Journal of The British Contact Lens Association最新文献

The Nidek KM-500 is a recently introduced hand-held automatic keratometer. If the accuracy and reliability of thisinstrument are good then it offers a number of benefits to contact lens practitioners and other clinicians. This study investigated the repeatability and reproducibility of readings taken using the hand-held Nidek KM-500, the Topcon RK-3000A and the Bausch & Lomb keratometer. The Nidek KM-500 was found to be reliable when used according to the manufacturer's instructions and the readings equated well with those obtained with the table-mounted Topcon KR-3000A. The repeatability of the Bausch & Lomb keratometer can be improved by taking the mean of three readings. Clinicians should consider conducting a simple repeatability study of the keratometer used in their own practice. The results may help to pinpoint a weakness in technique when using a non-automated instrument, and will establish the criterion for a true change in corneal radius.

Four practitioners each noted the details of 40 successive non-contact lens-wearing patients who consulted them for a routine eye examination. The subjects were divided into two equal groups. In the first group contact lenses were only discussed if the subjects solicited the discussion and in the other group subjects were actively encouraged to try contact lenses. Interested subjects were fitted with a monthly disposable lens and dismissed for 2 weeks. After 2 weeks the patients were asked if they would like to continue with lenses, which they would subsequently have to pay for. Approximately six times more contact lens patients were fitted with contact lenses by adopting a proactive approach.

In a randomised study, the relation between corneal thickness changes and Dk value of rigid gas permeable contact lenses was investigated in 10 volunteers. Each volunteer was fitted with lenses of different Dk values in each eye. A low Dk lens (Dk15) was fitted on one eye of each subject and a high Dk lens (Dk125) on the contralateral eye. After 2 months the reverse was done. After another 2 months, the lenses were again exchanged for the first pair. After each change corneal thickness was measured. A non-significant trend in corneal thickness was found in 13 of the 20 eyes. We conclude that for daily wear use the lower Dk materials meet corneal requirement.

Therapeutic contact lenses have been advocated as an important component of anterior segment ophthalmic careregimes since the late 1960s. Despite favourable reviews in the ophthalmic literature, the perception remains, among contact lens and corneal specialists alike, that the benefits associated with this type of treatment should be considered only as a last resort. The results obtained in 46 consecutive cases fitted with either hydrogel or silicone therapeutic lenses, over an 18-month period are reviewed. Results indicate that successful therapeutic lens programmes can be achieved through a combination of appropriate patient and lens selection, and the initiation of a suitable management strategy. Approximately 25% of patients were fitted successfully with a conventional hydrogel low water content therapeutic lens. Twenty-five per cent of patients required alternative hydrogel lenses of differing parameters. Thirty per cent required silicone lenses to overcome ocular surface and lid abnormalities which had rendered hydrogel lens wear inappropriate. Almost 80% of patients fitted achieved some success with therapeutic lenses. Virtually all of those fitted on the basis of ocular pain achieved relief during the course of the treatment. Results highlight the need for a management protocol for the provision of therapeutic bandage contact lenses on a regional basis.

Tear volumes of 15 normal Hong Kong (HK-Chinese were measured using a cotton thread test (CM and the phenol red thread (PRT) test on 6 different days. The results showed that both CTT and PRT tests performed on normal subjects were reliable over time. The mean CTT and PRT values were 11.8 (±4.4)mm/15s and 15.4 (±4.9)mm/15s respectively. There is a significant difference between the CTT values and the PRT values so the two tests cannot be used interchangeably. There is a day-to-day variation in both tests which may be clinically significant for some subjects and we suggested that more than one measurement be taken when an accurate tear volume measurement is important for the management of the patient. We also compared our PRT results with those of previous investigators and found that the mean PRT value is significantly lower in HK-Chinese subjects than in Caucasian subjects, while no difference was found between HK-Chinese and Japanese subjects.