SOClear

• 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 

• 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 

• 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

• 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

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.