Traditional management of the irregular cornea has, for many years, revolved around corneal RGP contact lenses. Soft lenses represent an excellent alternative course of management for those new to contact lens wear and those who are unable to tolerate rigid lenses.
Applications
Rose K2 Soft is used for the optical correction of the irregular cornea including keratoconus, pellucid marginal degeneration, keratoglobus and post corneal graft.
It is ideal for patients new to contact lens wear or making the transition from standard soft toric lenses to speciality lenses. Rose K2 Soft is also a valuable tool in the management of those intolerant to corneal or other rigid lenses such as sclerals, as well as those for whom other lens types are not appropriate.
[CaptionComponent="1874"]Technical features
Rose K2 Soft provides for optical correction of an irregular corneal surface through the use of an aspheric back optic zone in combination with a front surface toric. The lens is stabilised by prism ballast and the design also features front-surface aberration control.
It is currently available in two materials:
- Lagado Silicone Hydrogel
(three-monthly replacement); and
- Contamac 49 per cent hydrogel (6-12 monthly replacement). It is planned to offer Menicon 72 per cent hydrogel as a further option in the near future.
It is recommended that the fitting lens should be the same as the final intended material.
Fitting procedure
The first fitting lens is selected according to the condition (see Table 1).
The lens is applied to the eye and assessed after three to five minutes. The lens should demonstrate movement on blink of 0.5-1.0mm.
If there is excessive movement a steeper BOZR should be selected, conversely if the lens fails to move sufficiently a lens with a flatter BOZR should be tried.
Once the lens movement is within the optimum range, sphero-cylindrical over refraction should be performed and the visual potential assessed. Once an endpoint to the over-refraction is reached, the practitioner should ask the patient to squeeze the eyelids shut and report, on opening the eyes, whether the vision is better immediately then deteriorates, or whether the vision improves slowly after an initial worsening.
The former indicates that a flatter BOZR is required to achieve optimum acuity and the latter indicates that a steeper BOZR may be required.
If the lens that gives the optimum movement is not the same BOZR that yields the best acuity, then the latter should be ordered with the periphery adjusted to achieve the fitting characteristics of the former. See Table 2 for a summary of fitting assessment.
It is recommended NOT to proceed with fitting Rose K2 Soft if the visual acuity with the optimum BOZR trial lens in situ and over- refraction in place is not satisfactory for the patient’s requirements.
Parameter range
- BOZR: 7.40 to 9.00 (0.20 steps)
- Diameter: Standard 14.80mm (14.30 to 15.30 in 0.1mm increments)
- Power: -30.00D to +30.00D (0.25D steps)
- Cylinder: -0.25 to -10.00 (0.25 steps), Axis 0-180 (1° increments)
- Centre thickness: Standard 0.35mm (0.25 – 0.60mm in 0.01 steps)
- Edge lifts: Standard (0),
Increased (+1),
Double increased (+2),
Decreased (-1),
Double decreased (-2)
Also available with asymmetric corneal technology (ACT) quadrant specific steepening.
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Rose K2 Soft is supplied in the UK by David Thomas Menicon
Jennifer McMahon is optometry lead at Great Western Hospitals NHS Foundation Trust. She has no financial interest in the product described above