Journal of The British Contact Lens Association最新文献

Twenty-five Quantum II rigid gas permeable corneal lenses, in a range of five negative back vertex powers but otherwise of identical nominal specification, were immersed in distilled water for up to 6 weeks and the back optic zone radius of each lens was measured periodically to determine the magnitude and time course of curvature changes during hydration. Changes in back optic zone radius were of small magnitude and were less than the tolerance limits of ±0.05mm listed in British Standard BS7208: Part 1: 1992 (‘Specification for Rigid Corneal and Scleral Contact Lenses’) for rigid gas-permeable corneal lenses.

Infrared thermography was employed to measure the change in ocular surface temperature on eye opening within agroup of 11 dry-eye patients and seven control subjects. Qualitatively, the colour coded thermograms were found to be disorganised and irregular in the dry-eye group. Quantitatively, the decrease in temperature was found to be much more rapid in the dry-eye group (0.88 ± 0.23°C in 7s) compared with the control group (0.21 ± 0.27°C) (P<0.0001). This faster rate of cooling can be explained in terms of a greater evaporation rate and the increased ocular surface temperature on eye opening in a dry eye. This observation, if confirmed on a larger study group, potentially offers a new, objective, non-invasive system for analysis of the tear-film and dry-eye therapies.

Non-compliance in the contact lens field has been widely documented and discussed. The major areas of non-compliance in contact lens wear have been highlighted as the lack of hand and lens-case hygiene, the overwearing of contact lenses, the poor attendance of patients at aftercare appointments and the inadequate use of care and maintenance systems. Education is one of the factors thought to influence compliance. A prospective, randomised, controlled and double-masked study was performed to assess the effect of a ‘compliance enhancement strategy’ on levels of compliance among contact lens wearers over 12 months. Eighty experienced contact lens patients were allocated randomly to two experimental groups. A standard level of contact lens instruction was applied to the first group and, in addition, extra education was given to patients in the second group. Patients were given free supplies of ReNu Multi Purpose solution and Medalist 38 soft contact lenses (Bausch & Lomb, Rochester, New York). Compliance levels were assessed at a 12-month aftercare appointment by demonstration and questionnaire. The results indicate that the additional education had no significant effect on the compliance levels of the patients to whom it was applied. The population of contact lens wearers was generally very compliant and the contact lenses and care regimen were clinically successful. The results for the whole study population were compared with those reported in previous compliance studies. The results were found to be similar in many areas. Practitioners are encouraged to review the compliant behaviour of their contact lens patients at every aftercare appointment and pay particular attention to the areas of frequent non-compliance highlighted.

Two separate international ring tests were carried out to assess the measurement capability of the focimeter and the Moiré deflectometer as applied to the power-related parameters of toric soft contact lenses. The results show that in order to measure the sphere and cylinder powers and axis direction using the focimeter a high number of replicate measurements are required to be confident of the test to within reasonable tolerance limits. The availability of the deflectometer provides lens manufacturers with measurement technology which is objective and reproducible and can be used to measure the power-related parameters of toric soft lenses with increased reproducibility using relatively few replicate measurements.

A multicentre, controlled, masked and randomised trial was conducted to evaluate the benefits of proactive contactlens recommendation by optometrists on prescribing trends. From 1st January 1995, patients presenting for routine eye examination to the practices of three optometrists were selected according to the study criteria. The first 150 patients satisfying this criterion were prescribed contact lenses only if they specifically asked to try them. The next 150 suitable patients had the option of contact lens correction presented to them. Every patient trying contact lenses was offered a ‘free trial’ of 1.Day Acuvue, or Acuvue or Surevue (Vistakon, Johnson & Johnson). The practitioners had the freedom to use products of other manufacturers if this was clinically necessary. Patient-initiated trials resulted in 17% of patients being fitted with lenses, whereas practitioner-initiated trials resulted in significantly more patients being-fitted with lenses (31%; P < 0.0125). Presbyopic patients were less likely to try contact lenses than pre presbyopes (10% and 34% respectively; P < 0.0001); however, whether or not the patient was Presbyopic had no effect on the success of trials (nonpresbyopes = 90% presbyopes = 78%). Eighty-eight per cent of all patients in the trials were successfully fitted with lenses. The results of this study demonstrate that a proactive approach to contact lens fitting is likely to have a positive impact on increasing the number of contact lens wearers.