Ultrasound elastography for evaluating stiffness of the human lens nucleus with aging:a feasibility study

AIM:To investigate the significance of ultrasound elastography for evaluating stiffness of the human lens nucleus in volunteers with different ages.METHODS:A total of 90 volunteers(lens transparency,uncorrected visual acuity≥0.5,intraocular pressure:14-19 mm Hg)were divided into 3 groups according to age:Group A(30 people,median age:82±3.5 y,mean axial lengths 23.7±0.5 mm);Group B(30 people,median age:46±2.1 y,mean axial lengths 23.9±0.4 mm);and Group C(30 people,median age:22±3.5 y,mean axial lengths 24.0±0.4 mm).Lens nuclear stiffness was measured by Free-hand qualitative elastography by independent operators.Strain gray scale and color-coded elastography maps were recorded.In each case,three consecutive detections were performed and strain ratio was used for statistical analysis.RESULTS:Elastography analysis showed excellent diagnostic performance for lens sclerosis.Lens strain ratio was lowest(0.03±0.01)%in Group A and highest(2.03±0.43)%in Group C.Lens strain ratio was moderate(0.64±0.10)%in Group B.There were significant differences between these three groups(P<0.05).The lens nucleus strain rate changes with age.With aging,the lens nucleus strain rate and resilience decrease,demonstrating harder texture.CONCLUSION:The relationship between human lens stiffness and age is demonstrated by ultrasound elastography.Older age is associated with lower strain ratio and less resilience of the lens.

The effect of lens aging and cataract surgery on circadian rhythm

Many organisms have evolved an approximately 24-hour circadian rhythm that allows them to achieve internal physiological homeostasis with external environment.Suprachiasmatic nucleus（SCN） is the central pacemaker of circadian rhythm,and its activity is entrained to the external light-dark cycle.The SCN controls circadian rhythm through regulating the synthesis of melatonin by pineal gland via a multisynaptic pathway.Light,especially shortwavelength blue light,is the most potent environmental time cue in circadian photoentrainment.Recently,the discovery of a novel type of retinal photoreceptors,intrinsically photosensitive retinal ganglion cells,sheds light on the mechanism of circadian photoentrainment and raises concerns about the effect of ocular diseases on circadian system.With age,light transmittance is significantly decreased due to the aging of crystalline lens,thus possibly resulting in progressive loss of circadian photoreception.In the current review,we summarize the circadian physiology,highlight the important role of light in circadian rhythm regulation,discuss about the correlation between age-related cataract and sleep disorders,and compare the effect of blue light-filtering intraocular lenses（lOLs） and ultraviolet only filtering lOLs on circadian rhythm.

Idiopathic phacodonesis in senile cataract patients in Qinghai,China

AIM: To investigate the frequency of idiopathic phacodonesis (IP) in senile cataract subjects and the short-term clinical outcomes following cataract surgery. METHODS: This institutional case-control study included 1301 consecutive low-income cataract subjects from June to November 2009. Anterior segment were carefully evaluated with dilated pupil under slit-lamp. IP were screened and graded by a criteria set by the authors. Risk factors, surgical outcomes, and operative complications were analyzed. RESULTS:A total of 42 subjects (3.2%) with IP were diagnosed and classified as grade 1 (36 subjects), grade 2 (5 subjects) and grade 3 (1 subject). Harder lenses and intumescent cataracts were observed in the IP group than the control group (P <0.05). Logistics regression test also indicated the main risk factor was the hardness of the lens. The incidence of zonular dialysis during surgery was 23.8% (10 eyes), which was significantly higher than the controls (0.7%, ( P<0.001). Visual outcomes of the two groups were not statistically or clinically significant. CONCLUSION: Hard nucleus and intumescent cataract are related to IP in senile cataract subjects in Qinghai, China. With more care being taken, grade 1 and some of the grade 2 IP subjects achieved similar surgical outcomes as compared to controls.