Christopher J. McDevitt, M.D.

School of Ophthalmic Medical Technology, CE Course

May 19 and 20 Airport Hilton, Bloomington, MN

Corneal cross-linking (CXL), SMILE refractive procedure, Corneal inlays for presbyopia correction

Small incision lenticule extraction (SMILE) for high myopia (-6to-10 D

3 year follow up demonstrates good stability

Uses femtosecond laser and no flap

Potential for reduced laser energy, smaller superficial incision, less neurotrophic and dry eye

Results are comparable to LASIK

Compared eyes with LASIK and SMILE at 3 months showed statistically significant better in LASIK eyes. At 6 months SMILE outcomes like LASIK at 3 months.

Surgical correction of presbyopia options: LASIK monovision, clear lens extraction with multifocal IOL

Corneal inlay placed in corneal stroma in the nondominant eye under femtosecond laser keratome flap or in a pocket

KAMRA inlay relies on extended depth of focus created by a pinhole, 1.6mm in diameter in an annular disc with a diameter of 3.8mm.

Flexivue Microlens inlay: donut shaped high index of refraction lens distance vision central near vision outside.

Raindrop Near Vision inlay : 2mm meniscus with same refractive index as the cornea and ahs no refractive power in the cornea. Action is to biomechanically raise the stroma and epithelium over the inlay inlay is made of clear permeable hydrogel

373 patients in study, multicenter

Uncorrected near vision in treated improved 5.1 lines,

Uncorrected intermediate vision improved 2.5 lines

Stabilize cornea in patients with progressive corneal thinning disorders

FDA approval of Avedro KXL

FDA approval of 2 photoenhancers: Photrexa and Photrexa Viscous

Goal: halt progression of keratoconus at a point when vision is still relatively good

Other options are improved contact lens technology.

Photochemical reaction of corneal collagen resulting from combining photosensitizer riboflavin with ultraviolet light (UVA)

Avedro KXL approved for progressive Keratoconus(KCN) and post refractive surgery ectasia

Standard protocol for treatment Dresden protocol) : initial removal of the corneal epithelium + 0.1% riboflavin every 1 to 3 minutes for 30 minutes (imbibition)

Cornea then is irradiated for 30 minutes with 370nm UVA at a power of 3 milli- watts/cm2

Failure rate for KCN is less than 2%.

Mild KCN: contact lenses, soft toric, RGP contact lenses hybrid contact lenses, hard in the center , sort on he periphery of the lens.

Piggy bag lenses: soft lens on corneal surface and hard lens placed on top

Scleral lenses

Intracorneal ring segment (ICRS) to reshape cornea for patients that cornea has gotten worse and pt. cannot wear CL’s

ICRS reshape to allow CL fit

Corneal transplant: top layer : deep anterior lamellar keratoplasty (DALK)

DALK decreases graft rejection risk

Corneal transplant: full thickness, penetrating keratoplasty (PK)

Keratoconus:

Concern to intervene in young patients getting worse but that do not have severe KCN yet.

Criteria for progression are not well established

Older patient with stable KCN may not need CXL.

Good candidates are ages 15 to 35 with minimal corneal thickness of 440 to 450 micrometers

Post refractive surgery:

Mostly post LASIK and age is not a factor and results are good to stabilize ectatic corneas.

Contraindication: less than 400 micron cornea, severe corneal scarring, or opacification, history of herpes infection of poor epithelial wound healing

Depth of focus IOL, Trifocal IOL, Wrong IOL implanted

Outcomes study of more than 21,000 cases in US, since 2011 compared with procedures done in ASC/hospital in Kaiser Permanente Colorado Health Care system

Outcomes consistently excellent with safety profile of procedure performed in ASC’s (80 percent) and hospitals

Main cost of cataract surgery is facility fee: Medicare reimbursement average $964 for ASC and $1670 for hospitals (2013 data)

Two ACLS certified RN, one circulating one monitoring/charting and surgical technician. No anesthesiology.

No IV or injections given

Topical +/- intracameral anesthesia with oral triazolam

Adverse events : Intraoperative PC rupture 0.55% (119/21,501)

Vitreous loss: 0.34% (73/21,501)

Adverse events: Postop: endophthalmitis 0%; surgical reintervention within 3 months: 0.61% (131), 6 months 0.70% (150)

Surgical intervention: IOL exchange (44), repositioning( 17), insertion after lens removal (22), lens fragment removal (22), vitrectomy (16)

Office based cataract surgery pre-op testing not routinely done

Clinicians face challenges in acquiring optical data to optimize IOL selection

Error in IOL calculation 79%:

Effective lens position

Axial length

Postoperative refraction

Total corneal contribution to IOL calculation error contribute to errors of greater than 0.25 diopter in 25% of eyes

Increasing accuracy in axial length measurements by IOL master 700 and Lenstar are small with an dioptric errors of less than 0.05 Diopter.

Effective lens position (ELP) and refraction are the most persistent source of error

Better estimate of with inclusion of anterior chamber depth (ACD), lens thickness and corneal diameter.

Refraction multiple sources of variability: Patient responses

Refractionist abilities

Tear film status

Chart distance

Ocular higher order aberrations especially spherical aberration and coma

Warren Hill data base of 260,000 operated eyes

Percentage of eyes within 0.5 D of target refraction was

Equal to or less than 78% for over 50% of surgeons

79 to 84% for up to 6% of surgeons

89 to 90% for fewer than 1% of surgeons.

Results with Dr. Hill’s new RBF formula 91% of eyes within 0.5D

Eyes with AL: 20.97 to 29.10 mm

Therefore 1 in 11 normal eyes will be off by more than 0.5D

Worse outcomes with:

Short eyes

Eyes measuring cornea is problematic

Ablated

Ectatic

Postkeratoplasy

Better outcomes with Toric IOL’s with now <0.5 D for refractive astigmatism in 80% of eyes

Spherical power of the cornea

Astigmatism

Higher order aberrations

Determination of corneal spherical power

Perfect outcome: accurate measurements, good IOL power formulas, and updated formula IOL constants

Good fortune

Variable corneal easements

Anterior corneal measurement methodologies:

Reflection: manual K, Placido rings, point source LED, SimK values displayed

Scan slit imaging: Orbscan

Shheimpflug imaging: measure thickness of optical sections

OCT:

rastersteriography

Compare :

Atlas,

Galilei dual Scheimpflug,

IOL Master 500

Manual Keratometry

Intradevice deviations low

Interdevice: 95% agreement

IOL calculations based on measuring the anterior corneal curvature and assume a constant ratio between anterior and posterior corneal curvatures

Posterior/anterior ratio deviated from standard value

Standard value 1.3375

Indices lead to corneal powers greater than true power

IOL calculation formulas compensate for this error and others such as ELP, IOL optical features and use lens constant as a fudge factor

Posterior corneal power is ten times lower than anterior corneal power based on the refractive index of the adjacent media (air compared with aqueous humor)

Clinically challenging to measure the posterior cornea curvature

Posterior corneal measurements:

Scheimpflug

OCT

Reflection by color LED device

Ratio of posterior to anterior corneal curvatures:

Gullstrand: 0.883 now found to be too high closer to 0.81 for normal corneas (0.80 to 0.86).

Translates into error of 0.5 D

Myopic LASIK/PRK: lower than 0.81

Hyperopic LASIK: slightly higher than 0.81

Change anterior corneal curvature

Posterior corneal curvature unchanged

Greater range of variability in the anterior corneal power in the central 4mm after these procedures .

After RK, posterior corneal curvature is also changed in an unpredictable way

In addition introduces a second problem with ElP estimation. Solutions found in: Holliday with double K approach

ASCRS Post-Refractive Surgery calculator

Barret True-K

Method relying on prior clinical data:

Errors in pre op K’s errors

Postop refraction errors

Less than 60% accurate within 0.5 D

These methods have been removed from ASCRS calculator

Methods using combination of surgically induced refractive e change and present corneal power

Measure the surgically induced refractive change by some fraction and use this value to modify corneal power or IOL power after calculated

Some of the most accurate

Measurements based only on present data on the patient.

Regression formulas derived from analyses of pooled data

Using actual individual patient corneal power by Scheimpflug or OCT measurements

Comparing the regression formula and the OCT based formula within 0.5D was less than 70% with formulas and 68% with the OCT based formula

Intraoperative retinoscopy

Intraoperative autorefraction

Intraoperative aberrometry after cataract removed then aphakic refraction proprietary formulas used plus biometric data to calculate IOL power

Regression of data used

Outcomes: +/-0.5 D 69% to 74%

Abnormal cornea with:

the standard ratio of anterior and posterior curvature is altered

Cornea irregularity make it difficult to determine which value for the anterior corneal power to use for the calculation

Cornea are unstable

Some will undergo keratoplasty later

Few peer reviewed studies that offer helpful guidelines

Truong et al 22 eyes with mean errors of greater than 1Diopter using 3 different devices: IOL master, Placido topography and Pentacam

Errors: overestimate anterior corneal power, and underestimate the steepness of the posterior cornea (negative power).

PKP: cornea , like KCN, have high amounts of anterior corneal astigmatism, with large irregular component

PKP: uncertain posterior corneal power.

Post cataract surgery with toric IOL with residual astig of 2.61 diopters

Post cataract surgery with femto laser incisions with residual astigmatism within 1 D of intended in 76% of patients

DSEK produces modest corneal power changes with minimal astigmatism shift

DSEK produces hyperopic shift 0.7 to 1.5 D

Donor lenticule is concave and increases the minus power of the posterior cornea

Cataract s surgery and DSEK target of -0.75 to -1.5 D myopia reasonable to compensate for this hyperopic shift

Toric implant a possibility since DSEK adds little astigmatism.

DMEK adds less with hyperopic shift 0.24-0.50 and minimal astigmatism induced

DMEK effects of reversal of myopic shift from corneal edema

Residual astigmatism found

Overcorrection with the rule astigmatism WTR

Undercorrection against the rule astigmatism ATR

Posterior cornea is steep vertically in most eyes

Produces positive refractive astigmatism ATR

Reduces refractive astigmatism produced by anterior WTR

Adds to astigmatism produces by anterior WTR astigmatism

Antero WTR: as astigmatism increases the posterior corneal vertical steepness increases which decreases the total corneal astigmatism

ATR: posterior cornea does not change with increasing anterior ATR astigmatism

Baylor nomogram compensates for posterior corneal astigmatism changes as the orientation and magnitude of the anterior corneal astigmatism changes

Abulaafia-Koch formula

Barrett toric calculator

Measurement of the posterior cornea are not accurate

Presently adjustment are made based on anterior cornea curvature alone

Efficacy and safety meta analysis of 14,567 eyes compared manual cataract surgery (MCS) vs FLACS.

2802 screened articles ,15 randomized controlled trials and 22 observational cohort studies.

Primary visual and refractive outcomes no statistically significant difference detected between FLACS and MCS uncorrected visual acuity, corrected distance acuity

Secondary endpoints: effective phacoemulsification time, capsulotomy circularity post-op corneal central thickness, corneal endothelial reduction Flacs over MCS.

Distance vision quality like a monofocal IOL with near vision

AMO Symfony and Symfony toric

Incorporate a difractive echelette design with achromatic technology

Elongate focus

Correct chromatic aberrations with improved contrast sensitivities post op auto refractors may estimate more myopic result so need to refine with manifest refraction.

Better continuous intermediate vision

Good vision from distance to arms length

Readers +1.25 for near vision

IOL calcs Lenstar with Olsen ray tracing technique better than IOL master

NHS in UK wrong IOL implants even with surgical check lists; 178 (2010 to 2014)

Human factors to blame.

In US VA study confirms similar problem in US

One cause is incorrect transcription of the selected IOL to other sources and subsequent failure to refer to original source documents

Errors occur at every stage: biometry, transcription; intraoperative (change in planned procedure); perioperative (handwriting misinterpretations and wrong IOL in OR)

Misfile biometric date in wrong patient file

Mistakes in EMR

44 of unknown cause

IOL exchange 45 cases

Recommend simulation training practicing the actions, behaviors, communication skills teams

Visual tasks in the efferent system affected: convergence accommodation saccadic mechanism Vestibulo-ocular function Smooth pursuit

Common Symptoms:

Photophobia

Headache

Slowed speech

Dizzy feeling: examine the oculomotor system carefully.

Trouble with reading or using screens can be a sign of convergence problems

Motion sensitivity may be a sign of vestibular system malfunctioning

Sports Concussion Assessment Tool (SCAT 3):

Includes checklist for symptoms: memory, balance, cognitive changes

Does not use vision testing.

King-Devick Testing

Assess saccades and vergence

Tests the time to read numbers with variable spacing on 3 test cards

Assesses a variety of integrated visual systems at once: brainstem, cerebellum, and cerebral cortex.

Can capture concussions that other sideline tests may miss since athletes underreport symptoms

Can be administered by parents or coaches in one minute and requires no special equipment.

LTP by Optometrists, Nerve fiber OCT in Myopia, Cypass shunt, Intracameral implant for drug delivery

Stein et al found a clinically significant difference in the frequency of additional LTPs between optometrists and ophthalmologist in Oklahoma

Additional LTP has a decreased rate of success and an increased complication profile.

Medicare claims based study

36% of eyes treated by optometrists required more than one treatment. 15% of eyes treated by ophthalmologists required more than one treatment.

Discussion emphasizes the need for appropriate training to identify with gonioscopy the critical features of the anterior chamber angle and the application of laser trabeculoplasty.

New minimally invasive glaucoma surgery device (MIGS)

This is an new device following the iStent, approved 4 years ago.

CyPass patients achieved a reduction in IOP that was greater than those having cataract surgery

Decreased lasted for the full 2 years of the study

Microstenting reduced the long-term use of glaucoma medication to one third of those in the control group.

85% of the microstent patients were medication free compared with 59% of controls.

Bimatoprost SR as effective at 6 months as eye drops (2 year trial).

Drug is like Ozurdex implant with bimatoprost instead of dexamethasone

Drug slowly released through the Novadur biodegradable polymer platform

Decreased IOP within one day and all subsequent visits

Implant lasts 4 to 6 months

High patient satisfaction.

Contact lens sensor (CLS): Sensimed Triggerfish monitors IOP fluctuations for 24 hours

Triggerfish: records changes in the ocular dimensions ( IOP volume changes occurring at the corneoscleral junction term called measuring limbal strain

No direct conversion of this measurement to IOP

CLS parameters: number of large peaks, mean peak ration, wake sleep slope, etc.

Data is sent to a recording device that the patient wears then transferred to clinicians computer.

$650 for 1 Triggerfish CLS monitoring

Eyemate: IOP microsensor that is implanted into the ciliary sulcus during cataract or glaucoma surgery

Patient uses a hanheld reader that receives data from the device and displays the IOP value performing self-tonometry at home.

Further work being done.

New devices available in the future to provide continuous monitor rather than brief tonometer reading in clinic.

Abnormalities detected in RNFL in high myopia have high degrees of false-positive errors.

Normative databases of many OCT instruments do not include individuals with high myopia

Normal data base for Cirrus HD OCT had a mean refractive error of -0.82

Convergence of superior temporal and or inferior temporal RNFL bundles toward the macula in eyes with high myopia may render those values abnormal with reference to this normative data base.

Circumpapillary scan RNFL increases in diameter with distance from the OCT unit and the RNFL decreases a small amount

Retina becomes thin in high myopia since it is “stretched” to cover the area of the enlarged globe

Measurement circle is further from the center of the optic nerve so the measured RNFL is thinner than it would be for a 3.4 mm circle centered on the optic nerve head

The greater the axial myopia the greater the artefactual and actual RNFL thickness

Red disease pseudo condition with RNFL thickness outside normal limits and mistakenly interpreted as glaucoma myopia induced OCT artifacts deviations from normal data base , red, are diffuse and not limited to the superior and inferior area of the optic disc

Verifying abnormal OCT shows normal VF with mod to severe OCT abnormality such as less than 75% of normal

Solution is add normative data base for high myopia

Goal of home monitoring to catch the earliest signs of neovascularization as early treatment. Good vision at start of injections leads to best vision two years later.

Foresee Home (Notal Vision) was efficacious in a NEI sponsored clinical trial

Uses a preferential hyperacuity perimetry device (PHP) plus proprietary metamorphoropsia- detection algorithm

Specific tele monitoring protocols followed at a central reading center.

Notal Vision provides the equipment to the patient after receiving a prescription form the ophthalmologist

If changes from baseline test are found then a manual comparison is done by a specially trained O.D> or ophthalmologist

The location and the size of the metamorphopsia and scotomas are derived from the patient's responses to a series of dotted lines that the perimetry device flashes in the visual field at various locations.

Some of the lines are straight other intentionally abnormal and patient needs to confirm by clicking a mouse.

Errant or missing clicks may be a sign of early choroidal NV

Patients receive automatic reminders

For more than a decade the PHP system has undergone increasingly rigorous testing

Costs Medicare copay for the service is $15 per month with no patient costs and setup

Device is shipped to patient home

No cost to prescribing clinician.

Age- Related Eye Disease Study 2- Home Monitoring of the Eye study.

Foresee Home Device arm vs standard home monitoring

Device detected more early AMD and the vision was better at the time of detection

Study was stopped since the device worked so well compared to standard

Take home points: home monitoring may be useful: if patients detect a change then need to be seen in office for evaluation.

Smartphone and tablet-based mVT app (Vital Art and Science) looks for sign of progression

AMD, wet, dry, and diabetic macular edema

Testing has shown it equivalent to Amsler grid and ForeseeHome

Images of 4 circles, one of which has an irregular edge on a smartphone or tablet screen.

The degree of distortion decreases with each subsequent image

The patient uses the touch screen to choose the distorted shape and the results are tracked remotely and compared with the patients baseline performance

Small validation studies so far

Cost not decided yet and insurance coverage has not been approved

Expected approval in 1-2 years

ForeseeHome

Initial VA of 20/60 or better

Looks for metamorphopsia both centrally and outward to cover 14 degrees of the central visual field (VF)

Ease of use: 20 % in AREDS2-Home could not use device

Preexisting VF defects interfered with the PHP test

Patient could not adapt or fixate on the center light

mVT

Initial VA 20/100 or better

Macular testing and covers 3-degree center of central visual field

Feasibility trial no patients failed because of inability to perform the test.

Fixation not necessary to use the mVT app

High contrast images presented to the amblyopic eye, low contrast images to the fellow eye

Adapted to an iPAD device

Falling blocks game using red-green anaglyphic glasses

Compare one hour a day with 2 hours a day of patching

Aged 5 to 13 years with 20/40 to 20/200 amblyopoic vision.

16 weeks

AMD

Glaucoma

Dry AMD: no clear role, may consider genetic testing but does not change recommendations AREDS 2 supplements and good diet.

Smoking cessation

Not covered by Medicare and most insurance carriers

Testing is warranted if it will impact treatment or surveillance: Congenital glaucoma or juvenile-onset open angle glaucoma(JOAG)

Genetic testing allows ophthalmologist to identify patients with genetic variants that cause congenital glaucoma and JOAG

Follow them closely

Reassure family members who do not carry variants that their risk of glaucoma is no higher than the general population

Direct-to-consumer testing (DCT): variation in the cost ,scope, clarity of information content for DCT for ophthalmic conditions

DCT company 23- and- Me can report allele information for a few heritable conditions but can no longer provide interpretation need to consult genetic counselor

AAO recommends avoiding DCT services.

Genes that increase risk: many open angle glaucoma (POAG) cases the combined action of a number of genetic factors contribute to disease development

Each one increases a small increase but by themselves do not cause disease

Genes that directly cause the disease: three genes have been identified and a mutation in these genes is highly predictive of disease.

These occur in less than 5% of POAG.

Since the prevalence rate is so low it is not feasible to test for these genes in the broad unselected population.

Genetic mutation in genes myocilin (MYOC), optineurin (OPTN) and TBK1 can be a primary cause of glaucoma

Some patients with variant of MYOC respond differently to medical treatment for glaucoma

MYOC mutations are associated with 3% to 4% of POAG

OPTN or TBK1 are associated with 1 to 3 % of low tension glaucoma

Testing for early onset glaucoma(JOAG) associated with mutations with 6 genes (MYOC, PITX2, FOXC1, PAX6, CYP1B1, LTBP2). All together account for only 20% of JOAG)

If considering refer to a genetic counselor for interpretation ordering these tests many time

“Likelihood to recommend”

Press Ganey designs patient satisfaction surveys for health care providers

PG surveys used by 50% of US hospitals and 10,000 health care organizations

Patient’s perception of the time spent with the practitioner and the ease of appointment scheduling are 2 variables that best correlate with patients recommending practitioner to other patients

Friendliness/courtesy of the care provider correlated least with the likelihood to recommend