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Presbyopia

a slide presentation on presbyopia for ophthalmology residents

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Presbyopia

  1. 1. p PRESBYOPIA
  2. 2. PRESBYOPIA • Physiological progressive age related loss of accomodation due to reduced amplitude leading to progressive fall in near vision. • 1.3 billion world wide. • Starts early in life. • Loss of functional vision :in 40’s. • Complete loss of accomodation in 50-60 years.
  3. 3. THEORIES OF ACCOMODATION HELMHOLTZ THEORY Ciliary muscle contraction->zonular relaxation-> anterior capsule of lens become more convex
  4. 4. IN PRESBYOPIA ciliary muscle contraction ceases posterior zonular fibres pull the ciliary muscle backward increased tension on the zonular fibres increase in lens diameter, decrease in lens thickness and a flattening of the anterior and posterior lens surface curvatures decrease in optical power
  5. 5. • SCHACHAR THEORY • Contrasts helmholtz theory
  6. 6. IN PRESBYOPIA growth of equatorial diameter of the lens with age ,the perilenticular space is reduced ciliary muscle contraction no longer tense the zonules and expand coronally • Based on this theory new sx for presbyopia scleral expansion bands was introduced.
  7. 7. CATENARY THEORY BY COLEMAN lens zonules and anterior vitreous comprises of a diaphram b/w AC and vitreous
  8. 8. IN PRESBYOPIA Increased lens volume with age results in a reduced response of anterior radius of curvature to the vitreous pressure gradient created by ciliary body contraction.
  9. 9. RISK FACTORS • Occupation :near vision demand • Geographic factors:proximity to equator • Gender :females earlier onset • Systemic illness :DM,MS,CVA • Drugs :CPZ,anti anxiety & antidepressants hydrochlorthiazide,alcohol. • RE :hyperope >emmetrope >myope. • Hyperopia :additional accomodative demand • Iatrogenic factors :laser photocoagulation,intra ocular sx
  10. 10. CAUSES FOR PREMATURE PRESBYOPIA • Uncorrected hypermetropia • Premature sclerosis of crystalline lens • Presenile weakness of ciliary muscle • Chronic simple glaucoma
  11. 11. ETIOLOGY 1. LENTICULAR CHANGES: Biomechanical changes • Decreased elasticity of capsule of lens material • Sclerosis-> anterior shifting of equatorial fibres. • Changes in angle of insertion of zonules. Physiological changes • increased size of lens. Biochemical changes • increased disulphide bond between capsule and lens material. 2.EXTRA LENTICULAR CHANGES: • NM changes • Ciliary muscle changes
  12. 12. PATHOGENESIS
  13. 13. • N/l young p/t-> lens can autofocus. • Emmetrope:far point-α Near point –increases with age. • 10 yrs – 7 cms • 20 yrs- 10 cms • 30 yrs-14 cms • 40 yrs- 20 cms • 50 yrs-40 cms • Amplitude of accomodation: • 10 yrs-14 D • 20 Yrs-10D • 30 Yrs-7D • 40 yrs-5D
  14. 14. • For comfortable vision • >40 cms:1/2 of accomodation is to be kept in reserve. • <40 cms:1/3 rd of accomodation is to be kept in reserve. • Usually near work becomes difficult when amplitude of accomodation is <5 D. AGE & PREDICTED NEAR ADD • 45 yrs - +1D • 50 Yrs-+1.50 D • 55 yrs-+2.00 D • 60 yrs-+2.25 D
  15. 15. CLASSIFICATION • Incipient presbyopia: • beginning stage • Difficulty in near vision during dim illumination bt n/l on bright illumination • Premature presbyopia: • occur at an earlier stage than expected for n/l population. • Causes:ocular d/s,uncorrected hyperope,c/c simple glaucoma General debility,presenile ciliary muscle weakness , Premature sclerosis of lens. • Manifest presbyopia: • presbyopia with some amplitude of accomodation. • Absolute presbyopia: • Amplitude of accomodation is completely absent
  16. 16. C/F • Difficulty in near vision initially in evening and dim light and latter even in good light • Asthenopic symptoms like headache d/t fatigue of ciliary muscles • Intermittent diplopia due to associated disturbances of convergence. Aggravated by fatigue/ illness/ fever / other c/c d/ses. SIGNS • Reduced amplitude of accomodation
  17. 17. TESTS FOR NEAR VISION • Addition based on amplitude of accommodation. • Tentative addition based on age. • Plus build-up method. • Bichrome method. • Cross-cylinder method. • Relative accommodation method. • Dynamic Retinoscopy method.
  18. 18. ADDITION BASED ON AMPLITUDE OF ACCOMMODATION • PRESBYOPIA • NPA exceeds 8 inches (22cm) (Donders). • amplitude of accommodation < 5D (Morgan). Working distance (WD) = 40cm RAF (Amp accommodation) = 2.00D What should be the near addition ??? • Accommodation required for WD = 2.50 D Accommodation in Reserve = 1.00D • Amount of accommodation left = 1.00D • Amount of Near addition = (2.50 –1.00) = 1.50D
  19. 19. Working distance (WD) = 25 cm RAF (Amp accommodation) = 1.50D What should be near addition ??? Accommodation needed at WD = 4.00D Amplitude held in reserve = 0.50D Amplitude of accommodation left = 1.00D Amount of near addition = (4.00-1.00) = 3.00D
  20. 20. TENTATIVE ADDITION BASED ON AGE Amplitude of accommodation to age (Hofstetter) ◦ Maximum = 25.0 – 0.4 (age) ◦ Probable = 18.5 – 0.3 (age) ◦ Minimum = 15.0 – 0.25 (age)
  21. 21. PLUS BUILD UP METHOD • The least amount of + lens which gives p/t a better vision at near detected. • BCVA kept b4 the p/t. • At 40 cms: 6/6 line / letter : target. • Ask if p/t sees clearly. • If blurry add + lenses increased in steps of 0.25D to the amount necessary to read the desired letters at a customary working distance.if better:add 1 more +,if same :back up 1 to get end point. • Can be done binocularly or monocularly . • Monocular build-up has amount of near addition higher than binocular.
  22. 22. BICHROME METHOD • Chromatic aberration • Patient with distant BCVA • Bichrome test at habitual distance in NV • Ask patient which background letters are more clear , Green-add plus, Red-remove plus until he/she sees letters equally clear in both. • In presbyopic patients red & green are focused behind the retina with red farther away. • Green appears clear. • Plus lenses are added until both red & green appear equally clear
  23. 23. CROSSED CYLINDER TECHNIQUE • A near point grid is diffusely illuminated & placed at p/t’s customary working distance .Plus lenses are added until lines seen clearly. • Crossed cylinder (±0.50D) with their minus axes vertical are placed before the patient’s eyes & asked to report which sets of lines running across or up & down appear clearer, sharper, blacker • artificial astigmatism with an interval of sturm of 1D created. • If accommodates exactly for the target, both sets of lines should be equally clear. • under-accommodation, the horizontal lines will b clear.Add positive lenses until lines are equally clear.◦ Can be done monocularly or binocularly
  24. 24. RELATIVE ACCOMODATION METHOD • Patient is provided with plus lenses determined by other methods.target @ 40 cms 6/6 line. • Determine :Plus lens to blur (NRA) : Minus lens to blur(PRA) • Near add = NRA+PRA/2 • THE NEAR ADD IS 1.00 (SAY) • ADD MINUS LENSES UNTIL BLUR (1- 0.5)= +0.50 D • ADD PLUS LENSES UNTIL BLUR (1+1) = +2.00 D • FINAL ADD IS (+0.50+2.0)/2= 1.25D
  25. 25. TREATMENT OPTIONS 1. Glasses and contact lenses. 2. Surgery ◦LASIK presbyopic hyperopia ◦ Multifocal intraocular lens (IOL) ◦ Conductive keratoplasty (monovision) ◦ Scleral expansion
  26. 26. MONOVISION • presbyopia therapy • Achieved through contact lenses or surgically at the corneal or lenticular plane. • Mild myopia –0.5 to –1.5D in non- dominant eye (avoid anisometropia no more than 2D diff between the eyes) • Need to be able to suppress blurred image • Only a mild decrease in distance, good stereo, very good intermediate vision. • C/I: • with high visual requirements for near or distance • .
  27. 27. GLASSES AND CONTACT LENSES • Converging or plus lenses for near work . • Change in prescriptions every two to three years.
  28. 28. SURGERY • Corneal procedures:CK, LASIK, intracorneal inlays. • Scleral procedures : Scleral Expansion Bands Laser Presbyopia Reversal (LAPR) • Intraocular implants
  29. 29. CONDUCTIVE KERATOPLASTY • Radio frequency energy is applied to mid peripheral corneal stroma via probe that heats up the collagen and causes it to shrink . • Induces up to 1.5 to 2.0D of central steepening & corneal flattening . • Non-dominant eye corrected for near(monovision). • Amt. of steepening α no. of spots & rings. • Advantages:Extraocular, Relatively inexpensive,Can be done with slit lamp ,And by non refractive surgeons . • Disadvantage:Limited to hyperopes or emmetropes ,Induce irregular astigmatism , Regression of effect, Corneal scaring
  30. 30. Corneal Inlays • Made of Biocompatible material placed in a pocket created with a microkeratome or intralase flap within cornea . • Designed for use in emmetropic or hypermetropic eyes • Aperture 1.6mm, outer rim 3.8mm . • Pin hole effect increases depth of focus & alter the way light rays enter the eye . • Micro pores for nutrients. • Advantages: a) Extraocular surgery b) Reversible c) Exchangeable • Eg: Kamra small aperture corneal inlay
  31. 31. • Flexivue Microlens • 3-mm in diameter,15 microns thick. • The lens is placed about 280 to 300 microns deep in the cornea of non-dominant eye through a pocket created using a femtosecond laser. • The specific vision-correcting prescription is incorporated in the outer area of the lens. • Advantage : 10 min procedure, pocket created self-seals & holds the lens in place.
  32. 32. EXCIMER LASER SURGERY • Monovision: • Dominant eye corrected for distance & Non Dominant eye for near. • Difficult to tolerate by most of the patients. Loss of Contrast and depth perception by the patients. Limited useful time. • Multifocal Cornea: • Excimer Laser reshapes the cornea and alters the way light rays enter the eye. Hence called as PRESBYLASIK. • Both eyes see near & distance. • Temporary solution , Repeatable and/or reversible
  33. 33. Monovision LASIK
  34. 34. SCLERAL EXPANSION PROCEDURE • Based on Schachar theory • increasing zonular tension by weakening or altering the sclera over the CB in order to allow for passive expansion • Small incisions in sclera close to cornea->4 silicon bands inserted to tent sclera between band and limbus ->Increases distance between ciliary muscle and lens equator ->enhancing ciliary muscle contraction • Inconsistent results.
  35. 35. • Advantage :Extraocular No adverse effects on quality of vision • Disadvantage:Surgical time-40 mins per eye Bloody surgery Modest gains in near vision Does Not Restore Accomodation
  36. 36. LASER ASSISTED PRESBYOPIA REVERSAL (LAPR) • Infrared Erbium:YAG delivered through a fibre contact tip • 4 fornix based peritomies ->Ablations applied in scleral tissue 0.5mm posterior to the limbus to 80% thickness ->Peritomy sites closed with bipolar forceps. • complications :Microperforations Conjunctival cysts Iris atrophy • Advantage :Extraocular procedure. Surgically easy No adverse effects on vision • Disadvantage:Variable benefit to near vision Regression Expensive laser
  37. 37. LENS BASED SURGERIES • Phakic IOL • Multifocal IOLs : refractive diffractive • Accommodating IOL • Pseudo accommodating IOL
  38. 38. PHAKIC INTRAOCULAR LENSES • Lenses inserted over the iris/under the iris without removing the natural Lens. • Advantage :reversibility
  39. 39. MULTIFOCAL IOL • Multiple zone IOLs placed after removal of lens. • Diffractive multifocal IOL : • Near & distant correction put in each concentric rings Using diffraction optics with the principle of wave optics. • Anterior surface - convex • Posterior surface -stepped with step h8 in the range of wave length of light. • Diffraction from these rings produces waves in phase & in 2 diffractive orders,discrete optical foci & equal intensity. • 82% light of which 41% 4 near n 41% 4 distance. • Disadvantage: • present more than one image to the retina at the same time -> reduction in contrast ,Abberrations ( glare n halos) .
  40. 40. Refractive IOL /bull’s eye IOL • 2 ZONE IOL’S • Central (2mm) near vision segment surrounded by a distant vision segment. • ANNULUS TYPE IOL’S • Central segment has a distant vision segment n near vision ring outside it in turn surrounded by distant segment. REZOOM TECHNIS RESTORE
  41. 41. Disadvantages of MIOL >1 image presented to the retina at the same time . • reduction in contrast • Abberrations ( glare and halos) • Pupil size may be an issue
  42. 42. ACCOMMODATING IOL’S • mimic a juvenile lens - changes in shape by anterior movement and dioptic power when the ciliary muscle contracts • Advantage :reduction in contrast sensitivity–n/l. :corrects near, intermediate and distance :Abberrations -nil • Mechanism • optic shift principle :Has hinges at the lens haptic juncture. :optic lie against vitreous face. :ciliary muscle contraction-> vitreous pressure &  aqueous pressure. : 1D power generated for 0.6 mm movement . • Dual optics : 2 lenses :↑ +ve a.lens & -ve p.lens . seperated by spring like haptics . :unaccomodated :2 lenses close 2 each other. :accomodation:a. shifting of +ve lens.
  43. 43. • Pre-operative exclusion criteria – Hypercritical patients – unrealistic expectations – night drivers, pilots – Unmotivated patients • Pre-operative inclusion criteria – No eye pathology – Excelent visual potential – Astigmatism <1.5D – Presbyopic hypermetropes • Pre operative evaluations •biometry • IOL Master • Immersion USG • multiple k readings • Multiple IOL formulas • Post operative considerations • Astigmatism • PCO - yag • Glare and halos - brimonidine • Neural adaptation - 6months
  44. 44. THANQ

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