Abstract
Purpose:
to analyze in vivo three-dimensional iris morphology (thickness/width/volume and pupil size) by swept source anterior segment optical coherence tomography (SS-ASOCT) and to find an eventual correlation with different influencing factors in caucasian population.
Methods:
Consecutive healthy emmetropic (refractive error spherical equivalent between ± 3 Diopters) volunteers underwent standardized anterior segment photography to assess iris color and grade it. SS-ASOCT images of the enrolled eye were also obtained. Morphometric datas of the iris comprising volume, thickness, width and pupil size were calculated by OCT images analysis. Sectorial variations of morphometric datas among the main 4 sectors of the iris (superior,nasal,inferior,temporal) were assessed. Relationships between iris morphology and iris color, subject age and gender were studied.
Results:
135 eyes from 135 subjects (57 males and 78 females) fulfilled the inclusion criteria and were enrolled in the study. Mean age was 49±17 years (range 22-82). All the morphometric parameters of the iris analyzed in the study significantly change among the different sectors (all p<0.0001). Iris total volume and mean thickness significantly changed depending on the color (p<0.0001 and p=0.0384 respectively) with an increasing trend directly correlated with iris darkening. No correlation was found between iris color and width or pupil diameter. Age did not affect iris volume or thickness, whereas a significant (rs=0.52) increase in iris width was found with aging. In contrast pupil diameter significantly decreased (rs=-0.58) with subject aging. No correlations were found between sex and iris volume or thickness. Iris width significantly grater (p=0.007) in males. Pupil diameter did not change among genders.
Conclusions:
Morphology of the iris in caucasian population follows constant rules in sectorial variations that can be applied to identify pathological changes in single subjects. Iris volume and thickness differently from iris width and pupil diameter are influenced by iris color. Iris width and pupil size change with aging. Males have wider iris than females.