3.1.2 Uses a slit lamp to examine the external eye and related structures. Flashcards
Illumination style: Direct
Slit lamp settings for: Lashes, Bulbar conj, Palpebral conj
- Low (6-10x)
- Filter: No
- Slit size: wide
Looking for: - Lashes: Blepharitis/styes
- Bulbar conj: Hyperaemia/pterygium/pinguecula
- Palpebral conjunctiva: Hyperaemia/Follicles/Papillae
Illumination style: Direct
Slit lamp settings for: Lid margins, contact lens
- Med/high (16-25x)
- Filter: No
- Slit size: wide
Looking for: - Lid margins: Meibomian glands/tear duct patency
- contact lens: Lens fit
Illumination style: Direct
Slit lamp settings for: Cornea, iris, lens surface
- Med/high (16-25x)
- Filter: No
- Slit size: Medium
Looking for: - Cornea: Opacities
- iris: Naevus
- lens surface: Qualitiy/wetting/engravings
Illumination style: Direct
Slit lamp settings for: Limbus
- Med/high (16-25x)
- Filter: Red-free
- Slit size: Medium
Looking for: - Limbus: Vascularisation
Illumination style: Direct
Slit lamp settings for: Cornea (DEEP)
- Med (25-40x)
- Filter: No
- Slit size: Narrow
Looking for: - Limbus: Dellen/stroae/folds/endothelial
Illumination style: Direct
Slit lamp settings for: Cornea, Conjunctiva
Fluro
- Med/high (16-25x)
- Filter: Blue + Fluroscein
- Slit size: Medium
Looking for: - Cornea: Staining
- Conjunctiva: Staining
Red-free filter
- Blocks structures below retional pigmental epithelium (RPE) and enhances contrast of retinal blood vessels and haemorrhages
- Helps in cup to disc (C:D) ratio assessmemt
- Helps identify nerve fibre layer (NFL) dropout - a sign of glaucoma
Blue filter
- Can enhance reflectivity of optic disc drusen
- For use with fluorescein/fluorescrein angiography
*
Yellow filter
Reduces UV exposure
Common techniques for slit lamp:
- Decoupling a slit lamp allows free movement of illumination to allow for sclerotic scatter. Good for corneal opacities, corneal clouding, band keratopathy etc
- Specular reflection for endothelium viewing
- Neovascularisation seen using retroillumination & even green illumination
- Conical beam for cells & flare
- Iris & lens transillumination
Step by Step approach: anterior exam
- Wash hands or use hand sanitiser
- Set up patient at correct height, with canthus marker aligned. Always ask if height is okay for the patient
- Get patient to look at your right ear if starting with right eye & vice versa
- Start with lids & lashes. Scan across bottom then top lids with 6-10X mag, ideally bright diffuser beam
- Then conjunctiva & sclera with 10X mag. Make patient look left, then up, then right, then down (lift lid!) then straight at your ear
- Use 16X mag for cornea & lens with parallelepiped & working your way into optic section. This is when you do your van hericks nasal & temporal
- Use retroillumination on the lens by aligning the illumination & microscope at 0 degrees ,directed at the pupil then more towards the edge of the pupil and you will see an orange reflex
Van Hericks & Angles
- Assessor will ask you to do van hericks then ask you to grade it. So make sure you know where 60 degrees is! Nasal & temporal!
- It is worth learning about van hericks & angle closure glaucoma:
- Grade 1 <1:4, grade 2 1:4, grade 3 1:2 grade 4 1:1 or 1:1>
- Read College Management guidelines
- Grade 1 <1:4, grade 2 1:4, grade 3 1:2 grade 4 1:1 or 1:1>
- Risk of angle closure is after dilation is 0.07-0.09%?
Angle closure suspect:
- Description: Anatomically pre-disposed eye
- Symptoms: None
- Signs: high IOP, narrow angles (grade 1-2), schaeffer grade 1 or less
- Management: Laser iridotomy
Intermittent angle closure
- Description: Recurrent attacks lasting 1-2hrs
- Symptoms: Transient blurred vision/haloes, headaches
- Signs: High IOP & corneal swelling during attacks, narrow/occludable angles in between attacks
- Management: Laser iridotomy
Acute angle closure
- Description: total closure, sudden & painful
- Symptoms: Severe pain, nausea, blurred vision/haloes
- Signs: Redness, closed angles, corneal oedema, vertically fixed mid dilated pupil, very high IOP
- Management: Emergency referral. Oral acetazolamide if IOP 40+. Laser irodomy, miotics & carbonic anhydrase inhibitors used
Chronic angle closure
- Description: Progressive closure due to synechiae
- Symptoms: None (at first)
- Signs: Peripheral anterior synechiae on gonioscopy, disc changes (pallor), Hlaucomfleckem iris atrophy, dilated pupil
- Management: Laser iridotomy
Peripheral anterior synechiae and Glaucomflecken?
Peripheral anterior synechiae —> adhesions of anterior iris to TM blocking the iridocorneal angle
Glaucomflecken —> looks like “spilled milk” on the anterior lens capsule - from necrosis of lens epithelial cells
Prediposing Factors for Angle Closure
Anatomical
sex (F:M ratio 3:1)
ethnicity (e.g. Chinese, Vietnamese, Inuit). PACG is recognized as a leading cause of blindness in East Asia
family history
short axial length (hypermetropia)
shallow AC (F>M)
increasing age (AC becomes shallower as lens thickness increases)
small corneal diameter
Iatrogenic (secondary angle closure) - i.e. caused by medication or treatment
Drug induced (topical and systemic)
Adrenergic agents e.g. phenylephrine
Drugs with anticholinergic effects e.g. tricyclic antidepressants, antihistamines
Drugs that may cause ciliary body oedema, e.g. topiramate (for epilepsy and migraine), sulphonamides
Surgery induced
Angle closure may follow a number of surgical procedures, for example vitreo-retinal surgery with intraocular gas, especially in aphakic eyes
Treatment for acute angle closure glaucoma
And extra information
- Medication - acetazolamide, anti hypertensives
- Interventions - YAG laser treatment/iridotomy, clear lens/cataract removal
Extra Information
- Pupillary block —> angle between lens & posterior iris closed off
- Non pupillary block (plateau iris) —> iris bows forward to block angle between iris & posterior cornea
