Topical use of latanoprost for glaucoma can lead to an increase in iris and eye lash pigmentation but the precise mechanism is unclear. To study the possible effect of this drug on ocular melanogenesis, we used cultures of bovine iris melanocytes, iris pigment epithelial cells, retinal pigment epithelial cells, and choroidal melanocytes. Latanoprost (at concentrations of 10(-8) and 10(-6) mol) was applied for 3 days, and cell numbers as well as melanin content were measured prior to and 10 days after exposure and compared to untreated controls. In none of the cell types examined a significant increase in melanin content or an increase in cell proliferation was observed. Additional treatment with the tyrosinase inhibitor alpha-methyl-p-tyrosine showed no significant effect either. Our results support the concept of a rather complex mechanism underlying the increased iris pigmentation after treatment with latanoprost.

Animals↗

PubMedDate not supplied

Pneumococcal infection after temporary tarsorrhaphy for epikeratophakia.

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Anti-Bacterial Agents↗

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Electron microscopic examination of prelathed, lyophilized tissue used for epikeratophakia in humans.

Morphologic changes secondary to cryolathing and lyophilization have been described in tissue lenses used for epikeratophakia. We report the electron microscopic findings of an aphakic tissue lens which could not be used because of sudden preoperative myocardial infarction of the patient. Scanning electron microscopy revealed the presence of three distinct zones (peripheral, intermediate, and central) on the stromal side of the lens. The surface of the central zone appeared to be the smoothest, as a consequence of the different angle of lathing. The Bowman's layer side of the tissue lens exhibited a uniform, smooth surface. Transmission electron microscopy revealed a largely normal collagenous structure of both stroma and Bowman's layer. Interfibrillary distances were within normal limits. Several giant stromal spaces of various dimensions filled with homogeneous material were observed. Variably preserved keratocytes were a regular finding among the lamellae. Our findings confirmed some of the structural changes previously observed in tissue lenses not used for epikeratophakia in humans. The limited size of a smooth central zone of the posterior surface could explain some postoperative complaints such as persistent glare phenomena, as well as prolonged visual rehabilitation time, especially in those cases where centration of the epi-lens onto the recipient cornea is not optimal.

Cornea↗

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Epikeratophakia for the correction of myopia: lenticule design and related histopathological findings.

In spite of the numerous changes in surgical technique, epikeratophakia for the correction of myopia is still far from achieving optimal results. The removal rate of myopic lenticules is much higher than that of aphakic or keratoconus lenticules and has prompted the FDA to deny its approval to the industrial production of epi-lenses for the correction of myopia. We report a patient who underwent epikeratophakia for the correction of high myopia in his left eye and required removal of the lenticule because of unsatisfactory visual outcome. The histologic and electron microscopic examination of the removed lenticule revealed the presence of folds in both Bowman's layer and superficial stroma. These had been described in the past and related to the surgical technique used at that time; they were thought to be the cause of poor visual acuity n two patients, and had prompted, therefore, a change in surgical technique. Our findings suggest that the present lenticule design could be responsible for the presence of folds and the consequent poor visual result.

Adult↗

PubMedDate not supplied

In vivo evaluation of epikeratophakia lenses by means of Scheimpflug photography.

The recovery of clarity in frozen, lyophilized human tissue lenticules used for epikeratophakia has been a matter of controversy. According to some authors, several months are necessary for the lenticules to resume normal transparency; others report clinical experience of much shorter times. Up to now, objective documentation of such findings has not been substantiated. We used a Topcon LS-45 camera to photograph four eyes that underwent epikeratophakia, preoperatively and at 2, 4, 6, and 8 weeks after surgery, and analyzed the film negatives by linear microdensitometry. The degree of film blackening, that is the density of the tissue, was expressed graphically by peaks of various height measured in millimeters. Best spectacle corrected Snellen visual acuity was also recorded. Similar measurements of corneal transparency were performed in 20 healthy adult volunteers whose best corrected spectacle visual acuity was 20/20. In the four operated eyes, (two keratoconus, one aphakia, and one myopia), the light scattering was increased in both the host cornea and the donor lenticule. The lenticule had a considerably increased light scattering in all patients at both 2 and 4 weeks after surgery, but was comparable to that of unoperated corneas in three of four patients at 6 weeks.

Adult↗

PubMedDate not supplied

Cyanoacrylate in retinal surgery.

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Cadaver↗