Validation and verification of the OPI 2.0 System

Abstract

PurposeThe Ocular Protection Index (OPI) 2.0 System was developed to evaluate ocular surface protection under a natural blink pattern and normal visual conditions. The OPI 2.0 System implements fully automated software algorithms which provide a real-time measurement of corneal exposure (breakup area) for each interblink interval during a 1-minute video. Utilizing this method, the mean breakup area (MBA) and OPI 2.0 (MBA/interblink interval) were calculated and analyzed. The purpose of this study was to verify and validate the OPI 2.0 System for its ability to distinguish between dry eye and normal subjects, and to accurately identify breakup area.MethodsIn order to verify and validate the OPI 2.0 System, a series of artificial images and a series of still image frames captured during an actual clinical session using fluorescein staining videography were analyzed. Finally, a clinical validation process was completed to determine the effectiveness and clinical relevance of the OPI 2.0 System to differentiate between dry eye and normal subjects.ResultsSoftware analysis verification conducted in a set of artificially constructed images and in actual videos both saw minimal error rates. MBA and OPI 2.0 calculations were able to distinguish between the qualifying eyes of dry eye and normal subjects in a statistically significant fashion (P < 0.001 for both outcomes). As expected, dry eye subjects had a higher MBA and OPI 2.0 than normal subjects (0.232, dry eye; 0.040, normal and 0.039, dry eye; 0.006, normal, respectively). Results for the worst eyes and all qualifying analyses based on staining, forced-stare tear film breakup time, and MBA were numerically similar.ConclusionThe OPI 2.0 System accurately identifies the degree of breakup area on the cornea and represents an efficient, clinically relevant measurement of the pathophysiology of the ocular surface.

A single-center study evaluating the effect of the controlled adverse environment (CAEsm) model on tear film stability

“…This is a result of significant strides in ocular surface biology research, and improvements in clinical assessment techniques such as, corneal staining, blink pattern analysis, and various measures of tear film stability 4,5. In two recent papers we described the stepwise development of our improved method of tear film analysis, which we have designated the ocular tear film analysis protocol OPI 2.0 (Ora, Inc. Andover MA, USA; patent pending) system 6,7. This method combines a number of optimized parameters with automated video data capture and analysis, to generate a more objective, quantitative measure of tear film dynamics.…”

“…For example, it was found that reduction and standardization of the quantity of fluorescein used, led to a shift of the reference values for TFBUT (to a mean value of 7 seconds for normal subjects, and 2.5 seconds for those with dry eye) 5. Similarly, our goal in developing the OPI 2.0 system was to enhance and streamline dry eye metrics by measuring tear film stability under conditions of natural, rather than forced stare blinking 6,7. Furthermore, by capturing the natural dynamics of the tear film with automated methods, it is possible to expand upon previous studies of the interaction between blinking and tear film behavior 8–13…”

“…We defined OPI as the ratio of interblink interval (IBI) and TFBUT; lower values of the index and particularly values less than one, were associated with increased risk of keratitis (since on average, break-up of the tear film and subsequent corneal exposure would occur prior to the next blink) 9. Our more recent studies employed break-up and blink data captured with the OPI 2.0 system, to yield another estimate of corneal surface exposure 7. This alternative index relied upon the mean break-up area (MBA) rather than a break-up time elicited under forced stare conditions 6…”

“…The OPI 2.0 system was designed to evaluate ocular surface protection under a normal blink pattern and normal visual conditions, using fully automated software algorithms that provide real-time measurement of corneal exposure 7. This system provides a simultaneous measurement of both break-up area and blink rate.…”

An evaluation of Retaine&trade; ophthalmic emulsion in the management of tear film stability and ocular surface staining in patients diagnosed with dry eye

“…Tear film stability and IBI, both assessments of drying on the ocular surface, were measured by the Ocular Protection Index (OPI) 2.0 System, an automated measure of ocular surface protection under normal blink pattern and normal visual conditions. 15 , 16 Video capture and analysis using the OPI 2.0 System allows for a calculation of mean corneal surface exposure, otherwise known as mean breakup area (MBA). Final endpoints were percent change in MBA and IBI in seconds.…”