The science of examination with a slit lamp is called Biomicroscopy as it allows in vivo study of living tissues at high magnification.
SET UP <ul><li>Prerequisites – Preferably a dark room and slit lamp biomicroscope </li></ul><ul><li>Position – Patient is seated comfortably on an adjustable stool, with chin resting against chin rest and forehead against head rest bar. </li></ul>
1. LIDS 7. Mites and Parasites 6. Regurgitation on Pressure over sac 5. Punctal Occlusion Papillae on lid margin 4. Tumours and Naevi Cilium 3. Hordeolum externum Meibomian gland orifice 2. Diffuse inflammation (Edema) Individual hair follicle 1. Hyperaemia – Capillary engorgement and suffusion of superficial vessels Direct Focal Illumination Diffuse Illumination
2. CONJUNCTIVA - As the conjunctiva is transparent it is mainly studied by light reflected from sclera. - Eversion of lid – Examination of upper tarsal conjunctiva - Double eversion of lid – Upper fornix examination.
<ul><li>Diffuse Illumination </li></ul><ul><li>Following things are noted </li></ul><ul><li>- General status of ocular surface. </li></ul><ul><li>- Conjunctival congestion </li></ul><ul><li>- Inflammation </li></ul><ul><li>- Presence of foreign body </li></ul><ul><li>- Tear Film assessment – Marginal tear meniscus </li></ul>
Diffuse Illumination <ul><li>- Cysts </li></ul><ul><li>- Concretions </li></ul><ul><li>- Tumours </li></ul><ul><li>- Nodules </li></ul><ul><li>- Conjunctival pigmentation </li></ul><ul><li>- Staining of tear film. </li></ul><ul><li>- Staining of any conjunctival defect. </li></ul>
(b) Direct Focal Illumination : - Detailed examination of all lesions - Depth of any lesion. - Papillae - Follicles - Blood Vessels over a tumour - Neovascularization - Extent of subconjunctival haemorrhage
(c) Specular Reflection - Zones of intensely brilliant reflexes - Conjunctival elevated zones - Mucus and Waxy meibomian gland secretions - Elevated papillae (d) Indirect Illumination : - Vessels - Conjunctival scars. (e) Sclerotic Scatter Technique : - Pannus in Trachoma
3. CORNEA Diffuse Illumination - Generalised view of surface of cornea - Size - Shape - Transperancy - Foreign Body - Opacity - Staining of Cornea
Direct Focal Illumination Integrity of corneal epithelium Thickness of cornea Depth of lesion Vascularisation-superficial/deep Folds in Descemet's membrane Rupture in Descemet's mvmebrane
Hypopyon Ulcer seen in Direct Focal Illumination
Direct Focal Illumination <ul><li>Keratic precipitates can be seen in high power </li></ul><ul><li>Opacity in anterior part of cornea. </li></ul><ul><li>Degenerations </li></ul><ul><li>Dystrophies </li></ul><ul><li>Pigmentation </li></ul><ul><li>KF ring </li></ul><ul><li>Argyrosis </li></ul><ul><li>Precorneal tear film </li></ul>
Specular Reflection - Endothelial cell count (average 2800 cells/ Sq.mm) - Morphology of endothelium - Endothelial dystrophics - Hassall Henle bodies which are warts in descemet's membrane. - Bullae - Blood staining of endothelium
Sclerotic Scatter - Central nebular corneal opacity - Dystrophies - Corneal oedema - Rupture in descemet's membrane
Corneal Staining Fit of contact lens Break up time Applanation tonometry Siedel's test Double staining Ulcers Abnormal and Devitalised epithelium Epithelial defect Keratin Corneal erosion Mucus Corneal abrasion Mucus Seen in red free filter Seen with cobalt blue filter Alcian Blue Rose Bengal 1% Fluorescein 2%
4. SCLERA AND EPISCLERA On Diffuse Illumination : - Deep, red, dusky congestion of episcleral vessels On Direct Focal Illumination - Episcleritis – Raised congested nodule - Deep Scleritis – Conjunctival congestion associated with episcleral vessel congestion with peripheral keratitis and uveitis.
5. AQUEOUS HUMOUR Diffuse Illumination : - Depth of Anterior Chamber - Contents of Anterior Chamber - Foreign Body - Hypopyon - Hyphaema - Vitreous prolapse in AC - Traumatic Catractous material in AC - Micro Filareae - Cyst and Tumours
Direct Focal Illumination - Attachment of pupillary membrane - Cells - Flare - Foreign bodies - Depth of Anterior Chamber
AQUEOS FLARE Flare is the ability to see the path of light when slit beam is obliquely aimed across the AC. It is due to light scattering by suspended colloid particles causing TYNDALL effect.
AQUEOS FLARE <ul><li>It is seen in 2 mm x 1 mm slit beam with maximum light intensity. </li></ul><ul><li>- It is seen against the iris plane. </li></ul><ul><li>- It can be seen in conical beam by direct focal illumination technique. </li></ul>
Grading of flare <ul><li>0 Absent </li></ul><ul><li>1+ Faint Barely detectable </li></ul><ul><li>2+ Moderate Iris and lens details clear </li></ul><ul><li>3+ Marked, iris and lens details hazy </li></ul><ul><li>4+ Intense fibrinous aqueous </li></ul>
Cells : Indication of active inflammation of iris and ciliary body. Slit beam is directed across the AC and beam is focused posterior to cornea. 2 x 1 mm slit beam is focused with maximum light intensity. 0 - 0 1+ - 5 – 10 2+ - 10 – 20 3+ - 20 – 50 4+ - > 50
ANTERIOR CHAMBER Van Herrick Method : For assessment of peripheral anterior chamber depth using a slit lamp. A comparison of depth of peripheral anterior chamber to the peripheral corneal thickness is used to determined the degree of shallowness of the anterior chamber.
ANTERIOR CHAMBER <ul><li>An optical section of peripheral cornea and anterior chamber is made on slit lamp with illumination and viewing arms at 60° to each other. </li></ul><ul><li>Viewing arm is perpendicular to cornea. Magnification is 15 X. </li></ul>
GONIOSCOPY It is done to see the structures in the recess of angle of anterior chamber. It is important in - Glaucoma - Foreign bodies entangled in angle of AC - Tumours arising in angle of AC. - Narrowing of angle can be identified by a steep configuration of iris and angulation of slit light reflex as it passes into the angle recess.
Direct Focal Illumination - High Illumination - Light beam focused from temporal side - First periphery is inspected then pupillary zone to avoid dazzling. Observation : - Exudates - Vascular changes - Atrophic Changes - Neoplastic Changes Optical Section : - Narrow beam is made to see details of crypts and furrows.
Retro Illumination - Visualization of iris is via light reflected from the lens - Atrophic patches in iris. - Holes - Tears and dehiscences. - Patency of Peripheral iridectomy
Indirect Illumination - Outline of Crypts - Atrophic areas - Perforations - Cysts and Tumours - Haemorrhages
Iris Scatter <ul><li>- Beam is focused on corneoscleral junction. </li></ul><ul><li>- Magnification is kept low or medium. </li></ul><ul><li>- Used to see – </li></ul><ul><li>- Iris contour, depression, discontinuities </li></ul><ul><li>- Any tumour </li></ul><ul><li>- Holes and other defects </li></ul>
7. LENS Diffuse Illumination : - To visualize anterior lens surface with part of its anterior capsule. - Surface and suture system of adult nucleus in older patients. - Embryonic Y suture. - Posterior Capsule when altered pathologically
Direct Focal Illumination : - Enables to see zone of discontinuity - Finer details of tissue stratification - Exact localization of minute changes. - Differentiate between congenital and developmental opacities, senile changes, traumatic opacities, complicated opacities.
Retro Illumination : 1. Used to observe whether the opacity is – - Obstructive – Opaque to light - Respersive – Scatters light - Refractile – Refracts, minimizes or distorts the views of background. 2. Observe anterior capsular changes - Deposits, Foreign bodies, Opacities Below Capsule.
Examination of Lens <ul><li>3. Direct Retro Illumination – Obstructive Lesion </li></ul><ul><li>Indirect Retro Illumination – Refractile and Respersive </li></ul>
Posterior Sub Capsular Cataract Seen in Direct Focal Illumination and Retro Illumination
Specular Reflection :- Mirror reflexes of anterior and posterior capsule can be seen as bright reflex, when the beam is moved from side to side across the surface of lens. It is due to irregular reflection caused by small irregularities of capsular surface known as SHAGREEN reflex. Any capsular opacity can be seen by this method.
Post Operative Evaluation of IOL Surgery : - IOL Centration and Stability. - Position of IOL - Pupillary Capture - Dislocated IOL - Early Uveitis - PCO : - Soemmerring Ring - Elschnigs Pears.
Examination of Pupil <ul><li>Direct Focal Illumination </li></ul><ul><li>- Direct Reflex </li></ul><ul><li>- Consensual reflex </li></ul><ul><li>- Accomodation reflex </li></ul><ul><li>- Neovascularisation at pupillary margin </li></ul><ul><li>- Exfoliative changes. </li></ul>
9. VITREOUS - Examination of Anterior 1/3rd vitreous can be made using direct focal illumination. - Illumination is kept maximum - Slit very narrow. - Illumination is brought from largest angle possible, without disturbing the slit. - It is seen as optically clear space with delicate undulating fibrils and membrane like structures.
Direct Focal Illumination : - Shape - Rigidity - Vitreo retinal attachments - Vitreous opacities - Vitreous Bands and Membranes - Any pigmented Debris. - Foreign bodies in vitreous - Haemorrhages in vitreous
<ul><li>Slit lamp biomicroscopy can be used is combination with various lenses and mirrors for a magnified stereoscopic evaluation of retina and vitreous by vertical tilting of a slit 10° - 20°. </li></ul>
Goldmann Three Mirror Lens Examination : - Central planoconcave lens – 64 D. - It has 3 mirrors at 59°, 67° & 73°. - Central lens allows a magnified stereoscopic examination of central 30° of retina giving an erect image. - Oblong mirror gives a view of posterior retina. - Rectangular and anterior retinal mirrors examine corresponding retinal areas respectively.
Indirect Slit Lamp Biomicroscopy : - Carried out by hand held high plus condensing lenses. - + 90 D, + 78 D. - An inverted, stereo magnified image is formed between lens and slit lamp. - Lens is held 5 – 10 mm from patient's cornea. - Magnification is 10 X or 16 X. - Coaxial illumination for fundus examination. - Slit beam is angled 10° – 20° from axis of observation for vitreous examination.
Hruby Lens Biomicroscopy : - Planoconcave – high minus lens (–55D) - Neutralises the optical power of the eye. - Forms a virtual erect image of fundus.
Auxillary Devices : These can be used along with slit lamp. 1. Gonioscope for angle structure examination. 2. Applanation tonometer for IOP. 3. Endothelial cell counts using Eisner grid. 4. BUT 5. Staining Procedures.
Auxillary Devices <ul><li>6. Corneal Thickness – Pachymetry </li></ul><ul><li>7. AC Depth – Van Hericks Method. </li></ul><ul><li>8. Ophthalmodynamometry – Pulsations of blood vessels. </li></ul><ul><li>Slit Lamp Photography </li></ul><ul><li>Delivery of Argon, Diode and Nd YAG laser </li></ul><ul><li>11. Laser Interferometry </li></ul><ul><li>12. Potential Acuity Meter Test. </li></ul>