RGP Complications Flashcards
What are the areas effected with RGP?
- Conjunctiva : Bublar, palpebral
- Cornea : Epithelium, Stroma and Ednothelium
- Tear film
- Lids
What are the 4 diffrent complications of GP?
- Hypoxia
- Drying
- Mechanical
- Toxic / hypersensitivity
What are the 3 consequences of Hypoxia?
- Oedma
- Polymegetheism
- Neovascularisation
What is endothelial polymegthism and what is it caused by in relation to rgps?
- Structural damage/ change of shape and size of endothelial cells
- Caused by long term hypoxia
What are three associations for corneal neovasc?
- Poor lens fit
- Chronic irritation
- Poor tear exchange
What causes vascularised Limbal keratitis? + what type of reaction can it lead to?
not enough lubrication and low edge lift which causes chronic induced irritation—> leads to an inflammatory reaction
What are signs of vascularised Limbal keratitis?
Corneal nodule called Pseudopterygium= coalesced localised superficial staining and stromal vascularisation along side it
What causes 3 and 9 o clock staining?
Mechanical/ drying, impression from lens edge
What are causes of 3 and 9 o clock staining (there are 8)?
- Poor or incomplete blinking
- Poor tear film
- Large eye (wide palpebral aperture)
- RGP material
- Excessive edge clearance
- Edges to thick
- TD too big
- TD too small
What are eight solutions to 3 and 9 o clock staining?
- Break from lens wear
- Correct blinking (blinking training)
- change care regime, ocular lubricants
- Refit with different material
- Refit with a soft cl
- Refit with lid attachment design
- Different TD
- Different peripheral design
What are seven signs which mechanical issues with RGPs can causes?
- Corneal shape changes
- Lens binding
- Dimple staining
- Foreign body tracks
- Ptosis
- Contact lens associated palpebral changes
- 3 and 9 o clock staining
What technique is good for monitoring and measuring corneal changes?
Corneal topography
Describe Fischer-Schweitzer pattern? + what it indicates?
- RARE - Poly mosaic wrinkling of bowman’s membrane, localised or cover whole cornea
- will disappear on lens removal
- stress indicator!!
Which condition out of Fischer-sweitzer or epithelial wrinkling will a px feel pain?
Epithelial wrinkling
What is epithelial wrinkling?
Small lines or furrows at any angle and it effects vision, Scl associated
If a px is showing signs of hypoxia and they have a small lens movement and low Dk?
Alter lens fit to increase mobility and cease wear temporarily
What is dimple staining ?
Small bubbles that mechanically compress and cause indentations in the epithelium and is caused
What is foreign body tracks?
Linear staining indicating the path taken by FB
How would you manage foreign body tracks?
- Assess depth and extent
- Remove lens for couple days
- address cause
- maybe replace the lens
- may need to address cleaning regime
What is thought to be the cause of Ptosis in contact lens wearers?
stress due to removing the lens there is pressure put on the levator muscle through pulling on the eyelid and over time this begins to weaken it causing Ptosis
Where is a mechanically caused CLAPC associated with rgps? (Papillae)
Towards lash margin
What causes CLAPC due to proteins?
Build up of protein deposits which denature and leads to an Ige mediated inflammatory response which leads to pappliae to develop
What is the management of clapc?
- Stop lens wear for couple weeks
- advise them to use lubricating drops x3 a day
- refit
- discuss protein removable tablets
- more frequent replacement
What is solution toxicity reaction ?
Px responds to preservative in solution which leads to localised epithelial reaction, conjunctiva hyperaemia and burning sensation
What are the four types of RGP complications?
- Hypoxia
- Drying
- Mechanical
- Toxic/hypersensitivity
What are three ways corneal oedema be caused?
- ill fitting PMMA lenses
- Low Dk
- tight fitting lenses due to restricted tear exchange
How can hypoxia effected the cornea and stroma? + effects on vision
- Oedema of stroma –> contrast + light scatter
- corneal clouding
- corneal steepening —> myopic shift (EXTREME CASE)
How is corneal oedema caused?
- CLs restricts O2creates hypoxic environment
- Epithelium begins to respire anaerobically to conserve energy producing lactate
- Lactate conc increases & moves into stroma
- Endothelial pump cannot remove water from stroma at same rate it is entering stroma
What three signs you would see from corneal odema?
Striae, fold, haze
What are striae? and what cases it?
- fine verticals lines in posterior stroma
- increases as oedema increases
- caused by fluid separation of collagen fibrils
What are folds?
Buckling of the stroma with depressed grooves and raised ridges
What is haze of the cornea?
Milky appearance caused by gross separation of collagen fibres
is corneal oedema a long term or short term issue?
long term
what can long term endothelial polymegethism lead to?
corneal exhaustion syndrome–> problems for future surgery
what slit lamp technique do you use to examine endothelial cells in endothelial polymegethism?
specular reflection
is polymegethism curable?
no
where is 3 and 9 o clock staining normally located?
nasal and temporal
what is dellen? + what is is associated with?
small area of cornea that dries out that leads to thinning as it is exposed + associated with 3 and 9 o clock staining
what may occur of you leave 3 & 9 o clock staining untreated?
vessel encroachment + opacification of tissue
what would you do to assess what has caused 9 and 3 o clock staining?
- assess tear film
- assess fit of the lens
you would then adjust the management accordingly
what would you do to assess what has caused 9 and 3 o clock staining?
- assess tear film
- assess fit of the lens
you would then adjust the management accordingly
what are 7 signs of mechanical issues?
- corneal shape changes
- lens binding
- dimple staining
- FB tracks
- ptosis
- contact lens associated palpebral changes
- 3 and 9 o clock staining
apart from mechanical cause, what is another cause of contact lens associated palpebral changes?
allergic
using corneal topography, what do red areas indicate?
steeper cornea
can PMMA cause corneal warpage (irregular shaped cornea)?
yes- no o2 due to PMMA= corneal oedema = more prevalent warpage
what will the px experience due to corneal warpage?
distortion in vision
how would you monitor corneal warpage?
corneal topography
What is a disadvantage of keratometry?
it only assess central cornea and cannot asssess periphery
how would you manage corneal warpage?
- cease lens wear
- wait until corneal oedema settled (couple weeks)
- then consider rx stability
what kind of surgery can be contraindicated for someone with an irregular cornea?
refractive surgery
if you see fischer-schweitzer pattern, what should you do?
as it dissapears on removal it is not and issue BUT big indicator that the RGP is not appropriate (due to fit)
how do you differentially diagnose between epithelial wrinkling and fischer-schweitzer pattern?
epithelial wrinkling is v painful, scl associated, vision affected
what is lens binding?
- immobile and decentred which due to eyelid pressure causes indenting of cornea from lens edge –> leads to suction effect + hard to remove lens
what eye condition can be noted with lens binding?
superficial punctate keratitis
how would you be able to tell if someone has lens binding?
indentation staining on removal
what is at an increased risk due to lens binding (think- immobile decentred bound lens on the cornea)?
HYPOXIA
how do you manage lens binding?
- re-fit lens for increase mobility (wait a little while before doing Ks incase cornea changes shape)
- cease wear temp
what can dimple staining indicate?
poor lens fit between cornea and lens (can occur with flat and steep fit lens)
would dimple staining in centre of cornea (rather than peripheral) would be due to a flat or steep fit RGP?
steep- if a v steep fit lens they will have a centre air bubble which squashed cornea
how would dimple staining due to a flat fitting RGP lens present?
peripherally
how is dimple staining managed?
- remove lens
- modify fit
can you get dimple veil staining in soft lenses?
yes - due to air bubbles
what symptoms may you see with someone with foreign body track?
- lacrimation
- discomfort
what must you check when you suspect contact lens-related ptosis?
neurological causes
how do you manage contact lens related ptosis?
- exclude neurological cause
- could try soft cl
- cease lens wear totally maybe
what are two ways a mechanical CLAPC can be caused by in relation to lens fit?
- excessive lens movement from loose lens
- good lens fit but edge lift too larger
is CLAPC due to protein deposits more prevelant in RGP or Soft cl wearers and why?
rgp because they are generally kept longer = more time for protein deposits to accumulate
where is CLAPC due to protein deposits on the everted lid found?
near the fold of everted lid
what sx would a px with toxicity reaction experience?
burning
what is the management for solution toxicity reaction?
- cease lens wear
- lubricant drops
- review in 3-4 days
- resume lens + address cause accordingly
what are two causes of solution toxicity reaction?
- reaction to preservatives
- peroxide in eye from hydrogen peroxide solution
is CLIP reversible?
YES!!
