Introduction

Soft hand painted prosthetic lenses are indicated for patients with corneal opacity or iris irregularities. These lenses are custom manufactured, often incorporating a reverse alignment curve or prism ballast weight to enable straight-ahead gaze. These lenses are typically manufactured in hydrogel 38% material with a centre thickness double that of a standard soft lens to mask corneal irregularities and ensure ease of handling.

Lens Decentration Issues

Often in cases with opacified corneas and superficial scarring, we are able to obtain a good fitting lens, but the lens will decentre onto the highest point of scarring, creating a cosmetic tropia. In such cases, we need to offset the iris on the lens to get a natural, forward-looking gaze with both eyes. We have developed a prism grid fitting set for such cases whereby the lens is fitted and the position of the prism can easily be noted to help determine the intended iris position.

Back and Front Surface Customization

Being able to customise the back surface and offsetting the iris on a prism ballast soft lens allows us to fit even the most complicated damaged eyes and get the best results possible.

The front surface of the soft lenses is hand painted with a paintbrush and dye. The whole process takes about two days. It involves painting on a hydrated lens before the lens dries out (± 20 min) and then developing the lens on a hot plate in the developer (± 20 min). After that the lens is rehydrated (± 1 hr), and then the painting process is continued in several layers. Typically, about five different lenses are created for different patients at the same time to keep the process going. The front surface is not treated at our lab once we have completed the artwork; the dye does not create a layer on the surface of the lens but rather bonds into the lens material. For required pinhole lenses, we are able to script the lens in any power from -30 D to +30 D with clear pupil sizes of 3 mm and 4.5 mm.

Case Example

A 50-year-old patient with a scarred cornea from an explosion in 1982 has had several surgeries to maintain intraocular pressure. He underwent phototherapeutic keratectomy laser treatment to remove the developing corneal opacity, and he had a blepharoplasty to lift the superior eyelid by 5 cm. The patient unfortunately developed a viral infection, which intensified the scarring (Fig 1, below). Eventually, he requested to be fitted with a soft prosthetic lens to regain the cosmetic appearance.

STEP 1

The patient was initially fitted using a standard range spherical fitting set. The most successful fit was with an 8.50 mm, 14.5 mm lens. The lens decentred 2 mm inferior and 3 mm temporal on forward gaze (figure 2, below).

STEP 2

We then fitted the prism grid lens 8.50 mm, 15 mm with weighted prism position marked. The iris would need to be placed 2 mm superior and 3 mm nasal with the prism located at 325 degrees (4 o’clock) in this case (figure 3, below).

STEP 3

The 8.50 mm, 15 mm prism ballast lens with an offset 12.5 mm opaque backing and 4 mm black pupil was used to check centration. Forward looking gaze centration with both eyes was achieved with this trial lens; the iris size was assessed to be 1 mm too big, pupil size was fine (figure 4, below).

STEP 4

The final lens was manufactured with the same 8.50 mm, 15 mm prism ballast lens with the iris size decreased to 11.5 mm and a black pupil of 4 mm. The hand paint work as described above was completed (figure 5, below).

Closing Remarks

Soft hand painted prosthetic lenses are a specialty lens modality that takes a lot of time and effort, but it is very rewarding. The input and assistance of an optometrist with the fitting of the lenses is always required, as is feedback to assist us with the design. All of our lenses are custom manufactured in our lab to each patient’s specifications and requirements. A fitting set must be used for the initial fitting. A wide range of sets are available; flat reverse geometry, prism ballast grid, out of range steep and standard fitting sets are needed for the initial fitting of every case. We will often have to customize the lens further to produce the best fitting lens before any artwork can commence. The combination of a good soft lens fit, respecting the shape of the eye, and the skills for the artwork is essential in this process for a good end result.



Bonita began her career in 2006 as an apprentice Ocularist. She studied and was taught the entire manufacturing process of prosthetic eyes and haptic shells by leaders in that field at the time, Jack and Mike Bernard. She found that she had the skill and patience to be able to replicate an iris pattern exactly on the prosthetics simply using paint and a brush.

In 2008, she joined The Contact Lens Laboratory of South Africa, which designs and manufactures soft and hard contact lenses. This new and technologically advanced manufacturing company gave her free reign to astound South Africa with the painting art that she had acquired. Every case is a unique challenge and never too difficult for her to endure; her ability and skills in all aspects of the contact lens industry have helped her push boundaries.

She is fulfilled in her position as Director at ‘The Contact Lens Laboratory of South Africa’ and is changing lives every day.