results. 
Q. How are UltraVision torics stabilised?
A.They are stabilised by a combination of dynamic stabilisation and ballast - not prism ballast. In dynamic stabilisation, off-axis front-surface lathing of the top and bottom areas of the lens, removes excess material from the areas of the lens in contact with the eyelids. The reduced thickness discourages the nasal rotation of the lens arising from the lid actions, especially the inward lateral contraction of the lower lid. In addition, the lathing operation leaves certain areas of the lens thicker than that of the surrounding structure. These thicker areas lie away from the lens edges but are symmetrically placed below the geometric centre of the lens to act as a stabilising influence. 
Q. How does conventional prism ballast differ from the UltraVision ballasting system?
A. Conventional prism ballasting is achieved by incorporating an element of base-down prismatic power that leaves the lower part of the lens thicker than its upper section. Being bottom-heavy therefore, it is less inclined to rotate off-axis. However, because prism power is being introduced to gain this stabilising effect, the manufacturer is restricted in the amount of prism that can be introduced, before the prism power at the optical centre of the lens becomes intrusive. Up to 1.25/1.50 prism dioptres is usually the limit before the active central prismatic power reaches this state. This assumes that prismatic power is not part of the prescription. The UltraVision ballasting system is not based on prismatic power although it is often mistakenly referred to as prism ballast. 
Q. How does the DuraWave design affect plus-powered lens centre thickness?
A. Plus-powered lenses made in DuraWave™ from are usually 25% (or more) thinner than their conventional lens counterparts. In conventional plus lens manufacture, the steeper front curve is always turning in towards the back curve. Any attempt to reduce the thickness must include an element of size reduction either through changing the overall size and/or lenticulation of the optic. DuraWave™ lenses can be made thinner because the control of aberration calls for flattening aspheric front curve that is less inclined to turn in towards the back surface. Through this, it is possible to bring the front surface closer to the back surface, thus making the lens thinner but without reducing overall size or front optic diameter. 
Q. What axis marks are used for torics?
A. Two fine lines, closely juxtapositioned to appear as one clear line, are placed in the 6 o'clock (270 degrees) position. Right and left lenses can be easily identified under slit lamp examination as the axis mark on the left lens is shown as a broken line. 
Q. In soft bifocal lenses, why is a centre-near, simultaneous vision design usually superior to centre-distance?
A. When the eyes converge to perform close work (e.g., reading) there is an automatic and significant contraction of the pupil area. This action is known as miosis. A simultaneous vision, centre-distance soft lens does not have the benefit of movement of the lens to bring the correct power area in line with the pupil. This being the case, miosis would bring the pupil down in size so that it is confronted by only the distance power, thus making near work impossible. With the DuraWave™ multifocal lens, which is centre-near, all powers, from distance through to near, are contained within the pupil area, even during miosis, although the proportion of power area devoted to near/intermediate powers may be slightly higher than that related to distance work. 
Q. With DuraWave multifocals, why is identification of the dominant eye important?
A. The centre of the power zone of the DuraWave™ multifocal is devoted to the near and near-intermediate powers. It has been found that the non-dominant eye, although presented with the full range of power from near to infinity, is more comfortable in a binocular situation when there is slightly greater area devoted to near vision focus. The diameter of this zone therefore, is usually made slightly larger in the lens for the non-dominant eye. In this situation, the individual performance of either eye is not affected; the binocular function is enhanced and said to be more relaxed. So, identification of the dominant eye exposes the non-dominant eye so that the above application can be made. 
Q. Why do we insist on independent over-refractions for distance and near with DuraWave multifocal lenses?
A. In this way, we can be sure that we do not misinterpret the practitioner's requirements. The point to note is that, although we refer to the near addition in the prescription, the powers shown are really an indication of the power 'spread' rather than specific powers of distance and near addition. The important element is the near correction.

Take the following example:
Distance power -4.00D near addition +2.00D. So the near correction is -2.00D.

The practitioner finds that near vision is good but distance vision responds to -0.50D. If the distance over-refraction is left in place during the near O/R there will need to be an extra +0.50D of power at near to compensate and the erring practitioner may include this in the instrutions sent to the laboratory.

When the laboratory receives the instruction, it calls for -0.50D for distance and +0.50D for near.

This would result in a distance power of -4.50D and a near correction of -1.50D.

The laboratory would then make the following lens:
Distance power -4.50D near addition +3.00D to give the near correction of -1.50D. But the patient was previously happy with the near correction of -2.00D so the lens is now overplussed.

If the practitioner had stated that near vision was good but -0.50D was needed at distance only, the lab would have made the following:
Distance power -4.50D near addition +2.50D to give near correction of -2.00D.

When this result is compared with the detail of the original lens, a difference in the power 'spread' will be evident although the near correction remains constant.
-4.00D with near addition of +2.00D. Near correction -2.00D. Power spread 2.00D.
-4.50D with near addition of +2.50D. Near correction -2.00D. Power spread 2.50D. 
Q. With DuraWave multifocals, what are the symptoms of:

a) flat fitting,
b) steep fitting?

A. a) Apart from an obvious excess of movement, a flat fitting will have an adverse effect on the vision achieved. Because the lens will tend to lie off-centre, the optical centre of the eye will not align correctly with the appropriate power zone so that both near and distance vision will be under par. In such a situation, the practitioner will be over-refracting with plus power to impove the distance vision and may also find extra plus power necessary to bring up the near vision. Additionally, if the Rx is toric, there may be significant changes to the cylindrical power and its axis. Furthermore, if the Rx is spherical, an unexpected cylindrical correction may appear. In both cases, the effect is due to the aspheric structure of the optical system of the lens which acts in this way if it is significantly off-axis. 
 b) A steep fitting will have insufficient movement with blinking and normal eye movements and vision will be adversely affected. With the lens vaulting the corneal apex, the ensuing tear lens will disturb the vision that will only clear for a brief moment during a blink when the lid presses the lens back against the corneal apex. Observation of keratometer images during blinking clearly confirms this situation.

 
Q. Why is it not possible to have a prism correction with the DuraWave multifocal?
A. Application of prismatic power involves decentration of the optical centre of the lens. The DuraWave™ multifocal uses a flattening aspheric curve on the front surface and any decentration of the system induces unwanted changes in the effective prescription. For this reason, prism power cannot be applied to DuraWave™ Multifocals. 
Q. Under the new system of DuraWave Multifocal labelling, why do we sometimes change the add value when the distance power is changed?
A. The DuraWave™ Multifocal is a centre-near system so that the power at the centre of the lens carries the reading correction. To clarify, the reading correction is the sum of the distance power and the near addition. If we change the distance power by adding minus power, we are effectively moving the distance power further away from the near correction. In that instance, it would require an increase in the spread of power to maintain the existing near correction.

Example:
Distance power -3.00D. Near addition +2.00D. Near Correction -1.00D. The power spread is 2.00D.

If we now add -0.50D to the distance power only and keep the near addition at +2.00D, this is what happens:
New distance power is -3.50D. Near addition +2.00D. Near correction -1.50D.
As we can see, the near correction is now over-minused. The answer is to increase the near addition to +2.50D to give the following:
New distance power is -3.50D. Near addition is +2.50D. Near correction -1.00D.

So it may now be clear that the near addition is really a means of controlling the power spread so that the effective distance, intermediate and near corrections can be realised. 
Q. Can the DuraWave Multifocal be used in a monovision system?
A. Yes. In fact it is ideal because of the following. In conventional monovision systems, the contact lens of the dominant eye carries the distance power whilst the non-dominant carries the near power. Although there may be a measure of binocular overlap in the far middle distance, essentially, both eyes are monocular in their respective roles. This frequently renders the system unacceptable to the patient especially when the near addition is high. With the DuraWave™ Multifocal carried by the non-dominant eye (and full distance vision power in the dominant) there is binocularity in the distance vision and possibly in the middle distance area. The use of an aberration controlled lens in the dominant eye (e.g., DuraWave™ Aspheric/UltraWave™) increases the likelihood of an increased range of binocularity in such a system. 
Q. What do air bubbles signify and what is required to solve the problem?
A. Air bubbles in the optic zone are usually indicative of a steep fitting. In some cases, especially with keratoconic fittings, a bubble may appear centrally or just off-centre immediately on insertion. This will frequently disperse after a minute or two. If it persists, the fitting should be flattened in increments of 0.20mm until optimum fitting criteria are realised.

Peripheral bubbles may indicate the presence of a pinguecula that causes the lens edge to lift at that point. In such a case, it is usual for a blink to be followed by a rippling of the lens edge that can induce a bubbling or frothing that follows the ripple effect and is a source of irritation of the wearer.

A reduction in lens size may be possible so that the lens edge does not reach out as far as the raised pinguecula. This may not be possible or desirable, especially if the Rx carries a high cylindrical element that requires a lens of large size to aid stability. Alternatively, UltraVision lenses can be made with a tunnel that is cut into the back surface to coincide with the position of the pinguecula. This allows the lens to bridge the raised surface of the pinguecula and retain positive scleral seating of the lens periphery. The tunnel is only effective if applied to the UltraVision toric design where the stabilisation system would keep the tunnel in the correct position.

However, if the prescription is not toric, standard spherical power can be applied to a spherical lens that is stabilised as if it were of toric prescription, so permitting the application of the pinguecula tunnel.
Q. How do I:

a) tighten, or
b) loosen
the fit of a soft lens?

A. a) To tighten the fit one can increase the overall size of the lens or steepen the BOZR. Occasionally, it may be necessary to do both. Generally, it is best to keep the diameter as large as possible, especially when the cylindrical correction is high. When deemed suitable by the practitioner, the overall size should be increased by 0.50mm. Where this is not acceptable, e.g., when palpebral apertures are narrow and lens insertion would be too difficult for the patient to manage, the BOZR can be steepened by 0.20mm until the optimum fitting is realised. 
 b) To flatten the fit one can decrease the overall size of the lens or flatten the BOZR. Given that the largest lens is usually the better option, the BOZR can be flattened in increments of 0.20mm until the optimum fitting is realised. 
Q. Soft lenses made in conventional materials are drying out.
A. When conventional hydrophilic material lenses are on-eye, their temperature rises closer to body heat and they are exposed to the atmosphere. These two factors contribute to a partial loss of moisture from the lenses that results in changes to the lens parameters that affect the fitting. A third factor is present if the patient has a tear volume deficiency that encourages the 'dry eye' to take moisture from the lens. With this relative dryness, the lens surfaces no longer wet so readily and become prone to attract surface deposition that leads to discomfort and a reduction in vision quality.

The answer is to use a lower water-content material such as standard 38% polyhema where water loss is minimal or those materials with a facility for water retention that reduces the risk of the problems mentioned. These are non-ionic (protein resistant) hydroxy-based materials with glycerol methacrylate (GMA). They are used for UltraWave™, DuraWave™ and KeraSoft™2 lenses whose aspheric designs benefit from the stability of on-eye parameters provided by these materials.
Q. Large cyl over-refraction Spherical lens?
A. This applies principally to lenses with aspheric options where it is usually an indication that the fitting is flat.

Off-centre aspheric systems induce cylindrical corrections that do not relate to the true prescription. 
Q. Fit of UltraVision torics is good, but the lens is rotating by xx degrees.
A.  There are three options open and it is sometimes necessary to take full advantage of all three. They are:  
 a) axis compensation
  This involves a change in the cylinder axis equal to the degree of rotation but in the opposite direction. UltraVision will usually recommend such an action if the rotation is no greater than 5 or 6 degrees.
 b)increased ballast 
  The initial level of ballast is governed by the lens Rx. The maximum figure for this loading is 1.20, so that the presence of this figure indicates that the maximum level of ballasting is already being deployed.

Where the figure is lower than this, additional ballast can be applied by requesting 'xx toric' status.
 c) increase in hydrostatic effect (fit change) 
  This basically involves increasing the area of the lens in contact with the scleral conjunctiva and requires an increase in the overall size of the lens. If the size is increased, assuming the original fitting was good, the BOZR of the lens must be flattened to ensure that the fitting characteristics of the lens remain unchanged. UltraVision recommends a ratio of 0.20mm of BOZR change for every 0.50mm change in overall size, e.g., 8.40/14.00 has the same fitting characteristics as 8.60/14.50.

In the case of KeraSoft™, insert Series A/14.00 and Series B/14.50 to the above example. 
Q. Why does the DuraWave Multifocal have its aspheric curve on the front surface and not on the back surface?
A. If the aspheric progression were to be placed on the back surface of the lens, the degree of power change would be limited by the effect the attendant curvature change would have on the integrity of the fitting. This restriction would be exacerbated by the fact that the asphere would be immersed in the tear layer so that the contrast between the refracting surfaces of the back of the lens and the cornea would be minmal. This being the case a far greater degree of asphericity would be required with an increased risk of an adverse effect on the integrity of the fit as a consequence. With the asphere placed on the front surface, the proposition is quite different. The aspheric refracting front surface lies in air so that there is a significant contrast in refractive indices of air and the lens material. Consequently, the degree of asphericity required is of a much lower order. Additionally, because it is on the front surface of the lens, it has no direct bearing on the fitting characteristics. Both factors combine to improve the potential for a greater range of near addition effects. 
Q. How do I choose between SAM® Multifocal Centre-distance and DuraWave Multifocal Centre-near?
A. The short answer is to think of SAM® designs for the rigid lens fittings and DuraWave™ Multifocals for soft lens fittings.

Practitioners generally consider the SAM® centre-distance design for the rigid lens fittings where the natural movement of the lens provides translation of the respective power zones. Also, its range of near additions is currently wider than that offered by the DuraWave™ Multifocal. For example, a +4.00D addition, which is available in the SAM® design, is not yet available in the DuraWave™ Multifocal.

The DuraWave™ Multifocal has a true multifocal function that is effective at all angles of gaze. Its centre-near power structure is sympathetic to the automatic pupil contraction (miosis) that occurs with convergence for near work. It does not rely on physical translation to bring the effective power zones into play as all zones are contained simultaneously within the pupil area so that the minimal movement associated with soft lens fits is not detrimental to vision at any distance or at any angle of gaze.
Q. The Patient is aware of the edge of the optic zone crossing the pupil line.
A. It is always difficult to establish if the problem comes from intrusion of the edge of the front optic or that of the minor axis of a back toric.

Extension of the front optic diameter can be affected by increasing the front optic diameter to its maximum. This is called for by requesting a F.O.D factor of 1.20. The minor axis diameter of the back optic can be maximised by requesting a 'remove' (referred to on some laboratory work schedules as 'segment depth') of 0.05. This dimension normally has a value dictated by the lens power but, given the 0.05 instruction, the laboratory can over-ride the programme and implement the change. 
Q. How can Wave optics (DuraWave/UltraWave) in spherical form, help with near and/or astigmatic corrections?
A. The control of positive spherical aberration in a contact lens/eye system by the use of a flattening aspheric anterior surface will increase the range of acceptable visual blur to create a greater depth of focus. This extends over a 360 degree area and will offer an effective additional power pool of around 1.00/1.25D.

This power can be used or not, depending on the brain's selective needs.

For example, it can be used in the weaker meridian of a toric eye but ignored in the stronger meridan: or it can be used, as required, for near vision tasks.

It's versatility will be governed by the placement of the back vertex power in relation to the actual Rx. This may be decided by the everyday requirements of the patient in that, for instance, patients whose activities incline towards near vision tasks may benefit from the BVP being set to carry an extra 0.50D of plus power that will not detract appreciably from the normal distance vision performance.
Q. Which Bandage lenses do you supply?
A. 
UltraVision provides a large range of hydrophilic bandage lenses for therapeutic use. Here are some examples of their application:

 
  • Pain relief, e.g., in bullous keratopathy where the soft lens prevents painful contact between the eyelid and exposed nerve endings of the abnormal cornea.
  • Post-keratoplasty, to prevent damage to traumatised corneal tissue and sutures by the eyelid and promote healing.
  • Stabilising of epithelium, some superficial corneal conditions result in poor adhesion of the epithelial cells to their base membrane. Extended-wear hydrophilic lenses can protect the cornea from lid friction and assist in the return to stability of the cornea.
  • Mechanical protection, in conditions such as Trichiasis and Trachoma, where the presence of the soft lens prevents abrasion of the cornea by the in-growing eyelashes or scar tissue. A soft lens can also be useful in protecting the sensitive cornea during examinations such as gonioscopy.
  • Drug delivery, a bandage lens soaked in an appropriate drug will permit a more controlled release of the drug than is normally possible with more conventional means.
  • Aqueous leaks, loss of aqueous fluid because of anterior chamber perforation can be contained by a large (usually 20mm+) soft lens. These lenses, and all lenses in excess of 16mm diameter, have an aspheric back curve.
 General

UltraVision bandage lenses can be made 'to Rx' or in standard parameters in plano powers. Full details appear in the product section of this website.
Q. Spectacle lens bifocals have been used to correct accommodative strabismus. Can DuraWave Multifocal lenses be used for this purpose?
A. They can be used for this purpose to good effect.  Accommodative strabismus is an off-axis turning of the eye brought on by the application of accommodative effort. In such cases, an eye that is normally straight in gaze when viewing distant objects, will turn inwards excessively when the eye is called upon to work at near.

The use of a bifocal or multifocal lens on the affected eye will reduce or eliminate the need for accommodative effort at near and help to maintain a more normal alignment. The DuraWave™ Multifocal is particularly suited for this task because the near and intermediate powers are not intrusive and are not apparent when their remedial effect is not required.  This is particularly important when the patient is a child.
Q. Which lenses are recommended in cases of high myopia?
A. In most cases, soft lenses provide a less problematical solution than that offered by rigid lenses. With the latter, junction thicknesses can create centration problems that do not arise with the soft lens whose larger diameters keep the thicker areas away from the influence of the lid margins.

The use of UltraVision DuraWave™ designs brings benefits of improved vision performance provided by the advanced aberration control system. At the same time, powers in the region of -9.00D and above (this varies with the BOZR value) attract a change in the nature of the controlling front asphere that enables the junction thickness to be reduced without any further reduction in the front optic diameter. 
Q. Which lenses are recommendeed in high hyperopia/aphakic cases/paediatric aphakic cases?
A. All plus powered lenses benefit from the enhanced vision provided by UltraVision DuraWave™ soft lens designs.

High plus powers have the added benefit of significant reductions in centre thickness that are effected without recourse to punitive lenticulation that reduces the front optic diameter.

Control of the on-eye aberration involves the use of a flattening asphere whose aspheric value varies with power and BOZR. As explained in earlier sections a conventional power curve for a plus-powered lens will always turn in towards the back curve, thus restricting the control of centre thickness.  The flattening factor used in DuraWave™ plus lens designs, allows the front curve to keep away from the back curve so that the two can be brought closer together to reduce thickness without compromising the front optic diameter.

This feature can bring reductions in thickness of around 25% when compared with a conventional lens equivalent.

When consdered in the context of paediatric aphakics, where powers can often be in excess of +30.00D, the reductions in thickness are significant, bringing important increases in comfort and oxygen transmissibility as a consequence.

Aphakic lenses are usually made up in high water content (77%) to maximise oxygen transmission.
Q. Which soft lens is recommended for high cylindrical corrections?
A. The UltraVision DuraWave™ Rx Toric. It can cater for cylindrical corrections up to 11.00DC and spherical power elements as required. Cylinder power axes are available in 1 degree steps from 0 to 179.

It has a back surface toric and its axis is stabilised by a combination of dynamic stabilisation and ballast.

The lenses are fitted empirically with lenses made up by the laboratory from ocular parameters supplied by the practitioner and based on computerised lens form patterns derived from years of study of individual cases. The resulting lenses will be viewed as trial lenses by the practitioners who will examine the lenses on-eye in the light of their own experience as contact lens practitioners. Records show that over 80% of these 'trial' lenses will meet their requirements and the expectations of their patients without any further modification.

The lenses are available in materials with a range of water content although many practitioners opt for water-retentive GMA-type materials whose characteristics ensure on-eye stability of lens parameters and sustained oxygen transmissibility. DuraWave™ designs offer advanced aberration-controlled optics based on wavefront conditions, a measure of near addition effect that will help the early presbyope and provide an optical system whose function will not be compromised by minor off-axis rotation: a more forgiving regime that will reduce the need for modification and give savings in chair-side time. 
Q. Residual cylindrical corrections
A. Residual cylinders are not a problem with a soft lens fitting. The absence of any significant 'tear lens' element ensures that, as with spectacle lens corrections, a soft lens prescription is based on the 'net' astigmatism as revealed by the initial refraction. 
Q. Which lens is best for the early presbyope?
A. Use the UltraWave™ for up to 1D of near addition effect. If there is no distance Rx use plano or +0.25/+0.50D in non-dominant eye or, if there is a distance Rx use that distance power for the UltraWave™ lens. The depth of focus should give the near effect required. Should near vision still need a slight boost, add +0.25/0.50D to the power of the lens in the non-dominant eye. 
Q. Which soft lens is recommended for the mature presbyope?
A. The DuraWave™ Multifocal. It is a centre-near, simultaneous-vision design with near additions up to +3.50D. It will cater for distance powers up to +/- 15.00D and can include cylindrical corrections up to a maximum of 6.00DC at any axis in increments of 1 degree. Prismatic corrections are not possible in multifocal forms.

Fitting follows empirical procedures with lenses being made up to a proved and tested formula applied to the precise ocular parameters provided by the practitioner. The first pair of lenses supplied should be viewed as trial lenses (so therefore, a warranty should be purchased upon ordering the lens) by the practitioner who then makes a professional judgement on the fitting and the suitability of the power structure for the patient's purposes. Any deficiency in distance, intermediate or near vision can be quantified by an over-refraction whose incorporation in new lenses will subsequently be implemented by the laboratory.

The majority of DuraWave™ lenses are now made up in water-retentive materials whose characteristics ensure that on-eye parameters and aspheric profiles remain constant.
Q. What about dry eye problems?
A. Dry eye problems for soft contact lens wearers arise chiefly from a tear deficiency that may be due to lack of volume or a meibomian gland disfunction that deprives the tear of a sufficiency of the oily outer layer that limits water loss through evaporation.

Occasionally both conditions may apply.

Where the conditions are marginal, difficulties may only be experienced in dry atmospheres, especially those created by air-conditioning systems.

It has been the practice to use soft lenses of low water-content or thicker high water-content lenses where water loss is minimalised but, in recent times, the use of silicone hydrogels and water-retentive materials has proved to be more benefical.

UltraVision is currently testing various silicone hydrogel materials for its soft prescription lens range, and water-retentive materials are already deployed throughout this important area of its production.

These materials resist water loss through evaporation thus supporting lens wear under adverse conditions.  At the same time, maintenance of the lens water-content sustains oxygen throughput and ensures that on-eye lens parameters are maintained.

This last is particularly important for aspheric lens designs where even minor variations can adversely affect optical performance.
Q. Which soft lens is recommended for Keratoconus?
A. KeraSoft®3.  Please see Product section for further details. 
Q. What level of prismatic correction can be applied to UltraVision soft torics?
A. Up to 2 prism dioptres at all axes in increments of 1 degree.

The prismatic power is applied only within the optic zone of the lens so that the peripheral area of the lens remains basically spherical. Stabilisation of the axis comes from the combination of front surface ballast and dynamic stabilisation systems that is applied to UltraVision torics.

This means that edges remain relatively thin and without the bottom lid awareness that accompanies lenses made using conventional prism ballasted systems.

If prismatic power is required for a non-toric prescription, the sphere can be made up in stabilised toric form but, of course, without cylindrical power.
Q. Which types of tinted and prosthetic soft lenses are available from UltraVision?
A. a) Tinted Lenses

Made by application of a dye by way of a jig that determines the diameter of the tinted area. The tint can be applied across the whole designated area or leave a selected clear central zone so that the colour is not intrusive.

The colour range is wide (see product leaflet) with the shade of the colour being determined by the lenght of time the lens is exposed to the dye.

Tinted lenses have a number of applications including the following:

i.  Enhancement of iris colour, especially as a balancing
    mechanism where the two irises have a slight but noticeable
    difference in hue. Where required, the pupil area can be left
    clear.

ii.  As a means of reducing the effect of colour blindness. In
    such cases the colour extends across the pupil area. There
    is also some evidence of benefit in cases of dyslexia by the
    application of particular colour tints in the pupil area.
 b)Prosthetic Lenses

Made by applying a jig-dispensed dye. The lens can incorporate an iris pattern for a more realistic appearance, together with hand-drawn limbal rings and/or pupil perimeter coronas.

Prosthetic lenses are used to disguise the effects of injury or disease or to alleviate the problems affecting sight arising from various conditions or injuries. Here are some examples:

i.  Unsightly white appearance in the pupil area resulting from
    cataract, especially congenital or leucoma. A soft lens with
    a black opaque pupil is used. The 'iris' area can be left clear
    if required.

ii.  Congenital Iris Coloboma. Here, a soft lens with an opaque
    iris and clear pupil will be aesthetically more aceptable and
    mechanically more efficient by providing a more regular
    pupil shape. The lens can be powered if required. It should
    be noted that toric prescriptions cannot be accommodated
    and over-spectacles should be prescribed to cater for the
    cylindrical correction.

iii. Aniridia. Similar to the above but an opaque iris is not
    always necessary if photophobia is not an issue.

iv. Photophobia, especially that associated with albinism.
    Similar solution to that suggested for aniridia. The lack of
    iris pigment in albinism may sometimes require good 'iris'
    opacity in the lens and the patient may benefit further from
    a tinted pupil area with a reduced diameter. Severe
    photophobia may call for a fully opaque pupil with a small
    (1-2mm) central clear area.
Q. Does the KeraSoft3 Toric lens have an orientation mark?
A. Yes. The KeraSoft®3 trial lenses are all prism ballasted and have a vertical orientation mark at the base of the lens.  The position of this trial lens mark is important when you order a toric lens, as it affects the axis of the final lens.

For example, if you find the mark on the trial lens is 20° nasal on slit lamp and the over refraction gives a cyl at 180°, you would have to order the axis at 160° to ensure the cyl sits at the correct axis. Alternatively, you could give us the over refraction as you find it and let us know the orientation mark position and we will calculate it for you. Many slit lamps have a facility for rotating the beam to align with orientation marks, for more accurate assessment.

When ordering, please let us know whether you want us to compensate for rotation or whether you have done this yourself.

When ordering, please give us the following information:
BCOR and power of trial lens used
Orientation mark position (or indicate that you have taken rotation into account)
Over refraction
HVID
BVD



Further information can be found at the KeraSoft®3 product website here.