What conditions are associated with weakened zonules?;"• PXF • Prior vitreoretinal surgery • Trauma • High myopia • Connective tissue disorders (Marfan's, homocystinuria, hyperlysinemia Ehler Danlos, scleroderma, Weil-Marchesani) • Uveitis • Retinitis pigmentosa" What are the absolute contraindications for LASIK?;"• Asymmetric bowtie • Areas of superior or inferior thinning • Ectatic disorder: keratoconus, pellucid marginal degeneration, keratoglobus • Thin central cornea • Residual stromal bed <300 μm • High preoperative potassium values • Young age" What refractive change can occur after scleral buckle?;"• Myopic shift secondary to axial elongation" What are the 3 main sources of error when calculating IOL power in post-refractive surgery eyes?;"1. Radius error (true central K is flatter than K reading obtained from instruments) 2. Keratometer index error (index of refraction assumes a certain ratio between the radii of curvature of anterior and posterior corneal surface) 3. Formula error All of these lead to hyperopic surprise" What are the types of topographic maps and what types of corneal power do they measure?;"• Axial power map/sagittal curvature map: based upon reference axis through line of sight and better estimation of central corneal power • Instantaneous/tangential or meridional map: gives corneal power based on best fit spherical approximation at corneal point measured and is better estimation of peripheral corneal power" What is photoablation?;"• Use high-energy ultraviolet photons to break covalent chemical bond, no heat is produced • Excimer laser (193 nm) • Used in keratorefractive procedure" What is photocoagulation?;"• Head generated by absorption of light denatures protein • Used in retinal photocoagulation (PRP) • Laser thermokeratoplasty (LTK) treat hyperopia" What is photodisruption?;"• Wavelength produced by the Nd-YAG laser. This type of laser is pulsed, so the energy it produces is released in a very short time, producing a large amount of momentary power • The laser beam is focused into a small area. In the vicinity of the focus, electrons are stripped from their atoms by ionization, but they quickly recombine, which produces a spark and an acoustic wave • During a photodisruption procedure, it is the mechanical (acoustic) wave and not the laser light itself that breaks the capsule." What is photoactivation?;"• The conversion of chemical from one form to another by light • Clinical application includes verteporfin used in PDT" What type of cataract is associated with Alport syndrome?;"• Anterior lenticonus (bilateral)" What is the most common ocular complication with chronic hyperbaric oxygen?;"• Nuclear sclerotic cataracts, results in myopic shift • ~50% of patients exposed to hyperbaric oxygen >150 times during 1-year period will develop cataracts" What is orthokeratology?;"• Rigid CL that is flatter than the cornea to push down on the cornea, cause remolding of corneal epithelium • Treats low orders of myopia • 73% experienced CL discomfort in the clinical trial, corneal edema occured in large number of patient" What is aqueous misdirection syndrome?;"• AKA ciliary block glaucoma • Aqueous is directed into vitreous instead of flowing through pupil Treatment: mydriasis and cycloplegia (phenyl 10% and atropine), aqueous suppressants, hyperosmotic. If medical treatment fails → disruption of anterior hyaloid face with YAG laser or PPV" What are the most common gases used in excimer lasers?;"• Argon and Fluorine" What are the wavelengths of different lasers?;"• Femtosecond: 1053 nm (infrared) • Excimer: 193 nm (UV light) • Nd:YAG: 1064 nm • Rhodopsin most sensitive at 510 nm (green light). Less absorption of blue and yellow light. Cannot absorb longer wavelengths (red)" What is Fuchs heterochromic iridocylcyitis?;"• Chronic uveitis; long and fragile vessels that cross angle and insert high in angle (25% nicked when entering AC) • Unilateral without severe pain or photophobia • Stellate KPs • Iris heterochromia (blue eyes appear dark; brown appear lighter) • Lack of anterior/posterior synechiae • PSC 75% • Difficult to control glaucoma (will likely require surgery) Treatment: not necessary to treat inflammation, focus on glaucoma screening/management and cataract removal" Where are lens epithelial cells mitotically most active?;"• Anterior pre-equatorial capsule" What are the different types of CL and duration of holiday needed before normalization on topography?;"• Soft spherical CL: 3-14 days • Soft toric lens: 2 weeks or more • Rigid contact lens: at least 2-3 weeks (causes epithelial migration), additional month for every decade of hard contact lens wear" What are limbal relaxing incisions?;"• 600 microns in depth • Just anterior to limbus ~2 mm • Done on steep meridian • Maintain spherical equivalent (coupling ratio = 1)" What is arcuate keratotomy?;"• 95% in depth • Placed at 7 mm optical zone • Done on steep meridian • Maintain spherical equivalent (coupling ratio = 1) • Flattening in the meridian of incision and steepening 90 degrees away (coupling)" What is spherical aberration ?;"• Higher order aberration (4th order) • Decrease in quality of vision after refractive surgery • Peripherally refracted light rays are focused in front of retina and central rays are focused on the retina • Halos around point light sources night myopia • Decreased contrast sensitivity" What is the most serious complication of piggyback lenses?;"• Interlenticular opaque membrane • Most commonly occurs when two acrylic IOLs are used especially if they are both placed in the capsular bag" What are transversion incisions?;"• Straight incisions • Parallel to limbus • Coupling ratio >1 • Hyperopic shift" What is coupling ratio?;"• Amount of flattening induced by incision • Amount of steeping induced 90 degrees away" What is corneal Collagen cross-linking?;"• Strengthens stabilize cornea • Used in ectatic corneal disorders (KCN, PMD, post-refractive ectasia) • Expose cornea to riboflavin (B2) and UVA • Increases rigidity of cornea and reduce ectatic process • UVA light penetrates 300 μm and can destroy endothelial cells. • Corneal thickness at least 400 μm prior to UVA • If cornea not thick enough, use hypotonic riboflavin until cornea swells over 400 μm • Contraindications: Corneal thickness <400 μm, prior herpetic infection, central corneal scarring, poor epithelial healing, severe dry eye, autoimmune disorders" What is chatter?;"• Nuclear fragment repelled by phaco tip • Not desirable because lens can’t be aspirated efficiently • Allows lens pieces to have greater chance of striking corneal endothelium • Happens when ultrasound stroke > vacuum • To decrease chatter-reduce phaco power which reduces stroke length of phaco tip or increase vacuum setting" What is duty cycle?;"• Proportion of time phaco energy is applied during specified period of time" What is stroke length?;"• Distance phaco tip travels • Usually 2-4 mil (1 mil=1/1000 of inch)" What is cavitation?;"• Shock waves that are released as gas bubble implodes at phaco tip • Due to compression and expansion of gas atoms • Shock waves helps break down lens fragments so they can enter phaco tip" What is the pathway responsible for diabetic cataracts?;"• Sorbitol pathway" What are the findings of Keratoconus?;"• Ectatic disorder • More common starts at puberty • Maximal thinning at apex • Asymmetric steepening • Scissoring with retinoscopy • Fleischer ring • Scarring is common" What is Pellucid marginal degeneration and its finding?;"• Less common, onset 20-40s • Maximal thinning inferior to area of protrusion • Scarring only after hydrops • Crab-claw confirmation on topography" What are the findings of Keratoglobus?;"• Very rare, onset at birth • Thinning greatest in periphery • Protrusion in generalized • No iron line or scarring" What is against-the-rule astigmatism?;"• Football sitting on one of its poles (horizontal meridian is shorter) • Too much power along horizontal meridian • Cylinder correction that provides focusing power vertically no additional power horizontal Treatment: • Minus cylinder vertically (exerts power long its axis) • Positive cylinder horizontally (exerts power 90 degrees away)" What is with-the-rule astigmatism?;"• Football lying on its side • Steepest part of cornea along vertical meridian • Cylinder correction that provides focusing power horizontally no additional power vertical Treatment: • Negative cylinder at 180 degree (exert power along its axis) • Positive cylinder at 90 degrees (exert power 90 degrees away)" How many days prior to surgery should anti-platelet be stopped so normal platelet function is restored?;"• 10 days, i.e. Aspirin, clopidogrel, vitamin E • Hold for ocular surgeries at risk of suprachoroidal hemorrhage (PKP, glaucoma surgery)" What is Glaukomflecken?;"• High IOP during angle closure glaucoma lead to lens epithelial death leads to gray-white anterior subcapsular opacities • Pinpoint opacities measuring 2-3 mm or more in size" What is Brown Mclean syndrome?;"● Peripheral corneal edema after cataract extraction ● Edema begins several years after surgery ● Corneal edema characteristics: ○ Peripheral 2-3 mm ○ Central cornea spared ○ Starts inferiorly and extends circumferentially ○ Punctate brownish pigmentation, localized guttae ○ No neovascularization of cornea ○ Associated with long term aphakia ○ After routing cataract surgery, vitrectomies ○ No etiology Most are asymptomatic, may complain of foreign body sensation secondary to ruptured bullae" What are zero order, 1st order, and 2nd order aberrations (lower order aberrations)?;"• Zero order: piston • 1st order: vertical and horizontal prism • 2nd order: myopia, hyperopia, regular astigmatism" What is the rate of visually significant PCO?;"● 28% at 6 years ● Rate of formation for different intraocular lens (lowest to highest): Acrylic < silicone < PMMA ● Occurs when lens epithelial cells migrate across posterior capsule and cause contraction of secreted collagen matrix, this can result in capsular wrinkling and PCO" What is a Soemmering Ring?;"• After cataract surgery, residual lens epithelial cells proliferate in closed space between anterior and posterior capsules. • Consists of nucleated bladder cells = Wedl cells" What is an Elschnig pearl?;"• Epithelial cells proliferate in large spherical aggregates like “fish eggs” where each “ fish egg” is nucleated bladder cell" What are the risk factors for choroidal hemorrhage?;"• Older patients (brittle choroidal blood vessels) • Glaucoma • Previous hemorrhage in fellow eye with intraocular surgery • Myopia • Hypertension • Arteriosclerosis • Bleeding diathesis • Recent trauma or surgery with active inflammation • Prolonged hypotony • Anticoagulation" What is the minimal residual stromal bed thickness needed for LASIK?;"• 250 microns, most leave > 300 microns" What situation is associated with highest rate of endophthalmitis after cataract surgery?;"• Hypotonous eye with leaking wound • Leaking wound acts as conduit for bacteria to enter eye" What is the holding force?;"• Force that is exerted on the nuclear piece when tip if fully occluded" What is Epi-LASIK?;"• Blunt microkeratome to remove epithelium, then ablate stromal bed • Plane of separation is between basement membrane and Bowman’s layer" How is LASEK performed?;"• Place alcohol on epithelium, remove epithelium, laser the bed, then replace epithelium back on the stromal bed • Plane of separation is between lamina lucida and lamina densa • Leaving behind lamina densa may provide better postoperative refractive result compared to epi-LASIK (controversial)" What is PRK?;"• Scrape epithelium off with brush or spatula then ablate stromal bed" What are the various forms of potential acuity estimation for cataract evaluation?;"• Potential acuity pinhole (PAP): read a brightly lit near card through standard pin line aperture. Dilate prior to this test • Potential acuity meter (PAM): projecting Snellen chart through tiny aperture. Projected chart is moved around patient pupil until clear path is obtained and patient can see projected Snellen chart • Laser interferometry (LI): Projects 2 separate laser beams onto retina. 2 light beams interfere with each other creating a diffraction fringe pattern on the retina. Pattern independent of lens opacities. Spacing of the fringe pattern is decreased until patient cannot distinguish separate lines, may sometimes overestimate potential acuity" What is photostress recovery time?;"• “Poor man’s electroretinogram” • Bright light is shined into patient’s eye for 10 seconds through undilated pupil • The time required before patient can read BCVA line or one line larger = photostress recovery time • >90 seconds indicates significant maculopathy • Distinguishes optic nerve disease from macular disease" What are the Y sutures in lens?;"• Anterior upright Y suture • Posterior inverted Y suture • Y sutures appear around 8 weeks of gestation" What is a posterior chamber phakic intraocular lens (PIOL)?;"• Used in refractive surgery when patient has contraindications to corneal refractive surgery • Lenses are flexible collamer material, inserted through small corneal wound into ciliary sulcus • “Vaulted” over crystalline lens to prevent contact with it • Space between PIOL and crystalline lens allows aqueous to flow over crystalline lens which prevent cataract formation • Ideal space 0.5-1.5 corneal thickness • Vault less than 250 micron → risk of anterior subcapsular cataract • Vault greater than 750 microns → risk of crowding angle and pupillary block glaucoma, iris chafing" What is the most common type of cataract in acute diabetes?;"• Cortical in nature-snowflake cataracts" What are the causes of AC shallowing during cataract surgery?;"• Inadequate infusion of BSS • Leakage through oversized incision >3.0 mm • External pressure on globe (improper speculum, too tight surgical drapes, tight eyelids, too much retrobulbar anesthesia) • Posterior vitreous pressure (obese, thick neck, COPD) • Suprachoroidal hemorrhage Shallow AC can lead to radialization of capsulorhexis, more phaco energy transmitted to corneal endothelium, repeated iris prolapse through main wound" What is diffuse lamellar keratitis (DLK)?;"• Interface inflammatory process that begins as dust/sand-like infiltrate in interface of periphery • Untreated → stromal melting and corneal scarring with resulting irregular astigmatism • Associated with epi defects, occur during LASIK, foreign material lodged in interface, contamination of sterilizer with gram negative endotoxin" What are the different grades of diffuse lamellar keratitis (DLK)?;"• Grade 1: peripheral faint WBCs, no central corneal involvement - Tx topical steroids, follow q2-3 days • Grade 2: WBC migrated to central cornea - Tx topical steroids, consider interface irrigation, follow q1-2 days • Grade 3: dense WBC clumped in central cornea, beginning of corneal scarring; ""threshold DLK"" permanent visual morbidity if treatment is not initiated; typically occurs post op day #2 or 3 - Tx lift flap, clean interface, intensive topical steroids consider oral steroids • Grade 4: stromal melting and permanent corneal scarring, hyperopic shift, ""mud cracks,"" poor prognosis even with above treatments" What is accommodation?;"1. Ciliary muscle contracts 2. Zonular tension decreases 3. Axial lens thickness increases Hardening of lens is primary cause of loss of accommodation (presbyopia) because a harder lens will prevent increase in convexity that occurs with ciliary muscle contraction Helmholtz theory of accommodation = most accommodative change in lens shape occurs at the central anterior lens surface; posterior capsule does not change at all with accommodation" What is the difference in ablation pattern in hyperopic LASIK versus myopic LASIK?;"• Myopic: center of bed is lasered to flatten cornea, make cornea less dioptrically powerful • Hyperopic: periphery of bed is lasered to steepen cornea and make cornea more dioptrically powerful • Once ablation is complete, flap is laid back down" What is the mechanism by which mitomycin C application after surface ablation prevents corneal haze?;"• Reduces number of keratocytes and their enzymatic activity (activation of keratocytes after surface ablation leads to haze, keratocytes lay down collagen and glycosaminoglycans)" What is the most common type of congenital and infantile cataracts?;"• Lamellar or zonular cataracts • Lamellar cataract: opacifications of specific zones within lens; typically bilateral and symmetric" What is TASS (toxic anterior segment syndrome)?;"• Sterile inflammatory reaction • Secondary to contaminants injected into the eye or incorrect pH of irrigating solutions • Commonly occurs when remnants of cleaning detergents are not properly washed out of reusable cannula • Presents in acute post-op period (12-24 hours), earlier than acute endophthalmitis (2-7 days) • Confined to anterior segment • Treatment: exclude endophthalmitis as cause of inflammation; intensive topical steroids; control IOP if elevated" What is Ectopia lentis et pupillae?;"• Iris with slit-like configuration that is displaced in opposite direction as subluxed lens • Autosomal recessive" What is the most common postoperative complication of LASIK?;"• Dry eye – secondary to transection of corneal nerves with flap creation" What is AcuFocus corneal inlays?;"• AKA alloplastic corneal inlay porous ring segments • Used in non-dominant eye of presbyopic patients • Small central aperture causes increase in depth of field" Where is the cellular ion pump located on the lens?;"• Anterior lens epithelium cells • Sodium-potassium-ATPase pumps sodium out of the lens and potassium into the lens" What is conductive keratoplasty?;"• Small circular burns are created in cornea to steepen the central cornea • Radiofrequency probe to heat points in the peripheral cornea → causes localized collagen shrinkage and corneal flattening around the points and central corneal steepening • Results in cornea that has more refractive power • Used to correct low orders of hyperopia to create monovision Rarely used in following situations: 1. Cases of over-corrected myopia LASIK or PRK 2. Keratoconus to flatten the cone 3. Ectasia" What is phacolytic glaucoma?;"• Lens proteins leaks through an intact capsule • Lens proteins are taken up by macrophages • Engorged macrophages and lens protein itself can clog trabecular meshwork" What is lens particle glaucoma?;"• Macroscopic portions of lens (mainly cortex) remains unnoticed after cataract surgery • These pieces make their way to anterior chamber and directly clog trabecular meshwork" What is phacoanaphylactic uveitis?;"• AKA phacoantigenic uveitis • Immune-mediated granulomatous inflammation that is elicited by lens proteins released through ruptured lens capsule • Typically trauma is the cause of this ruptured lens capsule • Can also occur if cortical material is left in the eye after cataract surgery • Granulomatous uveitis occurs days to weeks after inciting event" What is phacomorphic glaucoma?;"• Lens becomes so large it pushes iris forward and closes angle" What type of cataract is most common in patients with atopic dermatitis?;"• Anterior subcapsular • Generally bilateral shield-like anterior subcapsular cataracts • Occur in up to 25% of patients with atopic dermatitis • Onset 2nd/3rd decade" What is the most common side effect of conductive keratoplasty?;"• Regression of effect" What is a zonular dialysis?;"● Portion of bag detached from ciliary processes ● Occur secondary to ocular trauma or spontaneously ● Predisposed in PXF and Marfans ● Can occur due to inadequate hydrodissection and overly aggressive rotation of lens nucleus ● If this occurs intraoperatively: ○ Prevent vitreous loss with possible lost lens fragments ○ Prevent additional zonular damage ● Treatment: First inject abundant amounts of viscoelastic → Then detached area of capsule needs to be supported mechanically via capsular hooks or capsular tension ring" What causes early postoperative shallow AC with high IOP versus with low IOP?;"• Shallow AC with low IOP = wound leak • Shallow AC with high IOP = posterior pushing mechanisms 🡪 i.e. choroidal detachment" What are the types of lens crystallin?;"• Alpha: highest molecular weight • Beta: majority of crystallins by overall weight (55%) • Gamma: minority of crystallins by weight" What are the ways in which excimer laser is delivered to cornea?;"• Broad beam • Flying spot • Slit beam" How is radial keratotomy performed?;"• Partial thickness linear radial cuts in cornea → wound gape with mid-peripheral bulging of cornea → central cornea flattens → decreased refractive power and therefore decreased myopia " What are the findings from Prospective Evaluation of Radial Keratotomy (PERK) study?;"• 43% of patients had greater than 1D hyperopic shift over 10 years • 3% had irregular astigmatism" What are multifocal lens?;"• Diffractive lens with rings that go out to the periphery • Rings on posterior aspect of optic • True multifocal lens • 2 focal points - one at distance and one at near • No matter pupil size, diffraction causes near and far images to be in focus" What is a Symfony lens?;"• Diffractive lens • Rings are apodized = gradual shortening of step heights toward the periphery of diffractive zone, allows for smoother transition from distance to intermediate to near • Extended depth of focus lens" What is a Restor lens?;"• Diffractive lens • Rings are apodized - smoother transition from near to distance - extends to 3.6 mm • Difficulty reading in low light if pupils normal size" What is a ReZoom lens?;"• Multifocal images by refraction • Associated with large amount of glare and halos" What is Crystalens?;"• Accommodating intraocular lens • With near stimulation and contraction of ciliary muscle, silicone lenses either are anteriorly displaced or steepen anterior curvature of optic" What is the preop scotopic pupil size that will likely result in glare and halos after refractive surgery?;"• 7.0 mm • Majority excimer lasers have optical zone on 6.5 mm • Pupil larger than optical zone will result in halos" What is an implantable collamer lens?;"• Maintains natural shape of cornea (prolate - steep centrally and flatter peripherally) • Aspheric shape reduces higher order aberrations • (Most amount of aberrations due to radial keratotomy also occurs with LASIK)" What layer of cornea is the graft in epikeratoplasty placed?;"• Bowman's layer • Pre-lathing a donor corneal stroma and then suturing it to Bowman's layer • Not very successful because carving out exact shape is difficult → unpredictable refractive outcomes • Trauma induced by eyelid blinking could sometimes dislodge graft • Epithelial ingrowth is also a problem" What type of cataract is seen with congenital rubella cataract?;"• Pearly white nuclear opacifications; retention of cell nuclei within lens fibers • Rubella in 1st trimester: ocular (cataracts or glaucoma), auditory (deafness) and systemic (cardiac) • Patients who develop rubella cataract do not develop glaucoma, vice versa • Rubella in 2nd trimester: salt and pepper fundus" What type of cataract is seen in retinitis pigmentosa?;"• Posterior subcapsular • RP also associated with CME and zonular weakness" What conditions are associated with PSC?;"• Chronic steroid use • Radiation exposure (brachytherapy) • Chronic uveitis • NF2 • Fuchs heterochromic iridocyclitis • Retinitis pigmentosa" What is a wave-front guided ablation?;"• Aberometer used to calculate lower and higher order aberrations pre-operatively • Laser then takes the information from aberometer and applies a laser ablation that attempts to minimize lower and higher order aberrations" What is a wave-front optimized laser?;"• Surgeon enters patient’s preoperative Ks and attempted correction into laser • Laser has pre-programmed database of Ks and corresponding ablation patterns that from manufacturers testing has minimized higher order aberrations" What are the risks factors for buttonholes?;"• Increased risk with steep cornea (>48D) • More common after creating a flap with microkeratome" What are the ocular findings in myotonic dystrophy?;"• Christmas tree cataract • Ptosis • Pigmentary retinopathy • Ophthalmoplegia resembling CPEO • Low IOP due to ciliary body detachments" What is major intrinsic protein?;"• Protein expressed by lens fibers as they line up in the bow region and correlated with elongation of cell • Cells elongate and the points where cells from one side touch cells from the opposite side form sutures. Then cells lose their nuclei" What is the difference between radial incisions and arcuate incisions?;"• Radial incisions = flatten both in meridian of the incision and 90 degrees away • Arcuate incisions = flattening in meridian of incision and steepen meridian 90 degrees away" What is postoperative CME?;"• Peak incidence 6-10 weeks after cataract surgery • 95% uncomplicated cases resolve spontaneously • Topical NSAIDs + steroids speed up resolution than either alone" What organism is responsible for chronic ocular inflammation after cataract surgery?;"• Chronic P. acnes • Occurring 6 weeks after surgery • Typically responds to topical steroids and appearance of PCO • Culture and IVI antibiotics are indicated • If no resolution → vitrectomy with partial capsular bag removal, some require entire capsular bag and IOL removed" What is laser interferometry?;"• Two helium/neon lasers to create a fringe pattern on retina • Device has wavy patterns corresponding to visual acuity • Smaller distance between wavy lines corresponds to finer visual acuity" What are the types of remnants of fetal vasculature?;"• Bergmeister's papillae: remnant of hyaloid artery • Pupillary strands: remnants of anterior pupillary membrane • Mittendorf dots: remnants of tunica vasculosa lentis" What is pressure-induced stromal keratitis (PISK)?;"• LASIK complication classically caused by prolonged topical corticosteroid use • Steroid-response increase in IOP🡪causes fluid accumulation within interface • Measured IOP may be falsely low due to fluid acting as ""cushion“ • Check pressure in the peripheral cornea or using dynamic contour tonometry • May present with interface fluid cleft or diffuse stromal and interface opacity • Can be causes by anything that results in an acute IOP rise • Typically requires 10-21 days to develop (unlike DLK = very early complication of LASIK) • Anterior segment OCT aids in diagnosis • Treatment: stop topical steroids and IOP lower meds" What is Holmium:YAG laser used for in refractive surgery?;"• Photothermal effect • Wavelength of 2.13 microns • Procedure is called laser thermokeratoplasty • Used for low hyperopia" What is an excimer laser?;"• Photoablation, breaks carbon-carbon and carbon-nitrogen bonds. M/C are argon-fluoride lasers • 193 nm wavelength" What are the types of viscoelastic agents?;"• Viscoat = dispersive, better coating ability (protect corneal endothelium better); more difficult to remove from eye; lower molecular weight, less IOP spike if left in the eye • Provisc/Healon/Amvisc = cohesive agents; made from hyaluronic acid; clump more (high surface tension), more easily removed from the eye; higher molecular weight; raise IOP more" What is an epithelial ingrowth in post LASIK? What are the risk factors?;"• Epithelial cells are trapped underneath flap 🡪 these cells can growth toward visual axis and cause irregular astigmatism, foreign body sensation, flap melts • Risk factors: epi defect at time LASIK (more common in ABMD, diabetics, frequent use of topical preserved eyedrops), use of microkeratome for flap creation • Traumatic flap dehiscence • Re-treatments requiring flap lift Treatment: lift flap, scrape off epithelial ingrowth from both flap and underlying stromal bed, reposition flap, BCL" What is the Munnerlyn equation?;"• Optical zone usually 6.5 mm2 • Residual stromal bed = CCT - flap thickness - ablation depth " What is lens-iris-diaphragm retropulsion syndrome?;"• AC deepening, extreme pupil dilation, concave shape of iris, patient discomfort due to stretching of ciliary body • Risk factors: high myopia (stretched/thin zonules), deep AC, previously vitrectomized eyes, incision size • Cause: reverse pupillary block where iris contacts anterior capsule 360 degrees. AC pressure greater than PC/vitreous pressure. Pressure difference causes marked deepening of AC and posterior bowing of iris • Treatment: lift iris off anterior capsule with phaco tip/second instrument or I/A tip → break reverse pupillary block and allow compartments to equalize in pressure" What is the recommended time frame to remove bilateral versus unilateral congenital cataracts?;"● Bilateral cataract: ○ Removed before age 10 weeks ○ Once cataract is removed, second cataract should be removed <2 weeks for child <2 years, <4 weeks for child >2 years ● Unilateral cataract: ○ Removed before age 6 weeks" What are the risk of intracameral aminoglycoside/gentamicin?;"• Retinal toxicity" What is the pathophysiology of cataract formation?;"• Increase in amount of water insoluble proteins • Increase in urea insoluble proteins • Increase in crosslinking between proteins • Decrease in glutathione" What are the risk factors for intraoperative epithelial defects during LASIK?;"• ABMD - loose anchoring of epithelium into abnormal basement membrane • Older age • Manual microkeratome - moves across the eye • Abundant use of preserved topical eyedrops - toxic and loosens epithelium (tetracaine more toxic than proparacaine)" What are intracorneal ring segments (Intacs)?;"• Flatten cornea in keratoconus • Improves refractive error • Allows for better fitting of hard CLs" What is the definition of power in phaco?;"• Percentage of length phaco tip moves relative to maximal possible length" What is the definition of cavitation in phaco?;"• Formation of bubbles at the phaco tip results in lens breakdown" What is the definition of load in phaco?;"• Amount of surface area of nuclear material in contact with phaco tip" What is the most common type of cataract that occurs secondary to trauma/contusion?;"• Posterior star-like configuration/stellate" What are the risk factors for anterior capsular phimosis?;"• Pseudoexfoliation • Other causes of loose zonules (trauma, Marfan) • Small capsulorrhexis • Silicone IOL material • Plate haptic IOLs Treatment: YAG cap (more energy than posterior capsulotomy)" What is intraoperative floppy iris syndrome and what causes it?;"● Triad: iris prolapse into wounds, iris billowing/floppiness, progressive pupillary miosis ● Causes: ○ α1a antagonists (tamulosin, terazosin, doxazosin, alfuzosin, prazosin, silodosin) ○ Labetalol ○ Antipsychotics (chlorpromazine, quetiapine, risperidone)" What is the corneal thickness cutoff for increased risk of corneal decompensation after cataract surgery?;"• 640 microns" What type of IOL is ideal for a patient who has previously undergone myopic LASIK?;"• Aspheric lens that contributes negative spherical aberration • Examples: AMO technis monofocal; Alcon SN60WF • Sensitive to decentration" What type of IOL is ideal for a patient who has previously undergone hyperopic LASIK?;"• Traditional spherical lens that induce some positive spherical aberration or no spherical aberration – softport lens • For low hyperopic LASIK – aspheric neutral lens" What are the risk factors for diffuse lamellar keratitis?;"• Solutions used to clean microkeratome • Iodine prep • Gram negative endotoxin • Meibomian gland secretions • Laser ablation debris • RBCs in the interface" What conditions are associated with PAX6 mutation?;"• WAGR syndrome • Posterior embryotoxon • Peters anomaly • Axenfeld anomaly • Congenital cataracts" What are the findings for the Endophthalmitis Vitrectomy Study (EVS)?;"• Assessed endophthalmitis acutely after cataract surgery • 2 groups: immediate vitrectomy versus vitreous culture + IVI antibiotics • Majority of patients did better with simple tap and inject • ONLY patients with LP or worse vision benefited from immediate vitrectomy • Intravenous antibiotics is not of benefit once IVI are given" What is the management for suprachoroidal hemorrhage?;"• Should be closed with suture as quickly as possible • Consider posterior sclerotomies, 5-6 mm posterior to limbus and inferotemporal quadrant" What are the ocular effects of chlorpromazine and thioridazine?;"• Pigment deposition on posterior cornea and anterior lens capsule • High doses of thioridazine → severe retinopathy (initially RPE stippling in posterior pole then nummular/coin-shaped pattern) • Treatment: immediate cessation of drug" What are the advantages and disadvantages of femtosecond laser compared to microkeratome?;"● Advantages ○ Center your flap easier ○ More reliable flap thickness ○ Less risk of epi defect, free caps buttonholes ○ Greater ability to adjust flap parameters (i.e. sidecut angle, spot separation) ● Disadvantages ○ Longer suction and procedure time ○ Opaque bubble layer ○ AC bubbles ○ Increased postoperative pain ○ More expensive ○ Subsequent flap lifts more difficult" What are the differences between micro- and macrostriae after LASIK?;"Microstriae • Common after post myopic LASIK • Mismatch of flap to underlying stromal bed • Folds in Bowman layer • Gutter typically symmetric • ""Dried cracked mud” Treatment: observation Macrostriae • Local areas of flap slippage/dislocation • Involves entire flap thickness • Associated with wider flap gutter • ""Wrinkles in skewed carpet” Treatment: reflat flap immediately +/- stretch flap" What is the most common type of cataract in galactosemia?;"• Bilateral oil droplet cataracts • Develop bilateral cataracts within few weeks of birth" What is the most common cause of sunflower cataract?;"• Intraocular foreign body made of copper (chalcosis) • Abnormal copper metabolism (Wilson's disease), Primary biliary cirrhosis, etc" What can cause Christmas tree cataracts?;"• Myotonic dystrophy • Hypoparathyroidism" What type of excimer laser is most likely to produce central islands?;"• Broad beam lasers • Central islands = elevation of cornea more than 1D steeper than surrounding cornea and greater than 1 mm in diameter" What are the ocular findings of Weill-Marchesani syndrome and how is it treated?;"• Associated with microspherophakia → causes pupillary block angle closure glaucoma Treatment: • Cycloplegics which pull lens-iris diaphragm posteriorly, decrease anteroposterior lens diameter, relieve pupillary block • LPI to prevent angle closure attacks" What is the type of higher order aberration caused with decentered ablation?;"• Coma" What are the potential complications of mitomycin C use in refractive surgeries?;"• Destruction of limbal stem cells • Endothelial cell loss • Scleral melt • Failure to re-epithelialize" What can Mitomycin C can help prevent in refractive surgery?;"• Corneal haze" What is a morgagnian cataract?;"• Nucleus becomes mobile and sinks to the bottom of the capsule • Leads to phacolytic glaucoma" What is a hypermature cataract?;"• Part of the cortex of a mature cataract starts to liquefy and leak through the lens capsule • Gives lens capsule a shrunken appearance • Leads to phacolytic glaucoma" What is an intumescent cataract?;"• Cataract swells secondary to taking up abundant amount of water" What is a cerulean cataract?;"• Small bluish opacities located in lens cortex that do not typically cause visual disability • A type of autosomal dominant congenital cataract and occasionally found in Down syndrome" What are the common changes in lens fibers that occur with age?;"• Proteins progressively become more water insoluble (scatter light) • Lens protein aggregation and cross-linking 🡪 protein-to-protein and protein-to-glutathione disulfide bond formation 🡪 accelerated by oxidative damage • Glutathione is major molecule that promotes reducing environment" What factors can increase the risk of prolonged inflammation after cataract surgery?;"● Intraoperative reasons: ○ Iris prolapse ○ Iris manipulation ○ Vitreous prolapse/incarceration into wounds ○ Retained lens fragments ○ Intraocular lens malposition ● Other reasons: ○ Children ○ Diabetes ○ Previous intraocular surgery ○ PXF ○ PDS ○ Long term miotic use" What is temporal (pseudophakic) dysphotopsias?;"• Subjective distortion of temporal VF only after cataract surgery • Positive dysphotopsias: halo, staburt, flash, streaks of light • Negative dysphotopsias: shadows (more difficult to tolerate) • More common in IOL with square-edged design and high-index material • Reported in 10-20% of cataract surgery patients • Many patients will eventually neuroadapt Treatment: • If mainly at night → brimonidine or pilo for pupillary construction • Glasses with thicker frames (coincide with areas of negative dysphotopsia) • Reverse optic capture → optic of lens above anterior capsulorrhexis • Piggyback lens • Nasal anterior capsule removal with YAG • Last resort → IOL exchange (lower index IOL with rounded edge) Way to prevent: • Lower index lens with rounded edge • Capsulorhexis rim overlaps lens edge • IOL well centered • Optic-haptic junctions horizontally (3 and 9 o'clock)" What is the risk of RD after YAG capsulotomy?;"● 0.1% to 3.6% ● Half of these RDs occur within 1 year of capsulotomy ● Risk factors and hazard ratios: ○ Axial length > 25 mm → 11.1 ○ Vitreous complication (during surgery) → 4.4 ○ Male sex → 3.61" What is the congenital cataract 1/3 rule?;"• 1/3 systemic disease/illness • 1/3 inherited with minimal effects on vision • 1/3 undetermined causes" What are the increased risks in pseudoexfoliation syndrome during and after cataract surgery?;"• Accelerated PCO • Intraoperative mitosis, vitreous loss, floppy iris, iris prolapse • Dislocation of IOL due to zonular dehiscence" What is the thickness of the lens capsule?;" " What part of the lens capsule is responsible for the production of new lens fibers?;"• The outer edge of epithelial layer at lens equator (lens bow)" What are the characteristics of the lens capsule epithelium?;"• Anterior capsule has a monolayer of lens epithelial cells • No epithelium is associated with the posterior capsule" What is a posterior subcapsular cataract?;"• Epithelial disparage at lens equator followed by posterior migration of lens epithelial cells along posterior capsule • Cells migrate to center of posterior capsule and enlarge 5-6 times normal size • Swollen cells are called bladder or Wedl cells • Situations that cause pupillary enlargement (distance vision, night vision, dilating drops) improve vision • Situations causing pupillary constriction (bright lighting) worsen vision due to light forced to go through central posterior opacification" How does silicone oil complicate lens selection?;"• Obtaining measurement ultrasonic biometer can be unreliable, given different ultrasound velocity for silicone oil (980 m/s) and vitreous (1532 m/s) • Silicone creates a negative lens power in the eye when coupled with biconvex IOL, increasing IOL power by 3-5 diopters in order to avoid hyperopic surprise • AVOID silicone lens" What do you do to decrease movement of a contact lens on the cornea?;"• Steepening (decreasing) base curve • Increasing diameter of CL" What do you do to increase movement of a contact lens on the cornea?;"• Flattening (increasing) the base curve • Decrease diameter of lens" What are the low order wavefront aberrations?;"• Positive defocus: myopia • Negative defocus: hyperopia • Regular astigmatism produces a wavefront aberration that has orthogonal and oblique components" What is coma?;"• Coma is a 3rd order aberration • Occurs when rays at one edge of pupil converge before ray at opposite edge of pupil • occurs in decentered ablations correctable with RGP and wavefront-guided keratorefractive surgery" What is trefoil?;"• Trefoil is a 3rd order aberration • Can occur after refractive surgery and produces less degradation in image quality than does coma • Correctable with RGP and wavefront-guided keratorefractive surgery" What is spherical aberration?;"• Spherical aberration is a 4th order aberration • Occurs when peripheral light rays impacting a lens or the cornea focus in front of more central rays • Correctable with RGP and wavefront-guided keratorefractive surgery" What is Peters type 1 and what are the implicated genes?;"• Iridocorneal adhesion • PITX2, FOXC1, CYPB1, PAX6" What is Peters type 2?;"• Lens touch to area of vascularized corneal opacity • Failure of lens vesicle to separate from surface ectoderm • FOXE3" What is Peters plus syndrome?;"• Peters anomaly with systemic defects - congenital brain defect, heart defect, craniofacial anomalies"