SOClear Keratoconus

SOClear corneo-scleral lenses are designed to distribute pressure evenly over the corneal and scleral surfaces, delivering a unique combination of visual performance consistent with RGP lenses along with comfort and stability equal to hydrogel materials.

SOClear is a corneo-scleral contact lens with an average diameter similar to that of a soft contact lens, providing excellent initial comfort and rapid adaptation times. The lens shows smaller movement on blink than an RGP lens and sits comfortably under the patient's lid, reducing lid interaction and increasing lens comfort.

It has long been known that the levels of vision achieved with RGP lenses are often considerably greater than those obtained with soft lenses. SOClear provides visual performance consistent with these rigid lens optics. A stable lens fit combined with the tear lens optics enables correction of significant regular and irregular astigmatism without the need for complex toric designs.

SOClear is manufactured in Boston XO®, which delivers good stability and excellent oxygen transmission. Its highly wettable surface ensures wearer comfort is maintained for long periods and reduces the dryness sensations often associated with soft lens wear. SOClear lenses are also plasma treated to further enhance wettability and all-day comfort.

  • Handling
  • Fitting Guide Video Presentation
  • SOClear Fitting Assistant

Fitting SOClear for Keratoconus

Aim and Ideal Fit

  • There are four different fitting patterns to fit a keratoconic eye with SOClear.
    • Vaulting the cone entirely (Fig.1).
      • Best for patients with a very sensitive cornea or fragile epithelium.
    • Skimming the cone (Fig. 2).
      • Often the most successful type of fit as there is little/no pressure on the cone, vision is maximised and comfort is usually optimal.
    • Light cone touch (Fig. 3).
      • Often gives good acuity, though may not be tolerated by patients prone to staining or those with sensitive eyes and low tolerance levels.
    • Heavy cone bearing (Fig. 4).
      • May provide excellent acuity but might produce apical staining, spectacle blur and potential cone progression.
  • Peripheral curve should be in alignment with the scleral conjunctiva.
  • 1.00 to 1.25mm of scleral coverage.
  • Maximum of 0.25mm of movement on blink.

Figure 1: Vaulting The Cone

Figure 2: Skimming The Cone

Figure 3: Light Cone Touch

Figure 4: Heavy Cone Bearing

 

Trial Lens Selection

  • Always start with the standard set, and move to the KC set only when necessary.  You can fit around 70% of keratoconic patients with the standard design.
  • SOClear standard lenses are designed to fit the sag of a normal cornea. For a keratoconic eye the sag of the eye is not predictable.
  • The initial lens will be a best guess based on the estimated sag  based on the size, position and severity of the cone , which comes with experience. However, a good starting lens is the 7.34 lens.
  • Insert the lens, assess the fit and adjust from there.
  • The ideal fit will vault the cornea with no heavy contact at the apex of the cone or at the limbus.
  • If there is central contact the lens has too low a sag and a steeper lens is needed.
  • If the lens is too flat it will flare away from the sclera and will often be uncomfortable.
  • If the lens is too steep it will cause vessel blanching.
  • In general you want the flattest periphery that does not cause edge lift/discomfort/lens movement over 0.25mm whilst maintaining central clearance.
  • To avoid bubble formation it is ESSENTIAL that you FILL the lens with saline prior to insertion as described later in the insertion and removal page.  Bubbles under the lens give a false fitting pattern and will quickly become uncomfortable for the patient.
  • The ideal central fit has a 1.5-2mm band of mid-peripheral clearance
  • In most cases the correct peripheral fit will give the correct central fit.
  • Perform an over-refraction with the chosen lens.
  • Mid-peripheral Fit:
    • The ideal lens fit has a 1.5-2mm band of mid-peripheral clearance
    • If the chosen lens gives too little mid-peripheral clearance order the lens with a flatter central curve (two steps initially )
    • If there is excessive mid-peripheral clearance then order the lens with a steeper central curve. (two steps initially)
    • The power of the lens will need to be altered using SAMFAP rule. Conveniently the lenses in the fitting set differ by 0.50D.


Fitting and Troubleshooting

  • To assess the peripheral curve try gently indenting the sclera with the lid by pressing with your finger under the lens edge.  A well fitting lens will need a gentle nudge (Fig. 5).
    • If a hard push is needed then the periphery is probably too tight.
    • If very little pressure is required then the edge is probably too flat.
  • If the fit is good but bubbles seep in through the fenestration then order without the fenestration.
  • If the lens with the correct sag gives too tight a periphery then this may not be the appropriate lens for the patient.

Figure 5

 

 

 

 




 


Ordering

  • Please specify:
    • The diagnostic Lens that gives the ideal peripheral fit.
    • Any changes to the central curve required to alter the mid-peripheral fit
    • Total diameter: select a diameter that provides 1.00 to 1.25mm of lens coverage beyond the HVID. Bear in mind, large changes may affect the SAG of the lens
    • Material
    • Rx determined from diagnostic lens power, over-refraction and SAMFAP rule.


Handling SOClear Lenses


Insertion

  • Insertion on a healthy cornea: Place the lens on your finger and place a drop or two of saline into the bowl of the lens.
    • Place the lens directly onto the cornea, just like a soft lens. If there is a bubble beneath the lens then insert as for a keratoconic/irregular cornea.
  • Insertion on a keratoconic/irregular cornea:
    • Fill the lens with saline and dip a Fluoret into it.
    • Ask them to hold their lower lid while you hold their top lid, and then pop the lens on to the cornea, coming up from underneath.
    • If you don’t FILL the lens you will get air bubbles beneath it, giving a false fitting pattern- it will also quickly become very uncomfortable for the patient!
    • If you still get bubbles after doing this you will have to remove the lens and repeat the exercise.
  • If you still get bubbles after doing this you will have to remove the lens and repeat the exercise.


Removal

  • To remove the lens, the main thing to remember is that all you are trying to do is break the surface tension between the lens and the eye. The two simplest techniques are:
    • The 'tiddly wink' method-
      • Use the patient's top and bottom lids to lift or 'lever' the edges of the lens away from the eye, as you do to remove a corneal lens. (Fig 6a and 6b).
    • The 'finger touch' method-
      • If the lens is not too tight or dry this method should work well.
      • Ask the patient to look straight ahead. Hold their lids apart, place a dry finger on the centre of the lens and ask the patient to look quickly to one side. This should break the surface tension and the lens should fall into your hand.
      • If the peripheral curves are too tight, this may not work (this is also a useful fitting check).
  • You can also use a lens suction holder to remove the lens. However, please be mindful that you are trying to break the surface tension to get the lens out. Place the sucker towards the edge of the lens and twist or 'wiggle' it to remove the lens, rather then simply pulling!

Figure 6a: Lens Removal

Figure 6b: Lens Removal

 

Patient Guidelines for SOClear Cleaning and Maintenance

  • Standard RGP solutions are too viscous to use with such a large lens, and often make the lens surface rather sticky leading to poor wetting and causing a build up under the lens during wear.
  • We therefore recommend your patients use SOFT multipurpose solutions - preferably one which does not contain preservatives, such as REGARD, to rinse, wet and store their SOClears.
  • Daily digital cleaning with an alcohol-based cleaning solution such as Eyeye Crystal Cleaner (available from No7) or Miraflow will keep the lens clean and free from lipids and greasy build-up.
  • If your patient is prone to protein build-up on their lenses we recommend the use of Menicare PROGENT cleaning system as often as required (usually monthly).
Type No. Lenses Parameters Cleaning/Sterilisation

Keratoconus

12

5.82 - 7.18 / TD 13.60

Follow hospital sterilisation protocol for RGP lenses

Std + Kera

30  
  • Initial Comfort
  • Adaptation
  • Durability
  • Resistance to Dehydration
  • Low Infection Risk
  • Maximum Visual Acuity
  • High Oxygen Transmission
Design Keratoconus
Material Optimum Extra / Boston XO
DK 100 / 130
Tint Optimum Extra - blue and clear, Boston XO - ice blue and clear
Base Curve 5.80 to 7.60mm (0.01mm steps)
Reverse Curve N/A
Optic Zone 9.60mm (fixed)
Diameter 13.30 to 15.00mm
BVP +20.00 to -25.00D in 0.25D steps
Peripheral Curves Full range of curves to match flat and steep scleral profiles (20 steps flatter or steeper)

Click to enlarge image

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