Comprehensive Overview of Presbyopia: Causes, Types, and Clinical Management

Comprehensive Overview of Presbyopia: Causes, Types, and Clinical Management

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  Presbyopia Deepa Chhetri B Optom4th batch,
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  Introduction ● Presbyopia (eyesightof old age) is not an error of refraction but a condition of physiological insufficiency of accommodation due to reduced amplitude, leading to a progressive fall in near vision. ● Begins between 40 and 45 years ● Complete loss of accommodation by 5th to 6 th decade.
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  Pathophysiology To understand thePathophysiology of presbyopia ,a working knowledge about accommodation is mandatory. ● Near point (punctumproximum):Nearest point at which small objects can be seen clearly. ● Far point (punctumremotum): Farthest point that can be seen clearly. ● Range of amplitude : Distance between the near point and far point ● Amplitude of accommodation (A):Difference between the dioptric power ,needed to focus at near point (P) and to focus at far point (R ).i.e A=P-R
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  Pathophysiology contd In emmetropiceye far point is infinity and near point varies with age. ● 7cm at the age of 10 years . ● 25cm at the age of 40 years. ● 33cm at the age of 45 years. ● At the age of 10 yrs ,amplitude of accommodation (A)=P-R .i.e100/7-1/infinity =14D
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  Pathophysiology contd ● Sincewe usually keep the book at about 25cm ,so we can read comfortably up to the age of 40 years. ● After 40 years the NPA decrease beyond normal working or reading range leading to presbyopia.
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  Causes of presbyopia ●Age related changes in the lens like decrease in the elasticity of lens capsule and progressive changes in size and hardness of lens. ● Age related decline in ciliary muscle power.
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  Causes of prematurepresbyopia. ● Uncorrected hypermetropia ● Premature sclerosis of the crystalline lens ● General lack of strength causing presenile weakness of ciliary muscle
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  Theories of presbyopia ●Helmholtz ● Schachar ● Catenary
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  Helmholtz theory ● Inpresbyopia ciliary muscle contraction ceases. ● Posterior zonular fibres pull the ciliary muscle backward. ● Increases 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.
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  Schachar’s Theory ● Accordingto this theory contraction of ciliary muscle increased equatorial zonular tension. ● Anterior and posterior zonules are simultaneously relaxed. ● Central surfaces of the lens steepen. ● Peripheral surfaces of the lens flatten.
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  Catenary Theory ● Proposedby coleman ● According to this theory, initially ciliary muscle contracts. ● Initiates pressure gradient between vitreous and aqueous compartments. ● Ant capsule and zonule form trampoline shape . ● Radius of curvature steepens on the center of the lens with slight flattening of the peripheral ant lens.
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  Types of presbyopia ●Incipient ● Functional ● Premature ● Nocturnal ● Manifest ● Absolute
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  Incipient presbyopia ● Borderline,beginning, early or pre-presbyopia ● Earliest stage when symptoms or difficulty are first encountered in near vision. ● More difficulty in dim illumination while can do well in bright illumination. ● Patient’s history suggests a need for a reading add, but pt. performs visually on testing and ,given the choice ,may prefer to remain uncorrected.
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  Functional presbyopia ● Whenfaced with gradually declining AA and continued near task demands, adult pts. eventually report visual difficulties ● The interaction between the pt.'s AA and the patient's near vision demands is critical. ● The age at which presbyopic becomes symptomatic varies. ● Due to variations in distance vision status , environment, task requirements, nutrition, or disease state.
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  Premature Presbyopia ● Presbyopiaoccuring at an earlier age than expected for normal population. ● Usually associated with ocular diseases, nutritional deficiencies or ingestion of certain drugs. ● Uncorrected hyperopia. ● Premature sclerosis of crystalline lens.
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  Nocturnal Presbyopia ● Nearvision difficulties result from an apparent decrease in the AA in dim light. ● Increased pupil size and decreased depth of field are usually responsible for this reduction in the range of clear near vision in dim light.
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  Manifest presbyopia Presbyopia withsome amplitude of accommodation present Absolute presbyopia Presbyopia with amplitude of accommodation completely absent
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  Clinical features ofpresbyopia
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  Symptoms ● Difficulty innear vision.  Patients start complaining of vision for small print and finer objects at the usual reading distance. So the patient begins to hold the head back and the book slightly at a greater distance.  Such problems occurs initially in the evening and dim light and later even in good light .  Finally, the near work becomes an impossibility. ● Asthenopic symptoms like headache due to fatigue of ciliary muscle. ● Intermittent diplopia due to associated disturbances of convergence.
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  Signs ● Reduced amplitudeof accomodation.
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  Methods of determiningnear add ● 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
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  ● Amplitude ofaccommodation decreases with age ● Presbyopia is reported when NPA exceeds 22cm i.e. AA=4.50D(Donders) ● Presbyopia exists when amplitude of accomodation is less than 5D( Morgan) ● Measured by push up method or the minus lens to blur method ● For older person, AA can be measured with the pt.’s addition ● The amount of the add is then subtracted from the result of the test ● Amount of new add. should permit a certain percentage (50%) of the AA to remain in reserve. 1)Tentative add based on amplitude of accomodation
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  Adjustment for workdistance ● Power of the presbyopic add should be adjusted taking into consideration the working distance required by a particular patient and the remaining amplitude. ● For example, in a patient in late 40s with only 3D total amplitude left, the following adds give varying work distance and leave comfortable (50%) amount of accommodation in reserve.  +2.5 D : 25cm  +1.5D : 33cm  +1.0D : 40cm  +0.5D : 50cm
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  Example Working distance (WD)=40cm AA=2.00D What should be the near addition? Accomodation required for WD=2.50D Accomodation in reserve =1.00D Amount of accomodation left=1.00D Amount of near addition=2.50-1.00D=1.50D
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  2) Tentative additionbased on age ● Amplitude of accomodation to age (Hofstetter)  Maximum =25.0 - 0.4(age)  Probable=18.5-0.3(age)  Minimum=15.0-0.25(age)  Amount of near add calculated by holding certain amount of accomodation in reserve. ● Rule of 4’s Amplitude =4*4-(Age/4)
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  3) Plus buildup method ● Works best when the corrected VA is normal at distance. ● Can be done binocularly or monocularly. ● Plus lenses are increased in steps of 0.25D to the amount necessary to first read the desired letters at a customary working distance. ● The power of add is then increased in 0.25D steps to the amount preferred by the pt. ● Monocular build-up usually lands in more amount of near addition since less accommodation is available because of a lack of convergence accommodation.
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  4) Bichrome method ●Based on natural chromatic aberration of eye ● Widely used for determining spherical component of distant correction ● When an ametropic eye is out of focus for distance,  red target is clear in myopia  green target in hyperopia ● The same principles apply at near distance ● For presbyopic pts. red & green are focused behind the retina with red farther away ● For Uncorrected or undercorrected presbyopic pt.  letters on green background clearer ● An overcorrection for a near target  the letters on red background clearer
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  Bichrome method • Pt.'sdistance correction is placed on a trial frame • Bichrome target is placed at habitual near distance (40cm) • Tell the pt. to look at letters on both Green and red background carefully • Ask the pt. which side has the sharper and clearer letters - Green clear: add plus in 0.25 step - red clear : remove plus - until pt. sees letters equally clear in both background
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  Demerits of Bichromemethod • With the older patients,  the crystalline lens becomes markedly yellow  blue green light being partially absorbed and scattered  gives a red bias to the test • Difficult in protanopic patient; since the red background will appear much dimmer than the green • Precaution : the subject is instructed to emphasize on clarity of letters and not the background
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  The cross cylindermethod ● Jacques, an optometrist, introduced the cross cylinder test for determining presbyopia and prescribing corrective lenses. ● The test uses a cross target with three heavy black lines on each limb, placed 40 cm in front of the patient. ● A cross cylinder (+0.50 D x180-0.50 x 90º) is introduced before each eye, and the patient reports clarity or blurring of the bars. ● If the patient can accommodate adequately, both bars fall equally relative to the retina; if presbyopic (cannot accommodate enough), the horizontal bar falls closer to the retina.
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  The cross cylindermethod ● Plus lenses are added until equal clarity or blurring is obtained for both bars, overcorrection will cause vertical bar to be clearer. ● The test assumes the patient suspends accommodation between the bars and is invalid if active accommodation occurs on one set of lines.
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  6) Relative accomodationmethod ● NRA: measure of maximum ability to relax accommodation while maintaining clear, single binocular vision of a test object at a specified distance ● PRA : measure of the maximum ability to accommodate while maintaining clear, single binocular vision of a target at a specified distance ● The difference between the NRA and the PRA is called the relative accommodative amplitude
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  Relative accomodation method ●Based on the concept of placing the accommodative demand in the middle of the range of relative accommodation ● To measure NRA and PRA,  pt.'s distance refraction and a tentative add is placed in the phoropter (Trial frame)  the near point test card is placed at the reading distance (usually 40 cm)
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  Relative accomodation method ●NRA is determined by adding plus power lenses binocularly until the pt. is no longer able to read the fine print on the test card ● PRA is determined by adding minus power lenses until the pt. is no longer able to read the fine print ● Near add = (NRA+PRA)/2
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  Example ● Suppose pt.can read fine print with +1.00D add ● Blurring occurs when add increased to +2.00D and reduced to +0.50D ● Range of clear vision is 1.50D (from +2.00D to +0.50D add) ● Final add is (+0.50+2.0)/2= +1.25D
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  7) Dynamic retinoscopy ●Determine lag of accommodation ● Reduce amount of lag by +0.50 to +0.75D ● Prescribe remaining as addition for near
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  Comparing methods ofdetermining addition in presbyopes ● All the techniques display similar behaviour and provide a tentative addition close to the final addition ● Among the methods used, the age-expected procedure is recommended, as this technique produce results that correlate best with the final add ● Likelihood of error is high and supports the idea that any tentative add has to be adjusted according to the particular needs of each pt.
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  An evaluation ofestimation methods for determining addition in presbyopes ● All the methods used display similar behavior and provide a tentative addition close to the final addition ● Every tentative addition should be adjusted according to the particular needs of the patient
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  Determination of finaladdition ● Customary near working distance ● Nature of the near work ● Physical nature of the patient ● Illumination level ● Status of the accommodation-convergence relationship ● Change in the amount of the addition
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  Treatment 1. Optical correctionof presbyopia ● Done by supplementing accommodation with convex lenses of appropriate power ,required for a clear and comfortable near vision. ● Difference between the distance correction and the strength needed for near vision is called the add. ● The values in the table are just rough estimates for Presbyopic addition. The actual values may differ according to patients nature of near work. Age Addition power 40 years +1.00D 43 years +1.25D 45 years +1.50D 48 years +1.75D 50 years +2.00D 55 years +2.25D to + 2.50D 60 years +2.50 D to +3.00D
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  Basic principle forpresbyopic correction ● Always find out refractive error for distance and first correct it. ● Find out the presbyopic correction needed in each eye separately and add it to the distance correction. ● The presbyopic add prescribed should leave about 50% of the accomodation in reserve. ● Near point should be fixed by taking due consideration for profession of the patient.
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  ● The weakestconvex lens with which an individual can see clearly and comfortably with both the eye ( binocularly) at the near point should be prescribed ,since overcorrection will also result in asthenopic symptoms. ● An additional correction for the intermediate distance may be required ,if it is necessary for the patient to see clearly at that length .Various focal (progressive ) lens are good option.
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  Modes of prescribingpresbyopic add 1. Spectacles ● Single vision reading glasses ● Bifocal glasses ● Trifocal glasses ● Multifocal or Varifocal glasses If patient has no significant distance refractive error, the best correction is single vision reading glasses of the proper strength . If patient has a significant refractive error , then two pairs of glasses are required or a bifocal or multifocal lenses may be prescribed.
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  Drawbacks of readingglasses ● Very annoying to switch between regular glasses and reading glasses, and also to put on and take off their reading glasses all day long. ● Reading glasses need to be carried everywhere , so may be forgotten or misplaced. ● Even those who are used to wearing glasses, do not like the segments of bifocal. ● The new no line progressive addition eye glasses look better, but still these are glasses and also cause distorted vision to left and right .Also ,these are expensive.
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  2. Contact lenses Bifocalcontact lenses are available in many soft and rigid gas permeable lense design. Both are available in multifocal ,monovision, and bifocal correction. ● Multifocal contact lenses, correct intermediate distance and also to treat astigmatism. ● Monovision, where one eye wears a near vision contact lens and the other eye wears a distance vision contact lens.
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  ● Modified monovision,a single vision lens is in one eye and a bifocal lens in the other eye or two bifocal lenses with different near vision power. ● Hybrid bifocal fit, one contact lens with distance zone in the center and the other with a near zone in the center, both lenses have an intermediate zone in the surrounding area .Useful for patient with strong presbyopia. Note One thing to remember is that presbyopia does progress overtime and so contact lens and glass prescription have to be increased with time.
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  3.Surgical treatment ofpresbyopia A . Corneal procedures a. Non ablative corneal procedures ○ Monovision conductive keratoplasty ○ Laser thermal keratoplasty b. Laser ablation corneal procedures ● Monovision hyperopic or myopic LASIK ● Presbyopic bifocal LASIK ● Presbyopic multifocal LASIK ● PRESBYOND Laser Blended Vision
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  . c. Cornealinlay ● Acufocus inlay ● Biovision ● Presbylens ● refractive annular and lenticule ● Multifocal refractive inlay ● Presbyopic allogenic refractive lenticule ● Raindrop near vision inlay d. Intracor treatment
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  B. Lens basedprocedures or intraocular refractive procedures ● RLE (refractive lens exchange) ● Monovision with IOLs ● PRLs(post chamber phakic refractive lens)
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  C. Sclera basedprocedures ● Ant ciliary sclerotomy with tissue barriers ● Scleral spacing procedure ● Sclera ablation with Erbium
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  Reference  ❤❤https://healthkura.com/presbyopia-near-addition/❤❤ , AK Khurana optics and theories of refraction,  AK Khurana comprehensive ophthalmology  http://www.oculist.net/downaton502/prof/ebook/duanes/pages/v1/v1c0 38.html#:~:text=one%20set%20of-,lines.,-One%20investigator11%20used %20an"lines."
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  Thank you😇