In addition to rods and cones, the human retina contains light-sensitive ganglion cells that express melanopsin, a photopigment with signal transduction mechanisms similar to that of invertebrate rhabdomeric photopigments (IRP). Like fly rhodopsins, melanopsin acts as a dual-state photosensitive flip-flop in which light drives both phototransduction responses and chromophore photoregeneration that bestows independence from the retinoid cycle required by rods and cones to regenerate photoresponsiveness following bleaching by light. To explore the hypothesis that melanopsin in humans expresses the properties of a bistable photopigment in vivo we used the pupillary light reflex (PLR) as a tool but with methods designed to study invertebrate photoreceptors. We show that the pupil only attains a fully stabilized state of constriction after several minutes of light exposure, a feature that is consistent with typical IRP photoequilibrium spectra. We further demonstrate that previous exposure to long wavelength light increases, while short wavelength light decreases the amplitude of pupil constriction, a fundamental property of IRP difference spectra. Modelling these responses to invertebrate photopigment templates yields two putative spectra for the underlying R and M photopigment states with peaks at 481 nm and 587 nm respectively. Furthermore, this bistable mechanism may confer a novel form of “photic memory” since information of prior light conditions is retained and shapes subsequent responses to light. These results suggest that the human retina exploits fly-like photoreceptive mechanisms that are potentially important for the modulation of non-visual responses to light and highlights the ubiquitous nature of photoswitchable photosensors across living organisms.

The deterioration of sleep in the older population is a prevalent feature that contributes to a decrease in quality of life. Inappropriate entrainment of the circadian clock by light is considered to contribute to the alteration of sleep structure and circadian rhythms in the elderly. The present study investigates the effects of aging on non-visual spectral sensitivity to light and tests the hypothesis that circadian disturbances are related to a decreased light transmittance. In a within-subject design, eight aged and five young subjects were exposed at night to 60 minute monochromatic light stimulations at 9 different wavelengths (420–620 nm). Individual sensitivity spectra were derived from measures of melatonin suppression. Lens density was assessed using a validated psychophysical technique. Although lens transmittance was decreased for short wavelength light in the older participants, melatonin suppression was not reduced. Peak of non-visual sensitivity was, however, shifted to longer wavelengths in the aged participants (494 nm) compared to young (484 nm). Our results indicate that increased lens filtering does not necessarily lead to a decreased non-visual sensitivity to light. The lack of age-related decrease in non-visual sensitivity to light may involve as yet undefined adaptive mechanisms.

Cultures and eubacterial PCR are complementary techniques for bacterial identification in eyes with acute postcataract endophthalmitis. PCR technique was needed for identification of the involved microbial pathogen in 25% of all the cases. Eubacterial PCR is more effective than cultures in detecting bacteria in vitreous samples from patients with previous intravitreous administration of antibiotics.

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; for the French Institutional Endophthalmitis Study Group IMPORTANCE Although rare, postoperative endophthalmitis in patients undergoing cataract surgery can lead to anatomical or functional loss of the eye. Therapeutic strategies such as antibiotic prophylaxis and microbiological diagnosis are more effective with a target patient population. New prospective data are needed to identify prognostic factors. OBJECTIVE To identify baseline factors of visual prognosis in patients with acute bacterial endophthalmitis after cataract surgery. DESIGN Prospective study of consecutive patients undergoing cataract surgery, enrolled from March 1, 2004, through December 31, 2005. We analyzed outcomes to determine the effect on the final visual outcome, defined as poor (visual acuity [VA] worse than 20/100) or good (VA 20/40 or better) using univariate and multivariate analysis. SETTING Four academic hospitals. PARTICIPANTS Ninety-nine consecutive patients with cataract. INTERVENTION Corneal phacoemulsification. MAIN OUTCOMES AND MEASURES Factors related to the cataract surgery (complications), initial clinical presentation, and microbiological diagnosis and the final VA. RESULTS The significant baseline factors (at presentation) for good visual outcome (45% of the series) were the winter season, absence of complications during cataract surgery, initial VA, microbiological investigations revealing no microorganism or a coagulase-negative Staphylococcus species (CNSP), and fundus visibility. Quantitative factors associated with a good clinical prognosis were shorter duration of cataract surgery, younger age, and a hypopyon no greater than 1.5 mm. Significant factors associated with poor visual outcome were infection of the right eye, initial VA, corneal edema, a hypopyon larger than 1.5 mm, detection of bacterial species other than a CNSP, and the absence of fundus visibility. Multiple logistic regression analysis showed that high bacterial virulence was the only independent factor (odds ratio, 14.0 [95% CI, 2.7-71.0]; P = .001) for poor visual outcome. On the other hand, low bacterial virulence (odds ratio, 0.2 [95% CI, 0.03-0.6]; P = .01) and the absence of complications during cataract surgery (0.1 [0.01-0.4]; P = .003) were independent factors for good VA. CONCLUSIONS AND RELEVANCE Most clinical outcome factors in acute postoperative endophthalmitis can be identified at presentation. The bacterial virulence level is the main factor predictive of the final visual prognosis.

ABSTRACT.Purpose: Study the clinical and microbiological characteristics and the prognostic factors of post-traumatic endophthalmitis. Methods: Seventeen eyes were included between 2004 and 2010, with clinical and microbiological data collected prospectively. Conventional cultures and panbacterial PCR were performed on aqueous and vitreous samples. Results: Clinical signs of endophthalmitis were observed soon after trauma (1.5 ± 2.5 days). Laceration with an intraocular foreign body (IOFB) was noted in 53% of the patients. At admission, all patients had aqueous humour (71%) and ⁄ or vitreous (53%) samples. Fifteen patients (88%) underwent a pars plana vitrectomy. Bacteria were identified in 77% of the cases: Staphylococcus epidermidis (n = 5), Streptococcus (n = 4), Bacillus (n = 2), Pseudomonas stuzeri (n = 1), and Streptococcus salivarius and Gemella haemolysans (multibacterial infection, n = 1). Progression toward phthisis was observed in 35% of the cases; 41% of the patients recuperated visual acuity (VA) ‡20 ⁄ 40. A good final visual prognosis ( ‡20 ⁄ 40) was significantly associated with initial VA better than light perception (0% versus 70%, p = 0.01) and absence of pupillary fibrin membrane (80% versus 20%, p = 0.05). There was no correlation between visual prognosis and age, the type of laceration (corneal or scleral) or presence of an IOFB. We found a statistical trend toward an association between bacterial virulence and poor final VA. Conclusion: This series showed that better final VA outcomes were associated with initial VA better than light perception, S. epidermidis or culture-negative cases and absence of retinal detachment during the clinical course.

This study shows that corneal collagen cross-linking can stabilize progressive corneal ectasia, both primary and secondary, with no induced iatrogenic effects.

The sHFP technique offers a practical, reliable, and accurate method to measure lens density in vivo and predict lens transmittance over the visible spectrum. An accurate quantification of lens transmittance should be obtained in clinical practice, but also in research in visual and nonvisual photoreception.