International contact lens clinic (New York, N.Y.)最新文献

Blinking plays an important role in maintaining corneal integrity by spreading of the tear film. Although there are studies reporting on blink rate and tear stability, a consensus has not been reached. Therefore, the blink rate and tear breakup time (TBUT) test were performed in 159 healthy young females. The mean TBUT and blink rate values observed were 18.9 seconds and 18.6 blinks/min, respectively. A significant correlation (r = 0.74, p < 0.05) between TBUT and blink rate was found. These results demonstrate that blink rate may be dependent on TBUT, at least among subjects with TBUT less than 19 seconds. Thus, blink rate may depend not only on cortical stimuli but also on the stability of the tear film.

Central and peripheral corneal thickness has been used increasingly to obtain information about physiologic and clinical conditions of the cornea. In this study, a new method based on ultrasonic pachometry for topographical corneal thickness measurement is described. Results suggest that the technique is reliable for clinical determination of global corneal thickness. Measurements taken by one observer on different sessions (intersession variation) and measurements taken by different observers (interobserver variation) are not significant different (p = 0.586 and 0.273, respectively). This new ultrasound topographical pachometric method can be considered a useful tool for determination of topographical corneal thickness. It has implications for the use of topographical ultrasonic pachometry in contact lenses research, refractive surgery, and management of different pathologic conditions.

This project was designed to study the efficacy of orthokeratology and its related problems in a population of young myopic adolescents. Fifty-four young myopia adolescents ages 11 to 15 years were enrolled in the study and followed over a 6-month period. The procedures included (1) baseline refraction, assessment of tear quality and quantity, and cornea examination including cornea topography, A-scan ultrasound of cornea thickness, and spectromicroscopy of the corneal endothelium; (2) diagnostic lens fitting and evaluation; (3) lens dispensing and educating the patients or their parents; (4) follow-up schedule and data analysis; and (5) maintenance lens dispensing and analysis of wearing schedules. Myopia was reduced between −1.25 and −5.00 D (−3.00 D average). Myopia reduction was almost complete in the first 6 months, with most of the reduction occurring during the first 2 weeks. Seventy-five percent of the possible reduction occurred during this 2-week time period. Tear quality and quantity influenced reduction speed and amount. Corneal thickness and endothelium remained unchanged over the study period. Subjective refraction is the most reliable method to measure the status of ocular refractive changes. Corneal staining occurred in 45% of subjects during the procedure, mainly in subjects with tear problems. Eighteen percent of the subjects showed induced astigmatism, which could be reversed by refitting the lens or changing the wearing schedule. Maintenance lenses had to be worn every night for young adolescents to maintain myopia reduction. Orthokeratology is a reliable option for reducing some myopia in young adolescents. The first 2 weeks are critical for the procedure. Complete examination and the data analysis procedures are important for monitoring prognosis and eye health.

Radial keratotomy (RK) is a well-known procedure for reducing myopia. However, the complications associated with the procedure and the development of newer technologies, such as photorefractive keratectomy and laser-assisted in situ keratomileusis, has resulted in the technique of RK falling out of favor. A number of patients who received RK during the 1980s are now experiencing a shift in their prescription and are presenting to primary care practitioners for contact lens fitting. These patients pose a significant challenge to the contact lens practitioner, and novel methods frequently are required to fit corneas that exhibit such abnormal topography. This article reviews the potential problems associated with fitting patients who have received RK and describes a case in which a novel lens design was used to achieve a successful lens fit.