Ophthalmoscopy

OPHTHALMOSCOPY

PRESENTED BYDR. ANKUSH D WEGINWAR

OPHTHALMOSCOPY

Ophthalmoscopy is a test that allows a health professional to see inside the back of the eye (called the fundus) and other structures using a magnifying instrument (ophthalmoscope) and a light source.

It is done as part of an eye examination and may be done as part of a routine physical examination

HISTORY

The Ophthalmoscope was invented by Babbage in 1848.

In 1850, Hermann von Helmholtz reinvented the ophthalmoscope and revolutionized ophthalmology.

Helmholtz's instrument operated by using a mirror to shine a beam of light into the eye.

The observer would look through a tiny aperture (opening) in the mirror.

Helmholtz found that looking through the lens into the back of the eye only produced a red reflection.

By attaching a condenser lens he obtained a clearer inverted image, which was then magnified five times.

He called this combination of a mirror and condenser lens an indirect ophthalmoscope

PRINCIPLE

OPHTHALMOSCOPY

There are two types of ophthalmoscopy.

DIRECTOPHTHALMOSCOPY

INDIRECTOPHTHALMOSCOPY

OPHTHALMOSCOPY

Direct Ophthalmoscopy : It is an instrument about the size of a small flashlight with several lenses that can magnify up to about 15 times.

Indirect Ophthalmoscopy : It consists of a light attached to a headband and uses a small handheld lens.

DIRECT OPHTHALMOSCOPY

DISTANT DIRECT OPHTHALMOSCOPY : It is done at distance of 20-25 cm and features of red glow in pupillary

area noted It should be performed routinely before Direct Ophthalmoscopy

DIRECT OPHTHALMOSCOPY : It is done as close to the patient as possible

PRINCIPLE

PROCEDURE

In a semi dark room patient seated, pupils dilated.

A convergent beam of light is reflected into patient’s pupil

The emergent rays from any point on the patient’s fundus reach the observer’s retina through the viewing hole in the ophthalmosope.

The fundus examined

CHARACTERISTICS OF IMAGE

Characteristics of the Image formed Erect, Virtual 15 x magnified 10 degree (2DD) field of view 50-70 % fundus seen

Field of Vision : Smaller the sight hole better the field of vision Directly proportional to the size of pupil of observed eye and axial

length of the eye ball Inversely proportional to distance between observer and observed eye

Advantages

Portable Easy to use Upright Image Magnification 15 times Can be used without dilation

DIRECT vs INDIRECT OPTHALMOSCOPY

Good magnification Good for macular assessment Very useful in assessing media pacities Real image Light and Portable Easy to learn Good patient’s compliance - No painful indentation required