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PAVANI MURTHY PENUGONDLA, RR Sudhir, Sirisha Tadepalli, Deepti Talele, ARUSHI GOYAL, Sanjay Mahadik, Prema Padmanabhan, Karthikeyan Rangaswamy, Sangly P Srinivas; Measurements of aqueous flare objectively using an ocular fluorometer. Invest. Ophthalmol. Vis. Sci. 2017;58(8):562.
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The quantification of aqueous flare in post-cataract or uveitis patients is performed subjectively or using a laser flare meter. In this project, we have employed a newly constructed confocal spot fluorometer equipped with a lock-in amplifier for flare measurements in a cohort of post-cataract patients. Since the inclusion of lock-in amplifiers can overcome the influence of external light, we expect to make flare measurements with higher sensitivity and dynamic range than the conventional laser flare meter.
We used a confocal ocular fluorometer to measure the light scatter from the anterior chamber (a/c) as an index of aqueous flare. The fluorometer has a depth resolution of < 300 µm, and hence, can yield depth-resolved measurements from the a/c. Moreover, as a non-depth scanning device, one can place the focus of the excitation beam at any spot in the a/c. The instrument is also equipped with a white LED as a light source and a lock-in amplifier for emission/scatter detection. For scatter measurements, we removed the excitation filter, and placed the focal diamond in the a/c using either 0.5/0.25 mm slits in front of the LED. The excitation and emission arms were held 45° apart for all measurements.
The aqueous flare intensities (measured as scatter intensity in mV) in normal subjects were 0.177± 0.006mV (n = 12 eyes) and 0.069± 0.005mV (n = 13 eyes) at 0.5mm and 0.25mm slit widths, respectively. In the post cataract subjects (1 day), the mean flare intensities were 0.4 ± 0.023 and 0.231 ± 0.018mV (n = 16 eyes) at 0.5mm and 0.25mm, respectively, which were significantly different from normal eyes (p < 0.05). The corresponding eyes were scored at 0 to 2+ as per the subjective classification of Standardization of Uveitis Nomenclature (SUN) flare scoring system. Further comparison showed that the flare intensity measured with 0.25 mm is significantly different from contralateral eyes in cataract patients (p < 0.05).
Our data indicates that the ocular spot fluorometer can be employed to grade the aqueous flare quantitatively on a finer scale. A slit width of 0.25 mm, which enables higher depth resolution, is much more reliable for measurements of aqueous flare. Overall, we have shown a simple technique for assessing aqueous flare that could be used for monitoring the efficacy of pharmacological strategies quantitatively, and possibly, aid in early detection of relapses in uveitis patients.
This is an abstract that was submitted for the 2017 ARVO Annual Meeting, held in Baltimore, MD, May 7-11, 2017.
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