Aj Phillips

Can true monocular keratoconus occur

Evidence increasingly supports keratoconus as an inherited, genetic disorder. If this is the case, it would be expected to express itself as a binocular condition even though variable expression of the gene may show differing levels in the two eyes. It is a common occurrence in specialist contact lens practices to see pseudo‐monocular keratoconus, that is, an overt clinical level of the condition in one eye and forme fruste keratoconus in the other. The advent of videokeratoscopy has shown almost every case of apparent monocular keratoconus to be different expressions of the condition in the two eyes. Nevertheless, rare cases of the condition are seen that appear to be truly monocular. Such a case is presented in which the condition has been present for more than 23 years. The age of the subject makes the future onset of keratoconus highly unlikely and videokeratoscopy does not show the presence of forme fruste in the ‘good’ eye. There is no history of monocular eye rubbing. Pachymetry shows the normal eye to be well within the range of normal corneal thickness, while the keratoconus in the other eye is sufficiently advanced to warrant corneal grafting. Thus, it is a case of true monocular keratoconus and represents an extreme example of variable gene expression.

A prosthetic contact lens in the treatment of ocular manifestations of albinism

A patient with severe ocular albinism was fitted with a prosthetic soft contact lens which improved both photophobic symptoms and facial cosmesis.

How sterile is unpreserved saline

Thirty‐five percent of consulting room unpreserved saline bottles with jet dispensers were found to be microbially contaminated within two weeks of use. This increased to fifty‐five percent of bottles after 4–6 weeks of use. The advantages and disadvantages of each form of unpreserved saline storage are discussed and recommendations for practitioner guidance given.

A clinical comparison of the Johnson & Johnson Acuvue, the Barnes‐Hind Calendar and the Bausch & Lomb Medalist disposable contact lenses

We compared the clinical performacne of three brands of disposable contact lenses availble in Australia by refitting 82 Johnson & Johnson Acuvue wearers with either Barnes‐Hind Calendar or Bausch & Lomb Medalist lenses. Subjective lens assessments were analysed with regard to patient factors. Many of these factors wer not significant for predicting the success of a lens but overall lens preference and preference on the basis of comfort, handling and quality of vision were predictable from a history of keratitis, wearing mode or lens power. However, High individual variations did occur. Fitting success is imporved by following some simple guidelines but is maximised obly by trialing more than one lens type.

Surface cracking of RGP materials

Reports have emerged over the last two years of surface cracking of some rigid gas permeable contact lenses. These are largely the higher Dk silicone‐acrylate materials. The exact cause of the phenomenon has yet to be determined but is postulated to occur because of weaknesses in the structure of the lens material or surface stress induced during lens manufacture. As no means exists to remove the surface cracks, lenses showing this phenomenon must be replaced. The implications of this for the practitioner are discussed.

The use of a rigid gas permeable lens in ocular cicatrical pemphigoid

Ocular cicatrical pemphigoid is a chronic, progressive, auto‐immune disease characterised by shrinkage of the conjunctiva, entropion, trichiasis, xerosis and, finally, reduced vision from corneal opacification. The long‐term prognosis is always very poor, although systemic immunosuppressive chemotherapy, topical retinoids and contact lens wear are beneficial. Various types of contact lenses are useful in managing tins disease. In the case described, an RGP lens was used to improve vision, surface wetting and the physiological and visual prognosis.

The use of a displaced, tinted zone, prosthetic hydrogel lens in the cosmetic improvement of a strabismic, scarred cornea

A customised prosthetic soft contact lens with a displaced tinted zone and reversed prism zonal thinning for orientation of the lens was used to improve the cosmetic appearance of a strabismic eye with a scarred, opaque cornea.

Spontaneous tinting of rigid gas permeable contact lenses during wear

Over the past 12 months, I have observed two patients wearing Boston RXD material rigid gas permeable (RGP) contact lenses, which were originally pale blue and which have shown as a moderate brown colour at routine after-care. The problem occurred in the right and left lenses in both cases and both pairs were approximately two years old. Both patients were aware of a slight drop in visual quality and had observed that the tinting took place slowly. One patient used Optisoak (Alcon) storage solution and the other, Totalcare (Allergan). Over the same period, I have examined many hundreds of o ther patients wearing RXD material lenses and using the same as well as other storage solutions. None showed any lens discolouration. Similarly, many hundreds of patients were seen with older KXD material lenses that also showed no lens discolouration with age. Therefore, it can be surmised that the observation is not one of material ageing or polymer breakdown. Brown discolouration of soft contact lenses is a relatively common clinical observation and may be caused by adrenaline ( ep inephr ine ) , phenylephrine, nitrofurantoin, tetrahydrozoline, nicotine, tetracycline and clofazainine and may also Figure: A brown-tinted RGP contact lens maunted on clear acrylic

Surface deposition and cracking of a tinted hydrogel contact lens

For some years, anecdotal reports have been made that certain tinted soft contact lenses accumulate more deposits than non‐tinted lenses. Clinical observation and subsequent scanning electron microscopic examination of a blue tinted soft contact lens confirmed more marked surface deposition over the tinted zone of one lens. In addition, crazing of the surface film and cracking of the material surface were observed over the tinted area.

Iris coloboma managed with a prosthetic contact lens: a case report and review

Coloboma of the iris is a relatively uncommon congenital condition seen in optometric practice. Symptoms include photophobia, greater chromatic and spherical aberration, reduced depth of focus, and poor cosmesis. A case is reported of a prosthetic (cosmetic) contact lens used in the alleviation of these symptoms.