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Purpose: Lattice corneal dystrophy type I is an autosomal dominant corneal dystrophy caused by allelic mutations of the BIGH3 gene. Type I dystrophy is recognized clinically by the characteristic net of linear opacities within the corneal stroma that results from an accumulation of amyloid. This study was designed to evaluate the therapeutic potential of phototherapeutic keratectomy (PTK) for the treatment of lattice corneal dystrophy type I., Patients and Methods: PTK was performed with the Chiron Technolas Chiron Keracor 217c on a series of 19 eyes of 13 patients with lattice dystrophy type I. Mean patient age was 38.9 years. The mean follow-up period was 36 months. Localization of central opacities was determined by analyzing Scheimpflug images. The changes in spherical equivalent and best corrected visual acuity were evaluated at 1, 3, 6, 9, 12, 18, 24 and 36 months., Results: The central depth of the deposits measured with the Scheimpflug camera was on average 74.14+/-31.03 microm in the primary dystrophies and 30.1+/-10 microm in graft recurrence. We noted a clear improvement in visual acuity, which increased by 0.257+/-0.120 to 0.600+/-0.178 as of the 3rd month and stabilized at 0.684+/-0.257 until the 36th month. A disappearance of repeating ulcerations was observed at month 30. We found a statistically significant correlation (R=0.6776; p=0.0109) between the improvement in vision (in lines) and the depth of opacities (with the Scheimpflug camera). The mean hyperopic shift caused by photoablation (69+/-15 microm) was +0.71+/-1 D at 36 months., Conclusion: These results confirm that PTK is an effective method of managing corneal lattice dystrophy type I.

Purpose: The cornea is frequently associated to hypoxia, whether during residence in the heights or more often when wearing contact lenses. To evaluate the corneal modifications induced by hypoxia at an infraclinical stage, we have used redox fluorometry that enables to study in vivo the metabolic response of the cells while measuring the fluorescence of the flavoproteins (FAD) of the corneal cells., Methods: The variations of the corneal fluorescence were studied in 12 healthy subjects, before and after a topically-induced 5-minute corneal hypoxia, submitting 2 eyes to a prehumidified flow of nitrogen 100%. The results were compared to those found in the same subjects after exposure under the same conditions to an ambiant air flow (N2 = 69%; O2 = 21%). The measurements of the corneal fluorescence were carried out with the fluorophotometre Flurotron Master FM2., Results: The authors did not find any statistically significant difference in the corneal fluorescence between the right and the left eyes of these 12 subjects, whether under normal conditions, under hypoxia, or under air flow (wilcoxon T-test, Friedman test)., Conclusion: As there are no significant results, these authors suggest that the chosen exposure time, although sufficient in vitro to induce a modification of the fluorecence of the cellular flavoproteins, may be too "short" in vivo. The use of complementary filters with the FM2 system would yield more information. The study of these results led the authors to broaden their search whether by looking for conditions for general hypoxia (hypobarric box) or by increasing local hypoxia (contact lenses).

The corneal endothelium plays a major part in corneal deturgence and hydratation by functioning as a barrier and a pump. Fluorophotometry enables assessment of this barrier function because of endothelial permeability to fluorescein. After a description of the technique of fluorophotometry, the authors show its interest in the understanding of endothelial physiopathology: during aging, in compensated or decompensated endothelial dystrophy, during lens and corneal surgery, in irido-corneal endothelial syndrome and in pharmacology.

The oral fluorophotometric exploration is able to simultaneously quantify the permeability of the blood aqueous (KIN, KOUT) and blood-retinal (PVPR) barriers. It is possible to detect the breakdown of the blood aqueous barrier 3 days after cataract surgery with this fluorophotometric method. Ocular inflammation is responsible for this leakage and non steroidal anti-inflammatory drugs prevent this breakdown. In this paper, we studied the effect of 0.1% indomethacin treatment to patients before and after cataract surgery. This double-blind study was performed in 34 patients: 18 patients in the indomethacin group and 16 patients in the placebo group. We showed that the apparent transfer coefficient of fluorescein in the anterior chamber (KIN) was statistically lower in the indomethacin group (0.0220 +/- 0.0179 hr-1) than in the placebo group (0.0371 +/- 0.0187 hr-1) on the 3rd postoperative day (p = 0.027).

Kinetics of rod pigment regeneration were studied in vivo in Fauve de Bourgogne and Albino rabbits by adapto-electroretinography (AERG). Electroretinography in the rabbit using polychromatic flashes affords the means to dissociate the response of the cones (a-wave, b1-wave: photopic function), from that of the rods (b2-wave scotopic function). After photobeachting, electroretinograms were recorded at two minutes' intervals during dark adaptation of one hour duration. Variations of b2/b1 with time of dark adaptation provide an adapto-electroretinogram giving relative measurements of rod pigment concentration at various stages of regeneration. In the present study, photobleaching was provoked by monochromatic light (at 405, 436 and 546 nm) actinometrically controlled. Studies were conducted in two Fauve de Bourgogne and two Albino rabbits. The effect of four doses, varying from 4.10(17) photon.cm-2 to 1.10(19) photon.cm-2, was measured at each wavelength on the AERG in the four rabbits. First order kinetics for rod pigment regeneration were observed, mainly at 546 nm and at high dose levels: overall regeneration rate is apparently controlled by the isomerization step. For Fauve de Bourgogne and Albino rabbits, the regeneration rate depends on the bleaching wavelength and on the dose. At high dose levels and for long wavelengths, delayed recoveries are observed in the Fauve de Bourgogne animals. However, durations of delays are shorter with monochromatic light experiments than with polychromatic light bleaching, at the same dose. Differences of ocular media transmission may be responsible for a faster regeneration process at shorter than at longer wavelengths.

Photobleaching quantum yields of visual pigments extracted from retinas of the "fauve de bourgogne" and "albino" rabbit were measured in monochromatic light. For the "fauve de Bourgogne" rabbit, the photobleaching quantum yield was to be 0.65 at different excitation wavelengths (546, 491.6 and 436 nm); at shorter wavelengths, this quantum yield was lower ie. 0.36 at 405 nm. This wavelength effect has been observed on visual pigments extracted from bees retina. In contrast, in the "albino" rabbit, the photobleaching quantum yield was constant and equal to 0.31 whatever the excitation wavelength between 546 and 405 mn.

Among various fluorophotometric methods performed on the anterior segment, topical administration of fluorescein was developed. This local administration allows to measure the aqueous humor flow and the permeability of the corneal endothelial. The examinations are performed on a computerized fluorophotometer: the Fluorotron Master. This fluorophotometer has been designed to accurately measure fluorescein's concentrations into the eye and especially in aqueous humor and cornea. Anterior chamber adapter magnifies the scan for detailed work in the anterior chamber and lens. The Fluorotron is supplied with a cuvette holder and a cuvette which is adapted to the optical head for measuring the concentration of fluorescein in blood plasma or in buffered aqueous samples. A good linearity was obtained between the meter readings and the concentrations of fluorescein in phosphate buffer with pH 7.4, within the range between 1 ng and 1000 ng. Based upon the mathematical analysis of Yablonski the method by fluorescein instillation is simple and safe and gives the loss coefficient, ko, of the dye from the anterior chamber, the aqueous humor flow, F, and the endothelial transfer coefficient kc.ca. Calculations were carried out on twenty one normal eyes yielding average values for F 2.97 +/- 0.93 microliter.min-1 (Mean +/- S.D.) and for kc.ca 4.02 +/- 0.40. 10(-1) min-1. These values are comparable to those of other authors.

The effects of various drugs on the human aqueous humor flow were studied by the fluorophotometric method of Yablonski (topical fluorescein instillation). The effect of the beta-adrenergic blocker (Timolol) on aqueous humor flow and on intra-ocular pressure has been studied in ten normal eyes on the Fluorotron Master. We found that the acute decrease in intra-ocular pressure was equal to 1.39 +/- 0.44 microliter.min-1 for the Timolol treated eyes, and equal to 2.79 +/- 0.57 microliter.min-1 for the untreated eyes (Placebo). The difference between Timolol and Placebo was statistically significant (Student t-tested, and Wilcoxon W-tested). The fluorophotometric method is superior to the tonographic method by giving a more favorable condition to study the facility of outflow in steady physiological state. Our results are in good agreement with other authors and show Timolol to have little or no effect on the facility of outflow.

Recent studies of the photochemistry of visual pigments are reported. Results obtained on rhodopsine and model compounds, by means of techniques based upon continous or pulsed excitation are compared. The mechanique of the primary photochemical step of the bleaching of rhodopsine is discussed. The process is occuring on a time scale of picosecond and a new concept of proton transfer followed by a conformation charge is opposed to the classical cis-trans photo isomerisation of the retinal moiety. The origin of the electrical response of the photoreceptor cells is still controversial.