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HomemipatientThe Power of a Prosthesis

The Power of a Prosthesis

A prosthetic contact lens can make all the difference to a patient’s appearance, self-confidence, and the ability to fit into society.

Recently, I spent a week at the Khmer Soviet Friendship Hospital in Phnom Penh, Cambodia with Sight for All. During the week I saw a variety of patients including MC.

MC is a 30-year-old male who suffered from measles at age seven, which affected his right eye, resulting in a scarred white cornea. Unable to tolerate the bullying he received at school, he left at age 14.

Understandably, MC was very self-conscious. He believed that when people looked at him, they only saw his unusual eye and caught many people staring at him. Additionally, he had found it difficult to obtain jobs – he was discriminated against because he looked ‘different’ (Figure 1).

His fiancé… said that he was ‘handsome before, but now he was even more handsome’…

MC presented to the clinic with his fiancé. His vision was R NLP and L 6/6.

Examination revealed complete corneal scarring of the right eye (Figure 2).

MC was fit with a prosthetic soft contact lens (Figure 3). Being of Cambodian descent, he had dark coloured irises, and the Capricornia Eyecon Prosthetics in jet black provided an excellent match (Figure 4). MC expressed his gratitude for improving his cosmesis and restoring his self confidence. His fiancé, unable to stop beaming, said that he was “handsome before, but now he was even more handsome”.

Figure 1

MEASLES

Measles is highly contagious and has been one of the leading causes of death in children. It is estimated that approximately one per cent of children hospitalised with complicated measles subsequently become blind, however this does not take into account loss of vision in one eye.1

Although there is no known effective anti-viral treatment for measles, it can be prevented with a cheap, safe and effective vaccine.

Indeed, measles vaccination has prevented an estimated 20.4 million deaths between 2000 and 2016, resulting in an 84 per cent reduction in deaths in this period.2

Despite this success, measles infections are still endemic in developing countries – especially in Africa and Asia – with an estimated 60,000 cases of blindness per year. Measles affecting the eye can result in keratoconjunctivitis, xerophthalmia, keratomalacia, and corneal ulceration with subsequent corneal scarring, or phthisis bulbi. The prognosis is worse when compounded with malnutrition, in particular vitamin A deficiency.

MC grew up in a rural province in Cambodia, in a low income family, and had not been vaccinated against measles. Presumably, he suffered from corneal ulceration, possible keratomalacia resulting in corneal scarring, and complete loss of vision in his right eye.

However, loss of vision was only part of the problem for MC. He avoided social situations and would walk with his head down so that people could not see his eye. This is not uncommon – visual disfigurement can result in psychosocial distress, with many reporting anxiety, depression, self-consciousness, and social avoidance.3

Figure 2


Figure 3

 

PROSTHETIC CONTACT LENS FITTING

Prosthetic soft tinted and occlusion contact lenses can mask ocular abnormalities such as white opacified corneas, as in the case of MC. An iris occlusion contact lens has iris pigment on the front of the lens with black backing for complete occlusion. They may be ordered with either a black pupil or a clear pupil and in a range of pupil diameters, iris diameters, base curves, and lens diameters. As MC has no vision in his right eye and scarring through the centre of his cornea, a pupil occlusion lens was prescribed.

These lenses may be either printed or hand painted. Printed lenses are from a range of pre-determined iris colours and diameters, whereas hand painted lenses are completely customisable. Patients with darker coloured irises (e.g. dark brown) are easier to match and will often achieve a satisfactory result with printed prosthetic lenses, whereas patients with lighter coloured irises (e.g. blue and green) are more difficult to match and may require hand painted lenses if a satisfactory match cannot be achieved within the range of printed lenses. As the hand painted lenses are individually made, there are more options for iris colours, iris patterns, as well as iris and pupil diameters. There is also the ability to decentre the pupil and/or iris, which may be beneficial for patients with strabismus. However, these lenses generally require more chair and manufacture time.

Establish Expectations

When fitting prosthetic contact lenses it is important to set realistic expectations and patients should be made aware that exact matches are not always achievable. As printed lenses are pre-determined colours and patterns, reproducibility is high, and the print does not fade as quickly as hand painted lenses. These lenses are often available in a fitting kit so that patients are able to see their expected end result during the fitting process and before purchasing the lens.

If a patient is unsatisfied with the cosmetic result after several attempts, prosthetic contact lenses to be worn in both eyes may be required. However, these lenses are thicker, older hydrogel lens materials, and if the patient only has one seeing eye, it may not be worth the risk of any potential complications to this eye.

Finding the Right Match

When fitting the prosthetic contact lens, measurements of the corneal surface are useful, however in heavily disfigured eyes such as MC’s, these can be challenging to obtain. Corneal topography of these eyes is often difficult, and this was not an option for MC as there was no topographer in the clinic. Hence, trial lens fitting is performed to determine the desired contact lens parameters.

The goal with fitting is to achieve a lens that centres well, drapes adequately across the corneal surface, and does not move excessively. Often a clear soft contact lens can be fitted first, as was in this case, to ensure that the lens would adequately fit before committing to a costly custom prosthetic contact lens. Measurements of the fellow eye required include the eye colour, horizontal and visible iris diameter, as well as pupil size in bright and dim lighting. Prosthetic contact lens pupil size is fixed, but pupil size is a normal eye dynamic. It is important to find out about the patient’s lifestyle in order to pick the most suitable contact lens.

Figure 4

The fitting of prosthetic contact lenses can be relatively simple, especially when there is access to excellent contact lens laboratories that can manufacture them. However, even though sight cannot be restored for these patients, the improvement in cosmesis can have a significant improvement in their self-confidence and quality of life.

Measles blindness is rare in developed countries, however there has been recent controversial debate over vaccination and some parents are choosing not to vaccinate their children. This was the first case of measles blindness I have seen in practice, and hopefully I will not see any in Australia.

SIGHT FOR ALL

Sight For All is a not for profit organisation with the goal to develop and provide sustainable eye care in under privileged areas. Projects include collaborative research, infrastructure support, sustainable education, and awareness campaigns. I was part of a team of visionaries training a local ophthalmologist to provide speciality contact lens services.

Jessica Chi is the director of Eyetech Optometrists, an independent specialty contact lens practice in Melbourne. She is the current Victorian, and a past National President of the Cornea and Contact Lens Society, and an invited speaker at meetings throughout Australia and beyond. She is a clinical supervisor at the University of Melbourne, a member of the Optometry Victoria Optometric Sector Advisory Group and a fellow of the Australian College of Optometry and the British Contact Lens Association. Jessica writes ‘mipatient’ on alternate months with Margaret Lam.

References

1. Semba RD, Bloem MW. Measles Blindness. Surv Ophthalmol. 49(2)pp243-255:Mar-Apr 2004.

2. World Health Organisation. Measles, Fact Sheet. www. who.int/mediacentre/factsheets/fs286/en/

3. Clark A, Rumsey N et al. Psychosocial distress associated with disfiguring eye conditions. Eye (Lond). 2003 Jan:17(1):35-40