Common complaints related to Eye conditions

✤ Loss of Vision and blurred vision

Vision can be defective to a variable degree. It may be easy to detect gross decrease in vision but it may be more difficult to detect subtle degree of loss of vision. It is very easy to miss gross loss of vision in one eye when the other eye is healthy unless one consciously tests each eye separately. It is a good practice to test each eye separately at regular intervals using any fine reading material such as newspaper

✤ Double Vision

Normally the image formed by the two eyes is coordinated into a single image by the brain. Two distinct images are seen once this coordination is disturbed due to various diseases involving the muscles of the eye and the nerves that control the same. Multiple images often are an early symptom of cataract.

✤ Redness of the Eye

Visible redness of the one or both eyes is a common symptom pertaining to several varieties of diseases. One should not mistake every red eye as having viral conjunctivitis (So called Madras eye). Hence do not self medicate and delay seeking medical advice if you have a red eye. It could be something serious.

✤ Stickiness of eyelids

A common symptom of infection in the eye is stickiness of the eyelids due to discharge. This infection could be purely external or could be more serious. Persistent stickiness of the eye lashes needs early evaluation.

✤ Watering

Watering could be the result of mal alignment of the eyelids or eyelashes or a blockade of tear ducts that normally drain the tear fluid into the nose. Presence of tearing in newborn babies can indicate lack of patency of the tear ducts and may need attention.

✤ White reflex in the eye

Normally the center of the eye gives a black reflex due to the pupil. A white reflex can be due to opacification of the normally transparent cornea, the lens (cataract) or due to an abnormal growth of tissue behind the lens. A white reflex in a child can potentially be dangerous and should not be ignored.

✤ Abnormal looking eye

Abnormal look of the eye could be due to prominence of the eye, or could be the result of defects involving the eyelids. Prominence of the eye could be due to large eyeballs or due to protrusion of normal sized eye by abnormal growth behind the eye. Any change in appearance of the eye should be investigated. Previous photographs could be useful in comparing especially when one is not certain about the time of onset of the abnormal look of the eye.

✤ Drooping of the eyelid

Drooping of the upper eyelid could be present at birth or could occur later. If the defect has occurred later in life one should note the frequency of the occurrence and in what part of the day it is more prominent. These observations can help the doctor make important decisions.

✤ Squinting of the eyes

Squinting indicates the misalignment of the eyes. In children, this can potentially lead to reduction of vision in the squinting eye due to disuse (lazy eye). When in doubt, taking photographs with flash can help identify the squint in the photographs. This is especially useful to the doctor, in case of children who refuse to cooperate with the doctor for adequate examination.

Eye Examination Components

✤ Vision Testing

Vision testing involves making a person read standard sized letters at a specified distance. The doctors record the vision as a fraction e.g. 6/6 etc. The top number denotes the distance (in feet) at which the patient has been able to read the particular sized letter while the bottom number indicates the distance at which a normal person is expected to read the same letter. Near vision is tested separately in good illumination using special test charts held at normal reading distance. The testing is done with each eye separately. The doctors often test the vision using a pinhole. This gives an estimate of improvement possible with glasses. The patient in place of glasses cannot use the pinhole.

✤ Refraction

This is an important test that is done by the ophthalmologist or more often by the optometrist. The eye is like a camera. The light rays are focused on to the light sensitive film in the back of the eye called the retina. This focusing is made possible by the cornea (a clear watch glass like structure in the front of the eye) and by the lens in the eye (similar to the lens of a camera). Refraction is done usually in the normal state. On occasion (especially in children) it may have to be done using special eye drops (cycloplegics).

In this situation one may have to retest the power of the required glasses 2-3 days after the testing with the use of drops. Refraction involves two parts. The first part is objective where in the refractionist estimates the power needed by using a test called retinoscopy. This test can also be done with a machine called the automatic refractometer (so called computer testing). However one still needs to do the all-important subjective testing (i.e. testing the response of the patient with different powered glasses) before prescribing the glasses. Hence do not be misled by the so-called computer testing.

✤ Amsler grid testing

This test is done in selected group of patients depending upon their symptoms. The test involves looking at a chart that has a grid drawn with a central dot. The test is done using the near vision glasses (if one is using the same). The test permits the evaluation of function of the central 20 degrees of the retina. The patient is asked to look at the central dot and tell whether

All the corners of the chart are seen All the lines are seen straight and not crooked There are any areas of gray patches where the lines are not seen. Whether the central part of the chart or the peripheral part of the chart is clear. The Amsler's chart is very useful as a home monitoring device. If any defect is noted, immediate ophthalmologic examination is warranted.

✤ Dilatation

One of the most common procedures that is done in an eye specialist's office is dilatation. The pupils of the eye constrict or dilate depending upon the light that thrown at the eye. For examining the back part of the eye (fundus), the doctor uses an instrument called ophthalmoscope. To get a good view of the back of the eye, one needs to dilate the pupils. This permits more light to enter the eye and gives a better image of the fundus. To keep the pupils dilated despite the intense light, one needs to dilate the pupils. There are various types of dilating drops available.

The faster acting ones may dilate the pupil in 15-20 minutes time. Other variety of drops may take up to 30-45 minutes for good dilatation. The effect of dilatation usually lasts up to 6 hours. Some of them may retain the effect for 24 hours. Usually the drops used for routine eye examination do not have long lasting effect. A patient is expected to have glare in the sun light while still under the effect of the drops. Hence driving may become difficult. If you had similar dilatation in the past and have been noted to be allergic to any one of them, please inform the same to your doctor.

✤ Slitlamp examination

Slit lamp is an instrument that has an in built microscope and a bright illumination system. The special arrangement of the light and the microscope allows the doctor to view the eye in great detail under high magnification. The front part of the eye is examined without any other aids while the back part of the eye (fundus) is examined with help of special lenses held in front of the eyeball.

✤ Tonometry (eye pressure check)

Tonometry involves the check of the pressure of the eye. Normal pressure is a range and not a finite number. Raised pressure in the eye can be harmful to the nerve connecting the eye with the brain (optic nerve). The pressure is normally checked in one of the three ways.

✤ Schiotz tonometry

Here a metallic device is placed on the eyeball and the deflections of the needle on the scale are used as a guide to measure the eye pressure. At the best, this modality of testing can be used only as screening device. This is not very accurate.

✤ Applanation tonometry

In this a small prism mounted on the slit lamp is used to contact the eyeball and measure the pressure. This modality of testing is more accurate and is the standard today.

✤ Tonopen

This is an electronic device that is very accurate and useful in specialized situations. A drop of anesthetic is placed on the eye before these tests are carried out. The test is totally painless.

✤ Gonioscopy

Gonioscopy is the test in which the angle of the eye is examined. A fine balance between the inflows of fluid maintains the eye pressure and it's outflow. The outflow is through the angle of the eye. Studying this angle gives a lot of insight into the cause of a condition called glaucoma. This test is done with the help of the slit lamp and a special lens called gonioscope. The eye is anesthetized by placing a few drops of anesthetic to facilitate placement of the lens. This test totally painless.

✤ Ophthalmoscopy

This is a very important step in the total examination of the eyes. The visible portion of the eye is easily examined by the slit lamp examination. The back portion of the eye can only be examined by using the ophthalmoscope. This step usually needs dilatation of the pupils. This test involves throwing bright light into the eye and examining the image of the back of the eye using special lenses. For Indirect opththalmoscopy, the patient has to be in the reclining position for proper examination. Sometimes the slit lamp may be used for detailed evaluation of the areas of the back of the eye such as macula, optic disc etc.

Tests for patients undergoing cataract surgery

✤ Potential acuity meter testing (PAM)

Potential acuity meter testing enables one to have an idea about the possible visual recovery following cataract surgery. In this testing the doctor projects a chart of letters or numbers into the back of the eye through the gaps in the cataract that enables the patient to read the letters. Depending upon the number of lines that one could read, the potential for recovery of vision is estimated. One should realize that this is only an approximate estimate and very often the true recovery of vision is greater that the estimate.

✤ IOL master

This is a very important test that enables one to calculate the desired power of intraocular lens during the cataract surgery. This artificial lens implanted in the same location as the natural lens permits one to have good vision without needing to use the thick glasses or contact lenses after cataract surgery. The test involves use of ultrasound to measure the length of the eyeball and this information along with keratometry (the measurement of the curvature of the cornea) is used to calculate the IOL power by a complicated formula.

Special tests for corneal diseases

✤ Schirmer's Test

Schirmer's test is a measure of the tear secreting capacity of the eye. Deficiency in tear secretion can lead to a chronic condition called dry eye. The test involves placement of a special filter paper strip across the lower eyelid margin and measuring the length of the strip that is wetted by the tears over a one-minute period.

✤ Keratometry

Keratometry involves the measurement of the corneal curvature in two meridians. The cornea is the front portion of the eye that is clear like a watch glass. The curvature of the cornea helps it to focus the light partly. Measurement of the corneal curvature is needed for fitting proper contact lens. It is also needed for the calculation of the IOL power before

✤ Corneal Topography

Corneal topography is the detailed mapping of the surface of the cornea. Advanced computer analysis of several spots on the surface of the cornea using the study of the reflected image is done. Color coded graphs of the surface map enable the doctor to diagnose certain conditions such as keratoconus. Before undergoing excimer laser treatment for getting rid of glasses, one needs to perform this test to understand the surface of the cornea better and plan the treatment accordingly.

✤ Pachymetry

Pachymetry is the study of the thickness of the cornea. The accurate measurement of the thickness is made possible by using ultrasound or optical means. Measurement of the thickness is important in the diagnosis and management of certain corneal conditions such as keratoconus, corneal endothelial dystrophy etc.

✤ Specular microscopy

Specular microscopy is a test that enables the evaluation of the back most layer of the cornea called the endothelium. The health of this layer is important in maintaining the clarity of the cornea. With age, injury, surgery and in some diseases this layer may have reduced number of cells and become abnormal. Study of this layer is done by counting the number of cells per square millimeter as well as study the type of the cells. This study is important in planning certain surgeries.