Eye Conditions and Symptoms from A to Z

This page gathers, from A to Z, the eye conditions and symptoms explained on our blog: symptoms such as red eyes, a stye or floaters, and diseases such as cataracts or glaucoma. Each line leads to a full article, with its sources, that also says when to get your eyes checked.

Illustration of the back of the eye seen through an examination lens: the retina, the optic nerve and the small blood vessels. — The back of the eye, where an eye exam finds many of the conditions on this page.

When is an eye problem urgent?

An eye problem is urgent when your vision changes suddenly. The American Academy of Ophthalmology (AAO) says to call an eye doctor immediately if you suddenly see flashes of light, many new floaters at once, a shadow in your side vision or a grey curtain over part of your vision: these can be signs of a detached retina. The AAO also says to call for an eye infection, an injury or eye pain.

Our page on urgent eye care in Montréal explains what the clinic sees during opening hours and when to go straight to a hospital emergency room.

Illustration of an eye seen from the side: light focuses on the retina at the back of the eye, while in the upper part the retina lifts away from the eye wall like a curtain, with a small tear and fluid underneath. — A curtain over part of your vision can come from a detached retina (AAO).

Red, irritated or watery eyes

These articles cover a red eye, an irritated conjunctiva and tears that run or run short.

Pink eye or allergies?: inflammation of the conjunctiva, viral, bacterial or allergic, and how to tell them apart
Red eye with contact lenses: what to do right away and when to call
Red eyes and a red spot on the white of the eye: common causes, including a small bleed under the conjunctiva
Dry eye: why dry eye happens and what helps
Contact lenses and dry eyes: what helps when lenses leave your eyes dry
Watery eyes: why dry eyes can water, and the other causes

Illustration of an eye with a soft red patch on the white beside the iris and a few thin red vessels, next to a drop of artificial tears. — A red spot on the white of the eye, one of the causes of red eyes the article explains.

Illustration of two eyes side by side: the left one with a pink white and red vessels, the right one surrounded by small pollen grains. — Pink eye or allergies: two causes of red eyes that are treated differently.

Illustration of an eye seen from the front with tears pooling along the lower lid and drops running from the inner corner, with wind lines coming from the left. — Eyes that water in the wind: the article explains why.

Eyelids: a bump, crusts or twitching

These articles cover what happens at the edge of the eye, on the eyelids and lashes.

Blepharitis: itchy, red eyelids with crusts at the base of the lashes
Styes and chalazia: a bump on the eyelid, the difference between the two and what to do
Eye twitching: common causes and when to get checked

Illustration of an eye seen from the front with a small amber bump on the edge of the upper eyelid, beside a folded warm compress. — A stye on the edge of the eyelid: the article explains warm compresses and when to get checked.

Illustration of an eye seen from the front with reddened eyelid edges and small crusts at the base of the upper lashes, beside a folded warm compress. — Blepharitis affects the edge of the eyelids, at the base of the lashes.

What you see changes: spots, flashes, double images

These articles cover changes in what you see, and the signs that call for a prompt exam.

Floaters and flashes: spots that drift across your vision, and when it is an emergency
Retinal detachment: warning signs, types and treatment
Double vision: one eye or both, causes and when to get checked fast
Headaches and your eyes: when the eyes are the cause, including ocular migraine, and when it is urgent
Digital eye strain: why screens tire your eyes and the 20-20-20 rule
Color blindness: what it is, how it is tested and what helps

Illustration of an eye seen from the side: light focuses on the retina, small floaters drift in the gel inside the eye and a small flash appears at the top of the retina. — Floaters in the gel of the eye and a flash at the top of the retina.

Illustration of an eye looking at a street lamp that appears twice, a sharp lamp and a faint offset copy. — Seeing double: the article explains why the first question is one eye or both.

Eye diseases found at the exam: cataracts, glaucoma

Many serious eye conditions may not have obvious symptoms, the Canadian Association of Optometrists (CAO) notes; some only show symptoms at an advanced stage that is hard or even impossible to treat. These articles explain what is looked for and how.

Cataracts: symptoms such as cloudy vision, and when surgery is discussed
Glaucoma: risk factors and why it is found by testing, not by symptoms
Eye vitamins: what the studies actually show

Illustration of an eye seen from the front with a milky haze over the pupil, and soft lines of light coming from the left. — A cataract slowly clouds the eye's natural lens.

Illustration of an eye seen from the side, light entering from the left, with the optic nerve at the back of the eye marked by a warm glow. — Glaucoma affects the optic nerve, at the back of the eye.

In children: lazy eye and an eye turn

These articles cover two problems often found in childhood. At PrimeVision, children are seen from age 4.

Lazy eye (amblyopia): signs, causes and treatment
Strabismus: an eye turn, in children and adults
Your child's first eye exam: when to go and what to expect from age 4

Illustration of a pair of small round glasses, one lens covered by a fabric eye patch and the other lens clear. — The eye patch, one of the lazy eye treatments the article describes.

Blurry vision far away or up close

These articles cover the focusing problems that glasses or contact lenses correct.

Astigmatism: symptoms, causes and correction options
Hyperopia: symptoms, causes and how it differs from presbyopia
Myopia: causes, symptoms and options to see better far away
Presbyopia: why close-up reading gets harder after 40

Illustration of a nearsighted eye seen from the side: light comes to a focus in front of the retina. — In a nearsighted eye, light from far away comes to a focus in front of the retina.

Illustration of an eye looking along a dotted line at an open book held far away, under a reading lamp. — With presbyopia, you hold the book farther and farther away.

The tests that find these problems

These articles explain the eye exam tests used to find many of the problems on this page.

OCT scan: what retinal imaging shows
Visual field test: what it checks and how it feels
Pupil dilation: why, how long it lasts and whether you can drive after
20/20 (6/6) vision: what the number means and why it is not the whole exam

Illustration of the retina in cross-section, its layers stacked with a dip at the centre, and a beam of light coming in from the upper left onto that central point. — OCT shows the layers of the retina in cross-section.

Where to get your eyes checked in Montréal?

At PrimeVision, 9520 Boulevard de l'Acadie, Suite 222, in Montréal (Ahuntsic), optometrists and a licensed optician work under one roof. When a problem needs an ophthalmologist, the clinic writes the referral, sends it directly and gives you a copy; the wait depends on the hospital or clinic that receives it. RAMQ covers eye exams for children under 18 and adults 65+.

To book, go through our page on eye exams in Montréal. Book online: the times shown are the open ones.

Sources

The Eye Exam, Canadian Association of Optometrists, December 22, 2025.
Detached Retina Symptoms, American Academy of Ophthalmology.
Eye Exam and Vision Testing Basics, American Academy of Ophthalmology.