What is the Difference Between Cycloplegia and Mydriasis

The key difference between cycloplegia and mydriasis is that cycloplegia is an eye condition due to the paralysis of the ciliary muscle of the eye, resulting in the loss of accommodation, while mydriasis is an eye condition due to the dilation of the pupil for a reason unrelated to the levels of light in the environment, resulting in damage to the retina.

Eye is the organ of our body that gives us sight. It is a sensory organ that reacts to light and allows vision. The photoreceptive cells (rod and cone cells) are able to detect visible light and convey this information to the brain. The eye has a number of components that include the cornea, iris, pupil, lens, retina, macula, optic nerve, choroid and vitreous. Cycloplegia and mydriasis are two conditions related to the eye.

CONTENTS

1. Overview and Key Difference
2. What is Cycloplegia 
3. What is Mydriasis
4. Similarities – Cycloplegia and Mydriasis
5. Cycloplegia vs Mydriasis in Tabular Form
6. Summary – Cycloplegia vs Mydriasis

What is Cycloplegia?

Cycloplegia is an eye condition due to the paralysis of the ciliary muscle of the eye, resulting in the loss of accommodation. The ciliary muscle is a muscle in the ciliary body of the eye. It is an area of the eye that helps to focus. With the help of the ciliary muscle, the lens of the eye can be flattened or rounded. This process allows people to focus on distant and near objects. This muscle also controls a part of the drainage system in the eye that maintains proper fluid pressure. The ciliary muscle is attached to the eye lens through ligaments called zonules or suspensory. When the ciliary muscle is relaxed, the ligaments are pulled tight. This flattens the lens of the eye. With a flattened eye lens, people can focus on distant objects. When the ciliary muscle is contracted, the ligaments are slackened, and the lens is pushed into a rounded shape. This allows people to focus on near objects.

Causes and Symptoms of Cycloplegia

The symptoms of cycloplegia include headache, eyestrain, difficulty reading, and blurry vision. Cycloplegia destroys the fine-tuning of the focus in the eye. Cycloplegia can be partial or complete. It can occur due to diseases such as syphilis, diphtheria, articular rheumatism, locomotor ataxia, and diabetes. An important gene that is associated with cycloplegia is IRX6. The diagnosis of cycloplegia depends on constant symptoms. Eserine or Diocarpine can be used for the treatment of this condition. These medicines contract the pupil and stimulate the accommodation.

What is Mydriasis?

Mydriasis is an eye condition that occurs due to the dilation of the pupil for a reason unrelated to the levels of light in the environment. It results in damages to the retina. In mydriasis, the pupillary light reflex is lost. A mydriatic pupil will remain excessively large even in a bright environment, which will damage the retina from the sunlight.

Causes and Symptoms of Mydriasis

Mydriasis can happen for different reasons. Anticholinergics prescribed drugs, injuries to the eye, increased oxytocin, drug use (cocaine, ecstasy, etc.), cranial nerve neuropathy, and traumatic brain injury are several reasons for mydriasis. IP3R1 gene mutation can cause this condition. The symptoms may include dilated pupil, blurry vision, constriction around the forehead, headache, dizziness, and eye irritation. Doctors normally do visual acuity tests and ocular motility tests to diagnose this condition. Moreover, the symptoms of this condition can be minimized by avoiding direct sunlight, using sunglasses, and avoiding reading text too closer to the eye. As a treatment, it may recommend opaque contact lenses or light-sensitive sunglasses. Pilocarpine is a medicine typically used to constrict or narrow the pupils. Sometimes, it may need surgery.

What are the Similarities Between Cycloplegia and Mydriasis?

• Both conditions are related to the eye.
• They are both vision problems.
• These conditions can be caused by drugs.
• They can be treated through surgeries.

What is the Difference Between Cycloplegia and Mydriasis?

Cycloplegia is an eye condition that results in the paralysis of the ciliary muscle of the eye, causing loss of accommodation. On the other hand, mydriasis is an eye condition that occurs due to the dilation of the pupil for a reason unrelated to the levels of light in the environment, causing damage to the retina. So, this is the key difference between cycloplegia and mydriasis. Moreover, cycloplegia is due to a defect in the ciliary body of the eye. In contrast, mydriasis is due to a defect in the pupil of the eye.

The following infographic tabulates the difference between cycloplegia and mydriasis.

Summary – Cycloplegia vs Mydriasis

Blurry vision, spots, glare at night, and flashing lights are common eye complaints. Each could be harmless or an early sign of eye disease. Cycloplegia and mydriasis are two conditions related to the eye. Cycloplegia is due to the paralysis of the ciliary muscle of the eye, which causes the loss of accommodation. On the other hand, mydriasis is due to the dilation of the pupil for a reason unrelated to the levels of light in the environment that causes damage to the retina. Thus, this is the summary of what is the difference between cycloplegia and mydriasis.

Reference:

1. “Cycloplegia.” ScienceDirect Topics.
2. “Mydriasis: Causes and Treatment for Dilated Pupils.” Medical News Today, MediLexicon International, Available here.

Image Courtesy:

1. “Cyclopentolate 1 percent Pupils” By Ilovebaddies (talk) – Own work. (CC BY-SA 3.0) via Commons Wikimedia
2. “Mydriase prononcée 2006” By Raziel – Own work (CC BY-SA 3.0) via Commons Wikimedia