By pd aphakia & pseudophakia

1. PSEUDOPHAKIA APHAKIA Presenter: Pushkar Dhir Moderator:- DR.O.P .Gupta

2. ???APHAKIA??? Absence of crystalline lens from patellar foss

3. APHAKIA CAUSES Congenital Traumatic Absorption of Lens Posterior Dislocation in vitreous Surgical Removal

4. OPTICS OF APHAKIA CHANGES IN CARDINAL DATA Eye becomes highly HM(Far- Sightedness) Power reduces from +60 to +44d Anterior focal point becomes 23.2 mm in front of cornea Posterior focal 31 mm behind the cornea Two principle points are almost on anterior surface of cornea Nodal points are nearer and 7.2mm behind cornea

5. CLINICAL SYMPTOMS SYMPTOM Defective vision for both far and near . Erythropsia and cynopsia i.e., seeing red and blue Images due to excessive entry of ultraviolet and infrared rays in the absence of crystalline lens. SIGNS Limbal scar - Surgical Aphakia . Anterior chamber is deeper than normal. Iridodonesis . Jet black pupil. Purkinje image test: 3 rd and 4 th images are absent. Fundus examination: small hypermetropic disc. Retinoscopy shows high HM.

6. IMAGE FORMATION Image size depends on axial length and keratometry reading Vary from 20 to 50% Average 30 % ACCOMODATION IN APHAKIA Total loss of accommodation Glasses for near and distance are required BINOCULAR VISION Aneisokonia of 5% is compatible with binocular vision In aphakia aneisokonia is detrimental to development of normal binocular vision

7. TREATMENT

8. SPECTACLES Most common method of correction +10D is used Near vision-+3 -+4 D correction needed Advantage- Cheap Easy to use Safe method of correction

9. DISADVANTAGES 1)IMAGE MAGNIFICATION 1D of convex power leads to about 3 % magnification of image;thus 10 dioptre =30% Difference of image size between the two eyes of about 7 % is tolerable beside that give rise to diplopia i.e., two images of one object are seen one small (from normal eye) and other larger (from aphakic eye). Not useful in unilateral aphakics Objects appear larger they appear falsely closer than reality, and this leads to physical in-coordination.

10. Roving Ring Scotoma

11. Edge of a convex lens acts as a prism higher the power of the convex lens the greater is the prism angle (alpha). Light falling on the prism bends towards its base by an angle alpha/2 . Aphakic spectacles, the angle alpha being large, the light falling at the edge of the lens bends towards the center of the lens (base of prism) And does not reach the pupil and is, therefore, not seen. Resulting in an area of the visual field which is not visible to the patient, or scotoma . And because the edge of the lens is present all around the lens like a ring, so it gives rise to a ring shaped scotoma . Position of this scotoma is not fixed in the visual field because the eye keeps moving (or roving) in relation to the aphakic spectacle.

12. Jack-in-the-box Phenomenon

13. PIN CUSHION AFFECT Magnification of image is more at the periphery of the lens due to prism Effect,objects appear stretched out(large , nearer,elongated in radial. Direction) at the corners like a pin-cushion. Moving objects appear to be faster Straight lines become curves

14. Spherical Aberrations Light converges more near the edge of the lens than at the center. Rays of light falling near the edge are brought to focus in front of the rays falling at the center. Results poor quality of image despite appropriate correction of refractive error Chromatic Aberrations The shorter the wave-length the more is the refraction a ray of light undergoes. VIBGYOR the violet end undergoes greater refraction than the red. This causes diffraction of light and makes the edges of white object appear rain-bow colored.

15. 4)RESTRICTED VISUAL FIELD 50% all around Both monocular and binocular 5)COLOUR VISION PT may complain of colored hue Due to -absence of natural filter of crystalline lens 6)COSMETIC BLEMISH Eyes appear larger Seen more in young aphakics 7)THICK AND HEAVY GLASSES

16. 2)CONTACT LENS ADVANTAGES Less magnification of image No chromatic aberrations No prismatic affect Wider field of vision Cosmetically acceptable Better for uniocular aphakics DISADVANTAGES More cost Cumbersome to wear-both for young and old age Corneal complications may be associated

17. INTRAOCULAR LENS IMPLANTATION Secondary Iols - In Sulcus ACIOL Iris Claw SFIOL

18. REFRACTIVE CORNEAL SURGERIES Keratophakia Epikeratophakia Hyperopic LASIK

19. PSEUDOPHAKIA

20. Types of IOLs Anterior chamber IOL Iris-supported lenses Posterior chamber lenses Scleral Fixated IOLS

21. CALCULATION OF IOL POWER Most common method is SRK( Sanders Retzlaff and Kraff ) by regression formula P=A-0.9k-2.5L P=power of IOL A=constant L=axial length of eyeball

22. A1(new const.) Axial lenth of eye A1 3 <20mm A1 2 20 to <21mm A1 1 21 to <22mm A 22 to 24.5 mm A-0.5 >24.5mm For long eyeball some adjustment is made in the formula by taking new constant A1

23. OTHER FORMULAS WHICH ARE USED Hoffer Q SRK-T Holladay

24. REFRACTIVE STATUS OF PSEUDOPHAKIC EYE

25. EMMETROPIA It is produced when the power of the IOL implanted is exact. It is the most ideal situation. Such patients require plus glasses for near vision Yes!!! Got it

26. CONSECUTIVE MYOPIA

27. CONSECUTIVE HYPERMETROPIA

28. ASTIGMATISM

29. SIGNS OF PSEUDOPHAKIA Surgical limbal scars may be seen. Anterior chamber is slightly deeper than normal. Mild iridodonesis of iris may be demonstrated. Purkinje image test shows four images.

30. Pupil is black in colour but, when light is thrown in pupillary area, shining reflexes are absorbed . When examined under magnification after dilating the pupil , the presence of IOL is conformed. Visual status and refraction will vary, depending upon the power of IOL implanted.

31. References Gullstrand’s schematic eye: to listing reduced eye - Google Search Volume 1, Chapter 33. The Human Eye as an Optical System Epikeratophakia - Google Search Chapter 38 – Optics of Aphakia and Pseudophakia | Free Medical Textbook jack_in_box.pdf

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