Biomedical subjects

Eric Papas

Publications and source records attributed to Eric Papas.

3 recordsLinked to original sources

PubMed2006

Silicone hydrogel contact lenses and the ocular surface.

For 30 years, contact lens research focused on the need for highly oxygen-permeable (Dk) soft lens materials. High Dk silicone hydrogel contact lenses, made available in 1999, met this need. The purpose of this review is to examine how silicone hydrogel lens wear affects the ocular surfaces and to highlight areas in which further research is needed to improve biocompatibility. Silicone hydrogel lenses have eliminated lens-induced hypoxia for the majority of wearers and have a less pronounced effect on corneal homeostasis compared to other lens types; however, mechanical interaction with ocular tissue and the effects on tear film structure and physiology are similar to that found with soft lens wear in general. Although the ocular health benefits of silicone hydrogel lenses have increased the length of time lenses can be worn overnight, the risk of infection is similar to that found with other soft lens types, and overnight wear remains a higher risk factor for infection than daily wear, regardless of lens material. Future contact lens research will focus on gaining a better understanding of the way in which contact lenses interact with the corneal surface, upper eyelid, and the tear film, and the lens-related factors contributing to infection and inflammatory responses.

Contact Lenses, Extended-Wear↗

PubMed2005

A novel method for assessing variations in visual acuity after the blink.

A novel instrument was developed to assess the visual acuity in correlation with time after blink. The method uses an optical blink detector which triggers the display of a random target symbol on a computer monitor. The delay time between blink and symbol display varies randomly from blink to blink, the exposure duration is fixed at 100 ms. The subject has to identify the correct symbol, a score is kept of the correct responses in correlation to delay time. The recovery of visual acuity after blink was measured for subjects wearing two types of bifocal contact lenses and a control group of non-contact lens wearers. All groups required between 200 and 500 ms to achieve their best visual acuity. Subjects wearing the translating bifocal lenses recovered their vision significantly faster than the subjects wearing no lens or the simultaneous vision bifocal lens.

Adult↗

PubMed2005

Corneal mechanical sensitivity measurement using a staircase technique.

PURPOSE: To determine the repeatability of an unequal staircase technique (Garcia-Perez Staircase, GPS) to measure corneal mechanical threshold using the CRCERT-belmonte Aesthesiometer, and to compare this with a previously-reported psychophysical method (method of constant stimuli, MOCS). METHODS: The GPS, utilising unequal ascending and descending steps, was used to obtain a threshold measurement from the mean of six response reversals. repeatability was determined for the GPS and MOCS methods (N = 14), and threshold results obtained with each method were compared (N = 10). RESULTS: The GPS (65.0 +/- 16.9 mL min(-1); CoR +/- 18.3 mL min(-1)) method was more repeatable than the MOCS (64.0 +/- 15.7 mL min(-1); CoR +/- 37.3 mL min(-1)) and the absolute values obtained with the two methods were not significantly different. CONCLUSIONS: Although each method gave equivalent threshold results, the GPS method was more repeatable and quicker to apply and hence should reduce the influence of patient fatigue and help to minimise possible carry-over effects.

Adult↗