Laser flare photometry in the therapeutic management of bacterial chronic pseudophakic endophthalmitis

A Rayleigh Scatter-Based Ocular Flare Analysis Meter for Flare Photometry of the Anterior Chamber

PURPOSE

Existing flare photometers are based on the Tyndall effect, which requires sophisticated laser photometry. The ocular flare analysis meter (OFAM) is a nonlaser photometer that uses quantitative Rayleigh scatter and absorption from visible light to compute a flare value. This study is designed to correlate OFAM measurements with qualitative measurements of flare in vitro and in vivo.

METHODS

Following validation of the device on artificial anterior chambers containing known protein concentrations, flare readings were obtained from 90 subjects (46 with and 44 without uveitis) in one eye. Subjects were graded by the Standardization of Uveitis Nomenclature (SUN) working group flare scoring system and received the OFAM flare measurements.

RESULTS

The OFAM showed linear response in vitro to protein concentrations ranging from 0 to 0.5 mg/ml. In clinical use in subjects ranging from SUN flare scores of 0+ to 2+, OFAM showed statistically significant measurement accuracy (P = 0.0008 of flare 0 versus flare 2; P = 0.031 of flare 0 versus flare 1). Distinction of SUN scores 1 and 2 was borderline significant (P = 0.057).

CONCLUSION

The OFAM photometry correlates with the standard SUN scoring system. This method may provide an objective method to diagnosis and monitor uveitis. Further longitudinal studies are warranted.

TRANSLATIONAL RELEVANCE

Currently, ocular flare is assessed qualitatively in most clinical settings. The existing methodology uses only Tyndall effect to measure flare. The OFAM uses an alternate, nonlaser means for measurement of anterior chamber flare by measure of Raleigh scatter. This pilot clinical study suggests that the OFAM device may be useful in measurement of uveitis activity.

Postcataract surgical inflammation

PURPOSE OF REVIEW

To describe the epidemiology, pathogenesis, and recent developments in the diagnosis and management of postcataract surgery inflammation.

RECENT FINDINGS

In patients with pre-existing uveitis, control of inflammation with topical and/or systemic therapy for 3 months preoperatively continues to be important in lessening the risk of postoperative inflammation and complications. During cataract surgery, intraocular lens selection in these patients is important. Recent literature suggests that modern intraocular lenses (IOLs), particularly hydrophilic or hydrophobic acrylic lenses, generally have good uveal biocompatibility in uveitic patients. The postoperative course can be complicated by inflammation and cystoid macular edema (CME), and in uveitic patients, intensive perioperative steroid treatment can lessen these complications. Recent studies show that in uveitic patients, the improvement in CME and inflammation after intravitreal triamcinolone is better than after orbital floor triamcinolone injection, but that a single intraoperative orbital floor injection of triamcinolone is as effective as a 4-week course of postoperative oral prednisolone. Although postoperative inflammation in uveitic patients may be due to recurrence of uveitis, one must recognize other important potential causes of postoperative inflammation and treat accordingly.

SUMMARY

Most patients with postcataract inflammation have good visual outcomes provided that the cause is recognized and that there is adequate perioperative planning in patients predisposed to inflammation.

[Chronic postoperative endophthalmitis]

Chronic postoperative endophthalmitis designates delayed-onset postoperative endophthalmitis appearing more than two weeks after surgery, revealed by chronic intraocular inflammation with phases of inflammatory recurrence, which, at the beginning of the disease course, is partially sensitive to local corticosteroid treatment. It differs therefore from acute endophthalmitis in the immediate postoperative phase, from acute differed endophthalmitis after filtrating surgery, which appears years after the surgery, and from endogenous endophthalmitis. The most frequent presentation is granulomatous uveitis, often hypertonic, in an eye operated for cataract, presenting phases of recurrence sensitive to corticosteroid therapy but which recurs as soon as treatment is interrupted. Whitish condensations in plaques on the posterior capsule suggest the diagnosis and over several months the vitreous becomes inflamed. Ocular samples allow cytological analysis of an infectious process and bacteriological analysis in culture and with PCR. Treatment includes lavage of the sac with vancomycin and can be associated with posterior capsulectomy and intravitreal injections of antibiotics possibly associated with systemic antibiotic therapy. Treatment is prolonged because of the slow replication of the microorganisms involved. In approximately one-third of cases, the implant, the capsule, and the sac must be removed over 360° to permanently halt the intraocular infection. The diagnosis and specific treatment should be as early as possible since the aggressiveness of the treatment required is correlated with the time to management of the infection.