Investigations required for cataract evaluation
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Pre-op evaluation for cataract
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Investigations required for cataract evaluation
- 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. HISTORY MEDICAL SURGICAL ALLERGY OCULAR . H/o of all systemicdiseases,curr entmedications patient is on Medications relevant to eye surgery(alpha blockers-floppy irissyndrome,Steriods- delayedhealing&a mp;amp;IoP, Antihypertensive- e;lectrolyteimbalance Metabolic cataracts . Previous surgeries Past ocular surgeries(glaucoma/ Cataract ) . Drug allergy to sulfonamides ,localanaestheticsand other antibiotics Ocular Symptoms Like Blurring OfVision,colouredHalos,diplopia,glare Duration And Progression H/O Of Previous Intraocular Disease H/O Previous Cataract Surgery H/O Intraocular Injuries
- 6. 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
- 7. 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
- 8. 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)
- 9. ■ 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
- 10. 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
- 11. 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
- 12. 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-existing Primary glaucoma ■ If glaucoma, medically controlled- lens extraction ■ If NOT,perform a trabeculectomy followed by cataract extracion/combined procedure.
- 13. 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
- 14. 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.
- 16. 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
- 17. B-SCAN ■ Two dimensional B-scan -tool for the detection of hidden posterior segment lesions.
- 18. 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
- 19. THANK YOU