Slit-Lamp Illuminations Slit lamp

1 slit-lamp illuminations

1.1 diffuse illumination
1.2 direct focal illumination
1.3 specular reflection
1.4 transillumination or retroillumination
1.5 indirect illumination
1.6 sclerotic scatter or scattering sclero-corneal illumination

slit-lamp illuminations

various methods of slitlamp illumination required obtain full advantage of slit-lamp biomicroscope. there 6 type of illuminating options: 1. diffuse illumination, 2. direct focal illumination, 3. specular reflection, 4. transillumination or retroillumination, 5. indirect lateral illumination or indirect proximal illumination , 6. sclerotic scatter. oscillatory illumination considered illumination technique. observation optical section or direct focal illumination applied method of examination slit lamp. method, axes of illuminating , viewing path intersect in area of anterior eye media examined, example, individual corneal layers

diffuse illumination

diffuse illumination of anterior segment

if media, of cornea, opaque, optical section images impossible depending on severity. in these cases, diffuse illumination may used advantage. this, slit opened wide , diffuse, attenuated survey illumination produced inserting ground glass screen or diffuser in illuminating path. wide beam illumination type has light source set wide open. main purpose illuminate of eye , adnexa @ once general observation.

direct focal illumination

lesions seen in superficial layers of cornea direct focal illumination

observation optical section or direct focal illumination applied method. achieved directing full-height, hairline medium width, medium-bright beam obliquely eye , focusing on cornea quadrilateral block of light illuminates transparent medias of eye. viewing arm , illuminating arm kept parfocal. type of illumination useful depth localization.direct focal illumination used grading cells , flare in anterior chamber shortening height of beam 2–1 mm.

specular reflection

specular reflection, or reflected illumination paches of reflection seen on sunlit lake water surface. achieve specular reflection, examiner directs medium narrow beam of light (it must thicker optical section) toward eye temporal side. angle of illumination should wide (50°-60°) relative examiners axis of observation (which should nasal patients visual axis). bright zone of specular reflection evident on temporal, midperipheral corneal epithelium. used see endothelial outline of cornea.

transillumination or retroillumination

retro-illumination of anterior subcapsular cataract

in cases, illumination optical section not yield sufficient information or impossible. case, example, when larger, extensive zones or spaces of ocular media opaque. scattered light not bright absorbed. similar situation arises when areas behind crystalline lens observed. in case observation beam must pass number of interfaces may reflect , attenuate light.

indirect illumination

indirect lateral illumination of corneal ulcer

with method, light enters eye through narrow medium slit (2 4 mm) 1 side of area examined. axes of illuminating , viewing path not intersect @ point of image focus, achieve this; illuminating prism decentered rotating vertical axis off normal position. in way, reflected, indirect light illuminates area of anterior chamber or cornea examined. observed corneal area lies between incident light section through cornea , irradiated area of iris. observation against comparatively dark background.

sclerotic scatter or scattering sclero-corneal illumination

sclerotic scatter illumination showing kp on cornea

with type of illumination, wide light beam directed onto limbal region of cornea @ extremely low angle of incidence , laterally de-centered illuminating prism. adjustment must allow light beam transmit through corneal parenchymal layers according principle of total reflection allowing interface cornea brightly illuminated. magnification should selected entire cornea can seen @ glance.