An assessment of consecutively presenting orthokeratology patients in a Hong Kong based private practice

The aim of this study was to collect objective, subjective and demographic data on consecutively presenting orthokeratology (ortho-k) patients who attended for routine follow-up examination in a Hong Kong based private practice in May 2001.

Sixty-nine patients who returned to the surveyed practice for follow-up visits during the study period (May 2001) were interviewed and relevant data extracted from their files. Data collected included identification and estimation of the extent of complications encountered by ortho-k patients and their satisfaction with the treatment.

Among the 61 patients who had been wearing ortho-k lenses for at least one month, 50 patients were younger than 16 years old. Twelve children (24 per cent) had been reluctant to wear ortho-k lenses before undergoing the treatment but, after commencement of lens wear, only one child was not very willing to wear the ortho-k lenses. The mean pre-ortho-k spherical refractive error of these patients was -3.93 +/- 2.30 D (OS only). Of the 59 patients who wore ortho-k lenses for at least one month and who were on night therapy, 10 patients had to wear spectacles or contact lenses in the daytime due to significant residual myopia. There was no statistically significant correlation between post-ortho-k unaided visual acuity and pre-ortho-k refractive error (spherical, cylindrical or the equivalent sphere) in the 49 patients who did not need to wear any vision correction in the daytime. Of the 61 patients, four reported eye inflammation/infection during the treatment. All recovered their ocular health without any effect on their vision or corneal health. The incidence of corneal staining that required lens wear to be stopped appeared to increase with the duration of ortho-k lens treatment. The incidence of staining was not related to refractive error, unaided visual acuity or the age of the subjects. The most common problem reported by the patients was lens binding and there were also reports of increased redness, itching, light sensitivity and secretion of mucus in the morning after opening their eyes. More than 50 per cent of the patients experienced some distance vision blur, which was worse towards the end of the day. For most patients, these problems occurred only occasionally. Higher pre-ortho-k spherical refractive error was related to poor near and distance vision and worse distance vision towards the end of the day.

The majority of the patients interviewed were children who reported being 'happy with the results of the treatment'. Night wear is the main wearing modality and in view of the increased risk of complications in overnight wear and the fact that a large number of the patients are children, the need for strict compliance with the practitioner's instructions for lens use and care cannot be overemphasised. With careful monitoring and good compliance, complications with overnight ortho-k wear can be minimised. In view of the high incidence of lens binding, it is essential that patients and parents of young patients know the correct method to free a bound lens.