Menicon Time XL

Research shows that the shape of the limbus and the sclera is typically linear and not curved.¹ Furthermore, in 95% of cases, the scleral surface is toric and not spherical. This was the basis for the design of the TimeXL. The goal of the bitangential design was to realise an optimal distribution of pressure of the lens on the conjunctiva. This results in higher tolerance, which allows for longer daily use.^2,3

Design

For the TimeXL, two important innovations were combined for maximum comfort and optimum lens performance. More specifically, the periphery is produced linearly and torically (bitangential). The toric periphery of the lens can be precisely controlled in both flat and steep meridians and the sclera is outlined for a simple fit and stability. This allows the cornea to be optimally bridged.³ The toricity is limited to just the periphery of the lens: the back surface geometry of the optical zone is spherical. If necessary, the front of the TimeXL’s optical zone can be fitted with a corrective cylinder.

Periphery Benefits

Straight line in lens periphery

More control over the landing zone
Optimising pressure distribution at the scleral surface
Maximum control over the sagittal height

Mid Peripheral Zone

Controls the area between the optic zone and tangent zone
Makes the sag height and tangent zone independent of each other

Back Optic Zone

A constant 11mm, independent of lens diameter
Base Curve adjustable in increments of 0.20 mm (1 dpt.)

Fitting Philosophy

Menicon Time XL was designed to completely bridge the cornea and the limbus and to rest on the sclera. An optimally fitting, scleral lens has the following characteristics after being worn for 30 minutes:

• Pressure is distributed equally, no visible blanching

• Central corneal clearance of approximately 200 μm

• Limbal clearance of approximately 100 μm, with a minimum of 50 μm

Setup of the diagnostic set Menicon Time XL diagnostic set consists of 16 diagnostic lenses with a diameter of 16.0 mm, a base curve of 8.4 mm, and power of 0. All lenses feature a toric periphery and the toricity is expressed in tangent angles. The toricity is expressed in a difference of 6° between the flat and steep meridian for all diagnostic lenses

You can use Easyfit to determine the first diagnostic lens. In order to determine the diagnostic lens, import the topographical images into Easyfit. The programme uses the corneal topography measurements to estimate the scleral height. The program recommends the sagittal height and tangents of the diagnostic lens from the set.

Target Groups

Lens specifications

Parameters range

Sagittal height	3000 to 4600 μm in increments of 100 μm
Tangent to flat and steep maridian	Both meridians available from 28° to 50° in increments of 2°
Base curve	7.4 to 9.2 mm in increments of 0.2 mm
Diameter	14.0 to 17.5mm in increments of 0.5mm
Power	-25.00 to +25.00 D in increments of 0.5mm
Front toric parameters	Axis	0° to 180° in increments of 1°
	Cylinder power	-0.75 to -3.00D in increments of 0.25D
Material	Menicon Z
Handling tint	Clear

References

¹Van der Worp E, Graf T, Caroline PJ. Exploring beyond the corneal borders. Contact Lens Spectrum 2010; 25 (6):26–32.

²Van der Worp E. A Guide to Scleral Lens Fitting (monographyonline). Pacific University Common Knowledge: Books and Monographs. 2010. Available at: http://commons.pacificu.edu/cgi/viewcontent.cgi?article=1003&context=mono. Consulted on 13 June 2013.

³Visser, MedicalApplications and Outcomes of Bi-tangential Scleral Lenses. Optometry and Vision Science VOL. 90. No.10, October 2013.