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DR MD FERDOUS ISLAM DEPT OF OPHTHALMOLOGY CMH,DHAKA Contact Lens
32

Contact lens -Dr Ferdous

Jan 24, 2017

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Page 1: Contact lens  -Dr Ferdous

DR MD FERDOUS ISLAMDEPT OF OPHTHALMOLOGY

CMH,DHAKA

Contact Lens

Page 2: Contact lens  -Dr Ferdous

What Is A Contact Lens ? Artificial device whose front surface

substitutes the anterior surface of cornea. Used for correction of:

1. Refractive errors 2. Irregularities on anterior surface of

cornea

Page 3: Contact lens  -Dr Ferdous

Contact Lens Specifications Diameter 1. Overall diameter [OD] - x mm 2. Optical zone diameter (OZ)

Page 4: Contact lens  -Dr Ferdous

Curves Base curve (BC) or posterior central curve (PCC) Peripheral curves : 1. intermediate (IPC) 2. peripheral (PPC) Central anterior curve (CAC) or front curve (FC) Peripheral anterior curve (PAC) Intermediate anterior curve (IAC)

- Only in high power minus and plus lenses

Page 5: Contact lens  -Dr Ferdous

Edge Polished and blended union of the Peripheral posterior

curve & Peripheral Anterior curve of the lens

Power Central anterior curve curvature determines the power

of the lens Measured in terms of posterior vertex power. Unit: Diopters [D]

Page 6: Contact lens  -Dr Ferdous

Thickness Measured in the centre of the lens Varies depending upon the posterior vertex

power of the lens

Tint Color of the lens

Page 7: Contact lens  -Dr Ferdous

Types Of Contact LensesDepending upon nature of material used;

Hard Lens Rigid Gas Permeable Lens Soft Lens

Page 8: Contact lens  -Dr Ferdous

Hard Lens From PMMA (polymethylmethacrylate) High optical quality, stability, light weight,

nontoxic, durable & cheap Diameter of 8.5-10 mm Disadvantages: 1. Restricts the tolerance -

O2 impermeable 2. Corneal Abrasions 3. Stable tear film

Page 9: Contact lens  -Dr Ferdous

Rigid Gas Permeable Lens Material permeable to oxygen Popularized as Semi-Soft lenses Manufactured from a co-polymer of: 1. PMMA 2. Silicone containing vinyl monomer 3. Cellulose acetate butyrate

Page 10: Contact lens  -Dr Ferdous

Soft Lens Material: HEMA

(hydroxymethymethacrylate) About 1-2 mm larger than

corneal diameter Advantages: 1. Comfortable 2. Well-tolerated

Page 11: Contact lens  -Dr Ferdous

Soft Lens Disadvantages: 1. Wettability 2. Proteinaceous deposits 3. Can get torn 4. Limited life 5. Inferior optical quality 6. Increased risk of corneal infections 7. Cannot correct astigmatism > 2.00D

Page 12: Contact lens  -Dr Ferdous

Soft Lens Types: ▪ Disposable or Non-Disposable ▪ Clear or Colored ▪ Spherical or Toric ▪ Extended Wear ▪ Multifocal

Page 13: Contact lens  -Dr Ferdous

Spherical Soft Lens A spherical contact lens is one in which

both the inner and outer optical surfaces are portions of a sphere

Corrects both short- and long- sightedness

Cheapest & most comfortable Easy to get in a disposable form

Page 14: Contact lens  -Dr Ferdous

Toric Soft Lens A toric lens is one in which either or both

of the optical surfaces have the effect of a cylindrical lens, usually in combination with the effect of a spherical lens

Corrects astigmatism Lens is specially weighted to conform to

irregular cornea More expensive than spherical Some are available in disposable

Page 15: Contact lens  -Dr Ferdous

Disposable Soft Lens Daily, two-weekly or monthly

replacement Very simple cleaning (no cleaning for

daily) Latest designs and materials Very popular

Page 16: Contact lens  -Dr Ferdous

Colored Contact Lens Handling tint

Useful when inserting or removing lens

Enhancing tintMakes light coloured eyes more vivid

Opaque tintCan change colour of eyes

Page 17: Contact lens  -Dr Ferdous

Colored Contact Lens

Page 18: Contact lens  -Dr Ferdous

Extended Wear Contacts Lens New technology Made from silicone material which

transmits oxygen well Can wear for up to thirty days without

removing.

Page 19: Contact lens  -Dr Ferdous

MultiFocal Contacts Lenses Can have dual focus lenses New technology → More expensive Available as disposable lenses

Page 20: Contact lens  -Dr Ferdous

Indications For Use Optical Therapeutic Preventive Diagnostic Operative Cosmetic Occupational

Page 21: Contact lens  -Dr Ferdous

Optical Indications Anisometropia Unilateral

Aphakia High Myopia Keratoconus Irregular

Astigmatism

Page 22: Contact lens  -Dr Ferdous

Advantage Over Spectacles Can correct irregular corneal astigmatism No fall off,break Reducing aberrations. Reducing aniseikonia. Field of vision. Image magnifications. No distortion of image. No aberrations – peripheral / prismatic Binocular vision in high anisometropia No condensation of rain or fog Cosmetically more acceptable

Page 23: Contact lens  -Dr Ferdous

Disadvantages When the pupil is dilated rigid contact

lens may produce a halo. Eye strain in presbyopic myopes.

Page 24: Contact lens  -Dr Ferdous

Therapeutic Indications Diseases of Cornea – Non-healing corneal

ulcers, filamentary keratitis and recurrent corneal erosion syndrome.

Diseases of Iris – Aniridia, coloboma and albinism (avoid glare)

Glaucoma (vehicle for drug delivery) Amblyopia (Opaque lens - Occlusion) Bandage Soft Contact Lenses – Post-keratoplasty and microcornealperforation

Page 25: Contact lens  -Dr Ferdous

Preventive Indications Prevention of symblepharon and

restoration of fornices in chemical burns Exposure keratitis Trichiasis

Page 26: Contact lens  -Dr Ferdous

Diagnostic Indications Gonioscopy Electroretinography Examination of fundus in case of irregular

corneal astigmatism Fundus photography Goldmann’s 3 mirror examination

Page 27: Contact lens  -Dr Ferdous

Operative Indications Goniotomy operation for congenital

glaucoma Vitrectomy Endocular photocoagulation

Page 28: Contact lens  -Dr Ferdous

Cosmetic Indications Unsightly corneal scars (Coloured

lenses) Ptosis (Haptic lenses) Cosmetic scleral lenses in phthisis bulbi

Page 29: Contact lens  -Dr Ferdous

Occupational Indications Indications Sportsmen Pilots Actors

Page 31: Contact lens  -Dr Ferdous

Contraindications Mental Incompetence/Poor Motivation Chronic Dacryocystitis Chronic Blepharitis and Recurrent Styes Chronic Conjunctivitis Dry-Eye Syndrome Corneal Dystrophies and Degenerations Recurrent diseases like Episcleritis,

Scleritis & Iridocyclitis

Page 32: Contact lens  -Dr Ferdous

THANK YOU!