Surgery (Refractive, Retina, Cataract Surgery, Glaucoma Surgery) Flashcards
What is the first choice surgery for myopia less than -10.00D and astigmatism less than -4.00D?
LASIK and SMILE
These surgeries are preferred due to their effectiveness for these refractive errors.
What surgery is considered for patients with thin corneas or active lifestyles?
PRK (photorefractive keratotomy)
PRK is a safer option for those at risk of dislodging the flap during LASIK.
What is the maximum hyperopia that can be treated with Conductive Keratoplasty?
+4.00D
This procedure is specifically for mild hyperopia.
What are Peripheral Corneal Relaxing Incisions performed for?
Astigmatism
These incisions can be done at the same time as cataract surgery.
What surgical options are available for patients with high refractive errors?
- Refractive Lens Exchange / Clear Lens Exchange
- Phakic intraocular lens
These options are suitable for patients who have presbyopia and those who do not.
What are common postoperative complaints for any refractive surgery? (Name at least 3)
- Decreased/fluctuating vision
- Glare
- Halos
- Difficulty with night vision
- Foreign body sensation
- Pain
These symptoms can affect the patient’s recovery experience.
What are possible complications from any refractive surgery?
- Residual refractive error
- Infection
These complications can lead to unsatisfactory surgical outcomes.
What is the maximum myopia that LASIK and PRK can treat?
-10.00D
Both surgeries are effective for this level of myopia.
What additional postoperative complaints are common for LASIK and PRK?
- Starbursts
- Ghost images
These visual disturbances are specific to these procedures.
What are some complications specific to LASIK and PRK?
- Poor night vision
- Corneal haze and halos
- Decentration
- Regression over time
These complications may arise in patients post-surgery.
What is the primary reason PRK is chosen over LASIK?
Thin corneas or active lifestyles
PRK eliminates the risk of flap complications.
What is the process of PRK surgery?
- Removal of outer epithelial cells
- Application of laser to anterior stroma
- Allowing epithelium to regrow
This method requires longer recovery due to epithelial regrowth.
What is a notable risk associated with PRK compared to LASIK?
Higher risk of infection
The recovery process and epithelial healing contribute to this risk.
Fill in the blank: In PRK, the epithelium is allowed to ________ after surgery.
regrow
This regrowth process is essential for recovery.
What is LASIK?
LASIK is the first choice refractive surgery for eligible patients.
What is the first step in the LASIK procedure?
Femto second laser is used to cut a flap into the corneal stroma.
What is done after cutting the flap in LASIK?
Excimer laser is used to remove stromal tissue and flatten the cornea.
What happens to the flap after reshaping the cornea in LASIK?
The flap is laid back down.
How thick must the residual stroma be for LASIK?
250 microns.
What is the thickness of the flap in LASIK?
110 microns (can vary)
* residual bed 250 microns must remain after flap is made and tissue is ablated
How much stromal tissue is removed for each diopter treated in LASIK?
About 15 microns.
What is a common complication of LASIK related to the corneal nerves?
Dry eye due to severing of corneal nerves.
What causes Flap Trauma in LASIK?
Blunt trauma to the eye.
How should Flap Trauma be treated?
Immediate surgical flap repositioning.
What are Flap Striae?
Wrinkles in the flap.
What is the treatment for Flap Striae?
Urgent surgery to lift and refloat flap.
What is Diffuse Lamellar Keratitis (DLK)?
Sterile inflammation underneath the flap occurring within a week after surgery.
What is a critical treatment for DLK?
Topical steroids q1h initially
May require lifting flap and irrigating stroma bed to remove inflammatory debris
What may severe cases of DLK require?
Flap irrigation.
What is Epithelial Ingrowth?
Epithelial cells growing underneath the flap originating at the edge of the flap.
What is the treatment for severe Epithelial Ingrowth?
Epithelial debridement.
What is Keratectasia?
Removal of too much corneal tissue leading to a weakened, distorted cornea.
What is Central Toxic Keratopathy?
Noninflammatory pacification of the central corneal stroma following LASIK.
ICL (Intraocular collamer lens) anterior depth minimum
3.0 mm
*must be greater than 3.0 mm
*ICL for myopia and myopic astigmatism
What is the maximum corneal power considered for CXL?
65D
Higher keratometric values are associated with increased failure rates.
What age group has a greater risk of visual acuity loss after CXL treatment?
Patients over the age of 35
This group, along with those with distance visual acuity of 20/25 or better, faces increased risks.
What corneal thickness is an exclusion criterion for CXL using the standard protocol?
Less than 400 microns
This is to reduce the chance of UVA-induced corneal endothelial damage.
Who are the best candidates for CXL?
Patients 35 years of age or younger with:
* Eyes showing progression in adults or at diagnosis in children
* Moderate keratoconus (max K value less than 65D)
* Corneal thickness greater than 400 microns
* Visual acuities of 20/30 or worse
These criteria optimize the chances of successful treatment.
True or False: Patients with a corneal thickness greater than 400 microns are excluded from CXL.
False
A corneal thickness less than 400 microns is the exclusion criterion.
What is keratoconus?
A bilateral, asymmetric, non-inflammatory, progressive disorder in which the cornea assumes a conical shape due to loss of structural integrity
What are the hallmark signs of keratoconus? (3)
- Central or paracentral corneal stromal thinning
- apical corneal protrusion
- irregular astigmatism
What reflex is observed on retinoscopy in keratoconus?
Irregular ‘scissors’ reflex
What reflex is seen using a direct ophthalmoscope in keratoconus?
‘Oil droplet’ reflex
What are Vogt striae?
Fine, vertical, deep striae within the corneal stroma that disappear under external pressure
* feature of keratoconus, stress lines at apex of cone
What is a Fleischer ring?
Iron deposits surrounding the base of the cone at the level of the corneal epithelium in keratoconus
What is the Munson sign?
Bulging of the lower lid observed in downgaze in advanced cases of keratoconus
What occurs when there are ruptures in Descemet’s membrane in keratoconus?
Acute influx of aqueous into the cornea, resulting in hydrops
What is the typical keratometry value in mild cases of keratoconus?
Usually greater than 48D
What is the typical keratometry value in severe cases of keratoconus?
Can be greater than 54D in both meridians
What does corneal pachymetry data show in keratoconus?
Progressive corneal thinning corresponding to the area of conical protrusion
How does pellucid marginal corneal degeneration differ from keratoconus?
The cornea protrudes superior to the area of corneal thinning
Pellucid marginal degeneration: Painless, non-inflammatory
bilateral asymmetric corneal thinning of the inferior peripheral
cornea (usually from the 4- to 8-o’clock portions). There is no
anterior chamber reaction, conjunctival injection, lipid deposition,
or vascularization. The epithelium is intact. Corneal protrusion
may be seen above the area of thinning. The thinning may slowly
progress
What is the hallmark diagnostic sign of pellucid marginal corneal degeneration?
Kissing birds/gull-wing pattern on corneal topography
What occurs in keratoglobus?
Generalized ectasia and abnormal corneal thinning over the entire cornea
What characterizes Terrien marginal degeneration?
Peripheral corneal thinning that can be localized or extensive
True or False: Keratoconus is an inflammatory disorder.
False
What is Terrien marginal degeneration?
A condition characterized by peripheral corneal thinning that can be localized or extensive.
In which area of the cornea does degeneration typically begin in Terrien marginal degeneration?
Superior cornea
What type of opacities are seen in Terrien marginal degeneration?
Anterior stromal opacities.
What is the relationship between the opacities and the limbus in Terrien marginal degeneration?
There is a clear area between the opacities and the limbus.
What is a key feature of forme-fruste keratoconus?
Central or paracentral irregular astigmatism.
How do patients with forme-fruste keratoconus typically feel clinically?
Asymptomatic.
Fill in the blank: Patients with Terrien marginal degeneration show _______ corneal thinning.
peripheral
Compression/indentation gonioscopy indication
Angle closure attack
* apply pressure to cornea with a gonio lens which opens the angle and helps break the attack
Laser peripheral iridotomy procedure
Laser used to create a small hole at the 11:00-1:00 o’clock position in the superior Iris
* facilitates movement of fluid between the anterior and posterior chambers to equalize the pressure
* patient given 1 gtts pilocarpine to make pupil meiotic and stretches the Iris taught for the procedure
Iridectomy procedure
Triangular section of Iris is removed instead of a hole (as seen in LPI)
Iridoplasty procedure
Argon laser used to shrink spots of the peripheral Iris, shrink and pulls away from angle
*used when peripheral iridotomy is not effective such as in Plateau Iris
ALT
Laser applied in regular pattern 360 degrees around TM to increase aqueous outflow
*benefit may decrease after 2-5 years but procedure is not repeatable
SLT
laser applied to selective areas of TM to provide max benefit to decrease IOP
*effectiveness may decrease after 2-5 years but procedure can be repeated
Trabeculectomy
Portion of TM removed to help increase drainage
Shunt
Surgically inserted in patients where trabeculectomy failed to reduce IOP
* plastic tube inserted into anterior chamber to facilitate drainage of aqueous humor into attached silicone pouch located under conjunctiva
Paracentesis
Needle inserted into the peripheral cornea, penetrating cornea to allow aqueous humor to flow out of the globe from anterior chamber to reduce IOP
*used in cases of acute increase in IOP or emergency and IOP needs to be reduced faster
How long before LASIK should a patient wearing GPCL stop wearing them?
Minimum of 1 month
Plus 1 month for every decade of wear (or at least until corneal topography is stable)
What is the most common reason for reduced VA at 1-day post op for LASIK?
And what would be the most appropriate actions?
Dry eyes
- Perform pin hole exam
- Perform retinoscopy and evaluate for dry eyes
- VA can vary a lot during the first week after surgery
Is this a candidate for LASIK?
NO because pt has keratoconus
* shows “sagging bow tie” and skewing of radial axes
* keratoconus is an ABSOLUTE contraindication for LASIK
What is important to evaluate when assessing topography images?
- amount of corneal astigmatism
- regularity or symmetry of astigmatism
- overall steepness of cornea
