# What Causes a Squint?

Source page: https://www.kudretgozistanbul.com/en/blog/eye-diseases/what-causes-squint

**Author:** Kudret Eye İstanbul | **Medical Approval:** Op. Dr. Mehmet Ali Özdil | **Date:** 2026-09-13

> **Summary:** A squint (a turn in the eye) is a misalignment in which the eyes point in different directions, so they cannot focus on the same point and vision is disturbed. It is often present from birth or develops in childhood, and it can be treated with glasses, prism lenses, vision therapy or eye muscle surgery.

## Quick Facts
- **Directions:** One pupil may turn inwards, outwards, upwards or downwards
- **Onset of congenital squint symptoms:** Generally at three or four months of age
- **Eye muscles:** Six per eye
- **Most common type:** Inward turn (esotropia)
- **Treatments:** Glasses, prism lenses, vision therapy, squint surgery

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## What is a Squint?
Clear vision needs both eyes to look at the same point. In a squint one eye looks elsewhere, so the eyes cannot focus together. It can appear at any age but is most common from birth and during the growing years, often for genetic reasons; it can also start later in life.

## Causes
Each eye has six muscles: one moves it right, one left, and four move it up, down and at an angle. A squint can arise when these muscles are short or develop incorrectly, or from a problem in the nerves supplying them or in the brain's control centre. Other causes:
- Diabetes
- Thyroid conditions
- Stroke
- Head injury
- Cerebral palsy
- Myasthenia gravis
- Cataract
- Premature birth
- Down syndrome
- Hydrocephalus
- Damage to the eye muscles

## Symptoms
The most common sign is eyes visibly not looking at the same point. Others:
- Weakness in or around the eyes
- A pulling feeling around the eye
- Double vision
- Blurred vision
- Trouble focusing while reading or looking at something
- Lazy eye (amblyopia)
- Loss of depth perception
- Moving the head to see clearly

**False squint:** some children look misaligned, but light reflects on the same place in both eyes and vision is not disturbed. An untreated true squint, by contrast, leads to headache, eye fatigue and lazy eye.

## Types
Squints are classified as inward, outward or vertical.
- **Esotropia (inward):** the most common type.
  - **Accommodative esotropia:** usually from untreated hyperopia; the extra focusing effort leads to constant head movement or double vision.
  - **Intermittent esotropia:** the two eyes' movements are not coordinated properly, with headache, reading difficulty and eye fatigue.
- **Exotropia (outward):** less common than inward turns.

## Diagnosis
An ophthalmologist diagnoses a squint by examination, with alignment and focusing tests that show the type, degree and whether it can be treated.

## Treatment
A treatment plan is drawn up after assessment; early diagnosis makes treatment easier and shorter. Options are glasses, prism lenses, vision therapy and squint surgery.

## Squint Surgery
Squint (eye muscle) surgery aims to align the eyes and so improve vision. In typical squints the muscles around the eye are too tight or too weak; depending on the eye, certain muscles are loosened, tightened or moved, then repositioned so the eyes point in the same direction. It can be done on one eye or on both.