PXF Flashcards
Hallmark of PXF
Flaky deposits on lens
Scandinavian
Why does PXF make for complicated CE
Sampaolesi line on gonio, plus TM damage, plus damage to lens zonules
Types of glaucoma related to cataracts
Phacolytic and phacomorphic
Always repeat gonio on phakic patients
Signs of PXF
Flaky white deposits on the pupillary margin, the anterior lens capsule (bulls eye pattern), the lens zonules, and the TM
Deposits on the lens zonules may cause the release of pigment from the posterior iris epithelium, resulting in pigment deposits within the TM
The lens zonules are weaker in PXF (resulting in phacodonesis), and the pupil usually dilates poorly
Ocular findings are usually bilateral and asymmetric, but may also be unilateral
PXF and elevated IOP
At an increased risk for increased IOP due to the accumulation of toxic fibrillation deposits and pigment within the TM, leading to decreased AH outflow. An estimated 15% of patients with PXF develop glaucoma within 10 years
Phacolytic glaucoma
Hypermature cataract leaks lens material into the AC, resulting in obstruction of AH outflow though the TM and markedly elevated IOP. Cells, flare, and iridescent lens particles will be present within the AC.
Phacomorphic glaucoma
Occurs when the lens thickens (cataracts) and pushes the iris forward into the angle, resulting in angle closure glaucoma
PDS patients
Usually young myopic caucasian males.
Bowing of the iris backward, K spindle, TIDs, pigment on the iris surface and anterior lens capsule, and dense TM pigmentation
True exfoliation syndrome
Delamination of the anteiror lens capsule due to infrared exposure or thermal radiation (glass blower). This is very rare
Wilson’s disease cataracts
Sunflower cataract
Due to deposition of copper within the lens in a petaloid pattern
PXFtreatment
Managed the same as POAG, although IOP is often more difficult to control and PXF glaucoma is often more progressive compared to POAG
Initial therapy is topical ophthalmic medication. Glaucoma surgeries are reserved for severe cases of PXF glaucoma that are not controlled with max topical therapy. Removing the lens is not beneficial in PXF, as the white flaky deposits are more produced by the lens, the deposits will continue to accumulate within the TM, resulting in increased IOP
Indication of PUI
Angle closure or high risk of angle closure
What does PI do
Created an opening in the iris tissue that equalizes the pressure gradient between the posterior and the anterior chambers, allowing AH to flow freely into the AC, and causing the iris to move away from the angle. PI is performed with a laser; peripheral iridectomy is a similar procedure that is performed during intraocular surgery with instruments
Indication for goniotomy
Congenital glaucoma
What does goniotomy do
Makes an incision in the TM to allow for better AH outflow
Indication for trabeculectomy
Progressive glaucoma with inadequate IOP control with topical ophthalmic medication or laser trabeculoplasty
What does a trabeculectomy do
A small portion of the TM is surgically removed underneath a scleral and conjunctival flap, providing an alternative route of AH outflow through the partial thickness scleral flap and into the episcleral and conjunctival vessels. AH outflow elevates the conjunctiva over the scleral flap, creating a bleb. The bleb is most often located superiority due to a lower risk of endophthalmitis compared to lower blebs
Indication for ALT or SLT
Open angle glaucoma with inadequate IOP control
What does ALT and SLT do
ALT causes scarring of small areas of the TM, resulting in tissue contraction and opening of the pores in areas of the TM not damaged by the laser; ALT is thought to stimulate the endothelial cells and macrophages of the TM, resulting in less debris within the TM and increased AH outflow
Indication for glaucoma shunt procedures
Severe glaucoma with inadequate IOP control with optical ophthalmic medications, laser, and/or failed trab
What do glaucoma shunt procedures do
A tube is inserted into the AC, allowing AH to flow from the AC to the extraocular plate attached to the tube to drain through the episcleral and conjunctival vessels. The plate my be located underneath a partial thickness scleral flap or inserted under the EOMs
Indication for cycloablation
Last resort in advanced glaucoma with inadequate IOP control with optical ophthalmic drops, laser, trab, and/or shunt
Laser peripheral iridoplasty indication
Angle closure, plautea iris syndrome
What does a laser peripheral iridoplasty do
Argon laser is applied to the peripheral iris, resulting in scarring and tissue contraction that helps to pull the iris away from the angle
Otomy
Incision
Ectomy
Removal
Oplasty
Repair
MIGS
Minimally invasive glaucoma surgery
May also lower IOP in patients with mild to moderate glaucoma.
Assocaited with in Ab interno micro-incision that results in minimal trauma to surrounding tissue and rapid recovery.
Examples are iStent, trabectome, and canaloplasty
BBlockers and breathing
Cause bronchoconstriction, leading to increased shortness of breath and difficulty breathing. Remember to check the pulse of all patients on topical ophthalmic BBlockers. Betaxolol is a selective B1 receptor antagonist that has fewer pulmonary side effects compared to non selective BBlockers
When is AREDS1 beneficial
Category 4 AMD (CNVM or central GA in one eye, with ARMD reducing vision to <20/32 in the fellow eye)
What type of patient is AREDs 1 contraindicated in
Smokers because of beta carotene
Pattern standard deviation
- a high PSD represents a “lumpy” hill of vision with focal loss that is characteristic of glaucoma
- a low PSD represents a “smooth” hill of vision and is characteristic of healthy patients
Recall that glaucoma can often present with a low PSD, as the hill of vision is the same shape as a healthy patietns, but the overall sensitivity is reduced due to diffuse damage of the optic nerve. A larger stimulus size (V) may be needed for patients with advanced glaucoma who can no longer see the default stimulus size III; remember that stimulus size tangoes from I-V (smallest to largest)
Reliability on HVF
Indicated by the number of FLs, FPs, FNs, and STF (short term fluctuations). STFs are determined by randomly retesting certain points. FLs are tested by shining lights in the patients blind spot. FLs>20% or FP/FNs > 33% are often flagged by the instrument as “reduced reliability” or “abnormally high sensitivity.” Glaucoma patients tend to have high FN, which will cause the field to appear better than what it actually is
Gray scale of HVF
Gross representation of VF; darker areas indicate reduced sensitivity. Used for patient educated, but should never be used to make diagnostic or management decisions
Total deviation on HVF
Compares how well the patient performed at each point compared to the database of age matched healthy normals. A value of 0 indicates the patient performed as expected; a positive value indicates the patient performed better than expected; a negative value indicates the patient performed worse than expected. The darker the box on the total deviation plot, the greater the patient deviated from the values of the healthy norms
Pattern deviation HVF
Filters out overall depression (cataracts, small pupils, incorrect refractive error correction) from the total deviation probability plot to demonstrate areas of focal damage; this is very important in the interpretation of glaucomatous defects, as early to moderate glaucoma resutls in focal rather than diffuse damage
Glaucoma hemifield tests
Compare the same points in the upper and lower hemifield to detect asymmetry in the VF; recall that glaucoma causes asymmetric damage to the optic nerve, resulting in asymmetric VF loss between the upper and lower hemifields. The GHT isreported as within normal limits, borderline, outside of normal limits, or reduced sensitivity (overall depression)
Mean deviation (MD)
Averages all fo the dB in the patients visual field and compares this number to the averaged values of healthy normals; indicates focal areas of depression that are characteristic of glaucoma. A higher PSD indicates more focal damage
Visual field index (VFI)
Detects change in the VF over time; expressed as a percentage, with 100% indicates there is no visual field loss
First step in interpreting the VF
Look at the optic nerve. The location of the damage to the optic nerve will indicate the area that will be depressed in the visual field. Any possible progression on the VF should be confirmed to ensure it is a true progression rather than a normal fluctuation in the visual field. In general, VF testing should be repeated annually, although there are exceptions depending on the individual patients
