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Hypermetropia
This document discusses hypermetropia (farsightedness), where parallel rays from infinity are focused behind the retina when the eye is at rest. There are several types of hypermetropia based on etiology, including axial (most common, due to short axial length), curvatural (flattened cornea or lens), and index (increased refractive index). Symptoms range from asymptomatic to asthenopia (eye strain) and defective vision. Treatment includes optical correction with glasses or contacts, as well as surgical options like refractive surgery or phakic IOL implantation. Proper visual hygiene from an early age can help prevent complications like amblyopia.
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Hypermetropia
- 1. 1 By , Ranjan KumarMahanta DOT Final Year
- 3. HYPERMETROPIA :- Itoptical condition of eye where parallel rays coming from infinity are focused behind the retina with the accommodation is at rest . Poserior focal point is situated behind the retina causing blurrred image .
- 4. ETIOLOGY OF HYPERMETROPIA 1)AXIALHYPERMETROPIA :- • Most common . • Total refractive power is normal . • Axial length less than 24 mm . • Physiological hypermetropia at birth :- +2.50 D to +3.00 D • Pathologically seen in orbital tumours , coloboma , micropthalmous etc . (Axial length increase 1mm > increase power +2.50 to +3.00 D ) 2)CURVATURAL HYPERMETROPIA :- Flattering of cornea ,lens or both :- • 1 mm increase in radius of curvature 6D HM . • Congenital form :- Cornea plana .
- 5. 3) INDEX HYPERMETROPIA:- • Increased refractive index of cortex or vitreous . • Pathologically seen in Diabetic patients . 4) POSITIONAL HYPERMETROPIA :- • Posterior placement of crystalline lens ,may be due to trauma or congenital . 5) APHAKIA ( Absence of lens ) :- • Congenital :- ill development . • Acquired :- Surgical removal of lens . - Traumatic dislocation of lens .
- 6. CLINICAL TYPES OFHYPERMETROPIA 1) SIMPLE HYPERMETROPIA:- • Commonest from , result from normal boilogical variation in the development of eye ball . --- AXIAL / CURVATURAL . 2) PATHOLOGICAL HYPERMETROPIA :- • Beyond biological variation . • Congenital :- Absence of lens . • Acquired :- Cortical Sclerosis . :- sed curvature of outer lens fibers in old age .
- 7. • Positional :-Posterior dislocation of lens . • Consecutive :- Surgical over correction of myopia . :- Wrong IOL during cataract surgery . 3) FUNCTIONAL HYPERMETROPIA :- • Result from paralysis of accommodation due to third nerve palsy and internal ophthalmoplegia .
- 8. OPTICAL CONDITION • Convervingpower increase by accommodation .
- 9. • Converging powerincrease by convex lens . SOME POINTS:- • Parallel rays focus behind the retina causing blurred & indistinct image . • Image smaller than emetropic eye . • Rays diverse from from retina . • If converging power of eye increased then formation of clear image is possible .
- 10. NOMENCLATURE(on the basisof accommodation factor ) /TH=LH+MH (FH+AH) 1) TOTAL HEPERMETROPIA :- • Total amount of hypermetropia estimated after complete cycloplegia with atropine . • Divide into latent & Manifest hypermetropia . 2) LATENT HYPERMETROPIA :- • Corrected by inherent tone of ciliary muscle . • Usually about 1D . • High in children & decrease with age . • Revealed after abolising tone of ciliary muscle with atropine .
- 11. 3) MAIFEST HYPERMETROPIA:- • Remaining part of total hypermetropia . • Corrected by accommodation & convex lens . • Measured by addition of strongest convex lens with maximum vision . • Consists of Facultative & Absolute (Obligatary) hypermetropia . 4) FACULTATIVE HYPERMETROPIA :- • Corrected by patient accommodative effort .
- 12. SS 5)ABSOLUTE HYPERMETROPIA :- •Residual part which is not corrected by patient accommodative effort . • Can be measured by the weakest convex lens causing maximum visual acuity . EXAMPLE :-Patient has vision – 6/9 -Addition of +5.00 D – 6/6 (AH) -Increase in power upto +2.50 D–6/6 (MH) (Further increase in power causes blurring of visoin) MH=AH+FH => FH=MH-AH= 2.50-0.50=+2.00 D Cyclo Atropine reveals amount of HM is +4.00D- 6/6(TH) TH=LH+MH LH=TH-MH=4.00-2.50=+1.50 D
- 13. NORMAL AGE VARIATION Atbirth +2.50 to +03.00D HM . Hypermetropia Slightly increases in one yr of life & then gradually diminished until by the age of 05 to 10 yrs . Accommodation power decreases . As age increases FH decreases & becomes absolute , thus at the age of 40 yrs (MH=AH) . Practically after 65yrs old of HM becomes absolute .
- 14. SYMPTOMS :- Very dependingupon age & degree of HM . A)ASYMPTOMATIC :- A small amount of HM corrected by accommodtion . B) SYMPTOMATIC:- a) Asthenopia b) Decective Vn with Asthenopia. c) Defective Vn only .
- 15. a) Asthenopia :-Asthenopic symptoms include. Tiredness of eyes , headche(T&F) , watering , mild photophobia . Vn Normal . Refactive error fully corrected by accommodative effort . Sustained accommodation produces symptoms . Asthenopic symptoms increases due to prolonged Nr work & as day progresses .
- 16. b)Defective Vn withAsthenopia:- Vn not corrected by accommodation . Defective Vn for Nr more than Dist . Asthenopia due to sustained accommodation. Refractive error more ( 04 .00D ). c) Defective Vn Only :- Refractive Power 04.00D . Adult usually don’t accommodate & marked defective Vn for Nr & Dist .
- 17. SIGNS:- o Va maybe normal or defective . Eye ball :- Small or normal in size . Cornea :- May be smaller than normal . - May be cornea plana . AC :- May be shallow . Lens:- May be dislcated backward . A-Scan:- Short axial ( 24 mm ) . Fundus :- Disc :- Dark raddish colour . :- Irregular margines . :-Pseudo Papillitis .
- 18. Blood Vessels:- Showundue tortuosity & abnormal balancing . Backgrounnd:- Short silk retina . COMPLICATION :- Recurrent stye , Chalazion , Blephititis . Accommodative convergent squint . Amblyopia incase of – --Uncorrected bilateral high hypropia . --Unilateral hypropia . --Squint .
- 19. Prone to developprimary narrow angle glaucoma . (Because of change in size of lens during increaseing age ) TREATMENT :- No treatment is required if Vn normal error is small . Asymptomatis . No muscular imbalance .
- 20. IN YOUNG CHILDRENS:- Correction recuired in Asthenopic symptoms , if cover test , convergence & fusional reserve is normal . In case of convergence insufficiency , inadequate fusional reserve , if small refractive error is present then no need to glasses . In case of convergent squint , full cycloplegic correction . Follow up after 6-8 months should be carried out & if necessary the correction should be reduced .
- 21. IN ADULTS :- Ifasthenopic symptoms are marked appropriate correction should be done to relieve the accommodation . In case of spasm of accommodation need full correction after cyclo refraction , but initially undrcorrection is adviced for patients tolerence. Patients with absolute hypermetropia accept nearly full correction . In pathological hypermetropia treat the underlying cause .
- 22. MADE OF TREATMENT:- A) Optical T/t :- -- Spectacles (Covex lens ) . -- Cntact lens . B)Surgical T/t :- I) Refractive Surgery :- i) HK (Hexagonal Keratotomy ) . ii) LTK (Laser Thermal Keratoplasty) iii) PRK (Photo Refractive Keratotomy ) iv) LASIK (Laser Assisted Insitu Keratomileusis ) II) Phakic IOL , Clear lens extraction with IOL implantation .
- 23. VISUAL HYGINE :- Toprevent visual disability due to hypropia , squint & amblyopia specially in children , early detection & appropriate treatment should be started . Constant use of glasses . Regular Eye check up . Maintain proper distance during near work & watching TV . Near work sufficient illumination . Proper exercise & break to relax eyes during prolonged near work .
- 24. Prepared by :Ranjan kumar Mahanta Final yaer