Changes in eye colour during early childhood: sex and genetic differences

Men's preference for women's facial features: testing homogamy and the paternity uncertainty hypothesis

Male mate choice might be based on both absolute and relative strategies. Cues of female attractiveness are thus likely to reflect both fitness and reproductive potential, as well as compatibility with particular male phenotypes. In humans, absolute clues of fertility and indices of favorable developmental stability are generally associated with increased women’s attractiveness. However, why men exhibit variable preferences remains less studied. Male mate choice might be influenced by uncertainty of paternity, a selective factor in species where the survival of the offspring depends on postnatal paternal care. For instance, in humans, a man might prefer a woman with recessive traits, thereby increasing the probability that his paternal traits will be visible in the child and ensuring paternity. Alternatively, attractiveness is hypothesized to be driven by self-resembling features (homogamy), which would reduce outbreeding depression. These hypotheses have been simultaneously evaluated for various facial traits using both real and artificial facial stimuli. The predicted preferences were then compared to realized mate choices using facial pictures from couples with at least 1 child. No evidence was found to support the paternity uncertainty hypothesis, as recessive features were not preferred by male raters. Conversely, preferences for self-resembling mates were found for several facial traits (hair and eye color, chin dimple, and thickness of lips and eyebrows). Moreover, realized homogamy for facial traits was also found in a sample of long-term mates. The advantages of homogamy in evolutionary terms are discussed.

Prostaglandin postscript: a personal reflection

The long and arduous process that led to the development of ocular hypotensive prostaglandin derivatives over the past three decades has been reviewed several times. In this "postscript" to the second Survey of Ophthalmology supplement devoted to the ocular hypotensive effects of prostaglandin derivatives, only two aspects of this new approach to the medical management of glaucoma are discussed: 1) The implication of the observed prostaglandin-induced increase in iridial pigmentation with respect to the understanding of the role of prostaglandins and of iridial melanocytes in the protection against the damaging effects of light, and in the maintenance of normal intraocular microenvironment; and 2) The rationale behind the use of a combined formulation of a prostaglandin derivative and a beta-blocker for the protection against increased intraocular pressure. The need to consider not only target pressure, but also target mechanisms, in the selection of medical therapy regimen for any given glaucoma patient is emphasized.

Heterochromia after pediatric cataract surgery

PURPOSE

Changes in iris color have been noted anecdotally after cataract surgery in infants, but they have not been studied systematically. The mechanism for these iris color changes has not previously been reported in the biomedical literature.

METHODS

Photographs were taken of both eyes of 15 children and 11 rhesus monkeys who had undergone unilateral cataract surgery. Masked examiners reviewed the photographs and compared the iris color of the eyes that were operated on with the eyes that were not operated on. Between 4 and 6 weeks postoperatively, the level of prostaglandin F(2alpha) in the aqueous humor (n = 4) and vitreous humor (n = 2) was measured in both the operated and nonoperated eyes of 4 monkeys that had undergone a neonatal lensectomy during the first 5 days of life.

RESULTS

Thirteen of 15 children had a darker iris color in the operated eye in relation to the nonoperated (control) eye. Four of 11 monkeys had a uniformly darker iris in the operated eye; the other 7 monkeys had regional darkening or patches of darker iris in the eye that was operated on. The prostaglandin F(2alpha) levels in neonatal monkeys were higher in the aqueous humor and in the vitreous humor of the operated eye in relation to the nonoperated eye.

CONCLUSION

In some children, cataract surgery is associated with a darkening of the iris color in the operated eye. We speculate that this darkening results from an exuberant prostaglandin release stimulated by the cataract surgery and may occur through the same or a similar mechanism by which latanoprost causes the darkening of iris color.

Prostaglandins: a new approach to glaucoma management with a new, intriguing side effect

This introductory overview considers the advantages of a class of local hormones-the prostaglandins (PGs)-for the management of intraocular pressure (IOP) in glaucoma, over agonists and antagonists of neurotransmitters that dominated this field in the 20th century. PGs and PG analogues, in particular esterified prodrug forms of PGF2 alpha, are effective ocular hypotensive agents, but cause some conjunctival hyperemia and corneal sensory irritation at higher concentrations. Based on structure-activity studies, a 17-phenyl PGF2 alpha prodrug, latanoprost (PhXA41), was found to have a greatly improved therapeutic index, without compromising the ocular hypotensive potency of PGF2 alpha prodrugs. The IOP lowering mechanism of such PGF2 alpha s, increased uveoscleral outflow, can be expected to have great physiologic advantages, especially with respect to normal tension glaucoma, over most currently used ocular hypotensive drugs. The introduction of this new approach has already led to a new insight into the control and clinical significance of this outflow route. Similarly, the newly discovered ocular side effect, PG-induced increase in iridial pigmentation, can be expected to provide insight into the oculo-protective role of iridial melanocytes and into the punative association between a decline in the ocular melanin system and the vulnerability of the eye to some age-related diseases.

Relationship between hair/eye color and primary vesicoureteral reflux in children

The relationship between hair/eye color and primary vesicoureteral reflux was analyzed in more than 900 children. Children with blonde hair/blue eyes did not show an increased prevalence of reflux nor did any other hair/eye combination. With the possible exception of rufous coloring, the color of the hair and eyes are poor predictors of the competence of the ureteral orifice.

Heritability in visual-geometric illusions: a family study

The Müller-Lyer and Ebbinghaus illusions were tested in 203 mother-father-offspring triads and 303 sibling pairs. Significant familial resemblances were found in all but the overestimated segment of the Ebbinghaus illusion. These results suggest that responses to visual-geometric illusions, mediated by optical or neural interactive mechanisms, show patterns of familial resemblance which may be based upon heritable factors.