CLINICAL EXAMINATION OF EYE

CLINICAL EXAMINATION OF EYE

Examination of anterior segment of eye

1. Oblique (focal) illumination: 2 types.

• Loupe & lens examination
• Slit-lamp biomicroscopy

2. Transillumination

3. Gonioscopy for angle of the anterior chamber

4. Tonography for determining the facility of aqueous flow

5. Tonometry for assessement of IOT

6. Purkinje images test for lens pathology

7. Ultrasound microscope

Important corneal examinations	Used for
Keratometry	Curvature of cornea
Specular microscopy	Corneal endothelial density
Slit lamp	Corneal opacity
Pachymeter	Thickness of cornea
Placido’s disc	Corneal sheen
Fluroscein, Bengal rose stain	Corneal staining
Aesthesiometer	Corneal sensation

• Corneal thickness can be measured by pachymeter, USG, scanning slit based orbscan, optical coherence tomography (OCT).

Examination of posterior segment

• Includes fundus & vitreous humor.
• Fundus is the interior surface of eye, opposite the lens, & includes retina, optic disc (optic nerve head), macula & fovea & posterior pole.
• Important examinations of posterior chamber include:

1. Ophthalmoscopy (Fundoscopy)
2. Slit lamp biomicroscopy
3. Fluorscein angiography
4. USG
5. Optical coherence tomography
6. Computed axial tomography
7. MRI
8. Indocyanine green angiography

OPHTHALMOSCOPY (FUNDOSCOPY)

• Clinical examination of interior of the eye, i.e fundus by ophthalmoscope (fundoscopy).
• Method for examining the posterior segment of eye, i.e vitreous compartment & retina, including optic disc & macula.
• 3 types of ophthalmoscopy are:

1. Direct-

• M/c practiced method for routine fundus examination.
• Used to evaluate details of the optic disc, fovea centralis, retinal fixation & renal vasculate.
• Image is formed on the observer’s retina & has following characterstics:

1. Erect
2. Virtual
3. 15 times magnified

2. Indirect-

• It readily allows examination of the fundus as far as to the periphery.
• Examination through hazy media is possible.
• Image has following characterstics:

1. Real
2. Inverted
3. Magnified 4-5 times                

3. Distant direct ophthalmoscopy-

• The light is thrown into the patient’s eye from a distance of 20-25 cm.
• Uses:

1. Diagnose opacities in the refractive media.
2. Differentiate b/w a mole & a hole of the iris
3. To recognize detached retina or a tumor arising from the fundus.

ANGIOGRAPHY FOR FUNDUS EXAMINATION

• Used for dynamic flow study of Iris, Retina, or Choroid.
• Following types of Angiographies are used:

1. Fluorescein angiography:

• Sodium fluorescein dye is used for injecting it into antecubital vein.
• Primarily used for retinal vasculature.
• Conditions for which fluorescein angiography is used are:

1. Diabetic retinopathy
2. Papilloedema
3. Central serous retinopathy
4. Choroidal neovacularisation

2. Indocyanine green Angiography:

• Used primarily for choroidal vasculature, especially in choroidal neovascular membranes (CNVM).
• Used in :

1. Identification & delineation of poorly defined or occult choroidal neovascularisation
2. Retinal pigmented epithelium (RPE) detachments.

SLIT LAMP BIOMICROSCOPY

• Low power microscope (biomicroscope) combined with a high-intensity light source (slit-lamp).
• Used to examine:

1. Anterior segment: Eyelids, conjunctiva, cornea, anterior chamber, lens & its capsule
2. Fundus examination

PURKINJE IMAGES TEST

• When a strong beam of light is shown to the eye, 4 images (Purkinje images) are formed from the four different reflecting surfaces:-

1. 1^st from anterior surface of cornea-> Erect & moves in same direction.
2. 2^nd from posterior surface of cornea-> Erect & moves in same direction.
3. 3^rd from anterior surface of lens-> Erect & move in same direction.
4. 4^th from posterior surface of lens-> Inverted & moves in opposite direction.

• First three reflecting surfaces are convex & produces erect images.
• 4^th surface is concave, produces inverted images.
• In aphakia 3^rd & 4^th images are absent & only first two images are present.
• In cataract 4^th image is absent & first three images are present.

ELECTRORETINOGRAM & ELECTROOCULOGRAM

1. ELECTRORETINOGRAM (ERG)

i) Negative ‘a’ wave represent the activity in rods & cones

ii) Positive ‘b’ wave arises in inner retinal layers

iii) Positive ‘c’ wave is associated with the pigmentary epithelium.2. 

2.   2. ELECTROOCULOGRAM (EOG)

• Measures changes in the resting potential of eye induced by changes in illumination, when the eyes are moved from side to side.
• It indicates activity of pigmentary epithelium & outer segment of rods & cones.
• Therefore, any lesion proximal to the photoreceptor (rods & cones) will have a normal EOG.
• Arden index: Ratio of light peak over the dark trough in an EOG

1. >185: Normal
2. 150-185: Borderline

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