Abstract
Background: Interpupillary distance (IPD) measurements are crucial as IPD needs to be considered before frame selection. The correct positioning of lenses before the eyes is very important to eliminate potentially undesirable prismatic effects from the lenses. Aim: To investigate and report baseline or preliminary values and variations of IPD measurements amongst black South Africans. Setting: The study was conducted in a privately owned optometric practice in Polokwane, Limpopo Province of South Africa. Methods: This was a retrospective study conducted from 386 randomly selected record cards of patients seen in a private optometric practice. The record cards were selected randomly from patients who were examined by a single optometrist from 2017 to 2019. The Statistical Package for Social Sciences (SPSS) was used for analysis. Results: The study sample comprised of 386 participants, of which 214 and 172 were females and males, respectively. The mean IPD measurements were 67.2 millimetres (mm) ± 3 mm and 64.2 mm ± 3 mm for distance and near measurements, respectively. Conclusion: The study provides preliminary or baseline IPD for black South Africans that can be used by the optical industry. The vast majority of adult IPD lie within the range 63 mm to 76 mm. This study also established that there is a significant difference between distance and near IPD. On average, the near IPD is approximately 3 mm less than distant IPD. Knowledge of mean IPD is important in the design of optical devices and for the production of spectacle frames and lenses.
Highlights
Interpupillary distance (IPD) or pupillary distance (PD) is defined as the distance between the centres of the pupils of the two eyes of an individual,[1,2,3,4,5,6,7] and is commonly expressed or specified in millimetres but can be stated in centimetres
The results of this study showed that the mean distance IPD for black South African sample under investigation was 67.2 mm ± 3.0 mm with a range of 58 mm – 78 mm
It is important for clinicians to accurately measure the IPD before assessing the visual system and prescribing suitable optical devices without undesirable effects
Summary
Interpupillary distance (IPD) or pupillary distance (PD) is defined as the distance between the centres of the pupils of the two eyes of an individual,[1,2,3,4,5,6,7] and is commonly expressed or specified in millimetres (mm) but can be stated in centimetres (cm). Interpupillary distance is associated with stereoscopic function and is one of the important orbital parameters for measuring the distance between the eyeballs. The mean IPD and/or its variation is needed in the design of most optical devices and the production of optical instruments that use binocular or stereoscopic input, such as slit lamps, binocular indirect ophthalmoscopes and spectacle frames and lenses. Both distance and near IPD measurements are necessary for proper design and placement of ophthalmic lenses, multifocal lenses. The correct positioning of lenses before the eyes is very important to eliminate potentially undesirable prismatic effects from the lenses
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