EyeKnowMD — Clear Vision, Clear Knowledge
Evidence-based • Easy to understand
Simple, trustworthy education about opticianry, optometry, ophthalmic disease, and everyday eye care — created for students, patients, and anyone who wants to understand their eyes better.
Today’s Focus: “What does my glasses prescription mean?”
- Sphere (SPH) — how short- or long-sighted you are.
- Cylinder (CYL) & Axis — astigmatism (shape + direction).
- Add — near power for reading/multifocals.
On EyeKnowMD, you'll find similar short lessons on PD, base curve, progressives, cataracts, glaucoma, dry eye, and more.
Lesson 1 — What Is Pupillary Distance (PD)?
PD is the distance between pupil centers. If PD is wrong, the lenses do not align properly, causing:
- Headaches
- Eye strain
- Distortion or misalignment
- Unwanted prism
For Students — Exam & Practice Zone
Quick MCQs
Click each question to reveal the answer (expandable version can be added later).
- MCQ 1. Frame PD = 70, patient PD = 64 → 3 mm in each eye
- MCQ 2. Wrong PD → headaches, distortion, discomfort
- MCQ 3. Progressives use distance PD
Case Histories
- Case 1: Wrong PD in SV lenses
- Case 2: Progressive non-adapt
- Case 3: Off-axis cylinder
Find an Eye Care Provider
This directory uses only publicly available information (clinic websites, Google Maps).
Clinics (Examples)
- Example EyeCare Optometry — Winnipeg, MB
- Sample Vision Optical — Toronto, ON
Clinic owners: add yourself
Email your clinic information to edu@eyeknowmd.com.
About EyeKnowMD
Niamul Hasan
Eye Care Educator • Patient Services Specialist
I created EyeKnowMD to give patients and students clear, simple explanations about prescriptions, lenses, and eye health.
Contact & Feedback
Have questions or topics you want explained? Email anytime:
📧 edu@eyeknowmd.com