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model: MS-101
model: MS-102
model: MS-103
model: MS-104
Slit Lamp Microscope Illumination
To look at the magnified eye and make it easier to see its parts and adnexa properly, the ophthalmologist or optometrist uses the slit lamp microscope. This kind of ophthalmic equipment is a low power microscope with two eyepieces that gives the examiner a stereoscopic view of the patient’s eyes. A high intensity light is shone through a narrow slit that can be focused on the eye to illuminate it properly, allowing the ophthalmologist to see if there are cataracts, corneal abrasions, infections or haemorrhages in the eye.

A slit lamp examination is usually done with regular eye check-ups, along with the usual refractive tests and tonometry and sometimes other ophthalmic equipment. Some slit lamp microscopes have tonometers attached onto them so that the ophthalmologist can also measure the intraocular pressure (IOP) of the patient to see if they have a high risk for glaucoma or not. Glaucoma is an eye disease where optical nerves are damaged due to high IOP, resulting to pain in the eyeballs and, without proper treatment, eventual blindness. A slit lamp biomicroscope is also used to see if there are any abnormalities in the eye structure.

Measuring corneal thickness is also a great hurdle that ophthalmologists or eye surgeons have to face in performing an operation. Before ophthalmic microscopes like the slit lamp were designed, the ophthalmologist measured corneal thickness by injecting air into the epithelium of the eyes and looking at the space between the surface of the air bubble in the eye and the reflective surface of the surgical blade being used. This is at best only an approximation of corneal thickness, and nowadays, ophthalmic equipment like the pachymeter can be used to make an ultrasound scan of the surface of the eye. A corneal waveform can be made from pachymetry, which is like a topographical map of the eye surface. This waveform can then be used later to compare the shape of the cornea with previous results and monitor how the patient is responding to treatment if there are any.

To look at the surface of the eyes, the ophthalmologist would use diffuse illumination from the slit lamp microscope, which needs a white light at a low-level brightness. The slit lamp microscope needs to be at full height during diffuse light examination to allow the optometrist or ophthalmologist to diagnose if there are surface abrasions or ulcers on the eyes.

Direct focal illumination on the other hand, is used to view the anterior chamber or even a cross-section of the eye. This kind of ophthalmic examination is done with the slit lamp microscope at full height and the light at a medium-bright setting with the illumination directly focused on the eye.

To look at the posterior segments of the eyes, special lenses can be placed on the cornea (as with gonioscopy) in order for the optometrist to see the retina or even the optic nerve. Sometimes dilating drops are used to open up the cornea and allow the slit lamp microscope to view the back portion of the eyes. Dilating drops might cause an increase in IOP in very rare cases, however, so it is important for the patient to return immediately to an ophthalmologist or optometrist if they experience nausea. Normal reactions to the use of dilating drops entail light sensitivity which will last only a few hours.

To see if there is alien matter in the eye, like minute pieces of metal that cause abrasions and the like, an ophthalmologist might use a fluorescein dye. This is placed on the eye using eyedrops or even a piece of paper that would be placed against the side of the dye. Fluorescein is not permanent unless it stains contact lenses and can be washed away by tears.

The slit lamp microscope is a very useful ophthalmic instrument in performing comprehensive eye examinations, and the innovations on its design makes it easier for the ophthalmologist or optometrist to diagnose eye diseases or even vision disorders for them to be treated early.