Nissel Sixteen-50 – Cantor Barnard

Nissel Sixteen-50 by Cantor Barnard is a rigid gas permeable RGP scleral contact lens with a diameter of 16.50 mm, designed to create a vault over the cornea rather than resting directly on it, with the lens landing on the sclera.

This design creates a:

Tear Reservoir

between the lens and the cornea.

The fluid reservoir helps maintain hydration of the ocular surface and may provide additional comfort during wear, while also supporting improved optical correction and stability in selected regular and irregular corneas.

Delivery Time

The lenses are supplied within a maximum period of:

30 to 60 days

from the date the order is confirmed.

Sagittal Depth-Based Fitting

Fitting is based primarily on:

Sagittal Depth – SAG

rather than Base Curve alone.

Cantor Barnard provides a diagnostic fitting set containing:

12 trial lenses

with SAG values ranging from:

3.35 mm to 4.70 mm

allowing the eye care professional to select the most appropriate sagittal depth for the individual eye.

Independently Adjustable Zones

Three major areas of the lens can be modified independently:

• Apical Clearance
• Limbal Clearance
• Scleral Landing Zone

This allows the lens design to be customized according to the shape and fitting requirements of each eye.

Key Features

• Large-diameter 16.50 mm scleral lens
• Custom-made for each eye
• Vaults over the cornea rather than resting directly on it
• Creates a tear reservoir that supports hydration
• Provides good optical stability
• Suitable for selected regular and irregular corneas
• 12-lens diagnostic fitting set
• Wide Sagittal Depth range
• Independently adjustable Apical Clearance
• Independently adjustable Limbal Clearance
• Independently adjustable Scleral Landing Zone
• High oxygen-permeability RGP materials
• Daily Wear
• Manufactured in the United Kingdom
• Professionally fitted and monitored

Suitable Applications

Cantor Barnard states that Nissel Sixteen-50 may help with the correction or management of:

• Myopia
• Hyperopia
• Astigmatism
• Keratoconus
• Irregular corneas
• Cases that may benefit from a tear reservoir for improved comfort and hydration

The presence of one of these conditions does not automatically mean that the lens is suitable.

A full examination, corneal assessment, and diagnostic fitting should be carried out by an eye care professional.

Technical Specifications

Available Materials

Optimum Extra

• Material: Optimum Extra
• USAN: Roflufocon D
• Dk: 100
• Cantor Barnard Tint: Clear

Cantor Barnard lists Optimum Extra as a primary material option for the lens.

The material is described as having high oxygen permeability and being suitable for scleral, keratoconus, and other GP lens designs.

Optimum Infinite

• Material: Optimum Infinite
• USAN: Tisilfocon A
• Dk: 180
• Colors: Blue / Clear

Optimum Infinite is a Hyper-Dk material developed for demanding designs such as scleral lenses.

It offers:

• Dk 180
• High oxygen permeability
• Good flexural resistance
• Good scratch resistance
• High wettability

Material Comparison

Diagnostic Fitting Set

The Sixteen-50 fitting set contains:

12 Plano trial lenses

Lower-SAG lenses are more suited as starting points for eyes with normal or moderate sagittal depth.

The higher-SAG K lenses may be useful in keratoconus and eyes with greater sagittal depth.

Fitting Procedure

Before fitting, Cantor Barnard recommends:

• Full Refraction
• Complete eye examination
• Keratometry
• Corneal Topography where possible
• Selection of the initial trial lens according to ocular shape and K readings
• Assessment of the appropriate SAG

Lens Application During Fitting

Before insertion, the lens should be completely filled with:

Non-Preserved Saline + Fluorescein

Cantor Barnard specifically states that:

Aerosol Saline

should not be used for this purpose.

The lens is then inserted while the patient’s head is kept approximately parallel to the floor to help prevent air bubbles from becoming trapped beneath the lens.

Ideal Fit

Cantor Barnard evaluates several key fitting areas.

Apical Clearance

The ideal fitting pattern should show:

• No corneal touch
• No trapped bubbles
• A tear reservoir of approximately 300 microns

The diagnostic lens itself has a thickness of approximately:

300 microns

and may be used as a visual reference when assessing clearance.

Limbal Zone

The lens should vault completely over the limbal area with:

• Appropriate clearance
• Even fluorescein pattern
• No touch

Scleral Zone

A uniform fluorescein band should be visible beneath the scleral landing zone.

There should be no:

• Blanching
• Impingement
• Hyperaemia

Settling Period

Once an acceptable initial fit has been achieved:

Leave the lens on the eye for approximately 60 minutes.

After this settling period:

• Reassess the fit
• Recheck corneal clearance
• Reassess the scleral landing zone
• Perform Over-Refraction to determine final lens power

Available Design Adjustments

A major feature of the Sixteen-50 design is that the three principal zones can be adjusted independently.

Apical Clearance

Adjustment range:

• Increase: up to +5 steps
• Decrease: up to -5 steps

Each step:

50 microns

Total approximate adjustment range:

±250 microns

Limbal Clearance

Adjustment range:

• Increase: +3 steps
• Decrease: -3 steps

Each step:

50 microns

Total approximate adjustment range:

±150 microns

Scleral Landing Zone

Adjustment range:

• Increase: up to +5 steps
• Decrease: up to -3 steps

Each step:

50 microns

Moving from Sixteen-50 to Eighteen-20

Cantor Barnard states that if the fitter needs to increase lens diameter from:

16.50 mm

to:

18.20 mm

the other parameters do not necessarily need to be changed automatically.

The system is designed so that the fitter may transition between the two diameters while retaining other specifications when clinically appropriate.

Lens Removal

The lens may be removed:

• Using the eyelids
• Using a Plunger

When using a plunger, it should be placed on the:

Edge of the lens

rather than the center.

The lens should then be removed with a gentle twisting motion.

Lens Care

• Wash and dry hands thoroughly before handling the lens
• Use care products specifically suitable for RGP lenses
• Clean, rub, rinse, and disinfect the lens according to the recommended care system
• Use chemical disinfection only
• Do not use an Autoclave
• Do not use tap water on the lens or lens case
• Avoid swimming while wearing the lenses
• Avoid showering while wearing the lenses
• Use fresh solution during every cleaning cycle
• Replace the lens case approximately every 1–2 months
• If the lens has not been used for 28 days, fully disinfect it again and use a new lens case

Exposure of lenses or lens cases to non-sterile water significantly increases the risk of microbial contamination and infection.

Filling the Lens Before Insertion

Before placing the lens on the eye, fill the bowl of the lens using:

Preservative-Free / Non-Preserved Saline

Do not use RGP cleaning solution to fill the lens before application.

Wearing and Replacement Schedule

The lens is intended for:

Daily Wear

with a maximum wearing life of:

Up to 12 months

The eye care professional may recommend earlier replacement depending on:

• Lens condition
• Deposits
• Changes in fitting parameters
• Surface integrity
• Ocular requirements

Cantor Barnard’s general RGP instructions also state that the overall stated life of an RGP lens is:

Two years including storage and use

while the actual period of wear after starting use should not exceed:

One year

Important Warnings

Nissel Sixteen-50 is a specialized custom scleral medical contact lens manufactured according to the measurements and prescription of each eye. It must be prescribed, fitted, and monitored by an appropriately qualified eye care professional.

The lens is intended for:

Daily Wear only

and lens parameters or wearing schedules should not be changed without professional review.

Do not expose the lens or lens case to:

• Tap water
• Swimming pool water
• Shower water

Stop wearing the lens immediately and consult an eye care professional if you experience:

• Eye pain
• Persistent redness
• Light sensitivity
• Discharge
• Sudden changes in vision