Eye Care Glossary: Common Vision & Eye Terms Explained
- Astigmatism
- Myopia (Nearsightedness)
- Hyperopia (Farsightedness)
- Presbyopia
- Progressive Lenses
- High-Index Lenses
- Keratoconus
- Glaucoma
- Dry Eye
- PD (Pupillary Distance)
- Frequently Asked Questions
- What is the difference between myopia and hyperopia?
- At what age does presbyopia usually start?
- Can keratoconus be corrected with regular glasses?
- Why does my prescription mention high-index lenses?
- Turn this information into a personal eye-care plan
A quick reference for common eye-care terms you may see in your prescription or hear during an eye examination at Vision Concern.
In Kathmandu and worried about your eyes?
Book an eye exam (NPR 400 ≈ US$3) with our English-speaking optometrists in Lazimpat, Boudha or Makalbari — exams by appointment; optical shops open daily 8 AM – 8:30 PM. Card & cash accepted.
Astigmatism
An irregular curvature of the cornea or lens that causes blurred or distorted vision at any distance. Corrected with glasses, contact lenses (often toric lenses) or, in some cases, refractive surgery.
Myopia (Nearsightedness)
A condition where distant objects appear blurry while close objects are clear, caused by the eye focusing light in front of the retina rather than on it. Corrected with concave (minus-powered) lenses.
Hyperopia (Farsightedness)
A condition where close objects appear blurry while distant objects may be clearer, caused by the eye focusing light behind the retina. Corrected with convex (plus-powered) lenses.
Presbyopia
An age-related reduction in the eye's ability to focus on close objects, typically becoming noticeable in the early-to-mid 40s. Often corrected with reading glasses, progressive lenses or multifocal contact lenses.
Progressive Lenses
Lenses that correct near, intermediate and far vision within a single lens, without a visible line dividing the zones, unlike traditional bifocals.
High-Index Lenses
Lens materials with a higher refractive index than standard plastic, allowing a thinner and lighter lens for the same prescription strength — useful for stronger prescriptions.
Keratoconus
A progressive condition where the cornea thins and bulges into a cone-like shape, causing irregular astigmatism that often cannot be fully corrected with standard glasses or soft contact lenses. Specialty lenses such as scleral lenses, or treatments like corneal cross-linking, may be considered by a specialist.
Glaucoma
A group of eye diseases that damage the optic nerve, often associated with elevated eye pressure, that can cause irreversible vision loss if untreated. Usually develops without early symptoms, making regular eye examinations important for early detection.
Dry Eye
A condition where the eyes do not produce enough quality tears to stay lubricated, causing irritation, a gritty feeling, or sometimes watery eyes as a reflex response.
PD (Pupillary Distance)
The distance between the centers of your pupils, measured to ensure your lenses are positioned correctly in your frame.
Frequently Asked Questions
What is the difference between myopia and hyperopia?
Myopia (nearsightedness) makes distant objects blurry, while hyperopia (farsightedness) can make close objects blurry. They are corrected with opposite lens powers.
At what age does presbyopia usually start?
Presbyopia typically becomes noticeable in the early-to-mid 40s, though this varies by individual.
Can keratoconus be corrected with regular glasses?
In milder cases, glasses may help, but as keratoconus progresses, specialty options such as scleral lenses are often needed, and a specialist should assess corneal progression.
Why does my prescription mention high-index lenses?
High-index lenses are usually recommended for stronger prescriptions, since they are thinner and lighter than standard lens materials for the same correction.
In Kathmandu and worried about your eyes?
Book an eye exam (NPR 400 ≈ US$3) with our English-speaking optometrists in Lazimpat, Boudha or Makalbari — exams by appointment; optical shops open daily 8 AM – 8:30 PM. Card & cash accepted.
Turn this information into a personal eye-care plan
If this topic relates to your symptoms or vision, book an eye assessment at Vision Concern. Share your main concern when booking so the team can confirm the appropriate appointment or referral.
Book an eye assessment Ask about appointment times on WhatsApp See eye examination details
Replies within minutes
Yes. Many visitors, particularly from Bangladesh and West Bengal (Kolkata), come to Nepal for cataract, retina, or other eye surgery at a hospital and also want new glasses, a general eye exam, or contact lenses at the same time, before or after their procedure. Vision Concern is an optical and eye-examination clinic, not a surgical hospital, so we work alongside hospitals such as Tilganga: we are happy to see you for glasses, contact lenses, or a routine check-up either side of your surgical treatment elsewhere.
No conversion is needed. Eyeglass prescriptions from Germany, France, the UK, the USA, China, Russia, and almost every other country use the same international format, SPH (sphere), CYL (cylinder), and AXIS, measured in diopters. Our opticians read this directly, so you can bring your prescription paper, a photo of it on your phone, or simply your current glasses, and we will use the same values. If your prescription is more than a year or two old, we recommend a quick, free re-check before we make your new pair.
Yes. Above roughly 3,000 metres, UV exposure increases sharply because of the thinner atmosphere and reflection off snow, and ordinary sunglasses (category 2-3) do not block enough UV to prevent snow blindness (photokeratitis). We recommend glacier glasses or category-4 sunglasses with side shields, and can fit these with your own prescription if needed. Vision Concern offers ZEISS polarized, UV400-certified sunglasses with prescription lenses, which we can prepare before you set off on your trek.