Contact Lenses


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Contact Lenses

  1. 1. Contact lenses Author: Irina Jagiloviča e-mail: optometristiem @ gmail .com www:
  2. 2. Contact Lenses and Ocular Anatomy Tear film <ul><li>95% of volume is produced by lacrimal gla n d </li></ul><ul><li>Gland and cell of the lids and conjunctive produce the rest of the components </li></ul><ul><li>50% of the tear is located among the lid margin and is called tear meniscus or lacrimal lake, the rest is spread over the cornea and conjunctival surface </li></ul><ul><li>Tear film has 3 layers: </li></ul><ul><li>- lipid - aqueous - mucus </li></ul>
  3. 3. Tear film <ul><li>In contact lens wear, the tear film provides a smooth optical surface anterior to the contact lens. </li></ul><ul><li>lubricates the ocular surface </li></ul><ul><li>provides antimicrobial function </li></ul><ul><li>helps to remove bacteria and devitalized epithelial cells </li></ul><ul><li>acts as a vehicle for the diffusion of oxygen, nutrients, and local growth factors to theocular surface </li></ul><ul><li>Careful evaluation of the tear film, both prior to and during contact lens wear, is beneficial in promoting success with contact lens wear. </li></ul>
  4. 4. Contact Lenses and Ocular Anatomy Cornea <ul><li>Cornea layers: </li></ul><ul><li>Epithelium (5-6 cell layers thick) </li></ul><ul><li>Bowman’s membrane </li></ul><ul><li>Stroma </li></ul><ul><li>Descement’ membrane </li></ul><ul><li>Endothelium </li></ul><ul><li>Cornea is the most powerful refracting surface of the eye (ave 48,8 D) </li></ul><ul><li>Optical quality of cornea depends on the integrity of the epithelium </li></ul>
  5. 5. Cornea <ul><li>With c/l use, the corneal epithelium may have a loss of structural integrity, leading to greater sensitivity of the underlying nerve endings </li></ul><ul><li>Epithelium acts as a barrier to a foreign bodies and friction (from blinking). Regenerate in a week </li></ul><ul><li>Bowman’s membrane resistance to injury (FB) </li></ul><ul><li>Stroma thickest part of cornea, provides corneas transparency </li></ul><ul><li>Descemen’t membrane acts a barrier to the infection </li></ul><ul><li>Endothelium keeps the cornea layers dehydrated </li></ul><ul><li>When the cornea is stressed, as during c/l wear, the fluid balance shifts and the endothelial pump mechanism is unable to maintain the proper hydration of the cornea. This imbalance will lead to stromal edema </li></ul>
  6. 6. Contact Lens Materials FDA classification <ul><li>FDA Group I: Low water, non-ionic </li></ul><ul><li>FDA Group II: High water, non- ionic </li></ul><ul><li>FDA Group III: Low water, ionic </li></ul><ul><li>FDA Group IV: High water, ionic </li></ul><ul><li>Ionic materials demonstrate considerable higher levels of lysozyme uptake compared to non-ionic. Not only water uptake plays significant role in protein uptake but also the polarity of the materials </li></ul>
  7. 7. Oxygen permeability and transmissibility of contact lenses <ul><li>Dk value- oxygen permeability. Ability of a material to allow oxygen to pass through it </li></ul><ul><li>Dk/t value- oxygen transmissibility </li></ul><ul><li>For DW Dk/t – 24 For EW Dk/t – 87 </li></ul><ul><li>(Criteria for minimal oxygen transmission of contact lenses to allow for edema free contact lens wear were established by Holden and Mertz in 1984) </li></ul>
  8. 8. The relationship between oxygen flux and Dk/t is non linear <ul><li>Oxygen flux is a true index of the amount of oxygen that passes through the unit area of the lens in a given time </li></ul>
  9. 9. Water content, Wetting Angle, and Elasticity <ul><li>water content is specified as low (38% or less), moderate (38-45%), high (55% or greater). The water content is a factor in qualifying a lens for daily or extended wear use. </li></ul><ul><li>water content is also a critical factor in patient complains pertaining to “dry eye” symptoms. Lenses loose 6-10% of their water content within the first 6 hours of wear. When the lens dehydrates, it will tend to steepen and may become tighter to the eye. The tightness may be associated with additional patient complains to difficult lens removal, blurred vision, and ocular redness </li></ul>
  10. 10. Compare of Dk and Water Content
  11. 11. Water content, Wetting Angle, and Elasticity <ul><li>wetting angle - is the angle formed at the surface of the contact lens material when a drop of liquid is placed on the surface . Defines the ability of moisture to spread evenly over the lens surface. This is important in maintaining the hydration of the lens </li></ul>
  12. 12. Wetting Angle <ul><li>Galyfilcon A </li></ul><ul><li>Acuvue Advance </li></ul><ul><li>Senofilcon A </li></ul><ul><li>Acuvue Oasys </li></ul><ul><li>Lotrafilcon A </li></ul><ul><li>Night & Day </li></ul><ul><li>Lotrafilcon B </li></ul><ul><li>O2Optix </li></ul><ul><li>Balafilcon A </li></ul><ul><li>PureVision </li></ul><ul><li>Comfilcon A </li></ul>
  13. 13. Elasticity <ul><li>The modulus of elasticity defines the inherent flexibility of the material. Rigid lenses will maintain a low modulus of elasticity while hydrogel lenses will maintain a high modulus of elasticity . </li></ul>
  14. 14. Wear and Replacement Schedule <ul><li>1. DW- Daily wear : </li></ul><ul><li>Traditional replacement cycle> 3 months </li></ul><ul><li>Monthly replacement </li></ul><ul><li>Daily replacement </li></ul><ul><li>2. EW- Extended wear. Allowing lenses to be worn for 7 days/6 nights without removal. During one night per week the eyes are free of lenses. Weekly replaced by new lenses. </li></ul><ul><li>3. FW- Flexible wear . Compromise between DW and EW. Depending on the demand of the patient to once a while sleep in lenses </li></ul>
  15. 15. The Routine Contact Lens Examination Case History <ul><li>1. Motivation </li></ul><ul><li>2. Occupation, hobbies </li></ul><ul><li>3. Expectations (advantages and disadvantages of contact lenses) </li></ul><ul><li>4. Previous Ocular History </li></ul><ul><li>History of spectacle us e </li></ul><ul><li>Ocular trauma, eye lids infections and defects, conjunctivitis, cataract, glaucoma, eye surgery, dry eye </li></ul><ul><li>5. General health </li></ul><ul><li>Systemic and topical medications used : per oral contraceptives, antidepressants, beta-blockers, holinoblockers, diuretics, antihistamines. </li></ul><ul><li>These are the most common medications that can affect quantity and quality of tear film </li></ul>
  16. 16. Case History <ul><li>Allergies (seasonal and chronic) </li></ul><ul><li>The allergic patient is more susceptible to adverse reactions to contact lenses and their maintenance products. </li></ul><ul><li>Diabetes </li></ul><ul><li>There is occasionally corneal hypoesthesia, leading to a greater propensity for corneal erosion and infection. Not candidates for extended-wear contact lens use </li></ul><ul><li>Pregnancy and Menopause </li></ul><ul><li>Pregnant women with water retention may be intolerant of a contact lens. In general. Some patients in menopause may present significant changes in the quality and quantity of the lacrimal tear film that may cause contact lens intolerance. </li></ul>
  17. 17. Case History <ul><li>Chronic Respiratory Disease </li></ul><ul><li>May have difficulty in fitting a contact lens. During respiratory crises they may have conjunctival hyperemia, tearing, light sensitivity, and generalized discomfort that is aggravated by the use of contact lenses. </li></ul><ul><li>Other systemic diseases, where an anterior segment of the eye can be involved or problems with immune system (AIDS, tuberculosis, herpes infection, myasthenia gravis, Sjogrens syndrome, lupus) </li></ul>
  18. 18. Case History If patient had contact lenses before <ul><li>6. History of contact lens use </li></ul><ul><li>Contact lens type </li></ul><ul><li>Wearing Schedule </li></ul><ul><li>Additional contact lens history </li></ul><ul><li>Satisfaction with vision and comfort </li></ul><ul><li>Average wearing time (hours/day) and (days/week) </li></ul><ul><li>Contact lens wear in front of computer </li></ul><ul><li>Lens replacement schedule (if disposable or planned replacement) </li></ul><ul><li>Disinfection regimen </li></ul><ul><li>Reasons for changing the type of contact lens or discontinuation of use in the past </li></ul><ul><li>Previous contact lens- or solution-related complications </li></ul>
  19. 19. Case History <ul><li>7. Hygiene </li></ul><ul><li>8. Responsibility </li></ul>
  20. 20. Refractive and Binocular Vision Assessment <ul><li>Subjective correction. Best monocular correction </li></ul><ul><li>Manifest refraction with binocular balance </li></ul><ul><li>Test of accommodation </li></ul><ul><li>Convergence </li></ul><ul><li>Ocular dominance </li></ul><ul><li>Cover test (Phorias or tropias) </li></ul>
  21. 21. Keratometry <ul><li>Quality of mires </li></ul><ul><li>measure the front surface </li></ul><ul><li>(approx 2 - 4 mm radius) </li></ul><ul><li>curvature of the cornea </li></ul>
  22. 22. Examination of the Anterior Segment <ul><li>1. Entropion/ectropion </li></ul><ul><li>2. Horizontal visible iris diameter </li></ul><ul><li>3. Rate and quality of blinks </li></ul><ul><li>4. Palpebral aperture position and size (measured in mm) </li></ul><ul><li>5. Lacrimal puncta (position and reflux) </li></ul><ul><li>6. Pupil size and function </li></ul>
  23. 23. Biomicroscopy <ul><li>1. Tear film </li></ul><ul><li>● Tear breakup time </li></ul><ul><li>● Schirmer test </li></ul><ul><li>● Lacrimal lake </li></ul>
  24. 24. 2. Bulbar conjunctiva 3. Tarsal conjunctiva <ul><li>Biomicroscopy </li></ul>
  25. 25. Biomicroscopy <ul><li>4. Cornea </li></ul><ul><li>Fluorescein staining </li></ul><ul><li>Limbal vasculature </li></ul><ul><li>Endothelium </li></ul>
  26. 26. Intraocular pressure
  27. 28. <ul><li>Contact Lens Fit Evaluation </li></ul><ul><li>1 . Measure current contact lens parameters. </li></ul><ul><li>● Base curve </li></ul><ul><li>● Power </li></ul><ul><li>● Diameter </li></ul><ul><li>● Thickness </li></ul><ul><li>2. Observe at the slit-lamp biomicroscope. </li></ul><ul><li>● Centration </li></ul><ul><li>● Movement </li></ul><ul><li>● Lid and lens interactions </li></ul>
  28. 29. Contact Lens Fit Evaluation <ul><li>What are the signs and symptoms of a loose contact lens? </li></ul><ul><li>● Discomfort, even after a short period of time </li></ul><ul><li>● Excessive movement and displacement of the contact lens, compromising the visual acuity immediately after a blink. </li></ul><ul><li>● Worsening visual acuity with blinking </li></ul>
  29. 30. Contact Lens Fit Evaluation <ul><li>What are the signs and symptoms of a tight contact lens? </li></ul><ul><li>● Discomfort after several hours of use </li></ul><ul><li>● The visual acuity, keratometric mires, view in a tight-fitting contact lens may be distorted but improve immediately after the blink. </li></ul><ul><li>● Minimal or absent movement of the contact lens </li></ul><ul><li>● Perilimbal conjunctival hyperemia </li></ul><ul><li>● Microcystic edema </li></ul><ul><li>● Diffuse edema </li></ul><ul><li>● In severe cases of hypoxia, the following may also be noted: Blurred vision and/or halos around lights, produced by corneal hypoxia as a result of decreased diffusion of oxygen into the tear film </li></ul>
  30. 31. Contact Lens Fit Evaluation <ul><li>What are the characteristics of a well-fitted contact lens? </li></ul><ul><li>● Adequate lens centration with full limbal coverage: Adequate lens diameter selection will result in approximately 1 mm of limbal coverage around the circumference of the lens. </li></ul><ul><li>● Movement should be assessed using the following techniques: Straight gaze: With the patient viewing in primary gaze, the lens should move 0.3 to 1.0 mm with the blink.Upgaze: When the patient is asked to look up, the lens should move 0.3 to 0.7 mm with the blink. </li></ul><ul><li>● Push-up test: With the patient viewing in primary gaze, gently manipulate the patient’s lower lid to push the contact lens superiorly. The lens should move freely. </li></ul>
  31. 32. Contact Lens Fit Evaluation <ul><li>3. Evaluate fit and wearing capacity. </li></ul><ul><li>● Comfort </li></ul><ul><li>● Patient satisfaction </li></ul><ul><li>● Ocular reactions to the contact lens </li></ul><ul><li>● Tearing </li></ul><ul><li>● Photophobia </li></ul><ul><li>● Measurement of visual acuity at distance and near (if needed do over refraction) </li></ul>
  32. 33. Patient Education <ul><li>1. Always wash hands before handling lenses. </li></ul><ul><li>2. Perform training in the correct care and handling of the contact lens, including insertion and removal. </li></ul><ul><li>3. Explain the importance of cleaning and maintenance. </li></ul><ul><li>4. Provide the patient with written instructions and educational materials. </li></ul><ul><li>5. Explain importance of follow-up care. </li></ul><ul><li>6. Remove lens immediately for pain or red eye. </li></ul><ul><li>7. Recommend return visit at any sign or symptom of ocular irritation. </li></ul><ul><li>8. Reinforce proper care at every visit. </li></ul>
  33. 34. Follow-Up Visits <ul><li>1. Measure visual acuity. </li></ul><ul><li>2. Evaluate lens performance. </li></ul><ul><li>● Lens fit </li></ul><ul><li>● Surface inspection </li></ul><ul><li>● Over-refraction </li></ul><ul><li>3. Evaluate ocular health with slit-lamp biomicroscope. </li></ul><ul><li>4. Confirm care and handling instructions. </li></ul><ul><li>5. Confirm the parameters of the contact lens. </li></ul>
  34. 35. Astigmatism and Toric Contact Lenses <ul><li>Most patients can tolerate an astigmatic undercorrection </li></ul><ul><li>Lid will force a soft toric lens to rotate nasally on lid closure and temporally on opening </li></ul><ul><li>Constant blurred vision with soft toric lens implies that there is either an un corrected refractive error or constant misalignment of the lens axis </li></ul><ul><li>Soft toric contact lens starting form 1DC </li></ul>
  35. 36. Evaluating the Astigmatism <ul><li>CA (corneal astigmatism)- measure via keratometer </li></ul><ul><li>MA (manifest astigmatism)- measure via refraktometer </li></ul><ul><li>IRA (internal residual astigmatism)= MA-CA </li></ul><ul><li>cyl < 0,67- spherical equivalent </li></ul><ul><li>cyl 0,75- 2,50- soft astigmatic lens </li></ul><ul><li>cyl > 2,50- rigid contact lens more appropriate </li></ul>
  36. 37. Evaluating the Astigmatism <ul><li>With-the-rule astigmatism don’t require full correction </li></ul><ul><li>Against-the-rule astigmatism usually require full correction </li></ul><ul><li>Cylinder axis sensitivity test </li></ul><ul><li>! In order to evaluate the fit it is important to allow patient to wait for 30 min after the soft toric contact lens was inserted </li></ul>
  37. 38. LARS
  38. 39. Soft Toric Lens Stabilization <ul><li>Prism Ballast </li></ul><ul><li>Truncation </li></ul><ul><li>Thin zones (dynamic stabilization ) </li></ul><ul><li>Peri-ballast </li></ul><ul><li>the bigger is soft toric contact lens Ø the more stable is the lens </li></ul>
  39. 40. Contact Lenses Deposits <ul><li>The contact lens alters the natural defense mechanisms of the eye. As deposits form on the contact lens, an inflammatory reaction and/or infection may develop. </li></ul><ul><li>What types of deposits form mos t f requently on contact lenses? </li></ul><ul><li>Organic Deposits </li></ul><ul><li>The organic deposits are proteins, lipids, carbohydrates, pigments of organic origin, and deposits composed of microorganisms with other substances </li></ul>
  40. 41. Contact Lenses Deposits <ul><li>Inorganic Deposits </li></ul><ul><li>The inorganic deposits are calcium salts, phosphates and carbonates of calcium, ferrous oxide, salts, and pigments derived from inorganic chemicals . (The most common types of inorganic deposits are ‘‘jelly bumps,’’ which occur most frequently on extended-wear contact lenses. The jelly bumps are round, nodular deposits composed primarily of calcium, lipids, and cholesterol. These deposits are difficult to remove, and therefore the patient may be required to replace the contact lens.) </li></ul>
  41. 42. Contact Lenses Deposits <ul><li>Environmental Deposits </li></ul><ul><li>The most common environmental deposits are rust spots and particles from cosmetics. Rust spots are caused generally by the use of tap water or by foreign matter in the environment. They are generally orange and circular. Deposits from cosmetics have an iridescent, greasy appearance and may be caused by mascara, hair spray, creams, etc. </li></ul>
  42. 43. Why is it important to remove deposits? <ul><li>Aside from the fact that deposits can cause discomfort and visual disturbance,they may also produce mechanical abrasions and immunoallergic reactions and facilitate adherence of microorganisms and, subsequently, infections. </li></ul>
  43. 44. Contact Lenses Care products <ul><li>What is tonicity? </li></ul><ul><li>Tonicity is the quantity of salt contained in a solution. The standard for tonicity of a contact lens solution is the intracellular salt content of the body, 0.9% sodium chloride, or 300 milliosmoles (mOsm). An isotonic solution is one in which the tonicity is equal to 0.9% sodium chloride. Contact lens solutions are formulated to be isotonic, with the goal of maintaining the equilibrium of the ocular tissues and the water contained in the contact lens. An example of isotonic solution is natural tears. Tears do not provoke any swelling or dehydration in </li></ul><ul><li>the corneal cells. </li></ul>
  44. 45. Contact Lenses Care products <ul><li>What are the degrees of acidity and alkalinity (pH), and how can they interfere with the comfortable use of contact lenses? </li></ul><ul><li>Tear film pH normally varies between 7.0 and 8.5. Thus a contact lens solution can vary from 6.0 to 8.5 and still provide reasonable comfort. Changes in the pH may affect the stability, sterility, and viscosity of the contact lens solution. When solutions are outside the acceptable range of pH, they may provoke discomfort, burning, punctate keratopathy, and tearing. </li></ul>
  45. 46. Contact Lenses Care products <ul><li>What is the purpose of buffering agents, and which are most commonly used? </li></ul><ul><li>Buffering agents, either acid or alkaline, are used in contact lens solutions to stabilize the pH in the range of 7.0 to 7.4, i.e., within limits that do not adversely affect ocular comfort or the efficacy of the solution. The most common buffering agents used in contact lens solutions include borates, phosphates, citrates, and trimethamines. </li></ul>
  46. 47. Contact Lenses Care products <ul><li>How do viscosity agents work, and which are the most commonly used? </li></ul><ul><li>C ontact of the solution with the contact lens, to reduce friction, and thereby to improve comfort. Viscosity agents most commonly used in contact lens solutions include methylcellulose hydroxyethylcellulose, hydroxypropyl methylcellulose(HPMC), polyvinyl alcohol, glycolhexaline, carbomide, and dextran. </li></ul>
  47. 48. Contact Lenses Care products <ul><li>What are surfactant cleaners, and which are most commonly used? </li></ul><ul><li>Surfactants are detergent substances that affect surface tension and are effective for removing oils, fat, mucus, and cosmetics. They are most effective at a slightly alkaline pH of 7.4. The surfactant cleaning agents may be used separately or in association with multiuse solutions. The surfactant agents most commonly used for contact lenses include miranol, sodium salts, tiloxopol, propaline glycol, and polyvinyl alcohol. </li></ul>
  48. 49. Contact Lenses Care products <ul><li>What is the function of antimicrobial agents, and which are most commonly used? </li></ul><ul><li>Antimicrobial agents have two basic functions: first, to prevent microbial proliferation as bacteriostatic agents, and second, to destroy microorganisms when used as bactericidal agents. In many cases, preservative agents are used as disinfectants, as preservatives may have antibactericidal properties when used in higher concentrations. The antimicrobial agents most commonly used in contact lens solutions include quaternary ammonia and biguanides, oxidative agents, systems that produce chlorine and chlorine bases, alcohol, organic mercurial compounds, weak acids, and EDTA (ethylenediaminetetraacetic acid, disodium edatate). </li></ul>
  49. 50. Contact Lenses Care products <ul><li>What are the most common hypersensitivity reactions causedby contact lens solutions? </li></ul><ul><li>Contact lens solutions contain chemical preservatives that may induce toxic or allergic reactions. A toxic reaction may occur within minutes or hours of contact lens wear, producing conjunctival hyperemia, superficial punctate keratitis, and symptoms of burning and pain. An allergic reaction may occur weeks or months later and is associated with different symptoms and signs: burning, itching, photophobia, conjunctival hyperemia, superficial punctate keratitis, corneal infiltrates, superior limbic keratoconjunctivitis and corneal vascularization. The toxic reactions most commonly encountered are caused by benzalkonium chloride chlorhexidine, incomplete neutralization of hydrogen peroxide (H2O2). </li></ul>
  50. 51. What is the purpose of multiuse solutions? <ul><li>Multiuse solutions are designed to clean, rinse, and disinfect contact lenses, providing all of these functions in a single solution. A balance must be achieved among the properties of the contact lens solution (tonicity, pH, viscosity, cleaning agents, antimicrobial agents, and buffering agents), but this may diminish the effectiveness of any one of these functions, making it necessary for the patient to use additional agents. </li></ul>
  51. 52. How does oxidative chemical disinfection work, and what are its advantages and disadvantages? <ul><li>Oxidative chemical disinfection is accomplished using 3% hydrogen peroxide, which is a disinfectant with excellent antimicrobial activity against a broad variety of microorganisms. An oxidative reaction transforms the molecule of hydrogen peroxide into water and oxygen. </li></ul><ul><li>AO Sept (CIBAVision) </li></ul><ul><li>In the AO Sept system, neutralization is achieved by means of a disk. The disk is inserted into the small cylindrical container with a basket that holds the contact lenses. Old disks covered with residues may not completely neutralize the peroxide, and the remaining solution that fails to neutralize may cause significant ocular irritation. </li></ul>
  52. 53. How does oxidative chemical disinfection work, and what are its advantages and disadvantages? <ul><li>Advantages </li></ul><ul><li>● It penetrates the surface of the contact lens to remove small molecules in the hydrogel pores. </li></ul><ul><li>● It promotes cleaning action of the surface by oxidizing peptide chains, breaking down proteins and lipids. </li></ul><ul><li>● It promotes disinfection. In 10 minutes, it can kill both bacteria and viruses. Forty minutes are required to eradicate fungi, and 2 hours are required to eliminate Acanthamoeba. </li></ul><ul><li>● It can be utilized with all contact lens materials, both rigid and soft. </li></ul>
  53. 54. How does oxidative chemical disinfection work, and what are its advantages and disadvantages? <ul><li>Disadvantages </li></ul><ul><li>● It is toxic to the eye and may fail to neutralize. </li></ul><ul><li>● Exposure of hydrogen peroxide that is not neutralized may produce ocular irritation, intense hyperemia, keratitis, tearing, chemosis, burning, and punctate keratopathy. </li></ul><ul><li>● The solution loses its disinfecting capacity after neutralization. </li></ul>
  54. 55. Staingrid
  55. 56. Multipurpose Solution and A ntimicrobial Action
  56. 57. Contact lenses complications <ul><li>The principal causes of complications are: </li></ul><ul><li>● Inadequate lens-to-cornea fitting relationship </li></ul><ul><li>● Insufficient contact lens oxygen transmissibility </li></ul><ul><li>● The presence of preexisting ocular pathology </li></ul><ul><li>● Interference by environmental factors </li></ul><ul><li>● Intolerance of contact lens material </li></ul><ul><li>● Poorly maintained contact lenses </li></ul><ul><li>● Contaminated contact lenses and lens cases </li></ul><ul><li>● Use of incorrect contact lenses </li></ul><ul><li>Corneal infection/ ulcer </li></ul><ul><li>Acute red eye </li></ul><ul><li>Hypersensitivity reactions </li></ul><ul><li>Corneal neovascularisation </li></ul><ul><li>Gigant papillary conjunctivitis </li></ul><ul><li>Corneal infiltrates </li></ul><ul><li>Corneal oedema </li></ul><ul><li>Corneal stainig </li></ul><ul><li>Toxic staining </li></ul>
  57. 58. Corneal Infection/Ulcer
  58. 59. Corneal Infection/Ulcer
  59. 60. Corneal Infection/Ulcer <ul><li>Description: </li></ul><ul><li>Corneal ulcers are full thickness epithelial erosions with anterior stromal involvement . There is invariably a strong inflammatory response including sub-epithelial infiltrates and significant limbal and bulbar hyperemia. Treatment depends upon the aetiology. </li></ul><ul><li>Signs: </li></ul><ul><li>- small to large full thickness epithelial defect </li></ul><ul><li>- sub-epithelial & stromal infiltrates </li></ul><ul><li>- circumlimbal injection </li></ul><ul><li>- bulbar conjunctival redness </li></ul><ul><li>Symptoms </li></ul><ul><li>- significant pain </li></ul><ul><li>- photophobia </li></ul><ul><li>- tearing </li></ul><ul><li>- watery or purulent discharge </li></ul>
  60. 61. Corneal Infection/Ulcer <ul><li>Associations </li></ul><ul><li>- EW </li></ul><ul><li>- overwear </li></ul><ul><li>- lens contamination </li></ul><ul><li>- solution contamination </li></ul><ul><li>Differential diagnosis </li></ul><ul><li>- Type of ulcer (Herpetic, Acanthamoeba, Pseudomonas, Staphylococcus, Fungal etc ) </li></ul><ul><li>- Full thickness sterile epithelial erosion (sterile ulcer) </li></ul><ul><li>- CLARE </li></ul><ul><li>- Peripheral sub-epithelial infiltrates </li></ul>
  61. 62. Acute Red Eye <ul><li>This example of acute red eye response shows the classic signs of cicumlimbal injection, excessive bulbar conjunctival redness, and the peripheral infiltrates are clearly visible near the limbus, indicating that this is indeed an inflammatory response, even though there is no epithelial defect </li></ul>
  62. 63. Acute Red Eye <ul><li>Description: </li></ul><ul><li>CLARE can be caused by number of conditions such as hypoxic stress due to “overwear” of contact lenses, excessively tight fitting worn overnight, excessive deposition on lenses, microbial contamination of lenses. In general there will be no epithelial defect, indication this reaction is similar that is seen in allergic response rather than due to infection and/or trauma </li></ul><ul><li>Signs </li></ul><ul><li>- circumlimbal injection </li></ul><ul><li>- bulbar conjunctival redness </li></ul><ul><li>- sub-epithelial infiltrates </li></ul><ul><li>- usually no epithelial compromise </li></ul><ul><li>Symptoms </li></ul><ul><li>- frequently monocular </li></ul><ul><li>- watery discharge from the eye </li></ul><ul><li>- extreme pain, often awakening patient from asleep </li></ul><ul><li>- photophobia </li></ul>
  63. 64. Acute Red Eye <ul><li>Associations </li></ul><ul><li>- EW </li></ul><ul><li>- acute or chronic hypoxia </li></ul><ul><li>- inadequate replacement of lenses </li></ul><ul><li>- excessive protein deposition </li></ul><ul><li>- sensitivity reaction to care system ingredients </li></ul><ul><li>- reaction to excessive microbial contamination of lens </li></ul><ul><li>- idiopathic </li></ul><ul><li>Differential diagnosis </li></ul><ul><li>- corneal ulcer </li></ul><ul><li>- Acute corneal hypoxia </li></ul><ul><li>- Superior limbic keratoconjunctivitis </li></ul>
  64. 65. Hypersensitivity to contact lens solution
  65. 66. Hypersensitivity to contact lens solution
  66. 67. Hypersensitivity to contact lens solution <ul><li>Description: </li></ul><ul><li>Often patients are allergic to some component and can demonstrate mild SPK, limbal injection, and stinging or burning upon lens insertion </li></ul><ul><li>Signs </li></ul><ul><li>- SPK </li></ul><ul><li>- bulbar conjunctival redness </li></ul><ul><li>- tearing </li></ul><ul><li>Symptoms </li></ul><ul><li>- stinging/ burning </li></ul><ul><li>- occurs after several weeks or months of wear </li></ul><ul><li>- photophobia </li></ul><ul><li>- tearing </li></ul>
  67. 68. Hypersensitivity to contact lens solution <ul><li>Associations </li></ul><ul><li>- thimerosal / chlorhexidine/ benzalkoniumchloride based solutions </li></ul><ul><li>- rarely patients may also react to EDTA & sorbic acid </li></ul><ul><li>Differential diagnosis </li></ul><ul><li>- allergies to soaps, cosmetics etc </li></ul>
  68. 69. Corneal Neovascularisation
  69. 70. Corneal Neovascularisation <ul><li>Description: </li></ul><ul><li>Neovascularisation refers to the ingrowths of the limbal blood vessels towards the centre of the cornea. Classically related to chronic hypoxia, also can accompany corneal ulcers </li></ul><ul><li>Signs </li></ul><ul><li>- Ingrowths towards centre of cornea limbal vessels </li></ul><ul><li>Symptoms </li></ul><ul><li>- None </li></ul><ul><li>- Symptoms associated with chronic corneal edema </li></ul>
  70. 71. Corneal Neovascularisation <ul><li>Associations </li></ul><ul><li>- chronic hypoxia </li></ul><ul><li>- EW </li></ul><ul><li>- High plus, toric or bifocal lens </li></ul><ul><li>Differential diagnosis </li></ul><ul><li>- Corneal nerves </li></ul>
  71. 72. Giant Papillary Conjunctivitis (GPC)
  72. 73. Giant Papillary Conjunctivitis (GPC) <ul><li>Description: </li></ul><ul><li>GPC is a contact lens related condition which presents with symptoms of lens discomfort and intolerance in previously successful contact lens wearers. Dual aetiology: abrasion and deposited lens surface (allergic response) </li></ul><ul><li>Signs </li></ul><ul><li>- increased injection of superior palpebral conjunctiva </li></ul><ul><li>- hypertrophic papillae on superior palpebral conjunctiva </li></ul><ul><li>- superior decentration of previously well-centered lens </li></ul><ul><li>-mucus or watery discharge </li></ul><ul><li>Symptoms </li></ul><ul><li>- Intolerance to lens in previous successful wearer </li></ul><ul><li>- watery discharge from the eye </li></ul><ul><li>- discomfort & grittiness </li></ul>
  73. 74. Giant Papillary Conjunctivitis (GPC) <ul><li>Associations </li></ul><ul><li>- excessive protein deposits </li></ul><ul><li>- denaturation of protein </li></ul><ul><li>- infrequent lens replacement (EW) </li></ul><ul><li>Differential diagnosis </li></ul><ul><li>- vernal conjunctivitis </li></ul>
  74. 75. Corneal Infiltrates
  75. 76. Corneal Infiltrates
  76. 77. Corneal Infiltrates <ul><li>Description: </li></ul><ul><li>Sub-epithelial infiltrates are believed to be collections of inflammatory cells, which ether congregate in the mid-periphery of the cornea (focal infiltrates), or move from the limbal region in a wide sheet of cells. Can be secondary to trauma, infection, allergy. Sub-epithelial infiltrates are usually seen in cases of CLARE, SLK, corneal ulcers, and non contact lens related anterior response such as conjunctivitis, iritis, uveitis. </li></ul><ul><li>Signs </li></ul><ul><li>- cloudiness of the cornea </li></ul><ul><li>- congregation of white cells around epithelial defect suspected to be infected </li></ul><ul><li>- significant localized or circumlimbal injection </li></ul><ul><li>Symptoms </li></ul><ul><li>- Intolerance of the lens </li></ul><ul><li>- photophobia </li></ul><ul><li>- discomfort </li></ul><ul><li>- none </li></ul>
  77. 78. Corneal Infiltrates <ul><li>Associations </li></ul><ul><li>- CLARE </li></ul><ul><li>- SLK </li></ul><ul><li>- corneal ulcer </li></ul><ul><li>- EW </li></ul><ul><li>Differential diagnosis </li></ul><ul><li>- epithelial microcysts </li></ul><ul><li>- acute corneal hypoxia </li></ul><ul><li>- corneal ulcer </li></ul>
  78. 79. Corneal Edema
  79. 80. Corneal Edema
  80. 81. Corneal Edema
  81. 82. Corneal Edema <ul><li>Description: </li></ul><ul><li>The stromal involvement in corneal edema is usually described as corneal swelling, since the cornea reacts to pre-corneal hypoxia by increasing its thickness </li></ul><ul><li>Signs </li></ul><ul><li>- increased corneal stromal backscatter </li></ul><ul><li>- corneal stromal striae </li></ul><ul><li>- corneal endothelial folds </li></ul><ul><li>- neovascularisation </li></ul><ul><li>Symptoms </li></ul><ul><li>- none </li></ul><ul><li>- eyes get increasingly red throughout wearing period </li></ul>
  82. 83. Corneal Edema <ul><li>Associations </li></ul><ul><li>- overwear of DW lenses </li></ul><ul><li>- overnight of EW lenses </li></ul><ul><li>- plus powers, bifocals, toric </li></ul><ul><li>Differential diagnosis </li></ul><ul><li>- corneal nerves vs striae </li></ul><ul><li>- corneal scars vs striae </li></ul>
  83. 84. Corneal staining
  84. 85. Corneal staining
  85. 86. Corneal staining <ul><li>Description: </li></ul><ul><li>Corneal staining with fluorescein is an indicator of corneal damage. A significant break in the corneal epithelium increases the risk of infection and possible scarring of the cornea </li></ul><ul><li>Differential diagnosis </li></ul><ul><li>- dehydratation </li></ul><ul><li>- foreign body </li></ul><ul><li>- infection/ulceration </li></ul><ul><li>- mechanical stress </li></ul><ul><li>- solution reaction </li></ul>
  86. 87. Superior Epithelial Arcuate Lesions (SEAL) <ul><li>Signs </li></ul><ul><li>A lesion along the superior corneal margin extended through the entire thickness of the epithelium, as indicated by diffusion of fluorescein into stroma </li></ul><ul><li>Cause </li></ul><ul><li>SEAL are produced by mechanical interaction between the lens bad the upper lid with certain lens designs. Tear characteristics and ocular topography also play a role </li></ul>
  87. 88. Superior Epithelial Arcuate Lesions (SEAL)
  88. 89. Contact lens contraindications <ul><li>What are the general contraindications </li></ul><ul><li>1. Any systemic or allergic illness that affects the eye and may be exacerbated by the contact lens </li></ul><ul><li>2. Inability to follow the instructions for cleaning, storage, and asepsis of the contact lens </li></ul><ul><li>3. Poor personal hygiene (particularly hands and nails) </li></ul><ul><li>4. Inability to understand the risks associated with contact lens use </li></ul><ul><li>5. Low refractive error in a patient reluctant to use glasses </li></ul><ul><li>6. Immunosuppressed patients </li></ul><ul><li>7. The use of systemic medications that may cause changes in the quality of the tear film </li></ul><ul><li>8. Pregnancy, nursing, and menopause—circumstances that may be associated with contact lens intolerance and refractive instability. It may be better to wai t until the end of pregnancy and lactation inorder to fit a contact lens </li></ul><ul><li>9. Very old or very young patients who cannot manage insertion, removal, or contact lens care without assistance </li></ul>
  89. 90. <ul><li>1. Any acute or subacute inflammation of the anterior segment of the eye </li></ul><ul><li>2. Acute and chronic ocular infections </li></ul><ul><li>3. Any eye disease affecting the cornea, conjunctiva, and lids (e.g., epithelial fragility, endothelial failure, dry eye, allergy, pinguecula, pterygium) </li></ul><ul><li>4. Corneal hypesthesia </li></ul><ul><li>5. Uncontrolled glaucoma </li></ul><ul><li>6 . Psychological intolerance to the placement of a foreign body in the eye </li></ul>What are the primary ocula r contraindications to the use of contact lenses?
  90. 91. Keratoconus <ul><li>Keratoconus, or conical cornea, is a noninflammatory ectasia of undetermined etiology characterized by thinning and subsequent protrusion of the corneal apex. Although usually bilateral, it is also commonly asymmetric. </li></ul>
  91. 92. Cornea Topography
  92. 93. Keratoconus
  93. 94. What is the clinical picture of keratoconus? <ul><li>15- to 35-year-old patient presents with varying degrees of astigmatism, usually associated with myopia. D ecreasing vision at distance and near, distortion of visual images, monocular diplopia, and ghosting of images </li></ul><ul><li>Keratometric values are generally steeper than 47 D (7.18 mm radius of curvature) </li></ul><ul><li>A difference in central keratometry between the two eyes of more than 1.00 D </li></ul>
  94. 95. What are the biomicroscopic signs of keratoconus? <ul><li>● Thinning of the corneal apex </li></ul><ul><li>● Vogt’s striae in the posterior stroma, observed as oblique or vertical lines that may disappear with digital pressure to the upper eyelid. </li></ul><ul><li>● Fleischer’s ring, a pigmented ring in the basal epithelium just anterior to Bowman’s membrane, partially (arc) or completely (ring) encircling the base of the cone, is composed of hemosiderin deposits. </li></ul><ul><li>● Increased visibility of corneal nerves. </li></ul><ul><li>● Ruptures in Descemet’s membrane </li></ul>
  95. 96. Vogt’s striae
  96. 97. Fleischer’s ring
  97. 98. References <ul><li>Contact Lenses in Ophthalmic Practice. Mark J. Mannis, MD, FACS Karla Zadnik, OD, PhD Cleusa Coral-Ghanem, MD, PhD Newton Kara-Joseґ, MD, PhD </li></ul><ul><li>Contact Lenses. Ken Daniels </li></ul><ul><li> </li></ul>
  98. 99. <ul><li>Thank you </li></ul>