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
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|
- 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:
- Ophthalmoscopy (Fundoscopy)
- Slit lamp biomicroscopy
- Fluorscein angiography
- Optical coherence tomography
- Computed axial tomography
- Indocyanine green angiography
- 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:
- 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:
- 15 times magnified
- It readily allows examination of the fundus as far as to the periphery.
- Examination through hazy media is possible.
Image has following characterstics:
- Magnified 4-5 times
3. Distant direct ophthalmoscopy-
- The light is thrown into the patient’s eye from a distance of 20-25 cm.
- Diagnose opacities in the refractive media.
- Differentiate b/w a mole & a hole of the iris
- 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:
- Diabetic retinopathy
- Central serous retinopathy
- Choroidal neovacularisation
2. Indocyanine green Angiography:
- Used primarily for choroidal vasculature, especially in choroidal neovascular membranes (CNVM).
Used in :
- Identification & delineation of poorly defined or occult choroidal neovascularisation
- Retinal pigmented epithelium (RPE) detachments.
SLIT LAMP BIOMICROSCOPY
- Low power microscope (biomicroscope) combined with a high-intensity light source (slit-lamp).
Used to examine:
- Anterior segment: Eyelids, conjunctiva, cornea, anterior chamber, lens & its capsule
- 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:-
- 1st from anterior surface of cornea-> Erect & moves in same direction.
- 2nd from posterior surface of cornea-> Erect & moves in same direction.
- 3rd from anterior surface of lens-> Erect & move in same direction.
- 4th from posterior surface of lens-> Inverted & moves in opposite direction.
- First three reflecting surfaces are convex & produces erect images.
- 4th surface is concave, produces inverted images.
- In aphakia 3rd & 4th images are absent & only first two images are present.
- In cataract 4th image is absent & first three images are present.
ELECTRORETINOGRAM & ELECTROOCULOGRAM
1. ELECTRORETINOGRAM (ERG)
- Negative ‘a’ wave represent the activity in rods & cones
- Positive ‘b’ wave arises in inner retinal layers
- Positive ‘c’ wave is associated with the pigmentary epithelium.
- 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
- >185: Normal
- 150-185: Borderline
- <150: Abnormal
- Corneal curvature measured by Keratometry.
- Shadow test is used in Retinoscopy.
- Corneal endothelial cell count is done by Specular microscopy.
- Gonioscopy is used to study Angle of anterior chamber.
- Thickness of cornea is best measured by Pachymeter.
- Corneal endothelium seen by Slit lamp bio-microscope.
- Quantification of corneal sensation is done by Aesthesiometer.
- Increased intraocular tension can be diagnosed by Tonometer.
- Inverted Purkinje image is seen on Posterior surface of lens.
- Fluoresciene stain is used in the eye to stain Cornea.
- The total area of retina seen in direct ophthalmoscopy is 2DD.
- In direct ophthalmoscopy, image is magnified by 15 times.
- Advantage of indirect over direct ophthalmoscopy is Useful in hazy media.
- Distance of distant direct ophthalmoscopy is 20-25 cm.
- The image in indirect ophthalmoscopy is Inverted, real, magnified.
- Indirect ophthalmoscopy is done for Periphery of retina.
- Examination of vitreous is best done by Indirect ophthalmoscope.
- The aqueous flare is best demonstrated by Biomicroscope.
- Angiography is the investigation of choice in Central serous retinopathy.
- Fluorescein angiography is used to identify lesions in Iris, Retina, or Choroid