The pair of eyes situated within orbital cavities in the skull are pivotal sensory organs, enabling people to view the outside world and witness myriad amazing visual experiences. Needless to mention, the eyes must be cared for by all age groups, to guarantee crystal clear vision, detect and correct for refractory issues like myopia, presbyopia, as well as avert impairing conditions later on in life, of age-related macular degeneration (AMD) and glaucoma.
A simple and elaborate diagnostic procedure known as an eye exam is carried out by ophthalmologists, to assess the overall health of the eyes and treat any vision-linked disorders. Also called an ophthalmic exam or a comprehensive eye exam, it entails a series of procedures - refraction assessment, colour vision testing, retinal examination and several other protocols, to examine all organelles of the eyes and evaluate their functions.
Why It Is Done:
The primary objective of an eye exam is to identify maladies of the visual organs in the early stages, in order to treat them effectively and resolve the defects for optimal vision. It is also useful in gauging the overall health of the eyes and helps the doctor recommend the appropriate glasses, contact lenses or other visual aids, medications, surgery as per the health issue, to ensure proper eyesight.
An eye exam helps in detecting various vision-linked anomalies such as myopia, astigmatism, lazy eye, night blindness, AMD, presbyopia, glaucoma. Moreover, it is beneficial in determining the overall health and function of the eyes in chronic diseases like diabetes, hypertension.
Ophthalmologists advise people to take regular eye exams at every stage in life, such as early childhood, adolescence, young adults, middle-aged and elderly. The test can be taken occasionally for normal, healthy individuals but it is recommended to be taken on a routine basis and more often if there is a family history of eye ailments, as well as if the person already uses visual aids of glasses/contact lenses on a daily basis.
Types And Procedures:
Before the comprehensive eye exam, the ophthalmologist conducts a physical exam of the eyes by shining a light source in both pupils and also records their family history and medical history of eye illnesses. Then an array of diagnostic protocols are carried out, to evaluate the different organelles of the eyes – the retina, pupils, lens, cornea, optic nerve. The tests done in an eye exam comprise:
Eye Muscle Test:
The doctor instructs the patient to follow an object such as a pen or a light source, to investigate the accuracy and strength of the eye muscles, to look for signs of hampered control or coordination in eye movement.
Visual Acuity Test:
An alphabet chart is placed at a medium distance away from the patient, with the letters becoming smaller in size from top to bottom. The person is asked to read out the letters aloud, with each eye separately, while keeping the other eye closed. This helps the doctor analyse how precise the vision of the individual is from a farther distance, while a printed card is given to the person to be held closer to the eyes and then read aloud, so as to gauge their near vision accuracy.
A retinoscopy is done to analyse the proper functioning of the retina in focusing light rays from the object to be able to view it clearly. A bright light is shined directly on the eyes and the doctor calculates the refractive error by analysing the motion of light rays reflected from the retina back to the pupil. Moreover, a rotating mask-like apparatus called a phoropter consisting of different lenses is utilised, wherein the patient is asked to wear this device and see things using many types of lenses, to determine which combination of lenses ensures accurate, sharp images.
Visual Field Test:
Visual field refers to the entire scope of view of the person without moving their eyes to the sides. This is done in two ways. One is manually by a confrontation exam wherein the doctor moves their finger from the centre of the patient’s line of sight towards a side. The other is performed using a device through automated perimetry, where the patient is seated facing a screen with blinking lights appearing suddenly and they are asked to press a button whenever they see a bright source.
Colour Vision Testing:
This is a simple test where the doctor displays different coloured letters and patterns in front of the patient and they are asked to identify them, to check if their colour and shape perception is normal.
Slit Lamp Examination:
A slit lamp is a device composed of a microscope that enlarges the parts of the eye by shining an intensely bright light close to it, wherein the doctor may also add a fluorescein dye to highlight the tear secretions. This test is useful in studying the lens, cornea, eyelids, iris, as well as to detect if any tissues are damaged in the eyes.
Using an ophthalmoscope, the doctor analyses the retina, optic disc and blood vessels leading up to the eye organelles employing a shining light source. The pupils are dilated with eye drops prior to the retinal exam, to prevent them from diminishing in size once the bright light source is turned on.
The tonometry technique is used to measure the pressure inside the eyes, termed intraocular pressure, which is a key marker for glaucoma. It is done either by gently applying pressure on the cornea to calculate how much force is required to flatten it or by releasing a puff of air in front of the eyes to gauge the pressure within the visual organs.
A comprehensive eye exam is a completely safe procedure that takes 30 – 45 minutes and does not result in any grave complications. The only minor difficulty is that when the patient’s eyes are dilated with eye drops, they tend to experience increased sensitivity to bright light, slight stinging sensation, hazy vision to a very small extent. However, these effects of the eye exam last only for a few hours after which the patient can resume all day-to-day activities at home and work. It is hence advised to bring someone along so that they can safely take the patient back home since the person cannot drive immediately post an eye exam.
The results from an eye exam indicate three main aspects related to the patient’s vision:
- If their eyesight is healthy and does not need any further visual aid, medication or surgery
- If they have refractive errors which require to be corrected with glasses, contact lenses, surgery
- If they have cataracts, glaucoma, AMD or diabetic retinopathy, to be resolved with appropriate medication and surgery