Internal Examination

• Direct Opthalmoscopy
• Binocular Indirect Opthalmoscopy
• Biomicroscopy (Fundus Lens)
• Tonometry
• Visual Field Testing

 

After the optometrist has carefully examined the external aspects of your eye the internal health must now be evaluated. A variety of instruments are at the optometrists disposal for this and are listed below

This is a very safe, non-contact examination of the inside of the eye and retina. The instrument used is a small handheld device called an opthalmoscope. The head of the tool contains many lenses and projects light through a variably sized aperature. This is attached to a handle which serves as the power source. The beauty of the opthalmoscope is that it uses the eye as a simple magnifier producing a magnified image for the eye-care physician to view. To obtain the best results from this analysis, lights in the exam room are generally dimmed allowing the pupil to maximally dilate. If the pupil is still to small, a topical mydriatic solution may be used to aid in dilation. The patient is then asked to fixate on a target. By varying the lenses, the distance from the patients eye, and aperature size; the doctor can survey the iris, crystalline lens vitreous, retina and optic disc.

Like its Direct counterpart described above, is used to inspect the retina. However, with the Binocular Indirect technique a large area of the retina can be viewed instead of a only a small portion as seen with Direct Opthalmoscopy. The device consists of a headband, an optical viewing system, and a controllable illumination source. The lens system has eyepieces which are adjusted depending on the practitioners distance from the patient. In addition, a condensing lens held in the doctors hand near the patiens eye is used to generate an image of the retina. With Binocular Indirect Opthalmoscopy the eye-care practitioner has the advantages of a large field of view, bright illumination, a comfortable working distance from the patient, and little periphery view distortion. The pupils are dilated prior to performing this test.

The fundus lens is another non-contact, well illuminated, retinal evaluation procedures. The fundus lens exam uses a powerful condensing lens to produce a magnified image. A biomicroscope is used allowing easy illumination and viewing. Similar to the binocular indirect exam, the condensing lens is held in front of the patient's eye. The examination provides high quality, highly magnified, 3 D view of the optic disc in addition to detailed inspection of the posterior portion of the eye.

This is a procedure that measures the pressure of the eye. The importance of this stems from the fact that increased pressure levels in the eye may indicate glaucoma. Your eye care practitioner can recognize the disease by examining the optic nerve head but this is only after it has begun to cause damage. Monitoring the intraocular (inner eye) pressure can give them a headstart on diagnosing and treating glaucoma before it causes irreparable harm to sight.

The pressure in the eye is measured with a tonometer. There are various types: a common type consists of a small probe on the biomicroscope. After a topical anesthetic and a dye is placed on the eye, the probe is extended until it just touches the eye where it records the presssure. Another instrument uses a puff of air to measure the intraocular pressure. There is no patient discomfort and examinationes with either instrument take a matter of minutes.

These tests determine if your peripheral vision is normal. The importance of this stems from the fact that visual field testing can de Á· @ ËÍÝogical probl ‰ 0as well as glaucoma and other eye diseases. Ty pically, this is done with al arge white bowl apparatus on which spots of light are projected. The patient fixates a central spot and then indicates when they see a small spot of light off to the side. The visual field can also be tested using a screen on which a white spot is moved and the patient indicates when the spot disappears.

The Amsler's Grid also tests the visual field, specifically the central vision capabilities of the patient. The test consists of a black grid on a white background with a central fixation point located in the middle. It is very easy to conduct and provides a fairly good barometer of the health of the macula (region of the retina responsible for our central vision). To take the test you will fixate on the dot in the middle of the grid. If your macula is healthy, the lines should appear straight and clear. By contrast, an unhealthy macula will sometimes view the lines as wavering or will see a blank spot in some areas. These are all indicators of a compromised macula.

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Examination Schedule

How often your should receive a vision examination depends on your age, predisposition to eye problems, family history and any vision related problems you have.

Contrary to popular belief, infants and small children can be given eye examinations. Initially, this should be done prior to the age of 1 to detect problems that might result in permanent vision loss. During the school years children should be examined yearly as their vision can change rapidly. From age 18-40 years individuals should be examined every 2 to 3 years, from 40-60 every 2 years and over 60 annually. Obviously if you have a vision problem it may be quite important to be seen more often. Likewise, any change in vision or discomfort following an eye or head trauma requires immediate care.

 

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Practitioner Lingo 

Have you ever wondered what that fancy and technical jargon means? Well if you are one of the curious this section gives some brief definitions about what you may hear on your visit to the eye doctor.

Astigmatism: An imperfection in the cornea preventing light rays from an object to focus on a single point. The cornea is shaped more like the side of a football rather than a basketball. Depending on the amount of astigmatism, a person may or may not experience vision difficuties. Usually, astigmatisms are easily corrected with minor spectacles or conctact lenses.

Cataract: An opacity in the crystalline lens of the eye. There may be small or large regions of cloudiness which may cause some vision impairment.

Glaucoma: An ocular disease where normal fluid drainage is blocked or the eye produces more fluid than usual. As a result the added pressure causes damage to the optic nerve head leading to loss of vision.

Hyperopia: Commonly referred to as farsightedness this is a refractive error where light rays are focused behind the retina when the eye is relaxed. As a result images are out of focus and most hyperopic patients see better at far distances than near. Fatigue and discomfort are common complaints because of the effort required to bring images into focus. This problem can be rectified with corrective lenses.

Myopia: Known as nearsightedness, it also occurs because of a refractive anomaly but light rays are focused in front of the retina not behind as in farsightedness. Images are again out of focus, but objects closer to teh patien may be in focus and clear. Corrective lenses will properly focus unclear images.

Phoria: A binocular vision problem. This is a tendency for one eye to move horizontally or vertically away from the point of focus. They can cause discomfort and headaches asocated with the use of the eyes at distances, near, or both. Some patients with phorias will see double when they get tired. Phoria can be detected with a cover test.

Presbyopia: Vision condition that is related to aging. The crystalline lens of the eye loses its flexibility and as a consequence the ability to focus on images at a normal reading distance. The tendency to hold reading materials farther away , blurred near objects, and discofort with reading are indicators. Corrective lenses are usually prescribed to compensate for the difficulty with near vision (bifocals, trifocals, or progressive addition lenses). 

O.D.: Oculus dexter, this is the medical term for the right eye. 

O.S.: Oculus sinister, this is the medical term for the left eye.

Strabismus or tropia: This is when only one eye fixates on an object and the other eye does not. Typical exampels are "cross eyes" or "wall eyed" individuals. Usually, with a strabismus only one eye is being used, the image from the other eye is suppressed. If the turning of the eye is due to a recent cause, the patient may see double. A strabsimic patient loses stereopsis and thus some depth perception.