Aim and Ideal Fit

Ideal fit (Fig. 1) will have:

• Alignment with the scleral conjunctiva, with no standoff or impingement
• Central alignment with at least 1.5-2mm band of mid-peripheral corneal clearance
• 1.00-1.25 mm of scleral coverage
• Maximum 0.25mm of movement on blink
• The lens should be easy to remove, with no signs of adherence, and there should not be any significant corneal staining 

Figure 1 – Ideal Fit 

The aim is to fit the SOClear lens so that it matches the sag of the eye and also aligns well with the sclera. The central curve of the lens can then be adjusted to alter the mid-peripheral clearance, allowing good tear exchange.

Trial Lens Selection

The SOClear lens is designed to have the sag of the average cornea. A larger diameter cornea will have a greater sag than a smaller cornea with the same central curve. Hence for an average sized cornea the initial lens is based on mean K whilst for a larger cornea a steeper (and hence greater sag)  lens is used and for a smaller cornea a flatter (and hence lower sag) lens is a good first choice.

Initial Lens Selection

• Measure HVID
• For average corneal diameters (11.5 – 12mm), select a lens as close to the mean K as possible
• For large corneal diameters (in excess of 12 mm), select a lens which is 1 Dioptre steeper than the mean K
• For small corneal diameters (less than 11.5mm), select a lens which is 1 Dioptre flatter than mean K
• Insert the lens and assess the fluorescein fit 

Sag and Peripheral Fit

• If there is central corneal touch then the lens is has too low a sag, select a steeper lens.
• A flat lens will flare away from the sclera and will often be uncomfortable (fig. 2)
• A steep lens may cause vessel blanching (fig 3)
• Aim for the flattest periphery that does not cause edge lift/discomfort/lens movement over 0.25mm and does not have central touch
• 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

Figure 2 – Flat Peripheral Curve

Figure 3 – Steep Peripheral Curve

Fitting and Troubleshooting

• If the lens is difficult to remove it may be too tight
• If you put fluorescein in once the lens is on the eye and it doesn’t diffuse quickly under the lens and seeps in slowly through the fenestration, it’s too tight
• If there are mid-peripheral bubbles the lens may be too tight
• If the lens is really uncomfortable it is probably too flat
• If in doubt err on the flatter side for the base curve – the vision will be better and any central pooling can cause adherence as well as build-up of mucus/debris
• 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. 4)
• 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

 Figure 4 – Indenting the Sclera

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.

A lens will be designed with the sagital depth and periphery of the peripheral diagnostic lens combined with the central curve required.

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

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 5a and 5b)

 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 than simply pulling.

Figure 5 – Lens Removal

Figure 5b – 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 recommend your patients use SOFT multipurpose solutions –  such as Oté Sensation – to rinse, wet and store their SOClear lenses
• Daily digital cleaning with an alcohol-based cleaning solution such as Oté Clean (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 they use the Menicare PROGENT cleaning system as often as required (usually monthly)

• Initial Comfort
• Rapid Adaptation
• Durability
• No Dehydration
• Maximum Visual Acuity
• High Oxygen Transmission

Parameters

*Multifocal also available on the standard design