Investigations required for cataract evaluation

Pre-op evaluation for cataract

1. RELEVANT Investigations for cataract evaluation -DR.DHIVYA SHRI S

2. CATARACT Latin-waterfall Any opacity in the lens or its capsule is called cataract Cataract is the leading cause of vision loss. Most common surgery performed on an outpatient basis.

3. INDICATIONS Refractive Medical Therapeutic Cosmetic

4. PRE OP CHECK LIST

5. OTHER HISTORY Factors limiting patients ability to cooperate or lie comfortably on the operating room table:- Deafness Language barrier Dementia Claustrophobia Restless leg syndrome Head tremor Musculoskeletal disorder

6. VISUAL ACUITY Visual acuity should be determined both for distance and for near. . PSC :Greatly impaired near vision Nuclear cataract : myopic shift (patient experience second sight) nuclear sclerosis, diminution of near vision more than that for distance should alert us to the possibility of macular dysfunction Cortical cataract: Hyperopic shift

7. OCULAR EXAMINATION Head posture External eye posture: prominent eye brow, Enophthalmos : may affect surgical approach LIDS: Entropion ,Ectropion ,Eyelid closure abnormality : adversely effect post operative recovery,Acne rosacea : risk of endophthalmitis and should be treated before cataract surgery  CONJUCTIVA:Inflammation CORNEA: Assessment of corneal thickness is important ,Specular reflection –endothelial cell count and cell morphology  ANTERIOR CHAMBER- Shallow (intumescent of lens or forward displacement by posterior pathology) . Gonioscopy to rule out the angle abnormalities (synechia, neovascularization)

8. PUPIL- Reacting promptly to light-both direct and consensual , Presence of RAPD-Implies substantial additional pathology , Readily dilating with mydriatics LENS-Grading-planning size of incision & type of surgery . Nuclear cataract are harder and need more power with phaco . Black nuclear opacity-extremely dense-ECCE . Postr polar cataract-prevent posterior capsular dehiscence and subsequent vitreous disturbances- avoid HYDRODISSECTION

9. DUCT PATENCY ROPLAS- Regurgitation on pressure over the lacrimal sac ( ROPLAS ) Also, Tested by syringing aim - to exclude chronic dacryocystitis , a major risk factor for postoperative endophthalmitis. If either no block or both upper and lower canaliculi block taken for surgery

10. FUNDUS EXAMINATION  Retinal and optic nerve function must be assessed pre- op,Because if it is defective operation becomes valueless. ARMD,RETINAL DETACHMENT Can adversely affect visual outcome  In eyes with very dense opacity,when fundus cannot be seen 5 tests are of value 1.PROJECTION OF LIGHT 2 POINT LIGHT DISCRIMINATION 3.MADDOX ROD 4.ENTOPIC VIEW OF RETINA 5.USG B SCAN-r/o vitreous haemorrage,retinal detachment,intraocular tumour & posterior staphyloma.  Foveal ERG

11. INTRAOCULAR PRESSURE MEASUREMENT Using Schiotz tonometry /non contact air puff tonometry Can be raised due to swelling of lens in INCIPIENT STAGE/due to phacolytic glaucoma in which case extraction is indicated. pre- ex i s t i n g Primary glaucoma If glaucoma, medically controlled-lens extraction If NOT,perform a trabeculectomy followed by cataract extracion /combined procedure.

12. A-SCAN BIOMETRY To calculate lens power result in desired post operative refractive outcome Two parameters:  Keratometry  Axial length KERATOMETRY Determines the curvature of anterior corneal surface K1&K2 Readings obtained For planning incision site along steepest meridian To calculate IOL power

13. AXIAL LENGTH MEASUREMENT A scan ultrasonography:  Direct contact  Immersion method Optical coherence biometry: Utilize two coaxial partially coherent low energy laser beam  22-25 mm and mean refractive power -25.0 -+1.0 D.

14. IOL POWER CALCULATION Use SRK formula (Sanders, Retlaff & Kraff ) P = A – 2.5L – 0.9K P Lens implant power for emmetropia (D) L : Axial length (mm) K : Average keratometric reading (D) A : Constant specific to the lens implant to be used That A = 113 for AC lenses & 119 for PC lenses. many other formulas like HAIGIS,HOFFER,HOLLADAY etc are also used. SRK2 : If AL is < 20mm then A + 3.0 If AL is 20 - 20.99 mm then A + 2.0 If AL is 21 - 21.99mm then A + 1.0 If AL is 22 - 24.0mm then A If AL is > 24.5 then A - 0.50

15. B-SCAN T wo dimensional  B - scan  -tool for the detection of hidden posterior segment lesions.

16. BLOOD INVESTIGATIONS NORMAL-RBS,CBC,RFT,S,ELECTROLYTES SCREENING FOR VIRAL MARKERS APTT,PT INR-in patients with individual risk factors or planned for general aneasthesia ,  OTHER INVESTIGATIONS ECG CXR

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