Retina surgery & procedures Flashcards
Dyes used to stain ILM
Brilliant blue G is a vital dye stains the ILM macular surgery (MC in Europe). Better safety than ICG.
ICG
Triamcinolone has a variety of uses in Ophthalmology including: 1) visualization of vitreous during either anterior or posterior vitrectomy; 2) as a intravitreal or subTenon’s injection for inflammatory ocular conditions (e.g. pars planitis) or macular edema; and 3) as an alternative to excision for chalazia.
FTMH (full-thickness macular hole)
occur in approximately 2% of cases following ERM removal.
o. mechanisms for hole formation:
weakening of the glial structure of the retina induced by the decapitation of Müller cells
opening or de-roofing of intraretinal cysts
contraction of residual ILM
direct mechanical trauma
ILM-staining dye toxicity.
Observation: eccentric FTMH has minimal impact on the patient’s subjective visual function unless it occurs either close to the fovea (within one disc diameter) or in the nasal macula within the papillomacular bundle.
eccentric FTMH does not seem to readily accumulate SRF with subsequent RD though there may be a small risk in highly myopic patients.
idiopathic ERM
idiopathic ERM is almost always associated with the presence of a PVD
Increased risk of ERM in pts with:
moderate to high myopia
retinal vascular diseases (like DR and RVO)
A) ERMs are found in 2% of patients over the age of 50 and in 20% of patients over the age of 75 at autopsy.
B) Although histologic examination may reveal the presence of fibroblasts, macrophages, and hyalocytes, RPE cells and retinal glial cells (astrocytes and Muller cells) are predominately found.
C) PPV with MP = recommended procedure for the management of a symptomatic ERM. Although 50-75% of patients improve after surgery, VA rarely returns to the level that existed prior to ERM formation (but post-op VA improves for 6-12 mo s/p surgery). Metamorphopsia Sx improve the most
D) ILM peeling in conjunction with ERM removal prohibits ERM regrowth in the postoperative period. ERMs are unable to re-proliferate on the surface of the nerve fiber layer, which explains the popularity of ILM MP for this condition.
Vitrectomy using an indirect visualization system compared to a direct visualization system:
indirect visualization system advantage= WIDER viewing angle as well as an easier view through media opacities, small pupils, and gas bubbles.
Direct visualization systems have the advantage of greater stereopsis, but with a more limited field of view.
Anterior segment ischemia
Risks: encircling scleral buckles detachment of extraocular muscles use of local anesthesia *with* epinephrine overzealous photocoagulation or cryopexy inadequate patient hydration inadequate patient oxygenation
Hard to fix RD
Worse for aphakic and pseudophakic eyes
worst for RDs 2/2 PVR, giant tears, choroidal detachment, inflammation, and traumatic posterior breaks.
Pneumatic retinopexy criteria
Classic indications to use pneumatic retinopexy for RD repair is that the breaks are confined to the superior eight clock-hours.
absence of proliferative vitreoretinopathy grade C or D
Clear media
Confidence that all breaks have been found
Anatomy worrisome for RD
RD 2/2 giant retinal tears (tears > 90 degrees) =high redetachment rate 2/2 PVR.
2/2 high risk of failure: do PPV, PFC, laser photocoagulation demarcation and complete FAX.
Retinal detachment treatment in phakic eyes
scleral buckle
Best Px for RD reapir
Px best for RDs 2/2:
small holes or retinal dialyses and those associated with demarcation lines.
Lasers - type of damage of photo-____
Mechanical damage (Photodisruption) occurs when the absorbed light is strong enough to produce gas bubbles that result in a shock wave to mechanically disrupt tissues. YAG capsulotomy is an example of light energy causing mechanical damage.
Thermal damage (photocoagulation) is when absorbed light causes a rise in temperature of surrounding tissues. Laser photocoagulation (e.g. panretinal photocoagulation) is an application of this type of damage.
Photochemical damage is when light induces biochemical reactions that cause tissue destruction without a rise in temperature. Solar retinopathy and overexposure from an operating microscope are examples of photochemical damage.
Photoablation occurs when laser pulses selectively ablate small areas of tissue without harming adjacent tissue. It is much less destructive than photocoagulation. Excimer lasers use photoablation in corneal refractive procedures because it allows selective ablation of tissue without resulting in damage or subsequent scarring of adjacent corneal tissue.
To decrease the risk of rupture of Bruchs membrane should you use large or small spot size
Small, not large, spot sizes increase the risk of rupture of Bruch’s membrane and subsequent CNV.
less painful laser wavelength
Green lasers are preferred since they are effective and less painful than the other wavelengths.
Should you use pars plana magnet with retinal tear?
Answer: no
Use of a pars plana magnet in the presence of an associated retinal tear risks further retinal damage and possible detachment.
disadvantages of small-gauge (e.g. 25-G) vitrectomy
The disadvantages of small-gauge (e.g. 25-G) vitrectomy are increased risk of post-op hypotony, retinal tears, and endophthalmitis. These complications relate to these small-gauge wounds typically not being sutured closed at the end of the case.
