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๐Ÿ‘It is an artificial device placed on cornea for optical or therapeutic purpose. It’s made of soft, flexible plastics that allow oxygen to pass through the cornea. 

๐Ÿ‘๐™Ž๐™ค๐™›๐™ฉ ๐˜พ๐™ค๐™ฃ๐™ฉ๐™–๐™˜๐™ฉ ๐™‡๐™š๐™ฃ๐™จ~๐™ƒ๐™ฎ๐™™๐™ง๐™ค๐™œ๐™š๐™ก๐™จ

ย  ย  โ€ข Soft contact lenses are made up of ย HEMA (hydroxyethylmethacrylate). HEMA is hydrophilic. This hydrophilic nature is because of cross linked polymers with carbon to carbon backbone, to which are attached hydrophilic groups. It’s refractive index 1.43.

   โ€ขPHEMA (poly- hydroxyethylmethacrylate) is still the basic lens material in use aa the soft lens material. 

   โ€ขPhysical properties of this lens material-

      I) Water content – โ–ช 38 to 80%

                                   โ–ช <40% low water content lenses.        

                                   โ–ช >55% high water content lenses.

                                   โ–ช  40 to 55% mid water content lenses.

    II) Elasticity – The soft contact lens material has to be elastic so that it can survive the repeated stress of insertion and removal. It should recover it’s shape very rapidly after stress. 

   III) Ionicity – Two groups based on iconicity- (a) Ionic, (b) Non- ionic

  โ€ข Several conpounds are added to hydrogens to improve it’s properties like wettability, water content, oxygen permeability on ionicity. 

The compounds are- 

  ๐Ÿ”นPVPโ€“ polyvinylpyrrolidone.

  ๐Ÿ”นMA- methacrylic acid.

  ๐Ÿ”นMMA- methyl methacrylate.

  ๐Ÿ”นGMA- glyceryl methacrylate.

  ๐Ÿ”นDAA- diacetone acrylamide.

  ๐Ÿ”นPVA- polyvinyl alcohol. 

๐Ÿ‘๐™Ž๐™ค๐™›๐™ฉ ๐™˜๐™ค๐™ฃ๐™ฉ๐™–๐™˜๐™ฉ ๐™ก๐™š๐™ฃ๐™จ ๐™™๐™š๐™จ๐™ž๐™œ๐™ฃ

     The design of soft contact lens depends upon the following parameters of a soft contact lens. 

a) Diameter – Average size 9.2 to 9.4mm.

b) Thickness.

c) Curvature – Front and back with thin flexible lenses design almost irrelevant. 

๐Ÿ”บBack surface design –

     I. Monocurve – Usually are not made in monocurve designs. 

ย  ย  II. Bicurve – It is common, an central optic zone design and one peripheral curve(0.8 to 1mm flatter) .ย  ย  ย  ย  ย  ย  ย  ย  ย  ย  ย  ย  ย  ย  III. Multicurve – lenses which have manyย curves, flexible lenses don’tย need a multicurve design.

 IV. Aspheric – Shapes cornea better, fewer  base curves need to be made with aspheric back curve design, it is difficult to manufacture.                                        

๐Ÿ”บFront surface design – 

     Front surface design contains the front optic zone depends upon the power. The front surface design varies in bifocals/ multifocals. 

๐Ÿ”บ Edge of soft contact lens – The edge has a little effect than rigid lenses as it is mostly under the lid. Yet, thick is less comfortable and a very thin lens edge cause mechanical cutting. 

๐Ÿ”บ Manufacturing technique and design – There are three main techniques of soft contact lens manufacturing, different techniques create different designs like~

       โ–ช๏ธA soft contact lens made with lathe is used to make simple designs.

       โ–ช๏ธThe spin technique creates simple back surface designs. 

๐Ÿ‘๐™๐™ฎ๐™ฅ๐™š๐™จ ๐™ค๐™› ๐™Ž๐™ค๐™›๐™ฉ ๐˜พ๐™ค๐™ฃ๐™ฉ๐™–๐™˜๐™ฉ ๐™‡๐™š๐™ฃ๐™จ- 

    ๐™„. ๐™Ž๐™ฅ๐™๐™š๐™ง๐™ž๐™˜๐™–๐™ก – A spherical soft contact lens bends light evenly in every direction(horizontally, vertically etc) . They are typically used to correct myopia and hyperopia. 

 ๐™„๐™„. ๐˜ผ๐™จ๐™ฅ๐™๐™š๐™ง๐™ž๐™˜ โ€“ Aspheric soft contact lens have different interaction between the lens and light entering the eye and make a clearer image, have varying curvatures across the surface, changing from the edge to the center of the lens. 

๐™„๐™„๐™„. ๐™๐™ค๐™ง๐™ž๐™˜ – 

                  โ€ขCorrect for astigmatism, 

                  โ€ขMore expensive than spherical,                       

                  โ€ขMarks or etching for fitting,                             

                  โ€ขDifferent focusing power horizontally/ vertically. 

๐™„๐™‘. ๐™ˆ๐™ช๐™ก๐™ฉ๐™ž๐™›๐™ค๐™˜๐™–๐™ก – 

                          โ€ขCan have dual focus lenses.

                          โ€ขMore expensive.

ย  ย  ย  ย  ย  ย  ย  ย  ย  ย  ย  ย  ย  โ€ขAvailable in disposable.ย 

๐Ÿ‘๐™Ž๐™š๐™ก๐™š๐™˜๐™ฉ๐™ž๐™ฃ๐™œ ๐™ฉ๐™๐™š ๐™ฅ๐™–๐™ฉ๐™ž๐™š๐™ฃ๐™ฉ ๐™›๐™ค๐™ง ๐™ฉ๐™๐™š ๐™จ๐™ค๐™›๐™ฉ ๐™˜๐™ค๐™ฃ๐™ฉ๐™–๐™˜๐™ฉ ๐™ก๐™š๐™ฃ๐™จ-

   ๐Ÿ”ธOptical – Anisotropia, unilateral aphakia, high myopia, keratoconus, irregular astigmatism. 

   ๐Ÿ”ธTherapeutic – corneal or iris abnormalities, glaucoma, amblyopia, bandage soft contact lens for post keratoplasty, dry eye syndrome. 

   ๐Ÿ”ธDiagnostic – Electro-retinography, Funduscopy, Gonioscopy. 

   ๐Ÿ”ธ Cosmetic – Corneal scars, Cosmetic scleral lenses in phthisis bulbi, ptosis. 

   ๐Ÿ”ธ Preventive – Prevention of symblepharon and restoration of fornices in  chemical burns, exposure keratitis, trichiasis. 

  ๐Ÿ”ธ Occupational – Sportsman, pilots, actor, actress. 

๐Ÿ‘๐˜ผ๐™™๐™ซ๐™–๐™ฃ๐™ฉ๐™–๐™œ๐™š ๐™ค๐™› ๐™Ž๐™ค๐™›๐™ฉ ๐™˜๐™ค๐™ฃ๐™ฉ๐™–๐™˜๐™ฉ ๐™ก๐™š๐™ฃ๐™จ

    โ€ข Being soft and oxygen permeable, they are most comfortable and so well tolerated.                

    โ€ข It can be used both day and night.

    โ€ข Decreases reflex tearing.

    โ€ข Easier fitting.

    โ€ข Change the colour of the eye.

    โ€ข Less chance of the lens being ๐˜ฅ๐˜ช๐˜ด๐˜ญ๐˜ฐ๐˜ฅ๐˜จ๐˜ฆ๐˜ฅ.

๐Ÿ‘๐˜ฟ๐™ž๐™จ๐™–๐™™๐™ซ๐™–๐™ฃ๐™ฉ๐™–๐™œ๐™š ๐™ค๐™› ๐™Ž๐™ค๐™›๐™ฉ ๐™˜๐™ค๐™ฃ๐™ฉ๐™–๐™˜๐™ฉ ๐™ก๐™š๐™ฃ๐™จ

   โ€ข Reduced VA ( visual acuity) if astigmatism remain uncorrected.

   โ€ข Cleaning and maintenance of the lenses are difficult .

   โ€ข More delicate, more easily damaged and gave a shorter life. 

   โ€ข Lower rate of oxygen transmission.

   โ€ข More chances of control infection.

   โ€ข More binding of ๐˜ฅ๐˜ฆ๐˜ฑ๐˜ฐ๐˜ด๐˜ช๐˜ต๐˜ด.


   โ€ข Corneal dystrophies. 

   โ€ข Dry eye syndrome.

   โ€ข Oedema.

   โ€ข Neovasc.ularization.

ย  ย โ€ข Chronic dacryocystitis.

   โ€ข Chronic blepharitis.

   โ€ข Chronic conjunctivitis.

   โ€ข Recurrent diseases like episcleritis, scleritis and iridocyclitis. 

๐Ÿ‘๐™๐™ž๐™ฉ๐™ฉ๐™ž๐™ฃ๐™œ ๐™ค๐™› ๐™จ๐™ค๐™›๐™ฉ ๐™˜๐™ค๐™ฃ๐™ฉ๐™–๐™˜๐™ฉ ๐™ก๐™š๐™ฃ๐™จ

  Successful fitting involves complete set of parameters. The parameters are – 

โ—ฝ๏ธDiameter – It is the 3rd basic parameter of the soft contact lens. Typical soft contact lens diameters range from 13 to 14.5 mm. Smaller corneas may need smaller diameters. 

โ—ฝ๏ธBase curve – It is chosen on the basis of the keratometry. Base curves range from 8.1 to 9.1mm.

โ—ฝ๏ธPower – Lens should have selected as close as possible to the spectacle power. Before fitting we must have to know that the power is cylindrical or spherical. 

๐Ÿ‘๐™„๐™ฃ๐™จ๐™š๐™ง๐™ฉ๐™ž๐™ค๐™ฃ ๐™๐™š๐™˜๐™๐™ฃ๐™ž๐™ฆ๐™ช๐™š

ย  ย โ–ช๏ธPull up the upper lid and pull down the lower lid.โ–ช๏ธPlace lens directly on the cornea/ place lens looking upwards/ place lens looking inwards.ย 

๐Ÿ‘๐™๐™š๐™ข๐™ค๐™ซ๐™–๐™ก  ๐™๐™š๐™˜๐™๐™ฃ๐™ž๐™ฆ๐™ช๐™š

  ๐Ÿ”ธPull up the upper lid and pull down the lower lid.

ย ย ๐Ÿ”ธSlidely lens down and out onto the sclera.

๐Ÿ‘๐˜พ๐™ก๐™š๐™–๐™ฃ๐™ž๐™ฃ๐™œ ๐™–๐™ฃ๐™™ ๐™™๐™ž๐™จ๐™ž๐™ฃ๐™›๐™š๐™˜๐™ฉ๐™ž๐™ค๐™ฃ ๐™๐™š๐™˜๐™๐™ฃ๐™ž๐™ฆ๐™ช๐™š

   ๐Ÿ”น๐™ฒ๐š•๐šŽ๐šŠ๐š— – Clean the lens surface by rubbing two drops of surfactant cleaner. 

   ๐Ÿ”น๐š๐š’๐š—๐šœ๐šŽ – Ribse off the cleaning solution with saline.

   ๐Ÿ”น๐š‚๐š˜๐šŠ๐š”๐š’๐š—๐š ๐šŠ๐š—๐š ๐™ณ๐š’๐šœ๐š’๐š—๐š๐šŽ๐šŒ๐š๐šŠ๐š—๐š – in fresh solution overnight.

   ๐Ÿ”น๐š๐š’๐š—๐šœ๐šŽ –  rinse off with saline before insertion. 

๐Ÿšซ๐™‰๐™š๐™ซ๐™š๐™ง ๐™ช๐™จ๐™š ๐™ฌ๐™–๐™ฉ๐™š๐™ง ๐™›๐™ค๐™ง ๐™ง๐™ž๐™ฃ๐™จ๐™ž๐™ฃ๐™œ ๐™ค๐™›๐™› ๐™ฉ๐™๐™š ๐™จ๐™ค๐™›๐™ฉ ๐™˜๐™ค๐™ฃ๐™ฉ๐™–๐™˜๐™ฉ ๐™ก๐™š๐™ฃ๐™จ. 

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