"Dist PD" stands for "Distance Pupillary Distance." It is the measurement of the distance between the centers of the pupils of the eyes when looking straight ahead. This measurement is crucial for proper alignment of optical lenses in glasses.
Importance of Distance PD:
- Lens Accuracy: Correct PD ensures that the optical center of the lenses aligns with your line of sight, which is vital for optimal vision.
- Comfort: Incorrect PD can lead to eye strain, discomfort, and headaches when wearing glasses.
- Lens Type Consideration: Different types of lenses (single vision, bifocals, progressive) may require specific PD measurements to function correctly.
How It Is Measured:
- Using a Pupillometer: An optical device that accurately measures PD.
- Manual Measurement: An eye care professional may measure PD with a ruler while the patient looks straight ahead. Typically, the measurement is taken in millimeters (mm).
Typical Measurements:
- PD can vary from person to person. Adult PD usually ranges from 54 mm to 74 mm.
- Children generally have a smaller PD, often ranging from 42 mm to 58 mm.
Types of PD:
- Distance PD: Measures the distance between pupils when looking at a distance.
- Near PD: Measures the distance between pupils when looking at something close, which is usually narrower than distance PD.
Conclusion:
Providing an accurate Distance PD measurement is essential for anyone ordering prescription glasses to ensure proper fit and visual comfort. When getting glasses, it is always advisable to consult with an eye care professional to confirm the correct measurements.