Cosmetic and Prosthetic Contact Lenses

Rigid lenses

Glass and polymethylmethacrylate (PMMA) lenses were originally clear. Later, corneal PMMA lenses were tinted for a variety of reasons:

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  as an aid to handling, making lens insertion and removal easier

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  to differentiate lenses from each other

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  to enhance or alter eye colour

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  to reduce photophobia.

PMMA buttons or rods were tinted in a wide range of colours before lathing. PMMA material has been superseded by rigid gas permeable (RGP) materials, which come in a variety of light-handling tints. Paragon/Menicon produce the SportSight Dark Grey RGP material that dramatically reduces light intensity and is useful for patients who are photophobic, but they should not be worn in low-light conditions. Effective coloured rigid lenses are still beneficial for many patients.

Scleral lenses

In an eye that retains useful vision and neither a soft lens nor a corneal prosthetic lens fits well, a transparent scleral lens can be made. This can later have an iris hand-painted onto it to match the normal eye, leaving the pupil area clear for vision.

Soft lenses

In the 1980s soft tinted lenses became available, initially as pale blue to act as a ‘visibility tint’, but they did not change the natural colour of the eye. A slight cosmetic change could be achieved by deepening the dye, which would enhance the colour in blue or green eyes, but had no effect on brown eyes (for the history of tinted soft lenses see Section 8 , History, available at: https://expertconsult.inkling.com/ ).

Cosmetic soft contact lenses are now produced by all the major lens manufacturers as well as several smaller local companies ( Table 25.1 ; see Table 25.2 ). They are available in a wide range of colours, prescriptions and disposability. Opaque cosmetic lenses have a natural appearance as three or more colours are used to produce each lens.

Table 25.2

A Cross-Section of Leading Custom-made Cosmetic, Prosthetic and Theatrical/Special-Effects Lens Manufacturers, Worldwide

Region	Company Name	Location
USA	Alden Optical	Lancaster, NY
	Custom Color Contacts	Manhattan, NY
	Orion Vision Group	Marietta, GA
	9MMSFX	Los Angeles, CA
Canada	Contour Contact Lens Ltd.	Langley, BC
Europe	Cantor & Nissel	Brackley, UK
	Ultravision CLPL	Leighton Buzzard, UK
	No 7 Contact Lenses	Hastings, UK
	Art-Lens Ocular Prosthesis	Barcelona, Spain
	Swisslens	Prilly, Switzerland
Asia/India	Wuhan Web Science	Wuhan, China
	Dreamcon Co.	Gyeongsangnam-do, South Korea
	Artificial Eye Co.	Kolkata, India
Australasia	Capricornia Contact Lens	Queensland, Australia
	Gelflex	Perth, Australia
	Corneal-Lens Corporation NZ Ltd	Christchurch, New Zealand

In-office tinting of cosmetic lenses is rarely done these days (for method of procedure, see Section 9 , Addendum, available at: https://expertconsult.inkling.com/
).

Coloured lenses are made using a variety of methods:

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  Dye dispersion – This method is usually used for rigid lenses. The dye is added to the monomer matrix and mixed to disperse the colour.

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  Vat dye tinting – The finished soft contact lens is soaked in a water-soluble dye to produce a uniform surface tint.

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  Chemical bond tinting – The lens is soaked in a dye solution together with a catalyst, which produces a chemical bond between the dye and the polymer ( ).

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  Printing – The iris pattern is printed onto the lens much like printing on paper, except the pigment is now enclosed within the lens matrix.

To make the cosmetic lens appear more natural, the pigment is printed to match the fibrous elements within the human iris. A black limbal band can be incorporated, along with colour variation from the pupil edge to the limbus.

The above methods are used for translucent tints. Different methods are used to produce opaque tints including:

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  Dot matrix tinting – An opaque-coloured dot matrix is applied to the front surface of a soft lens and chemically fixed to make it permanent ( Fig. 25.2a ).

  

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  Reflex colours printing (No 7 Contact Lenses, UK) – Colours are printed in layers (piggybacked) so that the iris colour is printed onto an opaque ‘underprint’ with varying collarette and limbal ring patterns. This provides a wide range of colours.

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  Hand-painted onto an opaque backing – An opaque white backing of barium sulphate is precipitated into the matrix of the back surface of the lens. The iris colour is then applied to the front surface and bonded (see below).

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  Laminating – This method is not often used now. The front surface of a soft lens button is lathed and polished, either tinted or hand-painted and sandwiched with a further layer of polymer.

Hand-painted lenses

The following applies to both rigid and soft lenses, although soft lenses are more commonly fitted. In rigid lenses, one or more fenestrations can be incorporated to provide some oxygen transmission, but this may affect the fit.

When commercial prosthetic or cosmetic lenses do not provide a good match for the normal eye, lenses can be hand-painted to order. The whole lens is coated with a medium that will not allow the tint to touch the lens surface. This medium is then removed in the areas where colour is to be applied for striae or the collarette, and so on. The tint is then poured over the lens surface as normal, where it will allow absorption into the ‘uncovered’ areas, and the process is repeated multiple times to build up the pattern (Jodie Davenport, Capricornia Contact Lens, personal communication 2017).

The colour to be matched can be sent to the company in one of three ways:

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  A photograph taken in daylight, otherwise the colour rendering can be poor. This can then be sent or e-mailed to the laboratory. Some laboratories provide a ‘fan’ showing their range of iris colours ( Fig. 25.3a ).

  

  Ultravision Capricornia Ltd in Australia uses a four-dot colour recognition or calibration strip that is held above the patient's eyes, and this allows the computer to align itself to the photographer's lighting background colours. Using the photograph and the calibration dots, the laboratory is then able to assess the colour of the normal iris and make a cosmetic lens as close a match as possible (see Fig. 25.3b and Clinical Case 8 ).

• 2.

  A palette of iris ‘buttons’ ( Fig. 25.4a ) can be matched to the patient's eye and the relevant number of the button sent with the lens order ( Fig. 25.4b–e ). Descriptive modifications can be made on the order form; for example, ‘enhance the green tone’ or ‘darker ring around pupil’. These lenses can be made as PMMA semi-scleral lenses (sometimes called a mini-prosthesis). PMMA is still used because it is possible to hand-paint or print on this material and not have adverse reactions with tears wetting the front surface. PMMA is still used with artificial prosthetic eyes for this same reason (see p. 474 ).

  

Painting Soft Lenses

Table 25.2 shows a number of companies that manufacture custom-made soft prosthetic lenses.

Because the lenses become thicker with the hand-painting, high–water-content hydrogel or silicone hydrogel materials are used in an attempt to improve oxygen permeability. Lenses can be made in diameters up to 24 mm, although these large lenses do not always move sufficiently on the eye.

The colour is applied on the front surface of the lens, and a chemical reaction is used to produce an opaque white pigment in the rear lens matrix to make the colour look effective by hiding the disfigurement ( Fig. 25.5 ). The white area can be extended beyond the iris, if necessary, to mask a discoloured sclera (see Fig. 25.8 ).

Ocular cosmesis

The optimum lens tint and design depends on the appearance of the eye and whether the pupil is normal or not. An eye that has suffered trauma may be redder than the fellow eye, which can affect the appearance of a coloured lens when matching it to the fellow eye.

With disposable soft coloured lenses such as Alcon's Freshlook Colorblends or Coopervision Expressions Colors, it may be possible to match the damaged eye to the good eye without the need for a custom-made cosmetic or prosthetic lens (see Clinical Cases 3 and 5 ).

When a custom-made lens is required, manufacturers usually provide a set of lenses with homogeneous iris tints and their own codes for the practitioner to use when ordering (e.g. Brown 4 or Grey-blue 1042).

Cosmetic lenses should always be trialled on the eye, as the colour will appear different on, for example, a white opacified cornea than on a large (dark) iridectomy.

Choosing the Type of Lens

Initial trial lenses

Like all lenses, prosthetic lenses can cause adverse reactions, and this is exacerbated because there may be little or no oxygen permeability. A clear trial lens can be used to establish the optimal BOZR and TD for the prosthetic lens. A standard 55% hydrogel lens, with its wide choice of radii and diameters, will give plenty of choice to determine whether the basic fit is correct. However, the finished lens will be thicker and less flexible, and may behave differently on the eye. A lens that moves excessively will be obvious to an observer because of its tint.

If a reasonable fit is possible with a disposable lens, consider using this to teach the patient lens insertion and removal rather than on the final, expensive custom-made lens.