Soft Contact Lenses

 

 

Hydrogel & Silicone Materials

 

Soft lenses first became available in the 1980's.  The material used was hydrogel.

Comfort was far better than rigid gas permeable and hard lenses.  But the amount of oxygen reaching the eye was limited.  Overwear of those lenses sometimes led to problems.

 

There are still some hydrogel lenses on our books, but we don't tend to fit them.

The main exception is MiSight.  Young corneas can tolerate hydrogel lenses well, and the overal benefits well outweigh the older material (more on this later)

 

The vast majority of contact lens fits utilise silicone material which are between 3x and 7x more breathable than hydrogels.  Comfort will be better, and the corneas will be healthier.

Dk/t refers to breathability and how much oxygen that can pass through a contact lens.

The higher the number, the more effective the lens is.

With hydrogels we would sometimes see corneal swelling, hypoxia and neovascularisation if the wearing times were too long.

 

Dk/t in Dailies	Name	Sphere	Toric	Multifocal
Hydrogel	Vitrea	26	26	26
	1-Day Moist	26	24	26
	MiSight	28
Silicone	Umere	86	57	86
	Aquiane	93
	Linarial	100	80	100
	Precision One	100	90
	1-Day Oasys	121
	Total One	156	127	156
	Serima Sph	171

 

Dk/t in Monthlies	Name	Sphere	Toric	Multifocal
Hydrogel	Vusion	42	25
Silicone	Uvicia	110	90
	Irisian	138	108	138
	Oasys	147	129	147
	Total 30	154	123
	Opteyes	160	116	142
	Orba	161		161

 

My Day = Linarial

Clariti = Umere

AquacomfortPlus = Vitrea

 

 

 

Fitting Contact Lenses

 

Virtually any presciption can be corrected with soft contact lenses.

 

Whatever the age of the patient, they may be an excellent candiate for contact lenses.

But they may not realise it until we tell them.

 

You could even ask:

"Why aren't you wearing contact lenses?"

 

Some have been told in the past that they have astigmatism and are not suitable for contact lenses..

They will be suitable for contact lenses now

 

From our 40's we find near vision trickier and even existing wearers sometimes give up with contact lenses becuase they are not aware that we have an incredible range of multifocals in both dailies and monthly.  We can even combine toric and multifocal in monthlies.

They will highly likely be suitable for multifocal contact lenses

 

 

The most extensive range of powers are in Linarial (daily) & Opteyes (monthly)

These are our first choice lenses not just for the power range, but also comfort and first time fit success.

 

Linarial Daily		Opteyes Monthly
Sph: +8.00DS to -12.00DS	SV	+15.00DS to -20.00DS
Sphere: +8.00DS to -10.00DS Cylinder: up to -2.25DC Axes: Every 10°	Toric	Sphere: +20.00DS to -20.00DS Cylinder: up to -5.75DC Axes: 5° or 10°
Sphere: +8.00DS to -12.00DS Adds: Low, Medium & High	MF	Sphere: +6.00DS to -10.00DS Adds: +1.00, +1.50, +2.00 & +2.50DS Centre NV or centre DV
	MF-Tx	Sphere +10.00DS to -10.00DS Cylinder: up to -5.75DC Axes: 5° Adds: +1.00, +1.50, +2.00 & +2.50DS Centre NV or centre DV

 

 

 

Vertex

 

We usually need to convert an eye exam prescription to a contact lens specification

We need to adjust powers when the eye exam Rx is ±4.00 dioptres.  This is to ensure that the focal point of light sits on the retina despite the contact lens being closer than spectacles.

Minus spheres are reduced in contact lenses.  Plus spheres are increased.

And because there are fewer parameters with contact lenses than with spectacles, we often need to adjust the cylinder and axes.

 

Examples:

Spectacle Prescription	Contact Lens Prescription
-2.50DS	-2.50DS
-4.50DS	-4.25DS
+4.50DS	+4.75DS
-4.50/-1.00x180	-4.25/-0.75x180
+4.50/-1.00x180	+4.75/-1.25x180

 

Multifocal contact lens powers can also vary in different designs

	RE	LE
Spectacle Prescription	+4.50DS  Add +2.00 dominant eye	+4.50DS Add +2.00
Opteyes MF	+4.75 D+2.00	+4.75 N+2.00
Linarial MF	+4.75 Low	+4.75 High
Umere MF	+5.00 Low	+5.25 Low
1-Day Moist MF	+4.75 Med	+4.75 High

 

 

 

MiSight

 

Miopia management has been extensively studied for the past seven years and it is proven to slow the progression of short sightedness in 90% of children and young adults. This technology will become the norm over the next few years and is available in both spectacles and contact lenses.

They may be fitted with MiSight contact lenses from age 8.

The lenses are only available in minus prescriptions.

Contact lenses would need to be worn for about 10 hours a day and worn 6 to 7x per week.

It will not reverse myopia, but it will help to slow down how quickly prescriptions change.

Once in adulthood, the patient should have a lower prescription than they would have had, had they worn normal contact lenses.

More information:  MiSight® 1 day contact lenses | Practitioner Hub | CooperVision UK