Contact Lens I: Introduction to Soft and Rigid Contact Lenses Lecture 1 PDF

Contact Lens I: Introduction to Soft and Rigid Contact Lenses Spring 2024 • Instructor of Record: Dr. Melissa Levine • Dr. David Libassi • Lab Sessions: Wednesdays & Thursdays AM’s • Lecture Outline posted in Moodle • Lab manual will be distributed in Lab • Tyler’s Quarterly ( list of Contact lens...

Contact Lens I: Introduction to Soft and Rigid Contact Lenses Spring 2024 • Instructor of Record: Dr. Melissa Levine • Dr. David Libassi • Lab Sessions: Wednesdays & Thursdays AM’s • Lecture Outline posted in Moodle • Lab manual will be distributed in Lab • Tyler’s Quarterly ( list of Contact lenses in US) distributed in Lab • Please watch Soft lens I&R video on UEC Website 1 Soft lenses newer to market 70 years of Rigid CL Wear cause fory inflammationbloutweigh et Soflenses I up bl tem benefits glasses alternative Ch rain Vot and infection Significant Therapeutic forpt lence get bettacrity of CL will tran spectacle corneal trauma Surge/dyege for Ex reason 2 In the aftermath of the Fusarium fungal keratitis outbreak: What have we learned? Clin Ophthalmol. 2007;1(4):355-66 Non-compliance and microbial contamination in orthokeratology. Optom Vis Sci. 2009;86(11):1227-34 Loading… National outbreak of Acanthamoeba keratitis associated with use of a contact lens solution, United States.External Emerg Infect Dis. 2009;15(8):1236-42. Risky Behaviors for contact lens–related eye infections among adults and adolescents — United States, 2016. MMWR Morb Mortal Wkly Rep. 2017;66(32):841-5 3 4 Loading… 5 Question ???? • So why should you learn how to fit a foreign object, (CL) that we know causes ocular inflammation, corneal edema, corneal infection? • Why should any one be fitting / wearing contact lenses? We know they cause ocular inflammation, edema, infection? • Should we send all of our myopic, astigmatic, hyperopic, irregular cornea, post trauma patients for refractive surgery, because surgery does not cause6 inflammation ????? CAN YOU THINK OF ANY OTHER SITUATION IN HEALTH CARE WHERE EXPOSING THE PATIENT TO A POTENTIALLY INFECTIOUS, INFLAMMATORY SUBSTANCE / PROCEDURE IS CONSIDERED AN APPROPRIATE TREATMENT ? 7 Risk vs Reward • Before initiating a corrective modality, therapeutic intervention, medication therapy, physical manipulation treatment, or surgical intervention, the practitioner determines the RISK of harm vs the REWARD of benefit. • Every decision you will make about any intervention requires you to evaluate the potential RISK of harm & REWARD of benefit. 8 Motivation & Responsibility Reward vs Risk of CL wear of complications 9 Increase Risks of Red Eye Events with CL Wear Typically Related to CL Abuse • Increased risk of ocular irritation or infection typically due to non compliance with – – – – Lens wear schedule (DW vs FW vs EW vs CW) lens replacement schedule (DD, 2 wk, 1 month, Quarterly, Annual Lens care system (before re-use of a lens) case replacement schedule. Every 3 months or sooner. (serious potentially blinding corneal infection occurs 1 in 500 cl wearers per year. • Approximately 99% of respondents reported at least one contact lens poor hygiene behavior previously associated with an increased risk of eye infection or inflammation 1 10 Fact: Over Night, Non-lens wear Closed eye situation called sleep, creates Corneal edema & inflammation. • This nightly 3.2% of corneal edema dissipates in the first 2 hours of open eye • This nightly 3.2% of corneal swelling is well tolerated by the average eye. Typically without vision or ocular health consequences. • So is all edema / inflammation unacceptable by the body? • Can you think of other examples where the risk of inflammation is acceptable to the body for a beneficial reward? Loading… 11 4 Signs of inflammation • • • • Redness Heat Swelling Pain • Keep in mind we estimate degrees of redness, heat, swelling, Pain • Scales are often 0-4, or 0 – 10. 12 Benefits of CL Wear: Cosmetic & Therapeutic • Cosmetic: alternative to spec wear – – – – Va in CL = to spec Va Full field view Improved self perception Improved sport or performance success • Therapeutic: improve Va vs spec Rx – – – – – Less minification than > -10myopic specs: Degenerative M Less magnification than > +10 hyperopic or aphakic specs: Neutralize effect of irregular cornea (disease, trauma, surgery) Bandage cl for wound healing Reduce potential progression of Myopia • Orthokeratology; over night wear to reduce daytime Rx • Specially designed Multi-focal Soft lenses – Infant aphakia & amblyopia 13 Spectacle distortion / Irregular Cornea =Distorted View 14 Purpose of Contact Lens Lecture 1. To help you collect all patient health information to determine the RISK of ocular compromise vs REWARD ? 2.Not ALL contact lenses the same ? 3.What minimal info is needed for Initial & Continued patient success? 15 1.FDA def Contact Lenses as • A Class II medical device used in patients for the diagnosis, cure, treatment or prevention of disease. Medical devices act by physical presence, mechanical ability, physio-chemical or chemically activity. Example???? • Classes & Examples • Class I: surgical instruments • Class II: Contact Lenses & IV infusion pumps • Class III: hemodialysis machine • Class IV: cardiac pacemaker • FDA determines / Regulates: Safety & Effectiveness of all Medical Devices in US. • BUT FDA evaluations May NOT mimic Real Life 16 All CL’s in US are FDA approved, tested for safety & efficacy, Approved with : • Recommended wearing purpose: – Cosmetic vs therapeutic • Recommended wearing schedule – DW (Daily), FW (Flexible), EW (Extended), CW (Continuous Wear) • Recommended replacement schedule – DD (daily disposable), 2 week, monthly, planned replacement (3 or 4 month replacement) • Recommended Care system – Chemical, oxidative, heat 17 2: Not all CL are the same, Two different Applications of CL Wear • Cosmetic (~85% of lens fitted) – CL Va = Spectacle Va • Therapeutic(~15% of lens fitted) Close Management Required. – Bandage, • pain relief, Delivery of medication, promotes corneal healing • Myopia control – Vision correction better spec Va in corneal disease – Artificial Iris Lenses: aniridia (photophobia), diplopia • . 18 19 2. Are all CL’s the Same? • 5 different Categories of Lens materials: – Hydrogel (Hemma), Silicone Hydrogel (SiHy), Silicone (Si), Gas Perm (GP) (Silicone Acrylic), Poly methyl methacrylate (PMMA) – Combination of SiHy edge & GP center called Hybrid • Range of Lens Diameters: edge to edge – 7.5 mm to 24.0mm ( approp diameter based on HVID = 11.7mm) • Range of Base Curve radii (concave surface fitting Curve) – 6.0mm to 9.8mm (related but not equal to corneal curvature) • Range of Powers: – +40 D to -40 D • FDA Investigated & Approved for safety & effectiveness Safe Wear 20 In USA, all CL’s are – If pts are correctly selected, fitted, monitored, cared for & the will be successful 2014 CDC Mandate 21 Current Status of Contact Lens Use In U.S. • 45 million CL wearers in U.S. – (8 million population of NYC) • • • • 4 million New wearers each year 4 million Drop outs each year #1 reason why patients DROP out ________? Can we do a better job of PREDICTING SUCCESS & LIMITING DROP OUTS ? 22 Reported Reasons for Drop Out • #1 Poor comfort due to end of day lens Dryness – Error in Pt selection, (rapid TBUT), error in wear time, error in selected lens material, error in lens care system – Dry lens wear environment, lack of blinking • #2 Poor Vision – Error in type of Rx ( unbalanced , over/under corrected, spherical Rx instead of sph-cylinder) • #3 Laziness: Error in pt selection (motivation) 23 • . In US, Where Do Drop Outs Go • 4 million pts drop out per year – Most go to wear specs – thousand go to refractive surgery • 10% pursue Post-Refractive CL correction • A Poor CL candidate is a Poor refractive surgery candidate. • A Good CL candidate is Not always a Good refractive surgery candidate. 24 CLFitters, Refractive Surgeons:Competing forPopulation • Non-invasive vs invasive • Complications: D/C CL wear, can not undo surgery • As pt Rx changes: – Change CL Rx if necessary, – or enhancement surgery – or return to spectacle Rx or CL Rx • • • • Complications: similar sight threaten % Over 6 year period, Similar Cost. Both eyes: DD $800/year x 6 yrs= $4800 Refractive Proc both eyes = $5000 . 25 Course Goal: What Lens Would You Fit? • • • • 24yoM 31yoF Ref: -5.00 sph OU -19.00 sph K: 42:25 /42.50 @ 180 48:00 sph HVID 11.7mm 10.5mm – Horizontal Visible Iris Diameter • Pupil 7mm dimlight • TBUT 13 seconds – Tear Break Up Time 8.5mm 7 seconds (dry eye) • Lid margins: clear chronic bleph • Motivation, Work environment, dexterity 26 6 Steps to Maximize CL Success 1.Careful Pre-fitting history / examination / screening 2 .Careful selection of Good CL candidate, – Review of systemic & ocular health – motivation, compliance, age, wear environment – Assessment of ocular tissue, TBUT, closure 3. Adjusting Expectations of the Poor CL candidate 4.Careful selection of material, Base Curve & Diametr – Careful selection of FDA lens material – Oxygen supply, tear exchange, wet vs dry eyes – Lens & lid interaction, loose vs tight lens fit – Careful instruction of lens wear & lens care – Over wear, lens surface deposits 5. Careful on eye assessment of CL fit (good / poor) 6. Careful monitoring of ocular health – Corneal edema, palpebral hyperemia 27 1.Pre-Fitting Exam Determines “Good vs Bad Candidate”. Is the Risk of lens wear worth the Reward • A. Health: Systemic / Ocular • • • • B. Previous CL experience C. Lens Wear Environment D. Clinical Exam Data E. Patient Motivation 28 A. Systemic Conditions that Contraindicate use of “Cosmetic” CL Wear • Steven-Johnson Syndrome * (toxic epidermal necrolysis) – Severe Allergic rxn to oral meds / systemic infection – Destruction of mucous membranes & epidermis – Results in Severe dry eye, dry mouth, dry mucous membranes Loading… • Sjogrens Syndrome * – Auto-immune disease – destruction of mucous membranes – Results in severe dry eye – (*These pts may benefit from Therapeutic wear of “Rigid scleral’ lenses to protect ocular tissue) 29 . A. Systemic Conditions Complicate Cosmetic & Therapeutic CLWear • Episodic Inflammatory Dx: decrease aqueous production due to destruction of lacrimal gland – – – – Dry eyes: (non-surgical & surgical) Blepharitis, Meibomianitis Abusive Contact lens wear complicates sevee alleges Environmental allergies: wear al cosmetic Recurrent Sinus infections: stugal - - • Auto Immune Disease: Degree of Sx/signs – Thyroid disease, incomplete blink graves deal lag ↳ exophal – Lupus: auto immune, lacrimal gland destruction d dehydra – Rheumatoid Arthritis: lacrimal gland destruction of blurred decreasing aqueous production 30 – Inflammatory Bowel Dis: lacrimal gland destruction & opthalmo m - lenz - Vision , lost MGD -- dy = Complicates ! • A:Systemic Medical Conditions Complicate Cosmetic & Therapeutic CLWear • Pregnancy: >corneal sensitivity, <lacrimation. • Diabetes I&II – Decrease mucin due to decrease density Goblet cell due to reduced microvascular supply – Decrease corneal sensitivity & rate of healing – +Meibomian Gland Dysfunction (MGD) reducing lipid layer • Psychiatric meds: – effect accommodation – Decrease aqueous production • Hyperthyroid – exophthalmus, exposure, decreased & incomplete blink – lagophthalmus • . 31 32 A. Systemic Medications Complicate Lens Wear • 1.Oral Antihistamines Benadryl, Zyrtec,Claritin, Allegra – Decrease mucous & aqueous production • 2. Antidepressants / anti-anxiety – Elavil, Thorazine, Compazine, Mellaril, Tofranil – Valium (Diazapan) – Block epinephrine & reduce tear production • 3. Acne Meds, (Acutane, Tegison, Isotretinoin) – Reduce meibomian secretions increasing meibomian viscosity, inducing Meibomian Gland Dysfunction • . 33 A. Systemic Medications Complicate Cosmetic & Therapeutic Lens Wear • 4. Anti-Hypertensive drugs (Lopressor, Lasix, HCTZ, Inderal) – Decrease lacrimal gland function • 5.Oral Contraceptives – Decrease lacrimal gland function • 6.Alcohol – Diuretic,vaso dilator,< lacrimation, dehydration – Decrease frequency of blink to < 10 / minute •. 34 A. Ocular Health: • What Ocular Conditions Contraindicate “Cosmetic” Contact Lens Wear ? Systemic health important ② myopicd hyperopic on Cornea Rx & on Currea 35 A. Ocular Conditions Contraindications for “Cosmetic” CL Wear • Active / Chronic ocular inflammation – Herpes zoster, Uveitis, Corneal Infection • Ocular Surface Disease (require therapeutic cl wear but NOT cosmetic) acquired or inherited – >50% Active/Recurrent Epithelial layer Disruption – Acquired- corneal trauma, laceration, scarring – Inherited Dystrophies – Chronic Epithelial erosions • History of Corneal Pterygium, or raised epithelial scarring • History of Extensive Corneal Vascularization – Vessels >4mm into cornea – therapeutic CL maybe needed 36 •. Dendritic Herpetic Disease, Anterior Uvetis 37 38 Epithelial Basement Membrane Dystrophy 39 Pterygium 40 Corneal Erosion & Resulting Neo-Vessels Epi Erosion Neo-Vascular 41 A. Ocular Health: • What Ocular conditions Complicate “Cosmetic” CL wear ? - 42 A:Ocular Complicating Factors • a. Allergies to environmental antigens • b. chronic or acute blephartis glands/lide !! > make can • c. incomplete lid closure - & sure - V – Graves Disease, Lagophthalmus - • d. pingecula • e. ocular dryness: system, ocular, environmental • f. ocular medications 43 Blepharitis, Meibomian Gland Dysfunction Incomplete Blink 44 Topical Medications & AT’s 45 Conjunctival Pingecula & Implants 46 I. Pre-Fitting Exam Decides Good vs Bad Candidate. “Careful Pt Selection”. Is the RISK of lens wear worth the Reward? • A. Health History: Systemic / Ocular • B. Previous CL experience WHY ? – Success or failure • C. Lens Wear Environment • D. Clinical Exam Data • E. Patient Motivation 47 B. Previous CL History you need to collect. • Previous Brand of lens? Un / Happy? – Base Curve, Diameter, Material, tint • Complexity of Correction – Sph, Astigmatic, Multifocal, MonoVision • Lens Care solutions: possible irritant • Lens wear Modality – DW, 2-3nights FW, 6 nights EW, 30 day CW • Replacement Schedule – DD, 2wk, Monthly, Plan Repl (q 1 -3 months, Quarterly, semi Yearly, Yearly) 49 B. Previous Contact Lens History: Success/Symptom • Quality of Vision • Comfort / End of Day Dryness @___ Hours – Need for rewetting drops – Non-preserved / preserved saline • • • • Lens Handling characteristics Wearing Schedule Complications Was patient happy & want to renew or why were they unhappy & want refit? 50 · g back zeview B. Previous Lens Care System I Solution Sensitivity is Immediate Upon Lens Insertion • Multi Purpose Solution (MPS) / Chemical Disinfection – Renu, Optifree PureMoist & Replenish, Biotrue, Revitalens – Chemical sensitivity problems. WHY ?? • Oxidative Disinfection (Hydrogen Peroxide) – Oxysept, Clear Care – Peroxide, Non-Preseved alternative – Neutralization of H2O2 necessary – residual 100ppm of H2O2 may create discomfort • Specialized Care Products – Dedicated cleaners: SofPro2 (15% Alcohol) – Dedicated enzyme agents (Protein Removers) • . 51 Chemical Disinfectant: Chemicals toxic to Bacteria/Fungus ,Possibly to Ocular Tissue 52 Oxidative Disinfection: Hydrogen Peroxide Neutralized to Non-Preserved Saline 53 I. Pre-Fitting Exam Decides Good vs Bad Candidate. “Careful Pt Selection”. Is the RISK of lens wear worth the Reward? • A. Health: Systemic / Ocular • B. Previous CL experience • C. Lens Wear Environment WHY ? – What effect does lens wear environment have on success • D. Clinical Exam Data • E. Patient Motivation 54 C. Occupation / Wear Environment ? • Air Quality Pt Expects to Wear Lenses In – Smoke filled environment (think of one?) – Airborne Foreign debris • pollution / construction debris (think of one?) – Airborne fumes (think of one ?) • Chemicals, oil, – Dry air conditioning / Dry heat / Air Controlled – SCL Never approved for swimming, showering •Chlorinated pool water, bacteria in tap, lake, well & sea water – Is There Another Option for Swimmers ?? 55 I. Pre-Fitting Exam Decides Good vs Bad Candidate. “Careful Pt Selection”. Is the RISK of lens wear worth the Reward? • A. Health: Systemic / Ocular • B. Previous CL experience • C. Lens Wear Environment • D. Clinical Exam Data WHY ? • E. Patient Motivation 56 D. Clinical Ocular Data • A: HVID, Vert Aperture, Pupil Size, Dominant Eye • B: Corneal Shape – Keratometry or Topography – Flat, Average (Median), Steep, (all are Aspheric) – Spherical or Astigmatic (WR, AR) or Irregular C: Refraction & Va – Spherical, Astigmatic, (is distortion possible) BestVA – Binocular stability, Presbyopia – Anisometrope (3 diopter difference OD/OS) or Amblyopia • D: Bio-Microscopy ocular tissue – Lids, lashes, conj, Tear Film, cornea 57 • . D. Clinical Data: Measured HVID & Pupil Size • Horizontal Visible Iris Diameter (HVID) – Average 11.7 mm • Vertical Visible Iris Dia – Average 10.6 mm • Pupil Size – Room illum avg 3.5mm – Subdued illum avg 7.5 • Vertical Aperture – Range 5 to 12mm – Average 9.0mm • Dominant Eye: – Hole in hand test 58 MM ruler/10x magnifier Measuring HVID 59 Measuring HVID with Slit Lamp Eye Piece Reticule & Corneal Topographer 60 Vertical Aperature Measure • Vertical height in Primary relaxed gaze • Normal range 9-10.6mm • Effects SCL diameter selection – HVID >11.7mm need SCL dia >14.0mm – HVID <10.5mm need SCL dia <13.0mm – Apert <9mm need SCL diam<13.5mm • Effects GP diameter selection – HVID >12mm consider >9.0mm diam – Apert <8.5mm consider <9.0mm diam • . 61 Measuring Pupil Size in Dim/Room Light Ideal CL Optic Zone size Optic Zone Diameter of Lens =Dark illum Pupil size +0.5mm 62 Pupil Size In Dim Illumination • • • • • • • • Why measure pupil size in DIM illumination ?? ??????????????????????? Black light & ruler, primary gaze Air Optics for Astigm OZD =7.5 mm Tyler’s pg 32 B&L PV Toric OZD = 8.5mm Tyler’s pg 35 B&L PV 2 Toric OZD = 8.0mm Tyler’s pg 35 Cooper BiofinityToric OZD= ?? Tyler’s pg 39 J&J Oasys for Astig OZD= ?? Tyler’s pg 41 • IDEAL CL optic zone is 0.5mm larger than pupil size in dim illumination 63 Dominant Eye: Hole in the Hands test. Eye that patient relies upon for sighting distant target. Never leave dominant eye blurry 64 65 Measure HVID by Corneal Topographer / OCT 66 B. Clinical Data: Measuring Corneal Radius Keratometery is Traditional • ONLY measures Central 3 mm of cornea (8% of cornea) • Isolated curvature of 2 points – 1.5mm up vertically & 1.5mm out horizontally from apex • • • • • Provides AVERAGE of cornea curvature No measure of Apex (steepest region) No location of Apex Does not demo Astigmatic vs Asphere cornea Costs $800 67 B. Clinical Data: Measuring Corneal Radii Corneal Topographer: Specialty imaging • Measures 1000’s points of data • Across central 7-13mm diameter of cornea • • • • Pictorial image of corneal Aspherocity Symmetrical / asymmetrical Astigmatism Identifies Off center Apex location Costs $10,000-50,000 68 • - Topography face Placido disc i l u r i a t e 8 vie a 69 Eccentricity = rate of flattening • • • • • • • Asphericity is recorded in terms of Eccentricity Eccentricity is defined as the rate of flattening. Sphere never flattens = Eccentricity is 0 Line is constantly flat = Eccentricity is 1 Aspheric surface can have different rates of E Flatter area of asphere have E closure 0.8 Sharply curved area of asphere have E ~.4 70 Eccentricity def; surface rate of flattening Football variety of eccentricity / Basketball eccentricity of zero Flat curvature along football laces Average curvature around basketball Steep curvature at football apex 71 Topography of a sphere, Eccentricity = 0, constant radius 360 deg 72 Topography of a surface with concentric circles of increasing rate of Eccentricity = rate of flattening • Central circle radius 45.00D or E= 0.2 (orange) • Paracentral circle radius 43.00D or E= 0.4 (yellow orange) • Mid perpheral circle radius 41.00D or E= 0.6 (yellow) • Perpiheral circle radius 39.00D or E= 0.8 (yellow green) 7 3 Every Cornea is Aspheric flattest Steepest know We want to and of Pt dimension Cornea Fat p Flat in diopters = lower Steep = #inD JButfo radi a 74 Aspheric Cornea Across horizontal / flat meridian there is a change in rate or speed of flattenening = Eccentricity. E= center to temporal = 0.35 E= center to Nasal = 0.65 MOST Soft & Gas Permeable lens Base Curves ( lens surface that aligns the corneal surface) are spherical. Will spherical Base Curve contact lenses stay center when fitted to an Aspheric surface ????? Not always!!!!! 75 B. Clinical Data: Corneal Asphericity • Asphere = gradual progressive flattening of corneal curvature from center to corneal edge – Central cornea is steepest curvature – Peripheral cornea is flattest curvature • “E”ccentricity = rate of flattening from central cornea to limbus Flattens at Different Rates: Nasally vs Temporal • Apex to Nasal= rapid flattening E=.65 – Flattens more rapidly from center to nasal edge • Apex to temporal slow flattening E=.35 – Flattens slowly from center to temporal edge – Wang, M; Keratoconus & Keratoectasia 76 Topography provides Simulated Flat & Steep Keratometry Values 77 Topography provides Simulated Flat & Steep Keratometry Values 78 B. Clinical Data: Catergorizing Corneal Curvature • Classify Patient corneal type by FLAT K value – Flattest Corneal Curvature (record steep K as well) – Flat: < 41.75 D (flat curve like laces on football) – Median: 42:00 – 44:75 D 80% of pts – Steep: > 45.00 D ( sharply curved like football apex) • Keratometry value Classify Patient as having ASpherical or Astigmatic Cornea – – – Regular (symmetrical mires) Irregular (distorted mires) With the Rule (steep vertical cornea) Against the Rule (steep horizontal cornea) 79 Regular With the Rule astigmatic cornea 80 Regular WR Astigmatism 81 Regular Against the Rule 82 Example of Irregular or Asymmetric Cornea 83 C. Clinical Data: Refractive Status & Va • Retinoscopy • Subjective & Best Va – Sensitivity to astigmatic axis correction • Binocular Balance Loading… • Near Correction & Va ( age 40ish) – Pre-Presby or Presbyopic – B/c of increased accommodation in CL’s, need for NVRx might present but not in spectacles Determine Dominant Eye Hole in the Hand test 84 D. Biomicroscopy, Subjective Lid Tension • Determined by strength of Orbicularis muscle & rigidity of Tarsal Plate • Subjective measure – determined by ease or difficulty of eversion • Impact of lens fit, rotation, comfort – Tight lids: Greater influence on lens • Possibly excessive lens movement with blink • Possibly less stable & more Rotation of astigmatic correction • Possibly Greater lens awareness, • Possibly more challenge with I&R – Flaccid lids: Minimal influence on lens • Possibly Minimal lens movement • Possibly most stable & No rotation of astigmatic lens • Possibly Less lens awareness • Possibly easier I&R • . 85 D. Clinical Data: Observed Blink rate • Normal rate 10 to 15 Blinks per minute – 1 blink q 4 to 6 seconds • Completeness of Blink – Complete Closure: rewetting entire lens/cornea – Incomplete Closure: inferior corneal dehydration & + staining. • Lagophthalmus ?? •. 86 What is the Purpose of Complete Blink ? • Maintain Hydration of Corneal epithelium – – – – Optical clarity of cornea Intact epithelium is 1st line of protection from bacteria/virus Physical comfort (avoid dryness) of non lens wearing Preserve metabolic function of epithelium • Pre Contact Lens Tear Film,1/3 of tear thickness – Optical clarity of Contact lens anterior surface – Maintain Hydration of anterior contact lens surface • Avoid dryness Avoid surface deposits • Post Contact Lens Tear Film, 2/3 tear thickness – Movement of lens by blink encourages tear exchange under lens • Tear exchange under soft – – – – – lens 1%, Corneal GP 20% , Scleral 0% • Maintains proper CL movement & fitting characteristics Removes epithelial waste products of cell metabolism Removes carbon monoxide New supply of tear film nutrients for epith cell metabolism New supply of oxygen for epith cell metabolism Maintain epith cell health & optical clarity 87 Result of Incomplete Blink: Dehydration of Pre-lens & Post-Lens Tear film • De-hydration of anterior lens surface – Build up of surface deposits – Poor comfort & Optical Quality • De-hydration of lens core – Entrapment of debris / mucous / protein in lens matrix • De-hydration of Posterior lens Base Curve – Steepening of lens BC – – – – • . Loss of lens movement – TIGHT lens- Loss of tear exchange Entrapment of epithelial metabolic waste products No new oxygen Epithelial cell layer compromise & staining. 88 • • • • • • • D. Clinical Data Bio-Microscopy: Outside/Inn How does the Cornea look before Lid – What role ? weMargins introduce the Contact Lens ? Tear Film – What role? Palpebral Conjunctiva – Important ? Bulbar Conjunctiva – Why ? Corneal appearance – Important ? Anterior Chamber Internal Lens of the Eye 89 D. Lid Function • 1.Mechanical defense of ocular surface • 2.Circulating tears, – supplying NEW O2 & nutrients – Eliminating epithelial cell waste products • 3.Maintain clear OPTICAL refracting surface – Closes like a zipper: from temporal to nasal • 4.Removes Foreign Bodies • 5.Creates CL Movement (acceptable / excessive) – Vertical, lateral, rotational lens movement – Cause upward translation of Bifocal SCL • . 90 Healthy Lid Margin: calm, thin, smooth 91 D. Clinical Data: Anterior & Posterior Lid Margins • Role of Lids ???? (Lid Wiper) – Closing motion moves debris toward nasal puncta – Opening motion reconstitute clear optical surface • Thin & Calm vs Thick & Engorged Lid margin – Healthy vs chronic infection / inflammation • Margin: Flat vs Notched – Healthy past vs prev infection / inflammation • Meibomian Gland Function – Lipid layer of tear film: key element – Open or blocked – Acute or chronic inflammation • Staphylococcal blepharitis > corneal infiltrates & Ulcers • . 92 Meibonian Gland Health • Ideally clear liquidfied lipid • MGD: Meibonian Gland Dysfunction – Frothy lid margins – Inspissated (toothpaste like expression) – Waxy capped orifice • .Treatment: BID – hot compresses & swabs •. 93 Imaging Meibomian Glands Imaging upper & lower Meibomian Glands helps identify loss of glands versus blocked glands. 94 Frothing of Tear Film: suggest MGD 95 Blocked Meibomian Gland 96 Expression of Blocked Gland 97 Successful Expression: Inspissated 98 Notched Lid Margin-Scarred Meibomian due to Chronic Meibonianitis 99 Role of Tear Film • Primary Anterior Refracting surface • Primary Ocular Defense Mechanism • Primary System for Delivery of – O2, & Nutrients • Primary System for Removal of – Epith metabolic Waste, FB, Bacteria, Virus, Fungus • Primary System of Hydration – Epithelium & CL • Maintains Comfort & Optical Quality. 100 D. Tear Film • Thickness Tear Layer: 3.0-6.0 microns (range) – 1 mm = 1000 microns • Thickness Human Hair: 40-50 microns • Layers: – Lipid, meibomian glands, inhibit evaporation (cholesterol esters, fatty acids, phospholipids) 0.02- 0.1 micron thin – Aqueous, lacrimal glands Krause/Wolfring 2.5 – 4.0 microns THICKest – Mucous dble layer, outer mucous layer from Goblet cells, inner glycocalyx from & attaches to epithelial cells. Makes hydrophobic epith cells hydrophillic. 1.0 – 1.8 micron ½ thick as Aqueous • Tear Film: what role? – – – – Refracting surface Flushes debris. foreign matter, & Exfoliated Epi Cells Provides nutrition & oxygen to epithelium Lubrication for lids & CL • Avg.PH 7.45 101 D. Tear Film Composition • Electroltyes similar to blood plasm – Potassium, magnesium, calcium ( CL deposit) • Vitamin A – to maintain healthy goblet cells • Proteins – Albumin, lysozyme, lactoferrin (antimicrobial) • IgG, IgA, IgM, IgE Immunoglobulins – immunity to viruses, bacteria, fungi, parasites • Tear Osmolarity: 329 mOsm/l (0.9% NaCl). – Hypotonic tears in dry eye causes epithelial swelling – Hypertonic tears draws water out of epithelium 102 D: Pre & Post Lens Tear Film • Pre – Lens Tear Film (PreLTF) 0.8-1.5 microns – – – – Maintain clear refractive surface, remove foreign body Maintains hydrated anterior CL surface Contains lipid & aqueous What happens when PreLTF Dehydrates ? • Post – Lens Tear Film 2.2 – 4.5 microns – Supplies O2 & nutrients to epith – Removes CO2 & waste products of epi metabolism & foreign bodies – Contains aqueous & mucin – What happens when PostLTF Dehydrates ? – _____________________________________ • . 103 Lipid Layer = Outer Layer • Prevent external evaportion of tears • Blocked Meibomian Gld = incomplete lipid layer = evaporation of aqueous • Detect Lipid Layer breakdown = TBUT 104 D. Seconds until TBUT • Fluorescein Dye & Cobalt light – – – – Dry <9sec, indicates part time / social wear Wet >10 seconds (greater potential for successful all day wear) 6-9 sec indicate part time lens wear <5 sec contraindication for social SCL wear • Non-Invasive TTT (tear thinning time) – Keratometer Mires Break up – Healthy NI TTT > 10 seconds •. • Bennett, Clinical Manual of CL p375 105 D. Quality / Quantity of TBUT • Test of Tear Quality & Quantity • Predictor of ocular wettness vs dryness • Fluorescein & Cobalt & wratten 12 filter • Count Seconds to Black spots appear • How repeatable are spots ?? 106 What is etiology of rapid TBUT ? Lipid ? Aqueous ? Mucin ? 107 What is etiology of Non Repeatable / Scattered Spots of TBUT • Poor _______ layer (Blocked Meibomian Glands on Lid margins) result in inconsistant location of tear break up • Missing _______ layer can be in different regions of cornea from blink to blink • What conditions / meds effects this layer? – _____________________________ •. 108 Aqueous Layer = Mid Tears • Reduced due to – Dry lens wearing environment – Systemic meds • Diuretics, Anti-allergy, anti-anxiety, – Systemic conditions (Sjogren’s syndr) – Aging • > sx’s female gender • Lacrimal gland reduction in size & production • Decline in conjunctival Goblet cell density 109 What is etiology of very REPEATABLE spots of TBU Missing _______ layer. • • Traumatized epithelial cells lack surface villi (cilia). Consequently nothing to hold mucin layer over the epithlial cell • Without Mucin, aqueous layer recede from cell surface resulting in dry spot • Unprotected epithelial cell at risk of being sloughed off. 110 111 Stem Cell Migration to Heal Epi wound Gericke et al. RSC Advances Issue 39, 2019 112 Mucin Layer & Epithelial Cell Microvilli • Healthy Mature Epi cells have cillia (microvilli) protruding from cell surface • Microvilli become coated with Mucin creating a Hydrophilic cell surface • Traumatized or Immature Epi cells lack cillia (microvilli) allowing for epi surface dry spot. 113 Mucin Tear Layer • Inner most tear layer, clings to Microville • Conjunctival Goblet cells create mucin (glycocalyx) Bergmanson 1999. • Prevents bacterial adherence to Epi • Makes hydrophobic epithelium hydrophilic • Mucin held against epith by microvilli • Also entraps debris to blink out of eye 114 Identifying Mucin Defieicncy • Traumatized / New / Fragile Epithelium • Vital stains used to identify Mucin deficient – Fluorescein – Rose Bengal (devitalized cells) – Lissamine Green •. 115 Tear Meniscus • Height of Tear Meniscus – – – – Lower / upper lid tear prism, lacrimal lake Tears reservoir meets lid margin & epithelium Evident w/ Fluorescein Normal height: .3mm • >.3mm = Aqueous Sufficient • <.3 mm = Aqueous Deficient . 116 Tear Meniscus & Superficial Punctate Keratitis • .3 mm Normal anterior Tear Meniscus 117 Upper Lid Tear Meniscus 118 D: Eval of Palpebral Conj • Palpebral Conj & Tarsal Plate surface • Covered w/ – vascular Papillae: respond to bacteria insult – Lymphoid Follicles: respond to viral insult • Grade I-IV – Hypermia - injection – Hypertrophy - elevation 119 D. Palpebral Conjunctiva • Grade Hyperemia & Hypertrophy – – – – – Grade 0 = normal Grade 1 = slight red, small papillae Grade 2 = moderate red, 1 papillae/mm Grade 3 = severe, massive papillae Grade 4 = lubular elevations •. 120 Palpebral Hypertrophy, Grade I - 4 121 D: Evaluate Bulbar Conjunctiva for Abnormalities • Importance of Bulbar health: Goblet Cells & mucin • Measure size & location of anything unusual – – – – Pingecula, cyst, raised Loose conj Prominent ropy vessels Pigment spots – Size: Slit lamp apertures, – Location: clock position 122 Bulbar Conjunctival Abnormalities 123 D. Document Corneal Health • Peripheral & central Corneal Clarity 360 • Identify Corneal Abnormality – Scars, vessels Describe – Location by clock position & mm in from limbus – Size by slit lamp aperture – Density, borders, shape & Depth • Opaque vs tanslucent • Distinct vs faded or feathered • Circular, coma, stellate • Bowmans, Stroma, Endothelial 124 Sub epithelial Infiltrates, Non Staining Indistinct borders, Irregular shape Subepithelial , Pre Stroma 125 tellate (star like) Corneal scaring w/ feathery border 126 What is This ? 127 What is it & How active ? 128 D; Intact or Compromised Epithelium • Intact Epi cells Do Not Stain • Compromised Epi cells (+) Staining, – SPK: superficial punctate keratitis (isolated dots) – Coalesed: confluence of dots – Dellen: regional loss of epi cells due to cell death • Repeatable Negative Stain – Absence of tear film. Why ? • .Depth – Epithelial only – stromal 129 • • • • • Localized Superficial Epithelial Punctate Keratopathy SPK =Superficial punctate keratitis Superficial: intact basement layer, does not spread beyond compromised cell Punctate: dot like noting compromise in cell wall Diffuse: scattered across wide area of cornea Localized: confined to 130 xmm location SPK(Superficial Punctate Epithelial Staining) Typically due to Solution Preservative Mild Diffuse SPK Severe Diffuse Central Superficial Punctate Epi Staining (Grade 3 SPK) 131 Coalesed Epithelial Staining • More severe form of epi compromise • Superficial localized region of SPK • If not treated will advance to a loss of epithelial cell and thinning of cornea to basement membrane 132 Corneal Erosion, Coalesced Dry Eye, Foreign Body 133 Corneal Dellen or Excavation of Epithelium • Loss of superfical /localized patch of epithelium, • Depth down to anterior stroma. • Localized thinning of corneal depth with distinct borders • Poss etiology: Trauma, dehydration, desiccation due to adjacent raised scar or fiberous tissue 134 What is it ? 135 Corneal Refractive Surgery Scars Post Radial Keratotomy Scars Post Lasik Flat Scar 136 Corneal Ulcers with Infiltration of White Blood Cells Peripheral Corneal, sterile Central Cornea Sight non vision threatening threatening, Ulcerated / Infitrate (+) staining Depressed Infected & Inflitrated 137 Spontaneous Subluxation of the Globe: Patients who are obese & flaccid lids, when elevating upper & lowering lower lid simultaneously, globe moves forward. Uncomfortable, not an emergency. 138 Subluxation of globe: Predisposing factors: Obese patient Floppy Lid syndrome Bilateral Proptosis Shallow orbital upon MRI Hyper-extension of joints Long Optic Nerve Elongated EOM’s 139