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Objective: To develop and validate a noninvasive method for measuring tear break-up time (NIBUT) using readily available materials and comparing it to the standard fluorescein tear break-up time (TBUT) assessment. Methods: A prototype xeroscope was made from an ordinary round plastic lid. At its inner lining, a fluorescent green sticker paper printed with black circular concentric grid pattern was fixed to simulate modified placido rings on the precorneal reflection. A central rectangular cut-out measuring 2 cm x 1 cm was made into the base frame serving as the viewfinder for the device through which the precorneal grid reflection was observed. A 30-LED blue light strip was fixed in the inner rim of the lid using a double-sided adhesive tape and was powered by a multivoltage AC-DC power adapter set at 6-volts at 350mA (2 watts). The prototype device was tested on fifty (50) patients (100 eyes), aged 21 to 65 years old, with no apparent ocular surface disorders and eyelid abnormalities. Measurement of NIBUT was done on both eyes using the prototype xeroscope followed by fluorescein TBUT measurement. The two values were compared and their correlation determined by linear-regression. Results: Fifty (50) patients (100 eyes) were enrolled into the study. The mean age was 48.52 years (range 21 to 62 years). The mean NIBUT for both eyes was 20.10 secs, ranging from 11.56 to 36.17 secs, and the mean TBUT was 18.70 secs, ranging from 10.20 to 30.40 secs. The mean difference between NIBUT and TBUT was 1.40 sec. Regression analysis revealed a strong positive linear correlation between the 2 measurements with a computed Rsquared value of 0.9697. Conclusion: The noninvasive technique using the prototype device provided a good alternative approach for measuring tear film stability without disturbing normal tear physiology and dynamics at a fraction of the cost of current commercially-available xeroscopes and tearscopes. [ABSTRACT FROM AUTHOR]

Purpose: To determine the safety, efficacy, and stability of intrastromal corneal rings 10 years after placement for myopia., Methods: Ten eyes with myopia treated with the placement of 360 degrees complete intrastromal corneal rings with the ends sutured together were evaluated at 10-year follow-up for the following: uncorrected visual acuity (UCVA), best spectacle-corrected visual acuity (BSCVA), manifest refraction spherical equivalent (MRSE), induced manifest refractive cylinder, keratometry readings, slit-lamp findings, and ultrasound central pachymetry. Ten-year data were compared to 1-year results to assess visual stability over time., Results: No statistically significant difference was noted between UCVA at 1 year and 10 years. At the 10-year examination, 90% of patients had BSCVA > or = 20/25 and 100% had BSCVA > or = 20/30. There was no statistically significant difference between MRSE at 1 year and 10 years. At the 10-year examination, induced manifest refractive cylinder was >1.00 diopter (D) in 0% of eyes and < or = 0.25 D in 60% of eyes. There was no statistically significant difference between mean central keratometric power at 1-year follow-up compared with 10-year follow-up. No statistically significant difference was noted in central corneal thickness between 1 and 10 years in the eyes studied., Conclusions: Intrastromal corneal rings are an effective and stable method of correcting mild myopia based on optic parameters.

Purpose: Stability of correction is a major factor for successful refractive surgery. Intrastromal corneal rings were placed for the correction of low to moderate myopia beginning 10 years ago. The purpose of this study was to evaluate findings in patients 5 years after ring placement and to compare these findings with 1-year results to assess the stability of effect., Methods: Seventy-two patients (113 eyes) with myopia (range, -0.75 to -4.50 diopters [D]) were treated with the placement of intrastromal corneal rings (360 degrees ), in a multicenter clinical trial between 1993 and 1994 under U.S. Food and Drug Administration phase II and phase III clinical trials. Six insert sizes were evaluated: 0.21, 0.25, 0.30, 0.35, 0.40, and 0.45 mm. The long-term results that were evaluated were uncorrected visual acuity, best spectacle-corrected visual acuity, cycloplegic refraction spherical equivalent at 5 years and proximity of this value to the target refraction determined preoperatively, induced manifest refraction cylinder, and slitlamp findings., Results: Data at the 5-year follow-up showed that uncorrected visual acuity was 20/40 or better in 83% of eyes and 20/20 or better in 64% of eyes, compared to 88% and 43%, respectively, at the first year of follow-up. Only 7% of eyes lost two or more lines of preoperative best spectacle-corrected visual acuity at 5 years, compared to 11% at the first year. No eyes at the 1- or 5-year follow-up had a best spectacle-corrected visual acuity worse than 20/40. Cycloplegic refraction spherical equivalent was within 1.00 D of target refraction in 68% of eyes at 5 years, compared to 71% at the 1-year follow-up. Induced manifest refraction cylinder greater than 1.00 D was reduced to 5% of eyes in the fifth year, compared to 12% of eyes at year 1., Conclusions: Intrastromal corneal rings are a safe, effective, and stable method of correcting mild to moderate myopia, and most patients continue to be satisfied with the results after 5 years. There was no clinically significant change in refractive effect and the central corneas remained clear at the 5-year follow-up in all eyes studied. Further data are currently being collected for 10-year follow-up periods. It is hypothesized that the use of intrastromal corneal rings as a refractive option for mild to moderate myopia will be supported by these additional longitudinal data.