tPurpose: To investigate the distribution of different-sized vessels in the digital images of the ocular surface,an endeavor which may provide useful information for future studies.Methods: This study included 295 healthy individuals. From each participant, four digital photographs ofthe superior and inferior conjunctivae of both eyes, with a fixed succession of photography (right upper,right lower, left upper, left lower), were taken with a slit lamp mounted camera. Photographs were thenanalyzed by a previously described algorithm for vessel detection in the digital images. The area (of theimage) occupied by vessels (AOV) of different sizes was measured. Height, weight, fasting blood sugar(FBS) and hemoglobin levels were also measured and the relationship between these parameters and theAOV was investigated.Results: These findings indicated a statistically significant difference in the distribution of the AOVamong the four conjunctival areas. No significant correlations were noted between the AOV of eachconjunctival area and the different demographic and biometric factors. Medium-sized vessels were themost abundant vessels in the photographs of the four investigated conjunctival areas. The AOV of thedifferent sizes of vessels follows a normal distribution curve in the four areas of the conjunctiva. Thedistribution of the vessels in successive photographs changes in a specific manner, with the mean AOVbecoming larger as the photos were taken from the right upper to the left lower area.Conclusions: The AOV of vessel sizes has a normal distribution curve and medium-sized vessels occupythe largest area of the photograph.

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