Eye Health Science

Refractive surgery

Refractive eye surgery is any eye surgery used to improve the refractive state of the eye and decrease or eliminate dependency on glasses or contact lenses. This can include various methods of surgical remodeling of the cornea or cataract surgery. The most common methods today use excimer lasers to reshape the curvature of the cornea.

Eyeglass prescription

An eyeglass prescription is an order written by an eyewear prescriber, such as an optometrist or ophthalmologist, that specifies the value of all parameters the prescriber has deemed necessary to construct and/or dispense corrective lenses

Surface procedures

The excimer laser is used to ablate the most anterior portion of the corneal stroma. These procedures do not require a partial thickness cut into the stroma. Surface ablation methods differ only in the way the epithelial layer is handled.

Corneal incision procedures

Radial keratotomy (RK), developed by Russian ophtalmologist Svyatoslav Fyodorov in 1974, uses spoke-shaped incisions, always made with a diamond knife, to alter the shape of the cornea and reduce myopia or astigmatism; this technique is,

Hyperopia

Hyperopia can experience blurred vision, asthenopia, accommodative dysfunction, binocular dysfunction, amblyopia, and strabismus, another condition that frequently causes blurry near vision. Presbyopes who report good far vision typically experience blurry near vision because of a reduced accommodative amplitude brought

Keratoconus

Keratoconus can cause substantial distortion of vision, with multiple images, streaking and sensitivity to light all often reported by the patient. It is typically diagnosed in the patient's adolescent years. If afflicting both eyes, the deterioration in vision can affect the patient's ability to drive a car or read normal print.

Radial keratotomy

Radial keratotomy (RK) is a refractive surgical procedure to correct myopia (nearsightedness) that was developed in 1974, by Svyatoslav Fyodorov, a Russian ophthalmologist. Though it has been largely supplanted by newer operations, such as photorefractive keratectomy, LASIK, Epi-LASIK and the phakic intraocular lens,

Retina

The retina is a layered structure with several layers of neurons interconnected by synapses. The only neurons that are directly sensitive to light are the photoreceptor cells.

Retinal gene therapy

Gene therapy holds promise as a potential avenue to cure a wide range of retinal diseases. This involves using a non-infectious virus to shuttle a gene into a part of the retina. Recombinant adeno-associated virus (rAAV) vectors possess a number of features that render them ideally suited for retinal gene therapy, including a lack of pathogenicity, minimal immunogenicity, and the ability to transduce postmitotic cells in a stable and efficient manner.

Retinitis pigmentosa

Retinitis pigmentosa (RP) is an inherited, degenerative eye disease that causes severe vision impairment due to the progressive degeneration of the rod photoreceptor cells in the retina. This form of retinal dystrophy manifests initial symptoms independent of age; thus, RP diagnosis occurs anywhere from early infancy to late adulthood. Patients in the early stages of RP first notice compromised peripheral and dim light vision due to the decline of the rod photoreceptors

Evolution of the eye

Complex eyes appear to have first evolved within a few million years, in the rapid burst of evolution known as the Cambrian explosion. There is no evidence of eyes before the Cambrian, but a wide range of diversity is evident in the Middle Cambrian Burgess shale, and the slightly older Emu Bay Shale. Eyes show a wide range of adaptations to meet the requirements of the organisms which bear them. Eyes vary in their visual acuity, the range of wavelengths they can detect, their sensitivity in low light levels, their ability to detect motion or resolve objects, and whether they can discriminate colours.

Retinal scan

A retinal scan is a biometric technique that uses the unique patterns on a person's retina blood vessels. It is not to be confused with another ocular-based technology, iris recognition, commonly called an "iris scanner." The human retina is a thin tissue composed of neural cells that is located in the posterior portion of the eye. Because of the complex structure of the capillaries that supply the retina with blood, each person's retina is unique. The network of blood vessels in the retina is not entirely genetically determined and thus even identical twins do not share a similar pattern.

Neuro-Ophthalmology

Neuro-Ophthalmology is a super specialty that merges the fields of neurology and ophthalmology. Neuro-ophthalmologists are responsible for the diagnosis and management of complex systemic diseases of the nervous system that affect vision, eye movements and alignment, as well as pupillary reflexes.

When should you visit your Neuro-Ophthalmologist?

Your eye doctor will usually suggest you visit an expert in Neuro-Ophthalmology after a comprehensive eye examination, in case you need special care. Often, the symptoms that prompt such a referral include those associated with optic nerve disease or diseases of the visual pathway (the nervous system component that connects the eyes to the brain). Other reasons could be the diseases affecting the pupils of the eye, and certain kinds of squint (especially paralytic).

Common Symptoms that Require Attention

The typical symptoms that could signify a neuro-ophthalmological problem include:

Sudden decrease or loss of vision
Sudden transient loss of vision (called transient ischemic attack or eye stroke)
Visual hallucinations
Double vision or diplopia
Intractable headaches

Pupillary abnormalities (sluggish reaction, the difference in size of the pupils)
Sudden onset of difficulties in identifying colors
Inability to tolerate bright light
Visual Field Defects
Squint or strabismus (especially adult onset)